GPB Multiphase Meter Tests 1

CONFIDENTIAL

Fi el d ev ev al uat i on of mul t i ph phas ase e fl ow m et er s f or hi gh gas gas fractt i on w el l t est frac metering

R e p o r t N o : S / E P T / 0 4 7/ 7/ 0 3

Andrew Hall Pipeline Transportation Team

Exploration & Production Technology Group January 2004

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Copyright © BP Explora Exploration tion Limited 2004 All All rights reserved. None None of the contents shall be disclosed, except to those those directly concerned with the the subject and no part of this document may be reproduced or transmitted in any way or stored in in any retrieval systemwithout prior prior written ritten permission of general management, BP Explo Explora ration tion Limited. Limited.

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Exploration & Production Technology Group

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EPTG Indexing Sheet BRANCH

REPORT NO. S / E P

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AUTHOR(S) Dr Andrew Hall

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TELEPHONE 01224 833507

JOB NO. 8 4 4

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LOCATION Aberdeen 1H-54

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DATE January 2004

MAIN TITLE Field evaluation of multiphase flow meters for high gas fraction well test metering

SUB TITLE

CLIENT Greater Prudhoe Bay

PRINCIPAL RECIPIENT Bruce Smith

COMMISSIONED BY Bruce Smith

PLEASE TICK UNCLASSIFIED

SECURITY CLASSIFICATION TQA COMPLETED

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KEYWORDS

ACKNOWLEDGEMENT PAGE

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FOR EXTERNAL CLIENT LISTING

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ABSTRACT

PREPARED BY:

APPROVED BY:

AUTHORISED FOR ISSUE BY:

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ISSUE DATE: January 26 26th, 2004


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DISTRIBUTION LIST

NAME

COMPANY

LOCATION

BDM/EPTG Library Mohammed Al-Nakhi Jerry Brady Victor Castro Castro Dave Christensen Sidsel Corneliussen Andrew Hall Hall Brant Hasebe Andrew Humphrey Humphrey Roger Leach Christopher Lindsey-Curran Girish Murarka Steven Petty Bill Priddy Jimmy Raper Bruce Smith Terri Tyssen Dennis Vavra Bob Webb

BP EPT BP BPXA BP Colombia BP GUPCO BP Norway BP EPT BPXA BP Angola Block Block 18 BP GOM DWP BP EPT BP EPT BP EPT BP EPT BP EPT BPXA BP GOM DWP BP EPT BP GOM DWP

Sunbury Abu Dhabi Anchorage Bogotá Cairo Stavanger Aberdeen Anchorage Leatherhead Leatherhead Houston Houston Houston Houston Sunbury Houston Anchorage Houston Houston Houston

Parviz Mehdizadeh

Production Technology

Phoenix

Harry Cellos Gordon Stobie

ConocoPhillips ConocoPhi llips ConocoPhillips ConocoPhillips

Anchorage Houston

Leonard Meaux Mike Mullally

ExxonMobil ExxonMobil

Houston Houston

Gary Fra Fransen (Section 9 only)

Agar Corporation Corporation

Houston

John Gre Greene ene (Section 10 only)

FMC

Houston

Alex V era (Section 11 only)

Roxar Flow Measurement

Houston

Bob Staa Staats ts (Section 12 only)

Schlumberger Oilfield Services

Prudhoe Bay

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GLOSSARY Agar AOGCC ASRC CMR DOR EPTG ESP FMC GOR GPB GVF MFM MI NEL NS O&M PSV Roxar SLB WLR

Agar Corporation Corporation Alaska Oil Oil and Gas Conservation Commission The Arctic Arctic Slope Regional Regional Corporation Corporation (ASRC Energy Services) Services) Christian Michelsen Research Institute (Bergen, Norway) Department of Revenue (Alaska) BP Exploration Exploratio n & Production Technology Group Electric Submersible Pump FMC Energy Systems Gas/Oil Ratio (Gas volume relative to oil volume, at standard conditions) Greater Prudhoe Bay Gas volume fraction (Gas volume % of total flow, at line conditions) Multiphase flow meter Miscible injectant National Engineering Laboratory (Glasgow, UK) North Slope Operations and Maintenance Pressure Safety Valve Roxar Flow Measurement Schlumberger Water in liquid ratio (= water cut at line conditions)

CONTACTS FOR MULTIPHASE FLOW METER PROJECT TEAM Jerry Brady Andrew Hall Brant Hasebe Parviz Mehdizadeh Bruce Smith

BP Exploration Alaska BP EPTG BP Exploration Alaska Production Technology Inc BP Exploration Alaska

[email protected] [email protected] [email protected] [email protected] [email protected]

+1 (907) 564 5291 +44 (1224) 833507 +1 (907) 564 4333 +1 (480) 661 7512 +1 (907) 564 5093

WEBSITES FOR MULTIPHASE FLOW METER VENDORS

Agar FMC Roxar Schlumberger

www.agarcorp.com www.fmcflowmeasurementsolutions.com www.fmcflowmea surementsolutions.com www.roxar.com www.framoeng.no


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1

CONTENTS

1

CONTENTS................................................................................................................................................7

2

EXECUTIVE SUMMARY .........................................................................................................................9

3

INTRODUCTION................................................................................................................................... 11

3.1 3.2 3.3 3.4 4

Background ...................................................................................................................... 11 Benefits ............................................................................................................................ 12 Trial specifics ................................................................................................................... 13 Multiphase metering qualification test.......................................................................... 13

MULTIPHASE FLOWMETERS........................................................................................................... 15

4.1 4.2 5

Summary of multiphase flow meter operating principles ............................................ 15 Descriptions of the multiphase flow meters .................................................................. 16

TEST INSTALLATION ......................................................................................................................... 21

5.1 5.2 5.3 5.4 5.5 5.6 5.7 6

Location and installation of meters................................................................................ 21 Reference system (ASRC test separator) ....................................................................... 24 Fluid property data ......................................................................................................... 25 Calibration of the multiphase flow meters .................................................................... 25 Data recording and processing ....................................................................................... 25 Data reprocessing ............................................................................................................ 27 Meter breakdowns ........................................................................................................... 28

TEST RESULTS ..................................................................................................................................... 31

6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 7

Meter results.................................................................................................................... 31 Definition of errors .......................................................................................................... 31 Summary statistics – all data......................................................................................... 32 Summary statistics – data in restricted operating e nvelope........................................ 33 Comparison with vendor specifications ......................................................................... 34 Summary of repeatability results................................................................................... 43 Comparison of the results from the four meters ........................................................... 45 Meter sizing analysis....................................................................................................... 53

CONFIDENCE IN TEST DATA........................................................................................................... 55

7.1 7.2 7.3 7.4 8

Tank tests......................................................................................................................... 55 Statistical analysis of reference data ............................................................................. 58 Comparison with laboratory test data ........................................................................... 58 Comparison with laboratory test data (repeatability) .................................................. 79

MULTIPHASE METER EVALUATION ............................................................................................. 81

8.1 8.2 8.3 8.4 8.5 9

Operating area................................................................................................................. 81 Three phase metering evaluation criteria ..................................................................... 85 Weighting of the multiphase metering evaluation criteria .......................................... 88 Scoring and ranking of multiphase meters.................................................................... 89 Meter liquid rate measurement at low l iquid rates ...................................................... 94

AGAR-401 MULTIPHASE FLOW METER .......... ........... ........... ........... ........... ........... ........... ........... . 97

9.1 9.2 9.3 9.4 10

10.1 10.2

Description of the meter.................................................................................................. 97 Summary statistics.......................................................................................................... 98 Test results (measurement accuracy) .......................................................................... 100 Test results (repeatability) ........................................................................................... 114 FMC FLOWSYS MULTIPHASE FLOW METER........................................................................ 117

Description of the meter................................................................................................ 117 Summary statistics........................................................................................................ 118


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10.3 10.4 11

Test results (measurement accuracy) .......................................................................... 119 Test results (repeatability) ........................................................................................... 133 ROXAR MPFM 1900VI MULTIPHASE FLOW METER ............................................................ 137

11.1 11.2 11.3 11.4 12

Description of the meter................................................................................................ 137 Summary statistics........................................................................................................ 138 Test results (measurement accuracy) .......................................................................... 139 Test results (repeatability) ........................................................................................... 153 SCHLUMBERGER VX29 MULTIPHASE FLOW METER........................................................ 157

12.1 12.2 12.3 12.4 12.5 12.6 12.7

Description of the meter................................................................................................ 157 Summary statistics........................................................................................................ 158 Test results (measurement accuracy) .......................................................................... 160 Test results (repeatability) ........................................................................................... 173 Test results after reprocessing with correct well profile data (accuracy).................. 176 Test results after reprocessing with correct well profile data (repeatability) ........... 189 Comparison of raw and reprocessed data .................................................................... 192

13

REFERENCE DATA QUALITY..................................................................................................... 201

14

PROJECT DOCUMENTATION..................................................................................................... 227

14.1 14.2 14.3 14.4 14.5 15

Calibration procedures – phase 1 ................................................................................. 227 Roxar installation and start up procedures................................................................. 229 Vendor requirements: Agar MPFM-401 ...................................................................... 230 Vendor requirements: FMC Flowsys............................................................................ 233 Vendor requirements: Schlumberger ........................................................................... 239 PROJECT CONSULTANT’S DAILY REPORTS ........................................................................ 243

15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 15.9 15.10 15.11 15.12 15.13 15.14 16

16.1 16.2

August 31st, 2003 ........................................................................................................... 243 September 1st, 2003 ....................................................................................................... 244 September 3rd, 2003....................................................................................................... 245 September 4th, 2003....................................................................................................... 246 September 7th, 2003....................................................................................................... 247 September 11th, 2003..................................................................................................... 248 September 15th, 2003..................................................................................................... 250 September 16th, 2003..................................................................................................... 252 September 18th, 2003..................................................................................................... 253 September 21st, 2003 ..................................................................................................... 254 September 23rd, 2003 ................................................................................................... 255 September 25th, 2003..................................................................................................... 256 September 28th, 2003..................................................................................................... 257 September 30th, 2003..................................................................................................... 258

FIGURES AND TABLES ................................................................................................................ 259

List of figures ................................................................................................................. 259 List of tables................................................................................................................... 264

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2

EXECUTIVE SUMMARY

Alaska North Slope operations has considered the deployment of multiphase flow meters (MFM) for a number of years, but has essentially been waiting for improvements in the ability of the technology to provide trouble-free, accurate measurements. Given the recent improvements in MFM and the potential economic and reservoir management gains with the use of MFM, North Slope operations has conducted a simultaneous test of four MFM. These four meters use a wide range of measurement techniques and strategies, which increased the probability of finding meters that would qualify for measuring the production from various fields. The four meters tested included Agar MPFM-401, FMC Flowsys, Roxar MPFM1900 VI and Schlumberger PhaseWatcher (VX29). A brief description of the measuring principles is included in the table below: Meter Agar MPFM 401 FMC Flowsys Roxar (MPFM 1900VI) Schlumberger PhaseWatcher Vx 29

Volume flow Positive displacement and Venturi Device Cross correlation and Extended Venturi Venturi Device and cross correlation Venturi Device

Gas fraction Venturi Device Venturi Device Gamma densitometer (137Cs 662 keV) Gamma densitometer (133Ba 80 keV)

Water cut Microwave (GHz) Electrical impedance (MHz) Electrical impedance (MHz) Gamma densitometer (133Ba 29 keV)

The North Slope provides numerous obstacles to the successful application of MFM. These obstacles include varying crude quality from three different horizons; water and miscible injectant breakthrough; high gas-volume fractions (85%-99% GVF); and a wide range of water cuts (0-100% WC). Monitoring is further complicated by the fact that a high percentage of the wells are on artificial lift either with gas lift or with jet pumps powered by water. In either case, artificial lift greatly increases the GVF or water cut of the liquid stream measured at the surface. Four applications for these meters have been identified. They include individual well deployment (usually for new developments), supplementation of current well test separators; a mobile test unit; and replacement of existing test separators. The results of the tests show that all four meters qualify in specific or limited operating areas. At least one metering system has been identified that is suitable for each class of application. In general, the higher GVF applications are much more problematic for the meters and result in a significantly higher measurement error. Wells with high gas lift rates or in the Gravity Drainage (GD) portion of the field fall into the high GVF flow regime. New developments or fields employing jet pumps or electrical submersible pumps (ESP) are potentially good candidates for the MFM technologies evaluated in this project.


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3

INTRODUCTION

3.1

Background

Multiphase testing, or the ability to measure multiphase flow accurately without requiring separation, has been the goal of a number of metering companies and operators alike for a number of years. The technology continues to improve, and BP has experience with a number of meters in both operated and non-operated fields, including Egypt (Gupco), Abu Dhabi, Columbia, Venezuela and the North Sea. A significant number of meters worldwide are also installed in subsea applications, where conventional test separation with a vessel of significant size is not practical. Long test pipelines in subsea fields require large capital investment and long stabilisation times for well testing. North Slope operations has considered the employment of multiphase flow meters for a number of years, but has essentially been waiting for improvements in the ability of the technology to provide trouble-free, accurate measurements. Previous BP experiences with earlier versions of multiphase flow meters include issues with constant re-calibration, mechanical breakdown, “black box” data output, and measurement inaccuracies at high GVF. BP now feels the technology is mature enough to warrant serious consideration for North Slope operations. Internal experts with EPTG were contacted to ensure Alaska was not operating in isolation, and to provide critical oversight and data analysis for this field trial. It should also be noted that various state agencies (AOGCC, DOR, etc.) have also shown an interest in multiphase metering and the potential implication on North Slope operations and allocations. BP has kept an open channel of communication to the noted agencies and facilitated a trip to Prudhoe Bay for representatives to witness part of the field trial. Prior to any wide scale use of multiphase metering technologies, as a prudent operator it is imperative that BP has hands-on, intimate knowledge of what is available in the marketplace. It is entirely plausible that the technology chosen for single well application is different from that most suited to a portable test unit or used to replace or augment existing traditional well pad separators. BP needed first hand knowledge of the various meters in order to make the most educated decisions. In addition, due to the benefits of multiphase metering, it is highly likely that companies such as ASRC and Schlumberger will offer multiphase metering as a lower cost alternative to traditional portable separators. Nearly every decision made in the oilfield, from well work to drilling, reservoir management to facility de-bottlenecking and optimisation, extends in some fashion from well test data. It is important for BP to understand what technology is being offered from various vendors, along with its limitations and advantages.


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3.2

Benefits

The rapid advancement of multiphase metering technology over the past several years is testimony to the significance of the benefits envisioned by the entire industry. The competitive vendors are marketing MFMs at reasonable prices, opening the potential to put a MFM on every well of a pad, new developments, or existing field. This would provide the ability to make much faster, better-informed decisions and well interventions. From a capital and operating expense perspective, this also has potentially significant impacts upon new developments. A MFM installed on the production flowline of every well would eliminate the need for a traditional test vessel, reducing the footprint of the pad and fire and gas suppression requirements, eliminating a separate test header and the associated divert valves, and reducing the necessary automation and safety systems. Many MFMs also claim considerable tolerance to emulsion, which has the potential to reduce the dependence and cost associated with emulsion breaker. The potential development of I-Pad as part of the Orion development is an imminent opportunity for BP Alaska and its partners to capitalize on this technology, and was one of the principle drivers for initiating this field trial. In order to make a decision impacting tens of millions of dollars of capital investment, understanding the various aspects of the existing products and technology is critical. This also extends to the impact of MFMs on O&M, which is also necessary to make the wisest decision spanning the life of a development. MFMs also have the potential to augment or replace traditional pad separators that are consistently troublesome. In Alaska, GPB has a number of pad separators which for a variety of reasons are yielding inconsistent and questionable results. A proven MFM that could handle the necessary range of water cuts, GVFs, and flowrates would prove extremely useful in augmentation of the existing separators. Ultimately this could reduce operator dependence on portable testing units which are currently employed for compliance testing, in addition to more frequent and timely information on well production. The fundamental difference between testing with a vessel as opposed to a MFM should also be noted – the fluid is measured instantaneously as it is produced from the well – therefore there is no dependency on separator liquid level, weir height, or solids build-up. Additionally there is less confusion created by well slugging. When additional compliance testing is required, there also exists another potential application of this technology – portable well testing. It is perhaps in this arena that this technology will be most quickly and readily applied, providing both vendors and BP the most immediate benefits. Elimination of the vessel traditionally employed for test separation means a more mobile operation and no purge time, reducing total test time and rig-up and rig-down time, enabling increased testing frequency at a give day rate. Elimination of the vessel also reduces HSE exposure by eliminating overpressure potential at a weak point in the system, required vessel clean-outs, chemical usage, etc.

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3.3

Trial specifics

The current trial involved four vendors: Agar, FMC, Roxar and Schlumberger. Each of the vendors provides a different approach to multiphase metering, and inclusion of all four in such a direct comparison is an event of some significance for both the vendors and BP worldwide. As mentioned previously, EPTG were included to ensure adequate and comprehensive communication of the test results and conclusions to other BP assets. Together the four vendors represent the major players in the MPM arena as well as a wide range of the available technology. Schlumberger and Roxar employ radioactive sources to identify the different phases and quantities of oil, water and gas, whilst Agar and FMC employ methods based on electrical signal analysis. All testing was done through the various MFMs in series, allowing for direct, real-time comparison, and then benchmarked through the ASRC portable test unit. The trial took place at V-Pad, utilizing the common test header to maximise efficiency, as well as providing the opportunity to test wells producing out of all three Prudhoe reservoirs – the Ivishak, Kuparuk, and Schrader. The tests also involved calibration and verification of the ASRC separator with nine tank tests, with at least one tank test per reservoir. In addition to the EPTG consultant, a third party consultant, Parviz Mehdizadeh of Production Technology Inc. was hired to oversee the entire test on behalf of BP. 3.4

Multiphase metering qualification test

3.4.1

Scope

• • • •

3 .4 .2 • • •

Evaluate the safety and environmental acceptability of operating multiphase metering systems. Qualify one or more multiphase meters for operation at Prudhoe Bay with operating ranges clearly identified. Utilize gas lift and jet pump water rates as necessary to test the meters over a broad range of gas volume fraction (GVF) and water cut. Evaluate multiphase meters for four potential applications: Individual well deployment (likely for new developments) o o Supplementation of current pad test separators o Replacement of existing pad test separators A mobile compliance test unit. o O p er a t i o n a l D e t a i l s

All tests were performed at V-Pad via the common test header Tests were performed on Ivishak, Kuparuk, and Schrader Bluff fluids Four different multiphase flow meters were rigged up in series Schlumberger o o FMC o Roxar o Agar


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• •

•

•

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•

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3.4.3 •

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All multiphase flow meters were isolated from the production facility for data acquisition and power. Each unit was essentially self-contained. Safety systems included pressure safety valves (PSV) upstream and downstream of the metering skid to account for a spec break from ANSI 1500 to ANSI 600 (#700 psi MAWP) at the Agar meter. The test skid was fabricated with 2” 1502 chicksan. VECO Wells Support fabricated the test skid, spill containment, weather protection tents, and angle-iron mounting stands for the Roxar and FMC meters. ASRC provided on-site supervision 24 hours a day, site-specific safety reviews (in coordination with North Slope Safety Personnel), and personnel sign-in sheets for the duration of the project. ASRC also provided a footprint design of the pad and project equipment, two 500 bbl exploration tanks for the open tank tests, and the lab containing the vendor data acquisition systems (industrial computers). All multiphase flow meters reported raw, line-condition data in a consistent format. BP then applied the correct (formation specific) shrinkage correlation to each data point, providing for a direct comparison of meter performance at stock-tank conditions without any inconsistencies resulting from minor variations in temperature and pressure between meters. Each meter company provided at least one technical expert available throughout the test to ensure the proper operation of their meter and to perform any required meter maintenance. Vendors were allowed whatever initial calibration they required: PVT analysis, flow rate tests, open-cavity tests, in-situ analysis, etc. After the initial round of calibration they were required to leave location, so as to avoid constant recalibration of meter parameters. Any calibrations to the meters required notification and documentation of the changes made. Each vendor provided shutdown and startup (including calibration) documentation, and also signed documentation attesting to the validity of the test set-up prior to the start of the trial. Evaluation

All multiphase flow meters were evaluated against the ASRC portable test separator. Nine open tank shrinkage tests were performed to verify test separator liquid readings, at least one per reservoir. Each vendor was allowed to audit the ASRC separator for details on operation and equipment, and each signed an agreement that ASRC would serve as the test benchmark. Each meter was evaluated for each potential application in the context of Initial Installation, Performance, and Operability. Evaluation of the meters was performed primarily by: o EPTG o BP Anchorage staff o BP North Slope operations Test data complemented an ongoing test of the Roxar meter at Conoco Phillips Kuparuk Unit. Data points were also compared to NEL data from previous meter testing.

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4

MULTIPHASE FLOWMETERS

4.1

Summary of multiphase flow meter operating principles

Meter Agar 401 FMC Flowsys Roxar (MPFM 1900VI) Schlumberger PhaseWatcher Vx 29

Volume flow Positive displacement meter Cross correlation

Gas fraction Venturi

Venturi meter or cross correlation Venturi meter

Gamma densitometer (137Cs 662 keV) Gamma densitometer (133Ba 80 keV)

Venturi

Water cut Microwave (GHz) Electrical impedance (MHz) Electrical impedance (MHz) Gamma densitometer (133Ba 29 keV)

Multiphase flow meter technology (volume flow measurement)

Positive displacement meter (Agar) – specially adapted for use in multiphase flow, the positive displacement meter records the total volumetric flowrate of gas + liquid. Cross-correlation (Flowsys, Roxar) – cross-correlation of high resolution time signals from pairs of electrodes can be used to calculate a characteristic velocity of the multiphase mixture. Venturi (Roxar, Schlumberger) – the differential pressure across the Venturi, corrected for gas fraction, can be used to determine the total mass flowrate of the multiphase mixture. Multiphase flow meter technology (gas fraction measurement)

Venturi meter (Agar, Flowsys) – given the total volumetric flowrate from the positive displacement meter or cross-correlation, the differential pressure across the Venturi meter can be used to determine the density and hence gas fraction of the multiphase mixture. Single energy gamma densitometer (Roxar) – the gamma densitometer measures the density of the multiphase mixture which can be used to determine the gas fraction. Dual energy gamma densitometer (Schlumberger) – the higher of the two energy levels in the gamma densitometer measures the density of the multiphase mixture which can be used to determine the gas fraction. Multiphase flow meter technology (water cut measurement)

Microwave water cut meter (Agar) – this uses the different absorption of microwave energy of water compared to hydrocarbons Inductive water cut meter (Flowsys, Roxar) – uses the difference in dielectric coefficient between water (75) and hydrocarbons (2). Needs to switch from capacitance measurement in oil-continuous flow to conductivity measurement in water-continuous flow. Dual energy gamma densitometer (Schlumberger) – the lower of the two energy levels in the gamma densitometer measures the water cut of the multiphase mixture


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4.2

Descriptions of the multiphase flow meters

4 . 2. 1

AG AR 401

The Agar MPFM-401 series multiphase flow meter consists of an Agar MPFM-300 series multiphase flow meter modified by the addition of a Fluidic Flow Diverter (FFD®) device and a gas bypass loop. The FFD® device uses the difference in flow momentum of the gas and liquid to divert most of the free gas in the multiphase stream into a secondary measurement loop around the core MPFM-300. The secondary measurement loop is a ‘wet gas’ metering system consisting of a Venturi and a vortex shedding flow meter in series. The remaining liquids flow through the core MPFM-300 series system. The gas in the bypass loop is metered and added to the oil, water and gas measured through the core multiphase meter. By reducing the amount of gas flowing through the core multiphase meter, a smaller meter can be used, and the accuracy of the multiphase measurement is increased as a result of decrease in the GVF. The MPFM-300 series multiphase flow meter has three main components: a positive displacement meter which measures the total volumetric flowrate; a momentum meter (dual Venturi meter) which measures the gas fraction of the flow; and a microwave monitor which measures the water cut of the liquid. Figure 4.1: Schematic diagram of Agar MPFM-400 series multiphase flow meter

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Figure 4.2: Photograph of the Agar-401 multiphase flow meter at the test site


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4 .2 .2

FM C Fl owsys

The Flowsys TopFlow multiphase flow meter is based on the measurement principles of a Venturi meter, capacitance/conductivity and cross-correlation. The major parts of the TopFlow meter are the Venturi insert and the electrodes incorporated inside the throat of the Venturi. The flowrates of oil, water and gas are calculated based on the measurements obtained by the electrodes and the measurement of the differential pressure across the Venturi inlet. No separating devices, mixers, by-pass lines or radioactive sources are used in the meter. Following a blind tee the flow passes directly upwards through the meter. The velocity (volumetric flowrate) of the multiphase stream is determined by cross-correlation of electrical signals. Since the Venturi meter can also be used to determine the total mass flowrate, these two measurements together can be used to determine the mixture density, and hence gas volume fraction of the flow. The electrical capacitance and conductivity measurement is used to determine the water cut.

Figure 4.3: Photograph of the Flowsys multiphase flow meter at the test site

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4 .2 .3

R o x a r M P F M 1 90 0V I

The Roxar MPFM 1900VI multiphase flow meter measures the rates of oil, water and gas without separation, mixing or moving parts. Following a blind tee the flow passes directly upwards through the electrical capacitance/conductivity sensor which measures the water cut, and a 137Cs (662keV) gamma densitometer which measures the mixture density. The gas volume fraction can be derived from the density measurement. The velocity of the mixture is measured by cross-correlation of electrical signals, or alternatively from a Venturi meter measurement. The choice between the cross-correlation and the Venturi measurement is determined by the flow conditions in the meter.

Figure 4.4: Photograph of the Roxar MPFM 190 0VI multiphase flow meter at the test site (centre meter, prior to installation of radioactive source)


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4 .2 .4

S c h l u m b er g er P h a s ew a t c h e r V X 2 9

The Phasewatcher VX29 multiphase flow meter employs two measurement techniques, namely a Venturi and a dual-energy gamma densitometer. Following a blind tee the flow passes directly upwards through a Venturi meter. All the measurements are made at the Venturi throat, i.e. absolute pressure, temperature, differential pressure relative to upstream conditions and phase fractions. Phase fractions are measured using a dual energy gamma densitometer using a 133Ba (Barium) source. This source has energy levels which are appropriate for measurement of gas fraction and water cut (29 and 80 keV) and the location of the densitometer at the narrowest part of the flow conduit allows these low energy levels to be feasibly used at a relatively low source strength (10 mCi). The nuclear acquisition frequency is higher (45 Hz) than used in other multiphase flow meters (typically 1 Hz) which allows rapid resolution of the dynamic behaviour of the multiphase flow passing through the meter. For this test, for logistical reasons, the radioactive source used was the 153Gd source from the prototype VX meter. This uses energy levels of 42 and 97 keV and is not considered to have had a significant impact on the measurement results compared to using a 133Ba source. Figure 4.5: Photograph of the Schlumberger m ultiphase flow meter at the test site

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5

TEST INSTALLATION

5.1

Location and installation of meters

Figure 5.1: Location of the field test site

V pad

The meters were installed at the Prudhoe Bay oilfield in northern Alaska on the V-Pad, at the location shown in Figure 5.1. This is a production pad consisting of 12 production wells, a well pad test separator and metering, and export pipelines. The well pad has space and connections available for hooking up to a portable test separator. For these tests the 4 multiphase flow meters were connected in series, then flowed through an ASRC portable test separator, and then to the well pad separator, as shown schematically in Figure 5.2 and in the photograph in Figure 5.3. To vary the range of GVF and water cut encountered in the tests, the gas lift rates to some of the wells were varied during the tests and water was injected to one of the wells. The temperature of the tests varied from 11°C to 45°C (52 to 112°F) and the pressure from 20 to 50 bar (283 to 721 psi) measured at the ASRC test separator. The pressures at the multiphase flow meters were typically 2 to 5 bar (30 to 70 psi) higher than the test separator pressure due to pressure losses through the MFMs and the connecting pipework.


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Figure 5.2: Schematic of multiphase flow meter installation

17 ft 3- 90’s

22 ft 7-90’s

A G A R

14 ft 4-90’s

15 ft 4-90’s

R O X A

12 ft 3-90’s

F

S

M

L

C

B

19 ft 5 90’s

R

ASRC

Length 90's

Inlet Run Lengths and 90's Inlet SLB FMC Roxar Agar 19 12 15 14 5 3 4 4

ASRC 22 7

Total 17 3

99 26

Figure 5.3: Photograph of multiphase flow meter installation

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After initial set-up and calibration, the meters were enclosed in temporary tents with diesel-fired warm air heaters to maintain an ambient temperature above freezing, shown in Figure 5.4.

Figure 5.4: Photograph of meter protection


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5.2

Reference system (ASRC test separator)

The ASRC test separator is a 40 bbl horizontal vessel utilizing either manual or automatic (Fischer) level control, MicroMotion Coriolis meter for liquid volume flow, Halliburton turbine meters for gas flowrate, and Phase Dynamics (combined with manual shakeouts) for water cut determination. The MicroMotion meter used for mass flow (serial #487016) was calibrated with water at the factory on July 10 th, 2003. The MMM transmitter was also configured at that time. The High Range Halliburton Gas Turbine Meter is calibrated at 71.70 pulses/ACF, and the Low Range at 338.41 pulses/ACF. A Phase Dynamics meter was used for water cut determination, upon field calibration as per the following procedure. A starting point for salinity is used from historical salinity values for each well during the purge time of each test. Spinouts are then gathered, and the water cut combined with the off gas rate, gas lift rate, gross liquid rate, and separator pressure and temperature were input into a reverse shrinkage calculator generated by Eric Ward (BP). This reverse shrinkage calculator takes into account the fact that the Phase Dynamics meter is reading the water cut at line conditions, while a shakeout is at atmospheric. Then the Phase Dynamics meter water cut is adjusted to match the shakeout, and the test proceeds. A simplified diagram of the layout of the ASRC Millennium unit is included below in Figure 5.5: Figure 5.5: Simplified ASRC Separator Schematic Necks down to 2” 20 Diameters upstream, back to 3” 5 Diameters downstream for both meters High rate 2” Halliburton Turbine Meter

8 Bypass

3” Gas Outlet

8

3” Inlet

Low rate 2” Halliburton Turbine Meter

Chemical Injection

Demister

Sight Glass

40 bbl capacity

Phase Dynamics Watercut Meter

MicroMotion Coriolis Meter Vessel Bypass

Bypass

3” Liquid Outlet

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5.3

Fluid property data

Fluid properties were obtained for each of the wells and PVT analysis conducted by Schlumberger prior to the multiphase flow meter tests. This data was shared with all the participating vendors, and is summarised in Table 5.1. Table 5.1: Well specific fluid property data

V03 V101 V102 V103 V106 V107 V108 V109 V113 V117 V201 V202

5.4

Oil Viscosity cp Temp 16.4 80.6 25.5 78.8 20.9 79.3 25.0 87.8 21.1 77.5 18.8 90.7 28.7 70.7 44.5 71.2 21.5 79.7 16.6 86.5 35.0 92.5 55.7 69.1

Oil Gravity @ 60F Sg API 0.894 26.8 0.904 25.1 0.899 25.9 0.906 24.6 0.901 25.5 0.906 24.7 0.904 25.0 0.915 23.2 0.899 25.9 0.898 26.1 0.919 22.5 0.921 22.2

Water Gravity Sg Temp 1.0123 72.0 1.0140 78.1 1.0150 74.7 1.0148 83.0 1.0158 83.0 1.0130 94.2 1.0154 83.7 1.0178 71.3 1.0139 94.9 -

Gas Sg 0.738 0.714 0.723 0.720 0.736 0.744 0.716 0.704 0.707 0.645 0.754 0.668

Mixture Visc cp Temp 19.5 73.0 99.0 70.7 35.0 71.4 77.1 70.9 60.2 71.4 413.6 70.9 80.6 70.7 79.8 71.6 26.9 71.4 450.0 69.8 47.2 71.2 52.5 72.3

BSW Reading 1 Reading 2 3.2 3.4 34.0 34.0 8.0 8.0 26.0 26.0 28.0 28.0 60.0 60.0 30.0 30.0 16.0 16.0 0.5 0.5 60.0 60.0 1.4 1.4 0.0 0.0

Calibration of the multiphase flow meters

The multiphase flow meters were set up and calibrated according to the vendors’ requirements, under the supervision of the project consultant, Parviz Mehdizadeh. The calibration procedure included three well tests under multiphase flow conditions for the Agar, FMC and Schlumberger meters. The Roxar meter joined the tests midway through, after delivery of their radioactive source to the test site, and their calibration included a single multiphase well test. The calibration procedures are documented in Section 14. Dr Mehdizadeh provided regular progress reports during the tests, which are shown in Section 15. 5.5

Data recording and processing

The MFMs were set up to record data continuously at 1 minute intervals. This information was written to data files starting at midnight on each day. The results could therefore be retrieved from the meters each day and converted into a standard format using various Excel conversion spreadsheets and macros, written by the meter vendors. 5 .5 .1

MF M data form at

The required data from each vendor was: Date and time Well name Oil rate (barrels of oil per day) Water rate (barrels of water per day)


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Gas rate (Thousand actual cubic feet per day) Water cut Gas volume fraction Pressure (psia) Temperature (°F) All data was reported from the meters at line conditions, i.e. at the temperature and pressure at the multiphase meter measuring Section. 5 .5 .2

ASRC dat a for m at

ASRC produced a data file at the end of each test which recorded the reference measurements from the ASRC test separator at 1 minute intervals. The format of the file was the same as the MFM data files. 5 .5 .3

P r essu r e, t em p er a t u r e a n d sh r i n k a g e c a l c u l a t i o n s

As the MFMs all operated at slightly different pressure (due to pressure loss through the meters and the installation pipework) and temperature, it was necessary to make some corrections to the readings to allow a truly valid comparison with the ASRC reference conditions. Gas rate was corrected from the reported meter line conditions and the ASRC reference conditions to standard conditions (1 atm, 60°F). Gas rates are therefore shown in MMscf/d. However for meaningful comparison with other MFM test data and the specifications for the MFM accuracies, the gas volume fraction (GVF) is required at the MFM line conditions. For GVF calculations the gas rate was evaluated at the ASRC reference temperature and pressure. Oil rate was corrected to stock tank conditions using reservoir specific shrinkage correlations provided by BP Alaska. Two correlations were provided, one each for Ivishak and Borealis crude. Both shrinkage factors are based upon updated Peng Robinson Equations of State based upon PVT analysis. The correlations are functions of pressure, temperature, and GOR. Effects of varying API gravity are taken into account via the different correlations for the different reservoirs. No reservoir specific shrinkage correlation has been developed for Orion to date; the Ivishak shrinkage factor was employed for the one well on V-Pad producing from the Orion development. Water rate was corrected to stock tank conditions using the following equation derived for the density of water: Density of water =

–1.407708×10 -10T4 + 4.338116×10 -8T3 – 7.611122×10 -6T2 + 5.261784×10-5T + 9.999032×10 -1

(T in °C), so that: Water shrinkage factor = density of water (60°F) / density of water (T meter)

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These pressure, temperature and shrinkage corrections do not fully represent the PVT behaviour of the wellstream fluids, but are sufficiently accurate for the purpose of the tests. There is in any case some uncertainty of the PVT behaviour of the fluids flowing in any particular well test due to the variable nature of the produced fluids and the gas lift composition. It is important to note that ultimately the correlations were only used for the purpose of compensating for very slight differences in pressure and temperature between meters – any deviations in one well’s behaviour from that described by the correlations would produce cancelling errors. 5 .5 .4

D a t a sel ec t i o n

Each ASRC reference data file was analysed using Excel, plotting the oil, water, liquid and gas flowrates and water cut against time to determine the valid period of the test. In some cases, for example, the early period of the test time was invalid as the flowrates were still stabilising. Two methods were used: visual inspection of the plots, and calculation of the statistical confidence in the average rates. The valid test period was selected to minimise the confidence value (as a fraction of the average rate). 5.6

Data reprocessing

Some of the multiphase flow meters use measurements to determine the multiphase flow rates which are dependent on the physical properties of the fluids. As can be seen from Table 5.1, the properties vary quite significantly between the wells. However, in addition to the variation between the wells as tested at that time, there can be variations in physical properties of the produced fluids with time, as a result of producing crudes from different horizons, from water and miscible injectant breakthrough, and from variability in the composition of the lift gas. One objective of the test was to determine the impact of variable fluid properties on the multiphase flow meters, and therefore all the tests were performed ‘blind’ without changing the calibration data for the well under test. At the end of the test programme, each vendor was provided with the raw data from their meter, and a schedule showing which wells were under test and the times of the tests, as shown in Table 5.2. This provided sufficient information to reprocess the data to produce new multiphase flow meter output. A t t h i s st a g e n o A S R C r ef e r e n c e d a t a w a s r e l e a sed t o t h e v en d o r s . Of the four vendors, Agar, FMC and Roxar did not consider reprocessing to be required. Schlumberger provided complete reprocessed data for each well, and this data has been analysed alongside the original meter outputs, to demonstrate the impact of fluid property reprocessing. Cross plots of these results are shown in Section 12.7.


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Table 5.2: Well test schedule Start time

End time

mm/dd/yy hh:mm

mm/dd/yy hh:mm

09/05/03 13:00 09/05/03 20:40 09/06/03 03:35 09/07/03 18:00 09/08/03 00:30 09/08/03 09:00 09/08/03 11:00 09/09/03 02:11 09/09/03 11:31 09/09/03 18:31 09/10/03 02:46 09/10/03 11:00 09/10/03 17:45 09/11/03 22:53 09/12/03 12:00 09/13/03 07:00 09/14/03 01:30 09/14/03 17:00 09/15/03 07:16 09/15/03 17:30

09/05/03 17:00 09/06/03 00:00 09/06/03 06:00 09/07/03 22:00 09/08/03 06:30 09/08/03 11:00 09/08/03 15:00 09/09/03 07:00 09/09/03 15:00 09/09/03 22:00 09/10/03 07:46 09/10/03 15:00 09/10/03 22:00 09/12/03 05:02 09/12/03 18:45 09/13/03 17:00 09/14/03 12:30 09/15/03 04:00 09/15/03 08:16 09/16/03 05:30

5.7

Well

V106 V102 V117 V106 V102 V117 V117 V101 V103 V107 V108 V109 V113 V202 V03 V102 V103 V106 V101 V107

Test duration hh:mm 4:00 3:20 2:25 4:00 6:00 2:00 4:00 4:49 3:29 3:29 5:00 4:00 4:15 6:09 6:45 10:00 11:00 11:00 1:00 12:00

Start time

End time

mm/dd/yy hh:mm

mm/dd/yy hh:mm

09/16/03 11:00 09/19/03 02:45 09/19/03 20:00 09/21/03 12:30 09/22/03 01:00 09/22/03 16:30 09/22/03 19:55 09/23/03 00:15 09/23/03 02:15 09/23/03 06:00 09/23/03 23:00 09/24/03 03:30 09/24/03 07:02 09/24/03 14:00 09/24/03 19:05 09/24/03 23:30 09/27/03 03:00 09/27/03 17:00 09/30/03 14:30 09/30/03 21:30

09/16/03 15:00 09/19/03 08:15 09/20/03 07:00 09/21/03 18:00 09/22/03 07:09 09/22/03 19:00 09/22/03 21:55 09/23/03 01:30 09/23/03 04:45 09/23/03 08:30 09/24/03 03:00 09/24/03 06:00 09/24/03 11:01 09/24/03 16:00 09/24/03 20:50 09/25/03 02:45 09/27/03 12:00 09/28/03 04:00 09/30/03 21:00 10/01/03 02:45

Well

V108 V108 V109 V03 V113 V107 V107 V108 V108 V108 V109 V109 V107 V102 V103 V117 V201 V113 V202 V202

Test duration hh:mm 4:00 5:30 11:00 5:30 6:09 2:30 2:00 1:15 2:30 2:30 4:00 2:30 3:59 2:00 1:45 3:15 9:00 11:00 6:30 5:15

Meter breakdowns

A number of sensor failures and breakdowns occurred during the tests, which are recorded here for completeness. 5 .7 .1

FM C Fl owsys

The temperature measured failed on the FMC Flowsys meter on September 10 th, and was noticed the following day. The fault was traced to a loose connection from the temperature transmitter at the data acquisition A to D converter on September 15 th. Because the temperature is used in the derivation of the gas and liquid flowrates, the multiphase meter outputs could not be relied on during this period. The raw data was taken from the Flowsys meter and sent to FMC with the average temperatures for the tests. The information was used to regenerate the correct multiphase flow meter output, and this has been used in the analysis in this report. 5 .7 .2

S c h l u m b er g er V X 2 9

On September 17th, after a generator power failure on ASRC’s MTU, the PhaseWatcher would not restart with the Service Computer. A Schlumberger representative was dispatched to V-Pad and there determined that a gamma detector failure had occurred. The detector (Model 770) was replaced with a spare detector (a previous model) from the Schlumberger WCP base in Deadhorse, which required about 4 hours, including 2 hours travel time between V-Pad and Schlumberger WCP. The PhaseWatcher outlet

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was opened and an empty pipe calibration was performed. Since well testing had been stopped for other operations; there was no lost time involved. The faulty detector was immediately sent to Schlumberger Princeton for investigation. 5 .7 .3

Aga r 401

Agar informed BP that based on the system log files, the positive displacement (PD) meter on their system failed September 30th, and therefore the data from that point on is not good. This is evident from the data, where the meter was reporting approximately 50% under-reading from this point, although the Agar meter continued tracking water cut. The lower flow rate (rather than zero rate) is due to the part of the stream passing through the wet gas metering loop. Agar has indicated that the cause of the PD meter failure is due to the sand/stone in the stream reaching the PD meter that was not protected by the strainer. When the meter is returned to Agar in Houston from the North Slope, a BP representative will attend at the time they open up the PD meter to audit the cause of failure. Data from the point of PD meter failure has not been used in the analysis as it is clearly erroneous. 5 .7 .4


Roxar suffered no meter failures during the tests. However, it is worth recording the reason that far less data was collected from the Roxar meter was a result of logistical difficulties in shipping the radioactive source to the North Slope. This delayed Roxar’s meter set-up until about half-way through the test programme.


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6

TEST RESULTS

6.1

Meter results

This section details the statistical analysis of each meter’s test data compared to the ASRC benchmark, the methodology behind the statistics, comparison of meter performance to vendor specifications, and a comparison of test results from all four meters. It should be noted that this section details only the quantitative results of the field trial. More complete analysis of meter performance, including issues associated with initial installation and operability, are in Section 8. 6 .1 .1

Aga r 401

The test points covered are shown in Table 9.5. The points are sorted into order by the well tested and the date of the test. Graphs of the test points plotted against the reference values are shown in Section 7. 6 .1 .2

FM C Fl owsys





The test points covered are shown in Table 12.5 and Table 12.8 (reprocessed data). The points are sorted into order by the well tested and the date of the test. Graphs of the test points plotted against the reference values are shown in Section 12.

6.2

Definition of errors

In this report, errors in oil, water, total liquid and gas flowrates, and GOR, are expressed as relative errors, defined as: Relative error = (Meter reading – reference reading) / Reference reading while for water cut and GVF the errors are expressed as absolute errors, defined by: Absolute error = Meter reading – reference reading


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6.3

Summary statistics – all data

Three methods have been used to quantify the measurement performance of the multiphase flow meters. 6 .3 .1

5% cr i teri a

The first calculation recognises the value of low measurement uncertainty and weights the results accordingly. Each test point is rated according to its deviation from the reference value for liquid flowrate, gas flowrate, and water cut. A value of 5 is allocated if the liquid or gas flowrate is within ±5%, and the water cut is within ±1%; a value of 2 is allocated if the liquid or gas flowrate is within ±10%, and the water cut is within ±2%; a value of 0 is allocated if the deviations lie outwith these ranges. To allow for uncertainty in the ASRC reference data, an allowance of 5% on liquid flowrate, 2% on gas flowrate and 0.5% on water cut has been made before calculating the above scores. The points are totalled and then divided by the numbe r of test points to give a normalised score. The values for each meter are shown in Table 6.1. Table 6.1: Summary scores for multiphase flow meter 5% criteria AGAR

FMC

ROXAR

SLB

SLB (reprocessed)

Liquid flowrate Gas flowrate Water cut

3.6 4.1 2.4

2.6 2.9 1.2

2.4 0.7 1.1

3.3 2.5 1.0

3.9 2.6 2.0

TOTAL score Ideal score

10.0

6.7

4.2 15

6.8

8.5

6 .3 .2

RM S aver ag e

The root-mean-square average has been calculated for the deviations between the MFM readings and the ASRC reference values for liquid flowrate, gas flowrate and water cut. This tends to produce a large average value, since all points are used in calculating the average. The RMS average values are shown in Table 6.2. Table 6.2: RMS average multiphase flow meter deviations

Liquid flowrate Gas flowrate Water cut Ideal score Page 32/264

AGAR

FMC

ROXAR

SLB

SLB (reprocessed)

12.3 8.8 5.6

71.8 41.8 12.0

26.9 38.4 10.2

14.8 14.1 12.9

13.6 12.4 9.2

The lower the value of RMS average the better Exploration & Production Technology Group

CONFIDENTIAL

6 .3 .3

P r o p or t i o n of p o i n t s w i t h i n r a n g e

For this evaluation, the proportion of test points has been evaluated where the deviation between the MFM and the ASRC reference is within a specified range. For liquid flowrate the range is ±10%, for gas flowrate the range is ±10% and for water cut the range is ±2%. To allow for uncertainty in the ASRC reference data, an allowance of 5% on liquid flowrate, 2% on gas flowrate and 0.5% on water cut has been made before calculating the above scores. A final calculation has been made of the proportion of test points where the combined error calculated by the equation below lies within ±10%:

RMS error =

(relative

% error in Q L

)2 + (relative

% error in Q G

)2 + (absolute

% error in WC

)2

3

Table 6.3: proportion of points within range

Liquid flowrate Gas flowrate Water cut Combined error

AGAR

FMC

ROXAR

SLB

SLB (reprocessed)

82.5 90.0 60.0 80.0

53.3 64.4 24.4 53.3

56.5 17.4 26.1 17.4

71.7 56.5 21.7 56.5

88.6 68.2 43.2 77.3

Ideal score

6.4

100

Summary statistics – data in restricted operating envelope

The following statistics have been calculated for a limited range of data for the operating envelope defined by: GVF Liquid rate

< 95% > 1100 stb/d

The reasons for these restrictions are that most of the meters had greatly increased measurement errors above 95% GVF, and that the size of the meters in the test limited their lower range of liquid flowrate measurement. Using data from a restricted operating range generally shows an improved overall meter performance.


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6 .4 .1

5% cr i teri a

Table 6.4: Summary scores for multiphase flow meter 5% criteria AGAR

FMC

ROXAR

SLB

SLB (reprocessed)


4.4 4.1 2.5

3.7 3.3 1.3

4.2 1.4 1.4

4.1 4.7 1.8

4.5 3.8 2.4

TOTAL score Ideal score

11.0

8.2

7.1 15

10.5

10.7

6 .4 .2

RM S aver ag e

Table 6.5: RMS average multiphase flow meter deviations


AGAR

FMC

ROXAR

SLB

SLB (reprocessed)

8.3 10.0 2.3

22.6 44.4 7.8

13.4 23.9 13.4

8.2 5.2 8.5

7.8 8.0 6.6

Ideal score 6 .4 .3

The lower the value of RMS average the better


Table 6.6: proportion of points within range

Liquid flowrate Gas flowrate Water cut Combined error Ideal score

6.5

AGAR

FMC

ROXAR

SLB

SLB (reprocessed)

95.2 90.5 66.7 90.5

76.2 71.4 28.6 71.4

88.9 33.3 33.3 44.4

85.7 100.0 38.1 85.7

100.0 95.7 52.2 95.7

100

Comparison with vendor specifications

Each of the vendors was asked to provide an uncertainty specification for their meter, giving the relative error in liquid and gas rate measurement, and the absolute error in water cut measurement. For most of the meters, the uncertainty specification was dependent on GVF. The following figures show the liquid flowrate, gas flowrate and water cut errors from the tests plotted against GVF for each of the meters, together with the vendor uncertainty specification.

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6 .5 .1

Aga r 401

The specification provided by Agar is: Gas flowrate uncertainty Liquid flowrate uncertainty Water cut uncertainty

±5% ±2% ±2%

Agar additionally specify an error based on the full scale reading, for example, liquid error is ±2% of reading plus ±1% of full scale. This significantly increases the relative error specification compared to the values shown above. This specification in valid for the whole GVF range from 0% to 100%.

Figure 6.1: Agar 401 liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error AGAR-401: all points

40

) e c n 30 e r e f e r o 20 t e v i t a 10 l e r % ( r 0 o r r e e t -10 a r w o l f -20 d i u q i l l -30 a t o T

AGAR-401: limited operating envelope limited operating envelope vendor specification

-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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Figure 6.2: Agar 401 gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error AGAR-401: all points

40

AGAR-401: limited operating envelope

) 30 e c n e r e 20 f e r o t e 10 v i t a l e r 0 % ( r o r r e -10 e t a r w-20 o l f s a G-30

limited operating envelope vendor specification

-40

-50 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 6.3: Agar 401 water cut error vs. ASRC reference GVF 25 +/- 5% absolute error AGAR-401: all points

20


) e 15 c n e r e f 10 e r m o r 5 f e t u l o s 0 b a % ( r -5 o r r e t u -10 c r e t a W-15


-20

-25 0

10

20

30

40

50

60

70

Reference GVF (%)

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6 .5 .2

FM C Fl owsys

The specification provided by FMC gives the uncertainty in gas flowrate, liquid flowrate and water cut as a function of the GVF:

Table 6.7: FMC Flowsys vendor uncertainty specification

GVF

Gas flowrate uncertainty 10 10 10 10 10 -

0-25% 25-60% 60-70% 70-85% 85-92% 92-97% 97-100

Liquid flowrate uncertainty 5 5 7 7 10 15 -

Water cut uncertainty 2 2 2 3 3 5 -

Figure 6.4: FMC Flowsys liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error FMC-Flowsys: all points

40

) e c n 30 e r e f e r o 20 t e v i t a 10 l e r % ( r 0 o r r e e t a -10 r w o l f -20 d i u q i l l -30 a t o T

FMC-Flowsys: limited operating envelope limited operating envelope vendor specification

-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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Figure 6.5: FMC Flowsys gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error FMC-Flowsys: all points

40

FMC-Flowsys: limited operating envelope

) e 30 c n e r e f 20 e r o t e 10 v i t a l e r


0

% ( r o r r -10 e e t a r w-20 o l f s a G-30 -40

-50 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 6.6: FMC Flowsys water cut error vs. ASRC reference GVF 25 +/- 5% absolute error FMC-Flowsys: all points

20




-20

-25 0

10

20

30

40

50

60

70

Reference GVF (%)

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6 .5 .3


The specification provided by Roxar gives the uncertainty in gas flowrate, liquid flowrate and water cut as a function of the GVF. The water cut uncertainty specification is additionally dependent on water cut. In Figure 6.9 only the higher water cut specification (for water continuous flow) is shown.

Table 6.8: Roxar MPFM 1900VI vendor uncertainty specification

GVF

Gas flowrate uncertainty

0-5% 0-30% 30-90% 90-96% 96-99% 99-100%

8 6 6 6 6

Liquid flowrate uncertainty 2 2 3 5 7 -

Water cut uncertainty wc<60% 1.5 1.5 2 3 4 -

Water cut uncertainty wc>60% 2.25 2.25 3 4.5 6 -

Figure 6.7: Roxar MPFM 1900VI liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error Roxar-MPFM1900VI: all points

40


Roxar-MPFM1900VI: limited operating envelope limited operating envelope vendor specification

-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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Figure 6.8: Roxar MPFM 1900VI gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error Roxar-MPFM1900VI: all points

40

Roxar-MPFM1900VI: limited operating envelope



0


-50 0

10

20

30

40

50

60

70

80

90

100

90

100

Reference GVF (%)

Figure 6.9: Roxar MPFM 1900VI water cut error vs. ASRC reference GVF 25 +/- 5% absolute error Roxar-MPFM1900VI: all points

20




-20

-25 0

10

20

30

40

50

60

70

80

Reference GVF (%)

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6 .5 .4


The specification provided by Schlumberger gives the uncertainty in gas flowrate, liquid flowrate and water cut as a function of the GVF. The water cut uncertainty specification is additionally dependent on water cut. In Figure 6.12 only the higher water cut specification (for water continuous flow) is shown.

Table 6.9: Schlumberger VX29 vendor uncertainty specification

GVF

Gas flowrate uncertainty

0-92% 92-96% 96-98% 98-100%

7.5 7.5 9 -

Liquid flowrate uncertainty 7.5 8 11 -

Water cut uncertainty wc<60% 9 10.5 16 -

Water cut uncertainty wc>60% 9.5 12 16.5 -

Figure 6.10: Schlumberger VX29 (reprocessed) liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error SLB-VX29 Reprocessed: all points

40

) e c n 30 e r e f e r o 20 t e v i t a 10 l e r

SLB-VX29 Reprocessed: limited operating envelope limited operating envelope vendor specification

% ( r 0 o r r e e t -10 a r w o l f -20 d i u q i l l -30 a t o T -40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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Figure 6.11: Schlumberger VX29 (reprocessed) gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error SLB-VX29 Reprocessed: all points

40

SLB-VX29 Reprocessed: limited operating envelope



0


-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 6.12: Schlumberger VX29 (reprocessed) water cut error vs. ASRC reference GVF 25 +/- 5% absolute error SLB-VX29 Reprocessed: all points

20




-20

-25 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

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6.6

Summary of repeatability results

For each of the parameters liquid flowrate, gas flowrate and water cut the repeatability is calculated as: repeatability =

max imum error - min imum error number of tests

Then a combined repeatability value is calculated using:

RMS repeatability =

(repeatability of QL )2 + (repeatability of QG )2 + (repeatability of WC)2 3

The tests were sorted and the points selected for repeatability analysis are shown in Table 9.6 ( Agar), Table 10.6 (FMC), Table 11.6 (Roxar), Table 12.6 (Schlumberger) and Table 12.9 (Schlumberger reprocessed). The repeatability results for the four meters are summarised in Table 6.10. Figure 13.16 to Figure 13.23 show the behaviour of the V-106 well tests, showing considerable variability. Hence this test has been excluded from the repeatability calculations. For comparison, the values in brackets show the repeatability values including V-106.

Table 6.10: Repeatability results for the four m ultiphase flow meters

Agar FMC Roxar SLB SLB (reprocessed)

Liquid flowrate repeatability 5.5 (6.4) 14.5 (22.6) 8.7 (10.9) 6.4 (7.1) 5.6 (6.4)

Gas flowrate repeatability

Water cut repeatability

Combined repeatability

3.1 (3.1) 6.2 (8.3) 7.2 (8.5) 3.1 (3.3) 2.9 (3.1)

1.3 (1.4) 3.6 (4.7) 3.1 (5.9) 5.5 (6.3) 4.3 (4.7)

3.9 (4.4) 9.7 (14.5) 7.1 (9.1) 5.9 (6.5) 5.0 (5.5)


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Figure 6.13: Liquid flowrate repeatability for the four meters 120 Agar FMC Roxar

100

SLB SLB reprocessed

y t i l 80 i b a t a e p e r e 60 t a r w o l f d i u q 40 i L

20

0 V03

V101

V102

V103

V106

V107

V107

V108

V109

V113

V117

V202

Figure 6.14: Gas flowrate repeatability for the four meters 35 Agar FMC

30

Roxar SLB SLB reprocessed

25

y t i l i b a t a 20 e p e r e t a r w15 o l f s a G 10

5

0 V03

Page 44/264

V101

V102

V103

V106

V107

V107

V108

V109

V113

V117

V202


CONFIDENTIAL

Figure 6.15: Water cut repeatability for the four meters 25 Agar FMC Roxar

20

SLB SLB reprocessed

y t i l i b 15 a t a e p e r t u c r e 10 t a W

5

0 V03

6.7

V101

V102

V103

V106

V107

V107

V108

V109

V113

V117

V202

Comparison of the results from the four meters

Figure 6.16 to Figure 6.29 show the results from the 4 multiphase flow meters plotted together. These figures are very useful in showing the different performance of the meters, for example Figure 6.22 quite clearly shows a different trend of metered gas rate against the reference for each meter. If, on the other hand, the four meters had given similar trends, this might indicate an underlying systematic error in the reference measurement.


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Figure 6.16: Oil flowrate from the 4 multiphase flow meters vs. ASRC reference oil flowrate 2000 +/- 10% relative error Agar

1800

FMC Roxar SLB

1600

1400

) d / b t s 1200 ( e t a r w1000 o l f l i o r 800 e t e M 600

400

200

0 0

200

400

600

800

1000

1200

1400

1600

1800

2000

Reference oil flowrate (stb/d)

Figure 6.17: Oil flowrate error from the 4 multiphase flow meters vs. ASRC reference GVF 50 +/- 10% relative error Agar

40

FMC Roxar

) 30 e c n e r e 20 f e r o t e 10 v i t a l e r 0 % ( r o r r -10 e e t a r w-20 o l f l i O-30

SLB

-40

-50 0

20

40

60

80

100

Reference GVF (%)

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Figure 6.18: Water flowrate from the 4 multiphase flow meters vs. ASRC reference water flowrate 2500 +/- 10% relative error Agar FMC Roxar SLB

2000

) d / b t s ( e 1500 t a r w o l f r e t a w1000 r e t e M

500

0 0

500

1000

1500

2000

2500

Reference water flowrate (stb/d)

Figure 6.19: Water flowrate error from the 4 multiphase flow meters vs. ASRC reference GVF 50 +/- 10% relative error Agar

40

FMC Roxar

) e 30 c n e r e f e r 20 o t e v i t 10 a l e r % ( 0 r o r r e -10 e t a r w-20 o l f r e t a -30 W

SLB

-40

-50 0

20

40

60

80

100

Reference GVF (%)


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Figure 6.20: Liquid flowrate from the 4 multiphase flow meters vs. ASRC reference liquid flowrate 3500 +/- 5% relative error Agar FMC

3000

Roxar SLB

) 2500 d / b t s ( e t 2000 a r w o l f d i u 1500 q i l r e t e M 1000

500

0 0

500

1000

1500

2000

2500

3000

3500

Reference liquid flowrate (stb/d)

Figure 6.21: Liquid flowrate error from the 4 multiphase flow meters vs. ASRC reference GVF 50 +/- 5% relative error Agar

40

FMC

) e c 30 n e r e f e 20 r o t e v 10 i t a l e r % ( 0 r o r r e -10 e t a r w o -20 l f d i u q -30 i L

Roxar SLB

-40

-50 0

20

40

60

80

100

Reference GVF (%)

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Figure 6.22: Gas flowrate from the 4 multiphase flow meters vs. ASRC reference gas flowrate 9.0 +/- 10% relative error Agar

8.0

FMC Roxar SLB

7.0

) d / f 6.0 c s M M ( e 5.0 t a r w o l f 4.0 s a g r e t e 3.0 M 2.0

1.0

0.0 0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Reference gas flowrate (MMscf/d)

Figure 6.23: Gas flowrate error fro m the 4 multiphase flow meters vs. ASRC reference GVF 50 +/- 10% relative error Agar

40

FMC Roxar

) e 30 c n e r e f 20 e r o t e 10 v i t a l e r 0 % ( r o r r -10 e e t a r w-20 o l f s a G-30

SLB

-40

-50 0

20

40

60

80

100

Reference GVF (%)


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Figure 6.24: Water cut from the 4 multiphase flow meters vs. ASRC reference water cut 100 +/- 5% absolute error Agar FMC Roxar

80

SLB

60

) % ( t u c r e 40 t a w r e t e M 20

0 0

10

20

30

40

50

60

70

80

90

100

-20

Reference water cut (%)

Figure 6.25: Water cut error from the 4 multiphase flow meters vs. ASRC reference GVF 25 +/- 5% absolute error Agar

20

FMC Roxar

) 15 e c n e r 10 e f e r o t e 5 v i t a l e r 0 % ( r o r r -5 e t u c -10 r e t a W

SLB

-15

-20

-25 0

20

40

60

80

100

Reference GVF (%)

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Figure 6.26: GVF from the 4 multiphase flow meters vs. ASRC reference GVF 100 +/- 5% absolute error Agar

90

FMC Roxar 80

SLB

70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 6.27: GVF error from the 4 multiphase flow meters vs. ASRC reference GVF 15 +/- 5% relative error Agar FMC Roxar

10

) e c n e r e f e r 5 o t e v i t a l e r 0 % ( r o r r e F -5 V G r e t e M

SLB

-10

-15 0

20

40

60

80

100

Reference GVF (%)


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Figure 6.28: GOR from the 4 multiphase flow me ters vs. ASRC reference GOR 100000 +/- 10% relative error Agar FMC Roxar SLB

) b t s / f c s ( R O G r e t e M

10000

1000

100 100

1000

10000

100000

Reference GOR (scf/stb)

Figure 6.29: GOR error from the 4 multiphase flow meters vs. ASRC reference GVF 50 +/- 10% absolute error Agar

40

FMC Roxar 30

SLB

) e c n 20 e r e f e r o 10 t e v i t a 0 l e r

% ( -10 r o r r e R-20 O G -30

-40

-50 0

20

40

60

80

100

Reference GOR (%)

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6.8

Meter sizing analysis

The tests were generally at high GVF (the majority of the points were above 90% GVF) and these points corresponded to relatively low liquid flowrate conditions. One of the issues which emerged from analysis of the data and subsequent discussion with the vendors was that loss of metering accuracy at high GVF could be a result both of the high GVF and the low liquid flowrate. For this reason, a ‘limited operating envelope’ was defined for analysis of the results at a minimum liquid flowrate limit of 1100 stb/d and maximum GVF of 95%. However, it is useful to be able to determine whether the largest contributor to meter error is from high GVF or low liquid flowrate, and therefore make an assessment of whether better accuracy could have been obtained by sizing the meter differently. EPTG has developed a model in Excel to describe the performance of a dual energy Venturi type of multiphase flow meter. This calculates the pressure drop across the Venturi and the uncertainties associated with measurement of the Venturi pressure drop and the phase fractions. For the Schlumberger VX29 meter, at the conditions of each well tested, the calculated Venturi pressure drop is shown in Figure 6.30. This shows that with the exception of two well tests, the average Venturi pressure drop for a test is greater than 500 mbar. This is well within the accurate measurement range for the Venturi dP transmitter. If the Venturi had been smaller, the dP would have been out of range for many of the tests. It can be concluded that the meter was correctly sized for the range of well tests undertaken, and the dominant source of error was due to high GVF measurement and not to low liquid rate. Figure 6.30: Venturi pressure drop for 29mm Venturi throat 5000 4500 4000 3500

) r a b 3000 m ( P2500 d i r u t n 2000 e V 1500 1000 500 Modelled Venturi dP 0 0

500

1000

1500

2000

2500

Oil flowrate (barrels per day)


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7

CONFIDENCE IN TEST DATA

7.1

Tank tests

Tank tests were conducted on selected wells to obtain additional data to assess the quality of the test separator liquid measurements. The availability of the wells and tank capacity dictated the number and duration of these tank tests. The steps described in Section 7.1.1 were used to conduct the tank tests. The ASRC equipment employed 2 test tanks, each had a total capacity of 400 bbl corresponding to a tank liquid level of 240 inches. Tank strapping was done using a W L Walker tape. Some of the wells flowed at high rate and in these cases the second tank was used so as not to interrupt the test. Tank strapping was done with a standard tank strap reel with a plum bob at the bottom and a bonding strap. The conversion factor for the tape measurements is 1.667 bbl per inch. With proper tank strapping methods, the estimated tank volume measurement accuracy is better than ± 1 bbl. The tanks were insulated and open to atmosphere. Figure 7.1 shows the schematic and Figure 7.2 shows a general view of the tank tests.

Figure 7.1: Schematic of tank test installation

R

A

O

G

X

A

A

R

F

S

M

L

C

B

R

ASRC

Tank


Tank

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Figure 7.2: View of the tank test location

7 .1 .1

T a n k T e st P r o ced u r e

Prior to a tank test the well was allowed to stabilize for at least 2 hours by flowing it through the test separator and directing the returns to the header. During this stabilization period, the ASRC operators established the well flow rate and separator level adjustments. These rates and levels were used to adjust the controls on the separator later on during the tank tests. Once a stable rate was established, the flow was diverted to the tank and a small amount of defoamer was injected by a chemical injection pump into the liquid leg of the test separator, shown in Figure 5.5, downstream of the MicroMotion flow meter. The following steps were then used to obtain tank data: • • • • •

Ten minutes before test time, the MicroMotion meter was by-passed. The transmitter was set to zero and verified. Slowly re-open the MicroMotion to avoid slug flow error and shut the bypass. At least one minute before starting the test stop and reset the PLC totalisers. At the same time at the top of the hour for the start test time, divert from the header/purge tank to the test tank and start the totalisers in the PLC. Obtain tank straps every half hour from the start test time. Watch for foaming during the tank level measurements.

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•

•

7 .1 .2

When the tank test duration is achieved, begin 15 minute tank straps until shrinkage subsides, and once shrinkage has stabilized, take two more one half hour straps to ensure shrinkage is complete. Freeze protect tank lines if it is cold and they will sit for a while, or purge with gas to blow-dry. T a n k T est a n d L i q u i d C or r ec t i o n

Table 7.1 shows the results from the 9 tank tests. The third and forth columns in the table show the liquid volumes measured by the tank and the corresponding liquid volumes measured by the test separator. The test separator (ASRC) volumes were further corrected for shrinkage using BP’s shrinkage correlations shown in Section 5.5.3. The shrinkage is applied to the oil portion of the liquid, as determined by the water cut values for each well. The corrected volumes and the variance with respect to the tank values are shown in columns 9 and 10 of the table. An average uncertainty of ±5%, based on the total tank volumes measured for all 9 wells and shrinkage corrected volumes reported by the test separator, was calculated and used as the estimate of uncertainty in the reference liquid flowrate.

Table 7.1: Tank Tests and corre ctions for the ASRC liquid volumes

Well

Date

3 103 106 106 108 109 113 117 202

9/21/03 9/24/03 9/7/03 9/29/03 9/19/03 9/20/03 9/21/03 9/25/03 9/30/03

Average

Tank ASRC Oil Volume - Volume(bbls) BBL BBL 157.0 212.9 102.7 99.4 78.3 110.8 89.3 233.8 198.3

156.1 209.2 106.9 102.9 69.2 102.1 83.1 231.3 204.9

140.3 143.1 62.7 62.1 47.3 83.1 83.1 77.2 204.9

1282.6


Water (bbls)

OSF

15.8 66.0 44.2 40.8 21.9 19.0 0.1 154.0 0.0

1.0682 1.0445 1.0503 1.0524 1.0536 1.0474 1.0542 1.0641 1.0543

Shrunk Liquid ASRC underOil Vol Shrinkage Reading 131.3 137.0 59.7 59.0 44.9 79.4 78.8 72.6 194.4

147.1 203.1 103.9 99.8 66.8 98.3 78.9 226.6 194.4

-6% -5% 1% 0% -15% -11% -12% -3% -2%

1218.8

-5.0%

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7.2

Statistical analysis of reference data

Data was recorded from the ASRC reference system at 1 minute intervals throughout the tests. For each test the oil, water, liquid and gas rates and the water cut were plotted against time and the most appropriate portion of the data was selected for the test period. For each test the statistical confidence of liquid rate, gas rate and water cut were calculated. This is the 95% confidence value, divided by the mean flowrate. The results of this analysis are shown in full in Section 13. 7.3

Comparison with laboratory test data

Most of the multiphase flow meters tested in this project have been subjected to extensive trials at multiphase flow test laboratories, during the development of the meter technology, as part of Joint Industry Projects, and qualification tests for meter installations. The three principal laboratories where these tests have taken place are at Humble, Texas (Texaco); Porsgrunn, Norway (Norsk Hydro) and the UK National Engineering Laboratory in Glasgow, Scotland. Unfortunately there are limitations to the use of this information, either for reasons of commercial confidentiality, or because the meter technology has changed substantially since the laboratory trials took place. Test results for the Schlumberger, Roxar and FMC multiphase flow meters are shown in Section 7.3.1, 7.3.2 and 7.3.3. 7 .3 .1

D a t a f or t h e S ch l u m b er g er V X m u l t i p h a se f l o w m e t er

The best quality data available to this study is for the Schlumberger meter tested at NEL. A prototype of the VX52 meter (with 153Gd radioactive source) was tested in a Joint Industry Project at NEL in 1999, and BP, Exxon and Phillips were all sponsors of this project at that time. A second VX52 meter, now with the 133Ba source, was tested at NEL in 2001 for the Maclure field development in the UK North Sea – BP, Conoco and ExxonMobil all had interests in this development, and therefore access to this test data. The following figures show a comparison of results from the NEL test of the Schlumberger VX52 prototype meter in 1999, the NEL test of the Schlumberger VX52 meter for the Maclure field in 2001, the Prudhoe Bay test of the Schlumberger VX29 meter in 2003, and the reprocessed results from the Prudhoe Bay test of the Schlumberger VX29 meter in 2003. Note that the figures are plotted in units of litres/sec at line conditions, as there is not a meaningful PVT correction to stock tank conditions for the laboratory fluids. There is very good consistency between the various data sets plotted in Figure 7.3 to Figure 7.14, showing agreement between the measurement results from three different versions of the Schlumberger multiphase flow meter in two different test locations (laboratory and field). This gives us confidence that the test procedure and the reference values obtained from the field test are of high quality.

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Figure 7.3: Schlumberger oil flowrate vs. reference oil flowrate 30 +/- 10% relative error VX52 Prototype, NEL 1999 Maclure VX52, NEL 2001 25

VX29, Prudhoe Bay 2003 VX29, GPB, 2003, Reprocessed

) d n o 20 c e s / s e r t i l ( e 15 t a r w o l f l i o r 10 e t e M 5

0 0

5

10

15

20

25

30

Reference oil flowrate (litres/second)

Figure 7.4: Schlumberger oil flowrate error vs. reference GVF 50 +/- 10% relative error VX52 Prototype, NEL 1999

40

Maclure VX52, NEL 2001 VX29, Prudhoe Bay 2003

) 30 e c n e r e 20 f e r o t e 10 v i t a l e r

VX29, GPB, 2003, Reprocessed

0

% ( r o r r -10 e e t a r -20 w o l f l i O-30 -40

-50 0

20

40

60

80

100

Reference GVF (%)


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Figure 7.5: Schlumberger water flowrate vs. reference water flowrate 10 +/- 10% relative error VX52 Prototype, NEL 1999

9


8

) d n o 7 c e s / s e r 6 t i l ( e t a r 5 w o l f r 4 e t a w r e 3 t e M


2

1

0 0

1

2

3

4

5

6

7

8

9

10

80

90

100

Reference water flowrate (litres/second)

Figure 7.6: Schlumberger water flowrate error vs. reference GVF 50 +/- 10% relative error VX52 Prototype, NEL 1999

40

Maclure VX52, NEL 2001

) e 30 c n e r e f 20 e r o t e v i t 10 a l e r 0 % ( r o r r e -10 e t a r w-20 o l f r e t a -30 W


-40

-50 0

10

20

30

40

50

60

70

Reference GVF (%)

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Figure 7.7: Schlumberger liquid flowrate vs. reference liquid flowrate 30 +/- 5% relative error VX52 Prototype, NEL 1999 Maclure VX52, NEL 2001

25

VX29, Prudhoe Bay 2003

) d n o c e 20 s / s e r t i l ( e t a r 15 w o l f d i u q i l 10 r e t e M


5

0 0

5

10

15

20

25

30

Reference liquid flowrate (litres/second)

Figure 7.8: Schlumberger liquid flowrate error vs. reference GVF 50 +/- 5% relative error 40

VX52 Prototype, NEL 1999


Maclure VX52, NEL 2001 VX29, Prudhoe Bay 2003 VX29, GPB, 2003, Reprocessed

-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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CONFIDENTIAL

Figure 7.9: Schlumberger gas flowrate vs. reference gas flowrate 100 +/- 10% relative error VX52 Prototype, NEL 1999

90


80


) d n 70 o c e s / s 60 e r t i l ( e t 50 a r w o l f 40 s a g r e 30 t e M 20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference gas flowrate (litres/second)

Figure 7.10: Schlumberger gas flowrate error vs. reference GVF 50 +/- 10% relative error VX52 Prototype, NEL 1999

40




-40

-50 0

10

20

30

40

50

60

70

Reference GVF (%)

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Figure 7.11: Schlumberger water cut vs. reference water cut 100 +/- 5% absolute error VX52 Prototype, NEL 1999 Maclure VX52, NEL 2001 80


60

) % ( t u c r e 40 t a w r e t e M 20

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100

-20


Figure 7.12: Schlumberger water cut error vs. reference GVF 25 +/- 5% absolute error VX52 Prototype, NEL 1999

20




-20

-25 0

10

20

30

40

50

60

70

Reference GVF (%)


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CONFIDENTIAL

Figure 7.13: Schlumberger GVF vs. reference GVF 100 +/- 5% absolute error 90

VX52 Prototype, NEL 1999 Maclure VX52, NEL 2001

80


70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 7.14: Schlumberger GVF error vs. reference GVF 15 +/- 5% absolute error VX52 Prototype, NEL 1999 Maclure VX52, NEL 2001

10


) e c n e r e 5 f e r m o r f e t u 0 l o s b a % ( r o -5 r r e F V G


-10

-15 0

10

20

30

40

50

60

70

Reference GVF (%)

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7 .3 .2

D a t a f or t h e R o x a r M P F M 19 00 VI m u l t i p h a se f l o w m e t er

Further data is available for the Roxar meter. Earlier versions of the Roxar meter when it was developed by Fluenta were tested in the NEL Joint Industry Projects in 1995 (MPFM1900VI) and 1999 (SMFM1000). Although these meters differed substantially from the current Roxar MPFM1900VI, the underlying technology is the same, and a comparison of their performance with meter tested in Prudhoe Bay is interesting. A Roxar MPFM1900VI was also tested by ConocoPhillips in the Kuparuk field in summer 2003, and this data is included for comparison. In the Kuparuk test, the Roxar meter was compared to an Accuflow multiphase metering system, and there was some doubt as to the quality of the Accuflow gas measurement. This may explain the unusual deviation in gas rate measurements from that test. Liquid rate and water cut measurement is generally consistent with the other test data sources.


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Figure 7.15: Roxar oil flowrate vs. reference oil flowrate 40 +/- 10% relative error Fluenta MPFM1900VI, NEL 1995 35

Fluenta SMFM1000, NEL 1999 Roxar MPFM1900VI, Kuparuk, 2003 Roxar MPFM1900VI, Prudhoe Bay, 2003

30

) d n o c e s 25 / s e r t i l ( e 20 t a r w o l f l i 15 o r e t e M 10

5

0 0

5

10

15

20

25

30

35

40


Figure 7.16: Roxar oil flowrate error vs. reference GVF 50 +/- 10% relative error Fluenta MPFM1900VI, NEL 1995

40

Fluenta SMFM1000, NEL 1999


Roxar MPFM1900VI, Kuparuk, 2003 Roxar MPFM1900VI, Prudhoe Bay, 2003

0

% ( r o r r -10 e e t a r -20 w o l f l i O-30 -40

-50 0

20

40

60

80

100

Reference GVF (%)

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Figure 7.17: Roxar water flowrate vs. reference water flowrate 40 +/- 10% relative error Fluenta MPFM1900VI, NEL 1995

35

Fluenta SMFM1000, NEL 1999 Roxar MPFM1900VI, Kuparuk, 2003

) 30 d n o c e s / s 25 e r t i l ( e t a r 20 w o l f r e 15 t a w r e t e M10

Roxar MPFM1900VI, Prudhoe Bay, 2003

5

0 0

5

10

15

20

25

30

35

40


Figure 7.18: Roxar water flowrate error vs. reference GVF 50 +/- 10% relative error 40

Fluenta MPFM1900VI, NEL 1995 Fluenta SMFM1000, NEL 1999

) e 30 c n e r e f 20 e r o t e v i t 10 a l e r 0 % ( r o r r e -10 e t a r w-20 o l f r e t a -30 W


-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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Figure 7.19: Roxar liquid flowrate vs. reference liquid flowrate 40 +/- 5% relative error Fluenta MPFM1900VI, NEL 1995 35


) 30 d n o c e s / s 25 e r t i l ( e t a r 20 w o l f d i u 15 q i l r e t e M10


5

0 0

5

10

15

20

25

30

35

40


Figure 7.20: Roxar liquid flowrate error vs. reference GVF 50 +/- 5% relative error Fluenta MPFM1900VI, NEL 1995

40


Fluenta SMFM1000, NEL 1999 Roxar MPFM1900VI, Kuparuk, 2003 Roxar MPFM1900VI, Prudhoe Bay, 2003

-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

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Figure 7.21: Roxar gas flowrate vs. reference gas flowrate 250 +/- 10% relative error Fluenta MPFM1900VI, NEL 1995 Fluenta SMFM1000, NEL 1999 200

Roxar MPFM1900VI, Kuparuk, 2003

) d n o c e s / s 150 e r t i l ( e t a r w o l f 100 s a g r e t e M


50

0 0

50

100

150

200

250


Figure 7.22: Roxar gas flowrate error vs. reference GVF 50 +/- 10% relative error Fluenta MPFM1900VI, NEL 1995

40




-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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Figure 7.23: Roxar water cut vs. reference water cut 100 +/- 5% absolute error Fluenta MPFM1900VI, NEL 1995

90


80

Roxar MPFM1900VI, Prudhoe Bay, 2003 70

) % 60 ( t u c r e 50 t a w r e t e 40 M 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100


Figure 7.24: Roxar water cut error vs. reference GVF 25 +/- 5% absolute error Fluenta MPFM1900VI, NEL 1995

20




-20

-25 0

10

20

30

40

50

60

70

Reference GVF (%)

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Figure 7.25: Roxar GVF vs. reference GVF 100 +/- 5% absolute error 90

Fluenta MPFM1900VI, NEL 1995 Fluenta SMFM1000, NEL 1999

80


70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

70

80

90

100

Reference GVF (%)

Figure 7.26: Roxar GVF error vs. reference GVF 15 +/- 5% absolute error Fluenta MPFM1900VI, NEL 1995 Fluenta SMFM1000, NEL 1999

10

Roxar MPFM1900VI, Kuparuk, 2003



-10

-15 0

10

20

30

40

50

60

Reference GVF (%)


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7 .3 .3

D a t a f o r t h e F M C F l o w sy s m u l t i p h a se f l o w m et er

Further data is available for the Flowsys meter. Test results are available from CMR in Norway, NEL in the UK and Trecate in Italy. The CMR multiphase flow loop was initially built for use in internal research and development projects. However, as an independent technological research institute, CMR has also offered external services based on these facilities. Examples of such are Factory acceptance tests on water fraction meters and multiphase meters, where CMR is an independent third party. It should be noted that the flow loop is not an accredited flow loop. Hence, the facility itself is not approved for calibration purposes. However, the reference instrumentation is subject to calibration once a year, and should therefore comply with general requirements for such a multiphase flow facility. A 3-inch Flowsys TopFlow was tested at CMR in 2000. Shortly after the CMR test, the meter was tested at NEL. Development of this meter was too late for the multiphase metering Joint Industry Projects run by NEL which provided data shown in Sections 7.3.1 and 7.3.2 for Schlumberger and Roxar. The test conditions for the Flowsys meter test were selected from the test matrix used for the Multiflow 2 Joint Industry Project, and the test procedures were similar, so the data is of equal value. The Trecate test loop was built in the years 1992-93, mainly to test multiphase meters and pumps, but it has also been used to test novel separators and ejectors as well, to collect fluid dynamic data for multiphase code qualification. The loop is located in the Trecate 2 satellite area of the Trecate/Villafortuna field outside Milan, Italy. A 3-inch Flowsys TopFlow meter was tested at Trecate in 2001. The fluids were mainly taken from two different wells: the TR 20 with nominally no water and the TR 10 with water cut in the range of 45%. All three data sets have been provided to the project by FMC.

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Figure 7.27: FMC oil flowrate vs. reference oil flowrate 25 +/- 10% relative error Flowsys, CMR, 2000 Flowsys, NEL, 2000 Flowsys, Trecate, 2001

20

Flowsys, Prudhoe Bay, 2003

) d n o c e s / s 15 e r t i l ( e t a r w o l f 10 l i o r e t e M 5

0 0

5

10

15

20

25

80

100


Figure 7.28: FMC oil flowrate error vs. reference GVF 50 +/- 10% relative error Flowsys, CMR, 2000

40

Flowsys, NEL, 2000

) 30 e c n e r e 20 f e r o t e 10 v i t a l e r 0 % ( r o r r -10 e e t a r -20 w o l f l i O-30

Flowsys, Trecate, 2001 Flowsys, Prudhoe Bay, 2003

-40

-50 0

20

40

60

Reference GVF (%)


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Figure 7.29: FMC water flowrate vs. reference water flowrate 16 +/- 10% relative error Flowsys, CMR, 2000 14

Flowsys, NEL, 2000 Flowsys, Trecate, 2001

) 12 d n o c e s / s 10 e r t i l ( e t a r 8 w o l f r e t a 6 w r e t e M 4


2

0 0

2

4

6

8

10

12

14

16


Figure 7.30: FMC water flowrate error vs. reference GVF 50 +/- 10% relative error Flowsys, CMR, 2000

40

Flowsys, NEL, 2000

) e 30 c n e r e f e r 20 o t e v i t 10 a l e r


0 % ( r o r r e -10 e t a r w-20 o l f r e t a -30 W -40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

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Figure 7.31: FMC liquid flowrate vs. reference liquid flowrate 30 +/- 5% relative error Flowsys, CMR, 2000 Flowsys, NEL, 2000 25

Flowsys, Trecate, 2001

) d n o c e 20 s / s e r t i l ( e t a r 15 w o l f d i u q i l 10 r e t e M


5

0 0

5

10

15

20

25

30


Figure 7.32: FMC liquid flowrate error vs. reference GVF 50 +/- 5% relative error Flowsys, CMR, 2000

40


Flowsys, NEL, 2000 Flowsys, Trecate, 2001 Flowsys, Prudhoe Bay, 2003

-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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Figure 7.33: FMC gas flowrate vs. reference gas flowrate 100 +/- 10% relative error Flowsys, CMR, 2000

90


80


) d n 70 o c e s / s 60 e r t i l ( e t 50 a r w o l f 40 s a g r e 30 t e M 20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100


Figure 7.34: FMC gas flowrate error vs. reference GVF 50 +/- 10% relative error 40

Flowsys, CMR, 2000 Flowsys, NEL, 2000



0


-50 0

10

20

30

40

50

60

70

Reference GVF (%)

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Figure 7.35: FMC water cut vs. reference water cut 100 +/- 5% absolute error Flowsys, CMR, 2000

90


80

Flowsys, Prudhoe Bay, 2003 70

) % ( 60 t u c r e 50 t a w r e t e 40 M 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

70

80

90

100


Figure 7.36: FMC water cut error vs. reference GVF 25 +/- 5% absolute error Flowsys, CMR, 2000

20

Flowsys, NEL, 2000

) e 15 c n e r e f e 10 r


m o r 5 f e t u l o s 0 b a % ( r -5 o r r e t u -10 c r e t a W-15 -20

-25 0

10

20

30

40

50

60

Reference GVF (%)


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Figure 7.37: FMC GVF vs. reference GVF 100 +/- 5% absolute error Flowsys, CMR, 2000

90


80

Flowsys, Prudhoe Bay, 2003 70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

70

80

90

100

Reference GVF (%)

Figure 7.38: FMC GVF error vs. reference GVF 15 +/- 5% absolute error Flowsys, CMR, 2000 Flowsys, NEL, 2000

10

Flowsys, Trecate, 2001



-10

-15 0

10

20

30

40

50

60

Reference GVF (%)

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7.4

Comparison with laboratory test data (repeatability)

Repeatability data is available from the NEL tests of the Schlumberger VX-52 and Fluenta MPFM1900VI meters. Repeatability has been calculated from that data using the same methods used for repeatability assessment of the current data. For each of the parameters liquid flowrate, gas flowrate and water cut the repeatability is calculated as: repeatability =



RMS repeatability =


The results are shown in Figure 7.39 and Figure 7.40 f or the Schlumberger and Roxar multiphase flow meters, against GVF. Although test results from different meters are being compared in both cases, the behaviour of RMS repeatability against GVF is very similar for the two tests of each meter.


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CONFIDENTIAL

Figure 7.39: Repeatability of Schlumberger VX multiphase flow meters 12 VX52, NEL, 1999 VX29, Prudhoe Bay, 2003 10

) 8 % S M R ( y t i l 6 i b a t a e p e R 4

2

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 7.40: Repeatability of Roxar MPFM1900VI multiphase flow meters 30 Fluenta, NEL, 1999 Roxar, Prudhoe Bay, 2003 25

) 20 % S M R ( y t i 15 l i b a t a e p e R10

5

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

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8

MULTIPHASE METER EVALUATION

GPB performed this field trial with the intent of identifying the potential for practical application of one or more multiphase flow meters in a number of different scenarios. Specifically, potential applications are seen in: • • • •

portable (compliance) well testing new builds (meter on every well) replacing or complementing an existing pad separator, and augmenting an existing pad separator.

The first step is to determine which meters qualify for a particular application, usually a function of meter performance at expected GVFs. Assuming more than one meter qualified, the second step would be a more holistic evaluation of meter applicability. Each of these scenarios is unique in its requirements for installation, operability, and performance (accuracy, precision, and repeatability), and thus it was desirable to have a consistent methodology by which to rank the applicability of each meter in an unbiased fashion. This section describes the development steps for the Kepner-Tregoe matrix that was employed to enact the most unbiased evaluation possible. In this manner, each meter was evaluated holistically, notably without undue weighting on accuracy or any other single element, which could result in an unsuccessful installation.

8.1

Operating area

One of the primary goals of this field trail was to qualify one or more meters for a number of different applications. In order for a MFM to qualify for an application, it must have acceptable performance (accuracy, precision, and repeatability) for the wells it will be used to monitor. As MFM performance is strongly a function of GVF, it follows that each meter will have an upper limit of GVF at which it successfully meters multiphase flow. This upper GVF limit was defined at the point of significant deviation from standard meter performance, for any of the three basic measurements: water cut, gas rate, or total fluid rate. The lowest GVF that caused significant deviation defined the operating envelope for each meter (if a meter performed adequately up to 98% GVF on liquid rate and gas rate, but had difficulty with water cut at 95% GVF, the acceptable GVF limit would be 95%). Some of the operating envelopes were constrained by only one measurement, others by all three. The operating envelope for each meter is overlaid on a plot of producing GVF for Prudhoe Bay, to illustrate both the reservoir mechanisms (gravity drainage, waterflood) and the percentage of wells at relatively high GVF. It should be noted that lift mechanism has a significant impact on producing GVF, with jet pumped and ESP lifted wells at significantly lower GVF than gas lifted wells.


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CONFIDENTIAL

Figure 8.1 shows the water cut and GVF of the most recent tests of all the wells in the Greater Prudhoe Bay field, and then Figure 8.2 to Figure 8.5 show the qualified operating envelopes for each of the multiphase flow meters tested.

•

Agar (Figure 8.2) was limited to ~95% GVF based only on total fluid rate deviations from the standard.

•

FMC (Figure 8.3) was limited to ~93% based on liquid rate, gas rate, and water cut.

•

Roxar (Figure 8.4) was limited to ~88% GVF based on gas rate.

•

Schlumberger (Figure 8.5) was limited to ~95% GVF based on liquid rate, gas rate, and water cut.

Figure 8.1: GPB well test map 100

75

% t u c 50 r e t a W

GD Endicott MPU ESP_JP MPU GL AUR_BOR GDWFI GPMA

25

PERIPHERY PT MAC PBU SAG PBU VISCOUS WF

0 0

25

50

75

100

GVF %

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Figure 8.2: GPB well test map, showing Agar-401 qualified operating envelope

Agar Qualification for Prudhoe Producing Wells 100

75

% C50 W 25

0

85

90

GVF %

95

MPFM Trial Gravity Drainage Other Satellites GDWFI

100

Waterflood

Figure 8.3: GPB well test map, showing FMC-Flowsys qualified operating envelope

FMC Qualification for Prudhoe Producing Wells 100

75

% C50 W 25

0

85

90

MPFM Trial

GVF %

95

100

Gravity Drainage Other Satellites GDWFI Waterflood


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Figure 8.4: GPB well test map, showing Roxar MPFM1900VI qualified operating envelope

Roxar Qualification for Prudhoe Producing Wells

100

75

% C50 W

25

0

85

90

MPFM Trial

Gravity Drainage

GVF %

95

Other Satellites

100

GDWFI

Waterflood

Figure 8.5: GPB well test map, showing Schlumberger VX29 qualified operating envelope

SLB Qualification for Prudhoe Producing Wells 100

75

% C50 W 25

0

85

90

GVF %

95

MPFM Trial Gravity Drainage Other Satellites GDWFI

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100

Waterflood


CONFIDENTIAL

8.2

Three phase metering evaluation criteria

Assuming the MFM in question qualified for an application based upon the GVF of the wells to be tested, then a more detailed evaluation of meter applicability is warranted. The decision matrix to assist with this evaluation was developed through the following steps: • • •

•

Identification and clarification of the key components of initial installation, performance (accuracy and precision), and operability. Weighting of these key components appropriately for portable testing, new builds, pad separator replacement, and pad separator augmentation. Each meter given a score to reflect its performance in that specific category. When possible, data was used to generate the most objective score possible for a particular category, though some categories require subjective interpretation. Multiplication of the meter score with the criteria weighting to yield a weighted final score for each application.

I t sh o u l d b e n o t ed t h a t f o r a m et er r ec om m en d a t i o n sp ec i f i c t o a n o t h er si t e, a si m i l a r f o r m a t c o u l d b e u s ed t o m a k e t h e m o st a p p r o p r i a t e d ec i si o n , b a sed u p o n t h e q u a n t i t a t i v e p er f or m a n ce d a t a f r om t h i s f i el d t r i a l , c om b i n ed w i t h si t e-sp ec i f i c r eq u i r em e n t s f o r i n s t a l l a t i o n , o p er a b i l i t y , a n d a c c u r a c y . 8.2.1

I n i t i a l i n st a l l a t i on

The expense to install a meter in the field is clearly dependent upon issues such as initial calibration requirements, connection to data acquisition system requirements, retrofitting for arctic conditions, design and install of peripheral systems (safety, fire and gas), etc. Depending on the number of meters in question and their application, the relative importance of the initial installation varies. Within the general category of Initial Installation, each meter will be evaluated with respect to the following elements: Mechanical design: Elements taken into consideration are primarily simplicity of design, requirements of peripheral systems, and footprint. The number of components with potential to erode, break down, or have another form of mechanical failure is taken into account in the Operability Section, via the Intervention and Repair category. E&I: Ease of connections to EIA (Electronics Industry Association) RS485 data communication systems, electrical ratings, etc. Calibration (initial): The initial calibration required depends upon each meter, including in situ measurements of oil and water, gas chromatograph analysis of samples, viscosity measurements, flow rate calibrations, etc. The level of sampling and initial calibration speaks directly to the ease of operation of the unit to achieve acceptable accuracy.


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8 .2 .2

Perf or m an ce

Determining the ability of each meter to measure production rates of oil, water, and gas accurately and consistently was one of the primary objectives of the field trial. The level of accuracy required, however, is not entirely straightforward, as performance requirements also are dictated by the application chosen. Meter scores in the Performance category are generated entirely from statistical analysis of the test results to provide an objective evaluation of each meter. The numerical method by which the meters were scored is described in detail in this section. Within the general category of Performance, each meter will be evaluated with respect to the following elements: Total liquid rate, gas flow rate, and water cut accuracy (5% criteria): The first calculation recognises the value of accuracy and weights the results accordingly. Each test point is rated according to its deviation from the reference value for liquid flowrate, gas flowrate, and water cut. A value of 5 is allocated if the liquid or gas flowrate is within ±5%, and the water cut is within ±1%; a value of 2 is allocated if the liquid or gas flowrate is within ±10%, and the water cut is within ±2%; a value of 0 is allocated if the deviations lie outside these ranges. To allow for uncertainty in the ASRC reference data, an allowance of 5% on liquid flowrate, 2% on gas flowrate and 0.5% on water cut has been made before calculating the above scores. The points are totalled and then divided by the number of test points to give a normalised score. Large deviations from the standard have no effect on this rating, value is given only to those close to the reference. Total liquid rate, gas flow rate, and water cut RMS average: The root-mean-square average has been calculated for the deviations between the MFM readings and the ASRC reference values for liquid flowrate, gas flowrate and water cut. This tends to produce a large average value, since all points are used in calculating the average. The lower the RMS average, the tighter the scatter around the benchmark and the better the reliability of the measurements. This calculation penalizes proportionately for values that differ significantly from the standard. Proportion of points within range: For this evaluation, the proportion of test points has been evaluated where the deviation between the MFM and the ASRC reference is within a specified range. For liquid and gas flowrate the range is ±10% error (relative to the standard), and for water cut the range is ±2% error (absolute error based upon 0100% full range). To allow for uncertainty in the ASRC reference data, an allowance of 5% on liquid flowrate, 2% on gas flowrate and 0.5% on water cut has been made before calculating the above scores. This measurement does not penalize for large deviations from the standard, and provides a bit more leniency on matching the standard, in effect downplaying the importance of matching the ASRC standard precisely. A final calculation has been made of the proportion of test points where the combined error calculated by the equation below lies within ±10%:

RMS error =

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(relative % error in QL )2 + (relative % error in QG )2 + (absolute % error in WC)2 3


CONFIDENTIAL

The other evaluation criteria rate meter performance on each measurement (liquid rate, gas rate, water cut) individually. This total measurement rates each meter on accuracy of all three measurements simultaneously for a given well test. Effect of high GVF or low liquid rate: Each of the meters has a specified operating envelope over which they claim to have accurate metering ability. In the practical application of such a meter, there may be instances where wells outside the operating envelope are tested. This rating is a quantitative measurement of the degradation in measurement accuracy outside the operating envelope, specifically at a low total liquid rate or high GVF. For simplicity’s sake, the “restricted envelope” was defined as liquid rate >1100 stb/d and GVF <95% for each meter. The same calculations described above (5% criteria, RMS, proportion of points within range) were performed over the entire data set. The difference in relative accuracy was used as a measure of the sensitivity to the operating envelope. The evaluation in the restricted envelope was termed “in-envelope performance” and the evaluation using all data was termed “full range performance”. Consistency (repeatability): The repeatability of a measurement is an important characteristic for both continuous monitoring and spot-testing of production wells, and also speaks the confidence in any given measurement. During the course of the test, some wells were tested multiple times, allowing for the evaluation of the consistency of the meter performance. The repeatability of each measurement (liquid, water cut, and gas) was performed for each well according to the following calculation: repeatability =


Finally, an overall repeatability score was calculated, similar to the combined RMS error described above, which accounts for overall repeatability of the liquid rate, water cut, and gas rate measurements from one test to the next, for a given well:

Combined repeatabil ity =

8 .2 .3

(liquid repeatabil ity)2 +

(water cut repeatabil ity )2 +

(gas repeatabil ity)2

3

O p er a b i l i t y

Depending upon the application, ease and simplicity of operation of the multiphase unit can be of critical importance. GPB and most mature assets are continually struggling to reduce O&M costs, requiring that any new equipment permanently installed in the field should need minimal oversight. Any successful installation of a MPM will realise the value of the investment over the full lifespan of the equipment, which requires buy-in from Operations personnel. Within the general category of Operability, each meter will be evaluated with respect to the following elements: HSE issues: Any installation in the field must be rated for the appropriate pressure and allow for safe operation of the unit. Potential for overpressure, mechanical failure leading to environmental release, and handling requirements for radioactive sources will be taken into consideration. Exploration & Production Technology Group

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Service: None of the multiphase flow meters are simplistic enough to justify extensive maintenance and troubleshooting by the resident instrument technicians and electricians available to Operations. Any detailed troubleshooting of the meter will require service from the vendor. The timeliness and competence of this service, as well as replacement parts and materials, are important elements of a sustainable installation. Expected O&M cost: Relative estimates of operating expense were made, depending on the application and the level of service necessary to both maintain and operate the units. O&M costs need to be taken into consideration for any permanent installation in the field. Calibration (periodic): All meters require periodic verification, simply as assurance if not for actual calibration. The level of re-calibration necessary to ensure measurement integrity is also variable among the meters and speaks to medium-term operability. Intervention / repair: Anticipated long term interventions and repairs are difficult to evaluate due to the limited timeframe of this field trial. However, based upon the intervention and repair during the test some general conclusions can be reached. Additionally, the mechanical design of the meters and the potential for elements to erode, break down, or have another form of mechanical failure is taken into account Data interface (downloading / reset / restart): The primary point of interaction between the operator and the meter will be the data interface, the PC and software used to evaluate meter performance and troubleshoot both the meter and well performance. It is thus desirable to have a clear, understandable, user-friendly frontend interface.

8.3

Weighting of the multiphase metering evaluation criteria

The first exercise weighted the major categories (Initial Installation, Performance, and Operability) appropriately for the application under discussion. For example, it was deemed that for portable well testing, Initial Installation would be worth 10% of the entire score, due to limited long term impacts to operations and O&M. However, for the new build application, this category was significantly more important, and was weighted to 30% of the total score. The second level of weighting was performed within each of the major categories, where each component was weighted on a scale of 1-10, again within the context of each application being considered (portable testing, retrofit, etc.). This process was done without respect to how each meter performed, providing for an impartial ranking process, as per the Kepner-Tregoe decision model. For the qualitative issues, the category weighting and meter performance evaluations were performed by Brady, Hasebe, and Smith, and endorsed by BP upper management. Table 8.1 lists the criteria discussed above and the weighting used for each application.

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8.4

Scoring and ranking of multiphase meters

Each meter was ranked from 0-10 on its performance against each criterion, without consideration consideratio n to the category’s relative weighting. Evaluation in the Performance category was based strictly upon statistical analysis of the test results, in an effort to objectify objectif y the conclusion as much as possible. Meter performance in the Initial Installation and Operability categories was again evaluated by Brady, Hasebe, and Smith and confirmed by BP upper management. The overall score obtained at the end of the exercise was then used as the relative recommendation for each application. Meter performance, without regard to relative importance or weighting for each potential application, is identified in Table Table 8.2. The weighting of the evaluation criteria is then multiplied mul tiplied by the meter the meter performance performance for each application, yielding the rankings shown in Figure F igure 8.6 to to Figure Figure 8.9.


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CONFIDENTIAL

Table 8.1: Multiphase meter evaluation – criteria weighting

Initial Installation Mechanical Design (footprint) E&I (hookup) Calibration (Initial) Total Possible Score

Performance In-Envelope Performance 5% Criteria Liquid Flowrate 5% Criteria Gas Flowrate 5% Criteria W atercut RMS Liquid Flowrate RMS Gas Flowrate RMS W atercut % in Range Liquid Flowrate % in Range Gas Flowrate % in Range W atercut % in Range Combined Full Range Performance 5% Criteria Liquid Flowrate 5% Criteria Gas Flowrate 5% Criteria W atercut RMS Liquid Flowrate RMS Gas Flowrate RMS W atercut % in Range Liquid Flowrate % in Range Gas Flowrate % in Range W atercut % in Range Combined Repeatability RMS Liquid Rate RMS Gas Rate RMS W atercut RMS Combined Repeatability Total Possible Score

Operability HSE Issues Service (vendor support) Expected O&M cost Calibration (Periodic) Intervention/Repair Data Interface Total Possible Score

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Portable Well Testing 10 Points 7 1 8

New Build (every well) 30 Points 8 8 7

WPS Replacement 10 Points 2 5 3

WPS Augmentation 10 Points 7 5 3

160

230

100

150

70 Points

30 Points

60 Points

60 Points

7 5 6 7 5 6 6 5 5 9

4 2 3 4 2 3 3 2 2 6

6 4 5 6 4 5 5 4 4 8

6 4 5 6 4 5 5 4 4 8

2 2 2 2 2 2 2 2 2 3

0 0 0 0 0 0 0 0 0 0

3 3 3 3 3 3 3 3 3 4

3 3 3 3 3 3 3 3 3 4

7 6 7 9

5 4 5 6

6 5 6 8

6 5 6 8

1110

510

1070

1070

20 Points 9 7 3 0 1 1

40 Points 7 10 9 9 9 8

30 Points 5 5 5 5 5 5

30 Points 5 5 5 5 5 5

210

520

300

300


CONFIDENTIAL

Table 8.2: Multiphase meter evaluation – meter pe rformance

AGAR

FMC

Roxar

Schlumberger

SLB raw

4 5 9

9 9 7

9 7 6

9 9 1

9 9 6

8.8 8.3 5.0 8.4 8.8 9.3 9.5 9.0 6.7 9.0

7.4 6.5 2.5 5.7 4.7 7.6 7.6 7.1 2.9 7.1

8.4 2.9 2.9 7.4 7.1 5.8 8.9 3.3 3.3 4.4

9.0 7.7 4.9 8.5 9.1 7.8 10.0 9.6 5.2 9.6

8.2 9.3 3.6 8.4 9.4 7.3 8.6 10.0 3.8 8.6

7.3 8.1 4.7 9.0 9.1 8.6 8.3 9.0 6.0 8.0

5.2 5.8 2.4 4.3 5.9 7.1 5.3 6.4 2.4 5.3

4.8 1.4 2.3 7.9 6.3 7.5 5.7 1.7 2.6 1.7

7.8 5.3 4.0 8.9 8.8 7.5 8.9 6.8 4.3 7.7

6.6 5.0 1.9 8.8 8.6 6.8 7.2 5.7 2.2 5.7

8.4 8.4 8.9 8.5

5.8 6.8 7.1 6.2

7.5 6.3 7.5 7.2

8.4 8.5 6.5 8.1

8.2 8.4 5.9 7.8

4 5 5 8 3 5

10 7 8 5 6 8

6 3 6 5 6 8

6 10 2 1 5 6

6 10 4 5 5 6

Initial Installation Mechanical Design (footprint) E&I (hookup) Calibration (Initial)

Performance In-Envelope Performance 5% Criteria Liquid Flowrate 5% Criteria Gas Flowrate 5% Criteria W atercut RMS Liquid Flowrate RMS Gas Flowrate RMS W atercut % in Range Liquid Flowrate % in Range Gas Flowrate % in Range W atercut % in Range Combined

Full Range Performance 5% Criteria Liquid Flowrate 5% Criteria Gas Flowrate 5% Criteria W atercut RMS Liquid Flowrate RMS Gas Flowrate RMS W atercut % in Range Liquid Flowrate % in Range Gas Flowrate % in Range W atercut % in Range Combined

Repeatability RMS Liquid Rate RMS Gas Rate RMS W atercut RMS Combined Repeatability

Operability HSE Issues Service (vendor support) Expected O&M cost Calibration (Periodic) Intervention/Repair Data Interface


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CONFIDENTIAL

Figure 8.6: Overall score for portable well testing (Assuming majority of wells lie in meter operating range)

73.7%

Schlumberger

73.6%

AGAR

70.2%

SLB raw

66.5%

FMC

Roxar 0%

57.5% 25%

50%

75%

100%

Figure 8.7: Overall score for well pad separator new build (Assuming majority of wells lie in meter operating range)

72.8%

FMC

70.5%

SLB raw

Schlumberger

64.2%

Roxar

63.2%

AGAR

63.1%

0%

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25%

50%

75%

100%


CONFIDENTIAL

Figure 8.8: Overall score for well pad separator replacement (Assuming majority of wells lie in meter operating range)

70.4%

AGAR

68.4%

Schlumberger

SLB raw

67.1%

FMC

65.5%

Roxar 0%

57.3% 25%

50%

75%

100%

Figure 8.9: Overall score for well pad separator augmentation (Assuming majority of wells lie in meter operating range)

69.8%

AGAR

69.2%

Schlumberger

SLB raw

67.4%

FMC

65.7%

Roxar 0%

57.9% 25%


50%

75%

100%

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CONFIDENTIAL

8.5

Meter liquid rate measurement at low liquid rates

It was noted after analysis of the performance of the meters, particularly when all meters were compared together, that the Agar and Schlumberger total fluid data sets were very similar. Both meters measured the total fluid rate with minimal scatter and indicated slightly higher rates than the ASRC standard, particularly at the lower range. Due to the extremely different measurement principles behind the Agar and Schlumberger meters, this began to raise the question of potential under-reading by ASRC, possibly due to gas breakout or carry-under through the MicroMotion Coriolis meter. An analysis of the dP across a 3-inch Venturi such as that used by Schlumberger, shown in Section 6.8, indicated very reasonable dP for the wells tested, therefore indicating the Venturi was reasonably sized and there should be no systematic error in the liquid measurement due to low flow rate. This further raises confidence that the Agar and Schlumberger meters may have independently verified a reading closer to the true liquid rate. Figure 8.10 shows the Agar and Schlumberger total fluid rate best fit lines, overlaid on the Agar data points. Figure 8.10: Best fit to Agar and Schlumberger liquid flowrate measurement data 3500 +/- 5% relative error AGAR-401: all points 3000

AGAR-401: limited operating envelope limited operating envelope

) d / 2500 b t s ( e t a r 2000 w o l f d i 1500 u q i l r e t e 1000 M

Linear SLB-r Best Fit Linear (AGAR-401: ALL data)

AGAR Best Fit Line: Y = 0.9149x + 207.44 2

R = 0.9745 SLB Best Fit Line: Y = 0.9002x + 195.53 2

R = 0.9786 500

0 0

500

1000

1500

2000

2500

3000

3500


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CONFIDENTIAL

This realization indicates that both Agar and Schlumberger’s liquid rate measurement may qualify over the entire range of GVF, up to > 99%. This has the most significant implications for the qualification of the Agar meter, as it showed no significant deviation at high GVF on either gas or water cut measurements, indicating the meter may qualify for metering wells at a full range of GVF. Because the Schlumberger meter still showed significant deviation in gas and water cut measurement above 95% GVF, it still would not qualify for metering wells above 95%. Similarly, this analysis does not change the qualification ranges of the Roxar or FMC meters.


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CONFIDENTIAL

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CONFIDENTIAL

9

AGAR-401 MULTIPHASE FLOW METER

9.1

Description of the meter

The Agar MPFM-401 series multiphase flow meter consists of an Agar MPFM-300 series multiphase flow meter modified by the addition of a Fluidic Flow Diverter (FFD®) device and a gas bypass loop. The FFD® device uses the difference in flow momentum of the gas and liquid to divert most of the free gas in the multiphase stream into a secondary measurement loop around the core MPFM-300. The secondary measurement loop is a ‘wet gas’ metering system consisting of a Venturi and a vortex shedding flow meter in series. The remaining liquids flow through the core MPFM-300 series system. The gas in the bypass loop is metered and added to the oil, water and gas measured through the core multiphase meter. By reducing the amount of gas flowing through the core multiphase meter, a smaller meter can be used, and the accuracy of the multiphase measurement is increased as a result of decrease in the GVF. The MPFM-300 series multiphase flow meter has three main components: a positive displacement meter which measures the total volumetric flowrate; a momentum meter (dual Venturi meter) which measures the gas fraction of the flow; and a microwave monitor which measures the water cut of the liquid. Figure 9.1: Schematic diagram of Agar MPFM-400 series multiphase flow meter


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CONFIDENTIAL

Figure 9.2: Photograph of the Agar-401 multiphase flow meter at the test site

9.2

Summary statistics

Three methods have been used to quantify the measurement performance of the multiphase flow meters. 9 .2 .1

5% cr i teri a

The first calculation recognises the value of low measurement uncertainty and weights the results accordingly. Each test point is rated according to its deviation from the reference value for liquid flowrate, gas flowrate, and water cut. A value of 5 is allocated if the liquid or gas flowrate is within ±5%, and the water cut is within ±1%; a value of 2 is allocated if the liquid or gas flowrate is within ±10%, and the water cut is within ±2%; a value of 0 is allocated if the deviations lie outwith these ranges. To allow for uncertainty in the ASRC reference data, an allowance of 5% on liquid flowrate, 2% on gas flowrate and 0.5% on water cut has been made before calculating the above scores. The points are totalled and then divided by the number of test points to give a normalised score. The values for the Agar meter are shown in Table 9.1.

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Table 9.1: Summary scores for multiphase flow meter 5% criteria AGAR


3.6 4.1 2.4

AGAR GVF < 95% Liquid > 1100 stb/d 4.4 4.1 2.5

TOTAL score

10.0

11.0

All data

9 .2 .2

RM S aver ag e

The root-mean-square average has been calculated for the deviations between the MFM readings and the ASRC reference values for liquid flowrate, gas flowrate and water cut. This tends to produce a large average value, since all points are used in calculating the average. The RMS average values are shown in Table 9.2. Table 9.2: RMS average multiphase flow meter deviations AGAR

AGAR GVF < 95% Liquid > 1100 stb/d 8.3 10.0 2.3

All data Liquid flowrate Gas flowrate Water cut 9 .2 .3

12.3 8.8 5.6



RMS error =

(relative % error in QL )2 + (relative % error in QG )2 + (absolute % error in WC)2


3

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CONFIDENTIAL

Table 9.3: proportion of points within range AGAR All data Liquid flowrate Gas flowrate Water cut Combined error

9.3

82.5 90.0 60.0 80.0

AGAR GVF < 95% Liquid > 1100 stb/d 95.2 90.5 66.7 90.5

Test results (measurement accuracy)

The test results for the Agar-401 multiphase flow meter are shown in Figure 9.3 to Figure 9.26. Several types of graphs are used to demonstrate the measurement accuracy of the meter. Figure 9.3 shows the oil flowrate from the multiphase flow meter plotted against the oil flowrate from the ASRC test separator reference. For perfect agreement between the multiphase flow meter and the test separator reference, the points would lie on the solid diagonal line. The dashed diagonal lines show a ±10% deviation from the reference values. Figure 9.4 shows the percentage error in the oil flowrate measurement from the multiphase flow meter (relative to the test separator reference) plotted against the gas volume fraction. This comparison is used because normally the GVF has the biggest influence on multiphase flow meter uncertainty, and can be seen to be true in this case as the oil flowrate errors increase with GVF. Figure 9.5 shows the error in the oil flowrate measurement plotted against water cut and GVF. The error is represented by a different coloured point depending whether it is < 10% (green), <25% (blue), < 50% (red) or >50% (black). Clearly the ideal multiphase flow measurement behaviour would be to have entirely green points on this plot. These plots can be useful to isolate any separate influence of water cut on the measurement, compared to the stronger trends with GVF. Similar plots are given for water flowrate, liquid flowrate, gas flowrate, water cut , GVF and GOR. For flowrates and GOR the errors are evaluated as relative percentage errors: Relative error = (Meter reading – reference reading) / Reference reading while for water cut and GVF the errors are expressed as absolute deviations, Absolute error = Meter reading – reference reading Figure 9.24 shows the flowrate errors as a histogram in bands of ±10%, 25%, 50% and > 50% errors.

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In Figure 9.25 and Figure 9.26 the cumulative error plotted in the y-axis is the proportion of test points giving an error less than or equal to the value on the x-axis. For example on Figure 9.25, 34% of test points had an oil flowrate error within ±10%. For the curve in Figure 9.26, RMS error is defined as:

RMS error =

(relative % error in QL )2 + (relative % error in QG )2 + (absolute % error in WC)2


3

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CONFIDENTIAL

Figure 9.3: Agar 401 oil flowrate vs. ASRC reference oil flowrate 2500 +/- 10% relative error AGAR-401: all points AGAR-401: limited operating envelope 2000

) d / b t s 1500 ( e t a r w o l f l i o r 1000 e t e M

500

0 0

500

1000

1500

2000

2500

80

100


Figure 9.4: Agar 401 oil flowrate error vs. ASRC reference GVF 50 +/- 10% relative error AGAR-401: all points

40


) 30 e c n e r e 20 f e r o t e 10 v i t a l e r 0 % ( r o r r -10 e e t a r -20 w o l f l i O-30 -40

-50 0

20

40

60

Reference GVF (%)

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CONFIDENTIAL

Figure 9.5: Agar 401 oil flowrate error vs. ASRC reference GVF and water cut 100

90

80

70

) % ( t 60 u c r e t a w 50 e c n e r 40 e f e R

Oil flowrate error < -50% -50% to -25% -25% to -10% -10% to +10% +10% to +25% +25% to +50% > +50%

30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 9.6: Agar 401 water flowrate vs. ASRC reference water flowrate 2500 +/- 10% relative error AGAR-401: all points AGAR-401: limited operating envelope 2000


500

0 0

500

1000

1500

2000

2500



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CONFIDENTIAL

Figure 9.7: Agar 401 water flowrate error vs. ASRC reference GVF 50 +/- 10% relative error AGAR-401: all points

40


) e 30 c n e r e f 20 e r o t e v i t 10 a l e r

limited operating envelope

0 % ( r o r r e -10 e t a r w-20 o l f r e t a -30 W -40

-50 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 9.8: Agar 401 water flowrate error vs. ASRC reference GVF and water cut 100

90

80

70


Water flowrate error < -50% -50% to -25% -25% to -10% -10% to +10% +10% to +25% +25% to +50% > +50%

30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)

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CONFIDENTIAL

Figure 9.9: Agar 401 liquid flowrate vs. ASRC reference liquid flowrate 3500 +/- 5% relative error AGAR-401: all points AGAR-401: limited operating envelope

3000


2500

) d / b t s ( e t 2000 a r w o l f d i u 1500 q i l r e t e M 1000

500

0 0

500

1000

1500

2000

2500

3000

3500


Figure 9.10: Agar 401 liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error AGAR-401: all points

40



-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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CONFIDENTIAL

Figure 9.11: Agar 401 liquid flowrate error vs. ASRC reference GVF and water cut 100

90

80

70


Liquid flowrate error < -50% -50% to -25% -25% to -10% -10% to +10% +10% to +25% +25% to +50% > +50%

30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 9.12: Agar 401 gas flowrate vs. ASRC reference gas flowrate 8.0 +/- 10% relative error AGAR-401: all points 7.0


6.0

) d / f c s M5.0 M ( e t a r 4.0 w o l f s a g 3.0 r e t e M 2.0

1.0

0.0 0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0


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CONFIDENTIAL

Figure 9.13: Agar 401 gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error AGAR-401: all points

40


) 30 e c n e r e f 20 e r o t e 10 v i t a l e r

0

% ( r o r r e -10 e t a r w-20 o l f s a G-30 -40

-50 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 9.14: Agar 401 gas flowrate error vs. ASRC reference GVF and water cut 100

90

80

70

) % ( t 60 u c r e t a w 50 e c n e r e 40 f e R

Gas flowrate error < -50% -50% to -25% -25% to -10% -10% to +10% +10% to +25% +25% to +50% > +50%

30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)


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CONFIDENTIAL

Figure 9.15: Agar 401 water cut vs. ASRC reference water cut 100 +/- 5% absolute error AGAR-401: all points

90

AGAR-401: limited operating envelope 80

70

) % ( 60 t u c r e 50 t a w r e t 40 e M 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100


Figure 9.16: Agar 401 water cut error vs. ASRC reference GVF 25 +/- 5% absolute error AGAR-401: all points

20

AGAR-401: limited operating envelope envelope



-20

-25 0

10

20

30

40

50

60

70

Reference GVF (%)

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CONFIDENTIAL

Figure 9.17: Agar 401 water cut error vs. ASRC reference GVF and water cut 100

90

80

70

Watercut error


< -25% -25% to -10% -10% to -5% -5% to +5% +5% to +10% +10% to +25% > +25%

30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

70

80

90

100

Reference GVF (%)

Figure 9.18: Agar 401 GVF vs. ASRC reference GVF 100 +/- 5% absolute error AGAR-401: all points

90

AGAR-401: limited operating envelope envelope limited operating envelope

80

70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

Reference GVF (%)


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CONFIDENTIAL

Figure 9.19: Agar 401 GVF error vs. ASRC reference GVF 15 +/- 5% absolute error AGAR-401: all points AGAR-401: limited operating envelope 10


) e c n e r e f 5 e r m o r f e t u 0 l o s b a % ( r o -5 r r e F V G -10

-15 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 9.20: Agar 401 GVF error vs. ASRC reference GVF and water cut 100

90

80

70

) % ( t 60 u c r e t a w 50 e c n e r e 40 f e R

GVF error < -25% -25% to -10% -10% to -5% -5% to +5% +5% to +10% +10% to +25% > +25%

30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)

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CONFIDENTIAL

Figure 9.21: Agar 401 GOR vs. ASRC reference GOR 1.0E+05 +/- 10% absolute error AGAR-401: all points AGAR-401: limited operating envelope

1.0E+04


1.0E+03

1.0E+02 1.0E+02

1.0E+03

1.0E+04

1.0E+05

Meter GOR (scf/stb)

Figure 9.22: Agar 401 GOR error vs. ASRC reference GVF 50 +/- 10% absolute error AGAR-401: all all points

40

AGAR-401: limited operating envelope envelope limited operating envelope

30

) e c n e r 20 e f e r m 10 o r f e v i t 0 a l e r % ( -10 r o r r e -20 R O G -30

-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


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CONFIDENTIAL

Figure 9.23: Agar 401 GOR error vs. ASRC reference GVF and water cut 100

90

80

70


GOR error < -50% -50% to -25% -25% to -10% -10% to +10% +10% to +25% +25% to +50% > +50%

30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 9.24: Agar 401 statistics

100 Oil

Water

Gas

Liquid

90

80

d n a b n i s t n i o p f o e g a t n e c r e P

70

60

50

40

30

20

10

0 < -50

-50 to -25

-25 to -10

-10 to +10

+10 to +25

+25 to +50

> +50

Error band

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CONFIDENTIAL

Figure 9.25: Agar 401 cumulative curves

100

90

80

) % ( 70 s t n i o p 60 f o r e b 50 m u n e v 40 i t a l u m 30 u C 20

Oil flowrate Water flowrate

10

Gas flowrate Water cut

0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Figure 9.26: Agar 401 cumulative curves

100

90

80

) % ( 70 s t n i o p 60 f o r e b 50 m u n e v 40 i t a l u m 30 u C 20 Total liquid flowrate 10

RMS error GOR

0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)


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CONFIDENTIAL

9.4

Test results (repeatability)




RMS repeatability =


The repeatability results are shown in Figure 9.27. It can be seen that repeatability of water cut is very good (always < 3%) while the repeatability of liquid and gas flowrate measurement varies depending on the well under test. Generally the larger repeatability values correspond to the less steady flow conditions. Figures in brackets exclude well V-106. Table 9.4: Repeatability results for the Agar 4 01 multiphase flow meter

Liquid flowrate repeatability 6.4 (5.5)

Agar




3.1 (3.1)

1.4 (1.3)

4.4 (3.9)

Figure 9.27: Agar 401 repeatability 18 Liquid 16

Gas Water cut

14

RMS

12

) % ( y 10 t i l i b a t a e 8 p e R 6

4

2

0 V03

Page 114/264

V101

V102

V103

V106

V107

V107

V108

V109

V113

V117

V202

Average


CONFIDENTIAL Table 9.5: Agar-401 test results (accuracy)

CONFIDENTIAL Table 9.6: Agar-401 test results (repeatability)

CONFIDENTIAL

10

FMC FLOWSYS MULTIPHASE FLOW METER

10.1


The Flowsys TopFlow multiphase flow meter is based on the measurement principles of a Venturi meter, capacitance/conductivity and cross-correlation. The major parts of the TopFlow meter are the Venturi insert and the electrodes incorporated inside the throat of the Venturi. The flowrates of oil, water and gas are calculated based on the measurements obtained by the electrodes and the measurement of the differential pressure across the Venturi inlet. No separating devices, mixers, by-pass lines or radioactive sources are used in the meter. Following a blind tee the flow passes directly upwards through the meter. The velocity (volumetric flowrate) of the multiphase stream is determined by cross-correlation of electrical signals. Since the Venturi meter can also be used to determine the total mass flowrate, these two measurements together can be used to determine the mixture density, and hence gas volume fraction of the flow. The electrical capacitance or conductivity measurement is used to determine the water cut. Figure 10.1: Photograph of the Flowsys multiphase flow meter at the test site


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CONFIDENTIAL 10.2

Summary statistics

Three methods have been used to quantify the measurement performance of the multiphase flow meters. 1 0.2 .1 5 % c r i t e r i a

The first calculation recognises the value of low measurement uncertainty and weights the results accordingly. Each test point is rated according to its deviation from the reference value for liquid flowrate, gas flowrate, and water cut. A value of 5 is allocated if the liquid or gas flowrate is within ±5%, and the water cut is within ±1%; a value of 2 is allocated if the liquid or gas flowrate is within ±10%, and the water cut is within ±2%; a value of 0 is allocated if the deviations lie outwith these ranges. To allow for uncertainty in the ASRC reference data, an allowance of 5% on liquid flowrate, 2% on gas flowrate and 0.5% on water cut has been made before calculating the above scores. The points are totalled and then divided by the number of test points to give a normalised score. The values for the Flowsys meter are shown in Table 10.1. Table 10.1: Summary scores for multiphase flow meter 5% criteria FMC


2.6 2.9 1.2

FMC GVF < 95% Liquid > 1100 stb/d 3.7 3.3 1.3

TOTAL score

6.7

8.2

All data

1 0 .2 .2 R M S a v er a g e

The root-mean-square average has been calculated for the deviations between the MFM readings and the ASRC reference values for liquid flowrate, gas flowrate and water cut. This tends to produce a large average value, since all points are used in calculating the average. The RMS average values are shown in Table 10.2. Table 10.2: RMS average multiphase flow meter deviations FMC All data Liquid flowrate Gas flowrate Water cut

Page 118/264

71.8 41.8 12.0

FMC GVF < 95% Liquid > 1100 stb/d 22.6 44.4 7.8


CONFIDENTIAL

1 0.2 .3 P r o p or t i o n o f p o i n t s w i t h i n r a n g e


RMS error =


Table 10.3: proportion of points within range FMC All data Liquid flowrate Gas flowrate Water cut Combined error

10.3

53.3 64.4 24.4 53.3

FMC GVF < 95% Liquid > 1100 stb/d 76.2 71.4 28.6 71.4


The test results for the FMC Flowsys multiphase flow meter are shown in Fi gure 10.2 to Figure 10.25. Several types of graphs are used to demonstrate the measurement accuracy of the meter. Figure 10.2 shows the oil flowrate from the multiphase flow meter plotted against the oil flowrate from the ASRC test separator reference. For perfect agreement between the multiphase flow meter and the test separator reference, the points would lie on the solid diagonal line. The dashed diagonal lines show a ±10% deviation from the reference values. Figure 10.3 shows the percentage error in the oil flowrate measurement from the multiphase flow meter (relative to the test separator reference) plotted against the gas volume fraction. This comparison is used because normally the GVF has the biggest influence on multiphase flow meter uncertainty, and can be seen to be true in this case as the oil flowrate errors increase with GVF.


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CONFIDENTIAL Figure 10.4 shows the error in the oil flowrate measurement plotted against water cut and GVF. The error is represented by a different coloured point depending whether it is < 10% (green), <25% (blue), < 50% (red) or >50% (black). Clearly the ideal multiphase flow measurement behaviour would be to have entirely green points on this plot. These plots can be useful to isolate any separate influence of water cut on the measurement, compared to the stronger trends with GVF. Similar plots are given for water flowrate, liquid flowrate, gas flowrate, water cut , GVF and GOR. For flowrates and GOR the errors are evaluated as relative percentage errors: Relative error = (Meter reading – reference reading) / Reference reading while for water cut and GVF the errors are expressed as absolute deviations, Absolute error = Meter reading – reference reading Figure 10.23 shows the flowrate errors as a histogram in bands of ±10%, 25%, 50% and > 50% errors. In Figure 10.24 and Figure 10.25 the cumulative error plotted in the y-axis is the proportion of test points giving an error less than or equal to the value on the x-axis. For example on Figure 10.24, 29% of test points had an oil flowrate error within ±10%. For the curve in Figure 10.25, RMS error is defined as:

RMS error =

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CONFIDENTIAL Figure 10.2: FMC Flowsys oil flowrate vs. ASRC reference oil flowrate 2500 +/- 10% relative error FMC-Flowsys: all points FMC-Flowsys: limited operating envelope 2000


500

0 0

500

1000

1500

2000

2500


Figure 10.3: FMC Flowsys oil flowrate error vs. ASRC reference GVF 50 +/- 10% relative error FMC-Flowsys: all points

40

FMC-Flowsys: limited operating envelope limited operating envelope

) 30 e c n e r e 20 f e r o t e 10 v i t a l e r 0 % ( r o r r -10 e e t a r w-20 o l f l i O-30 -40

-50 0

20

40

60

80

100

Reference GVF (%)


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CONFIDENTIAL Figure 10.4: FMC Flowsys oil flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 10.5: FMC Flowsys water flowrate vs. ASRC reference water flowrate 2500 +/- 10% relative error FMC-Flowsys: all points FMC-Flowsys: limited operating envelope 2000


500

0 0

500

1000

1500

2000

2500


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CONFIDENTIAL Figure 10.6: FMC Flowsys water flowrate error vs. ASRC reference GVF 50 +/- 10% relative error FMC-Flowsys: all points

40


) e 30 c n e r e f 20 e r o t e v 10 i t a l e r % 0 ( r o r r e -10 e t a r w-20 o l f r e t a -30 W


-40

-50 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 10.7: FMC Flowsys water flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)


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CONFIDENTIAL Figure 10.8: FMC Flowsys liquid flowrate vs. ASRC reference liquid flowrate 3500 +/- 5% relative error FMC-Flowsys: all points FMC-Flowsys: limited operating envelope

3000


2500


500

0 0

500

1000

1500

2000

2500

3000

3500


Figure 10.9: FMC Flowsys liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error FMC-Flowsys: all points

40



-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 124/264


CONFIDENTIAL Figure 10.10: FMC Flowsys liquid flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 10.11: FMC Flowsys gas flowrate vs. ASRC reference gas flowrate 8.0 +/- 10% relative error FMC-Flowsys: all points 7.0


6.0


1.0

0.0 0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0



Page 125/264

CONFIDENTIAL Figure 10.12: FMC Flowsys gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error FMC-Flowsys: all points

40


) 30 e c n e r e 20 f e r o t e 10 v i t a l e r 0 % ( r o r r -10 e e t a r w-20 o l f s a G-30 -40

-50 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 10.13: FMC Flowsys gas flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)

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CONFIDENTIAL Figure 10.14: FMC Flowsys water cut vs. ASRC reference water cut 100 +/- 5% absolute error FMC-Flowsys: all points

90

FMC-Flowsys: limited operating envelope 80

70

) % 60 ( t u c r e 50 t a w r e t e 40 M 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100


Figure 10.15: FMC Flowsys water cut error vs. ASRC reference GVF 25 +/- 5% absolute error FMC-Flowsys: all points

20




-20

-25 0

10

20

30

40

50

60

70

Reference GVF (%)


Page 127/264

CONFIDENTIAL Figure 10.16: FMC Flowsys water cut error vs. ASRC reference GVF and water cut 100

90

80

70

Watercut error


< -25% -25% to -10% -10% to -5% -5% to +5% +5% to +10% +10% to +25% > +25%

30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

70

80

90

100

Reference GVF (%)

Figure 10.17: FMC Flowsys GVF vs. ASRC reference GVF 100 +/- 5% absolute error FMC-Flowsys: all points

90


80

70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

Reference GVF (%)

Page 128/264


CONFIDENTIAL Figure 10.18: FMC Flowsys GVF error vs. ASRC reference GVF 15 +/- 5% absolute error FMC-Flowsys: all points FMC-Flowsys: limited operating envelope 10


) e c n e r e 5 f e r m o r f e t u 0 l o s b a % ( r o -5 r r e F V G -10

-15 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 10.19: FMC Flowsys GVF error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)


Page 129/264

CONFIDENTIAL Figure 10.20: FMC Flowsys GOR vs. ASRC reference GOR 1.0E+05 +/- 10% absolute error FMC-Flowsys: all points FMC-Flowsys: limited operating envelope

1.0E+04


1.0E+03

1.0E+02 1.0E+02

1.0E+03

1.0E+04

1.0E+05

Meter GOR (scf/stb)

Figure 10.21: FMC Flowsys GOR error vs. ASRC reference GVF 50 +/- 10% absolute error FMC-Flowsys: all points

40


30


-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 130/264


CONFIDENTIAL Figure 10.22: FMC Flowsys GOR vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 10.23: FMC Flowsys statistics

100 Oil

Water

Gas

Liquid

90

80


70

60

50

40

30

20

10

0 < -50

-50 to -25

-25 to -10

-10 to +10

+10 to +25

+25 to +50

> +50

Error band


Page 131/264

CONFIDENTIAL Figure 10.24: FMC Flowsys cumulative curves

100

90

80



10


0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Figure 10.25: FMC Flowsys cumulative curves

100

90

80


RMS error GOR

0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Page 132/264


CONFIDENTIAL 10.4





RMS repeatability =

(repeatability of Q L )2 + (repeatability of QG )2 + (repeatability of WC)2 3

The repeatability results are shown in Figure 10.26. Generally the larger repeatability values correspond to the less steady flow conditions. Figures in brackets exclude well V-106. Table 10.4: Repeatability results for the four m ultiphase flow meters


FMC




8.3 (6.2)

4.7 (3.6)

14.5 (9.7)

Figure 10.26: FMC Flowsys repeatability 120 Liquid Gas 100

Water cut RMS

80

) % ( y t i l i b 60 a t a e p e R 40

20

0 V03

V101

V102

V103

V106

V107


V107

V108

V109

V113

V117

V202

Average

Page 133/264

CONFIDENTIAL Table 10.5: FMC Flowsys test results (accuracy)

CONFIDENTIAL Table 10.6: FMC Flowsys test results (repeatability)

CONFIDENTIAL

Page 136/264


CONFIDENTIAL

11

ROXAR MPFM 1900VI MULTIPHASE FLOW METER

11.1


The Roxar MPFM 1900VI multiphase flow meter measures the rates of oil, water and gas without separation, mixing or moving parts. Following a blind tee the flow passes directly upwards through the electrical capacitance and conductivity sensor which measures the water cut, and a 137Cs (662keV) gamma densitometer which measures the mixture density. The gas volume fraction can be derived from the density measurement. The velocity of the mixture is measured by cross-correlation of electrical signals, or alternatively from a Venturi meter measurement. The choice between the cross-correlation and the Venturi measurement is determined by the flow conditions in the meter.

Figure 11.1: Photograph of the Roxar MPFM 1900VI multiphase flow meter at the test site (centre meter, prior to installation of radioactive source)


Page 137/264

CONFIDENTIAL 11.2

Summary statistics


The first calculation recognises the value of low measurement uncertainty and weights the results accordingly. Each test point is rated according to its deviation from the reference value for liquid flowrate, gas flowrate, and water cut. A value of 5 is allocated if the liquid or gas flowrate is within ±5%, and the water cut is within ±1%; a value of 2 is allocated if the liquid or gas flowrate is within ±10%, and the water cut is within ±2%; a value of 0 is allocated if the deviations lie outwith these ranges. To allow for uncertainty in the ASRC reference data, an allowance of 5% on liquid flowrate, 2% on gas flowrate and 0.5% on water cut has been made before calculating the above scores. The points are totalled and then divided by the number of test points to give a normalised score. The values for the Roxar meter are shown in Table 11.1. Table 11.1: Summary scores for multiphase flow meter 5% criteria ROXAR


2.4 0.7 1.1

ROXAR GVF < 95% Liquid > 1100 stb/d 4.2 1.4 1.4

TOTAL score

4.2

7.1

All data

1 1 .2 .2 R M S a v er a g e

The root-mean-square average has been calculated for the deviations between the MFM readings and the ASRC reference values for liquid flowrate, gas flowrate and water cut. This tends to produce a large average value, since all points are used in calculating the average. The RMS average values are shown in Table 11.2. Table 11.2: RMS average multiphase flow meter deviations ROXAR All data Liquid flowrate Gas flowrate Water cut

Page 138/264

26.9 38.4 10.2

ROXAR GVF < 95% Liquid > 1100 stb/d 13.4 23.9 13.4


CONFIDENTIAL



RMS error =


Table 11.3: proportion of points within range ROXAR All data Liquid flowrate Gas flowrate Water cut Combined error

11.3

56.5 17.4 26.1 17.4

ROXAR GVF < 95% Liquid > 1100 stb/d 88.9 33.3 33.3 44.4


The test results for the Roxar MPFM 1900VI multiphase flow meter are shown in Figure 11.2 to Figure 11.25. Several types of graphs are used to demonstrate the measurement accuracy of the meter. Figure 11.2 shows the oil flowrate from the multiphase flow meter plotted against the oil flowrate from the ASRC test separator reference. For perfect agreement between the multiphase flow meter and the test separator reference, the points would lie on the solid diagonal line. The dashed diagonal lines show a ±10% deviation from the reference values. Figure 11.3 shows the percentage error in the oil flowrate measurement from the multiphase flow meter (relative to the test separator reference) plotted against the gas volume fraction. This comparison is used because normally the GVF has the biggest influence on multiphase flow meter uncertainty, and can be seen to be true in this case as the oil flowrate errors increase with GVF.


Page 139/264

CONFIDENTIAL Figure 11.4 shows the error in the oil flowrate measurement plotted against water cut and GVF. The error is represented by a different coloured point depending whether it is < 10% (green), <25% (blue), < 50% (red) or >50% (black). Clearly the ideal multiphase flow measurement behaviour would be to have entirely green points on this plot. These plots can be useful to isolate any separate influence of water cut on the measurement, compared to the stronger trends with GVF. Similar plots are given for water flowrate, liquid flowrate, gas flowrate, water cut , GVF and GOR. For flowrates and GOR the errors are evaluated as relative percentage errors: Relative error = (Meter reading – reference reading) / Reference reading while for water cut and GVF the errors are expressed as absolute deviations, Absolute error = Meter reading – reference reading Figure 11.23 shows the flowrate errors as a histogram in bands of ±10%, 25%, 50% and > 50% errors. In Figure 11.24 and Figure 11.25 the cumulative error plotted in the y-axis is the proportion of test points giving an error less than or equal to the value on the x-axis. For example on Figure 11.24, 29% of test points had an oil flowrate error within ±10%. For the curve in Figure 11.25, RMS error is defined as:

RMS error =

Page 140/264



CONFIDENTIAL Figure 11.2: Roxar MPFM 1900VI oil flowrate vs. ASRC reference oil flowrate 2500 +/- 10% relative error Roxar-MPFM1900VI: all points Roxar-MPFM1900VI: limited operating envelope 2000


500

0 0

500

1000

1500

2000

2500


Figure 11.3: Roxar MPFM 1900VI oil flowrate error vs. ASRC reference GVF 50 +/- 10% relative error Roxar-MPFM1900VI: all points

40

Roxar-MPFM1900VI: limited operating envelope limited operating envelope


-50 0

20

40

60

80

100

Reference GVF (%)


Page 141/264

CONFIDENTIAL Figure 11.4: Roxar MPFM 1900VI oil flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

1800

2000

Reference GVF (%)

Figure 11.5: Roxar MPFM 1900VI water flowrate vs. ASRC reference water flowrate 2000 +/- 10% relative error Roxar-MPFM1900VI: all points

1800

Roxar-MPFM1900VI: limited operating envelope 1600

) 1400 d / b t s ( e 1200 t a r w o l f 1000 r e t a w 800 r e t e M 600

400

200

0 0

200

400

600

800

1000

1200

1400

1600


Page 142/264


CONFIDENTIAL Figure 11.6: Roxar MPFM 1900VI water flowrate error vs. ASRC reference GVF 50 +/- 10% relative error Roxar-MPFM1900VI: all points

40


) e 30 c n e r e f 20 e r o t e v i t 10 a l e r


0 % ( r o r r e -10 e t a r w o -20 l f r e t a -30 W -40

-50 0

10

20

30

40

50

60

70

80

90

100

90

100

Reference GVF (%)

Figure 11.7: Roxar MPFM 1900VI water flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

Reference GVF (%)


Page 143/264

CONFIDENTIAL Figure 11.8: Roxar MPFM 1900VI liquid flowrate vs. ASRC reference liquid flowrate 3500 +/- 5% relative error Roxar-MPFM1900VI: all points Roxar-MPFM1900VI: limited operating envelope

3000


2500


500

0 0

500

1000

1500

2000

2500

3000

3500


Figure 11.9: Roxar MPFM 1900VI liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error Roxar-MPFM1900VI: all points

40



-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 144/264


CONFIDENTIAL Figure 11.10: Roxar MPFM 1900VI liquid flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 11.11: Roxar MPFM 1900VI gas flowrate vs. ASRC reference gas flowrate 7.0 +/- 10% relative error Roxar-MPFM1900VI: all points Roxar-MPFM1900VI: limited operating envelope

6.0

) 5.0 d / f c s M M ( 4.0 e t a r w o l f s 3.0 a g r e t e M2.0

1.0

0.0 0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0



Page 145/264

CONFIDENTIAL Figure 11.12: Roxar MPFM 1900VI gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error Roxar-MPFM1900VI: all points

40



0


-50 0

10

20

30

40

50

60

70

80

90

100

90

100

Reference GVF (%)

Figure 11.13: Roxar MPFM 1900VI gas flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

Reference GVF (%)

Page 146/264


CONFIDENTIAL Figure 11.14: Roxar MPFM 1900VI water cut vs. ASRC reference water cut 100 +/- 5% absolute error Roxar-MPFM1900VI: all points

90

Roxar-MPFM1900VI: limited operating envelope 80

70

) % 60 ( t u c r e 50 t a w r e t e 40 M 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

90

100


Figure 11.15: Roxar MPFM 1900VI water cut error vs. ASRC reference GVF 25 +/- 5% absolute error Roxar-MPFM1900VI: all points

20




-20

-25 0

10

20

30

40

50

60

70

80

Reference GVF (%)


Page 147/264

CONFIDENTIAL Figure 11.16: Roxar MPFM 1900VI water cut error vs. ASRC reference GVF and water cut 100

90

80

70

Watercut error


< -25% -25% to -10% -10% to -5% -5% to +5% +5% to +10% +10% to +25% > +25%

30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 11.17: Roxar MPFM 1900VI GVF vs. ASRC reference GVF 100 +/- 5% absolute error Roxar-MPFM1900VI: all points

90


80

70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)

Page 148/264


CONFIDENTIAL Figure 11.18: Roxar MPFM 1900VI GVF error vs. ASRC reference GVF 15 +/- 5% absolute error Roxar-MPFM1900VI: all points Roxar-MPFM1900VI: limited operating envelope 10



-15 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 11.19: Roxar MPFM 1900VI GVF error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)


Page 149/264

CONFIDENTIAL Figure 11.20: Roxar MPFM 1900VI GOR vs. ASRC reference GOR 1.0E+05 +/- 10% absolute error Roxar-MPFM1900VI: all points Roxar-MPFM1900VI: limited operating envelope

1.0E+04


1.0E+03

1.0E+02 1.0E+02

1.0E+03

1.0E+04

1.0E+05

Meter GOR (scf/stb)

Figure 11.21: Roxar MPFM 1900VI GOR error vs. ASRC reference GVF 50 +/- 10% absolute error Roxar-MPFM1900VI: all points

40


30


-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 150/264


CONFIDENTIAL Figure 11.22: Roxar MPFM 1900VI GOR error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 11.23: Roxar MPFM 190 0VI statistics

100 Oil

Water

Gas

Liquid

90

80


70

60

50

40

30

20

10

0 < -50

-50 to -25

-25 to -10

-10 to +10

+10 to +25

+25 to +50

> +50

Error band


Page 151/264

CONFIDENTIAL Figure 11.24: Roxar MPFM 1900VI cumulative curves

100

90

80



10


0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Figure 11.25: Roxar MPFM 1900VI cumulative curves

100

90

80


RMS error GOR

0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Page 152/264


CONFIDENTIAL 11.4





(repeatability of Q L )2 + (repeatability of QG )2 + (repeatability of WC)2

RMS repeatability =

3

The repeatability results are shown in Figure 11.26. Generally the larger repeatability values correspond to the less steady flow conditions. Figures in brackets exclude well V-106. Table 11.4: Repeatability results for the four m ultiphase flow meters


Roxar




8.5 (7.2)

5.9 (3.1)

9.1 (7.1)

Figure 11.26: Roxar MPFM 1900VI repeatability 25 Liquid Gas

20

Water cut RMS

) %15 ( y t i l i b a t a e p e R10

5

0 V03

V101

V102

V103

V106

V107


V107

V108

V109

V113

V117

V202

Average

Page 153/264

CONFIDENTIAL Table 11.5: Roxar MPFM 1900VI test results (accuracy)

CONFIDENTIAL Table 11.6: Roxar MPFM 1900VI test results (repeatability)

CONFIDENTIAL

Page 156/264


CONFIDENTIAL

12

SCHLUMBERGER VX29 MULTIPHASE FLOW METER

12.1


The Phasewatcher VX29 multiphase flow meter employs two measurement techniques, namely a Venturi and a dual-energy gamma densitometer. Following a blind tee the flow passes directly upwards through a Venturi meter. All the measurements are made at the Venturi throat, i.e. absolute pressure, temperature, differential pressure relative to upstream conditions and phase fractions. Phase fractions are measured using a dual energy gamma densitometer using a 133Ba (Barium) source. This source has energy levels which are appropriate for measurement of gas fraction and water cut (29 and 80 keV) and the location of the densitometer at the narrowest part of the flow conduit allows these low energy levels to be feasibly used at a relatively low source strength (10 mCi). The nuclear acquisition frequency is higher (45 Hz) than used in other multiphase flow meters (typically 1 Hz) which allows rapid resolution of the dynamic behaviour of the multiphase flow passing through the meter.

Figure 12.1: Photograph of the Schlumberger multiphase flow meter at the test site


Page 157/264

CONFIDENTIAL 12.2

Summary statistics


The first calculation recognises the value of low measurement uncertainty and weights the results accordingly. Each test point is rated according to its deviation from the reference value for liquid flowrate, gas flowrate, and water cut. A value of 5 is allocated if the liquid or gas flowrate is within ±5%, and the water cut is within ±1%; a value of 2 is allocated if the liquid or gas flowrate is within ±10%, and the water cut is within ±2%; a value of 0 is allocated if the deviations lie outwith these ranges. To allow for uncertainty in the ASRC reference data, an allowance of 5% on liquid flowrate, 2% on gas flowrate and 0.5% on water cut has been made before calculating the above scores. The points are totalled and then divided by the number of test points to give a normalised score. The values for the Schlumberger meter are shown in Table 12.1. Table 12.1: Summary scores for multiphase flow meter 5% criteria SLB


3.3 2.5 1.0

GVF < 95% Liquid > 1100 stb/d 4.1 4.7 1.8

TOTAL score

6.8

10.5

All data

SLB (reprocessed) GVF < 95% All data Liquid > 1100 stb/d 3.9 4.5 2.6 3.8 2.0 2.4 8.5

10.7

1 2 .2 .2 R M S a v er a g e

The root-mean-square average has been calculated for the deviations between the MFM readings and the ASRC reference values for liquid flowrate, gas flowrate and water cut. This tends to produce a large average value, since all points are used in calculating the average. The RMS average values are shown in Table 12.2.

Page 158/264


CONFIDENTIAL Table 12.2: RMS average multiphase flow meter deviations SLB All data Liquid flowrate Gas flowrate Water cut

14.8 14.1 12.9

GVF < 95% Liquid > 1100 stb/d 8.2 5.2 8.5

SLB (reprocessed) GVF < 95% All data Liquid > 1100 stb/d 13.6 7.8 12.4 8.0 9.2 6.6



RMS error =


Table 12.3: proportion of points within range SLB All data Liquid flowrate Gas flowrate Water cut Combined error

71.7 56.5 21.7 56.5

GVF < 95% Liquid > 1100 stb/d 85.7 100.0 38.1 85.7


SLB (reprocessed) GVF < 95% All data Liquid > 1100 stb/d 88.6 100.0 68.2 95.7 43.2 52.2 77.3 95.7

Page 159/264

CONFIDENTIAL 12.3


The test results for the Schlumberger VX29 multiphase flow meter are shown in Figure 12.2 to Figure 12.25. Several types of graphs are used to demonstrate the measurement accuracy of the meter. Figure 12.2 shows the oil flowrate from the multiphase flow meter plotted against the oil flowrate from the ASRC test separator reference. For perfect agreement between the multiphase flow meter and the test separator reference, the points would lie on the solid diagonal line. The dashed diagonal lines show a ±10% deviation from the reference values. Figure 12.3 shows the percentage error in the oil flowrate measurement from the multiphase flow meter (relative to the test separator reference) plotted against the gas volume fraction. This comparison is used because normally the GVF has the biggest influence on multiphase flow meter uncertainty, and can be seen to be true in this case as the oil flowrate errors increase with GVF. Figure 12.4 shows the error in the oil flowrate measurement plotted against water cut and GVF. The error is represented by a different coloured point depending whether it is < 10% (green), <25% (blue), < 50% (red) or >50% (black). Clearly the ideal multiphase flow measurement behaviour would be to have entirely green points on this plot. These plots can be useful to isolate any separate influence of water cut on the measurement, compared to the stronger trends with GVF. Similar plots are given for water flowrate, liquid flowrate, gas flowrate, water cut , GVF and GOR. For flowrates and GOR the errors are evaluated as relative percentage errors: Relative error = (Meter reading – reference reading) / Reference reading while for water cut and GVF the errors are expressed as absolute deviations, Absolute error = Meter reading – reference reading Figure 12.23 shows the flowrate errors as a histogram in bands of ±10%, 25%, 50% and > 50% errors. In Figure 12.24 and Figure 12.25 the cumulative error plotted in the y-axis is the proportion of test points giving an error less than or equal to the value on the x-axis. For example on Figure 12.24, 34% of test points had an oil flowrate error within ±10%. For the curve in Figure 12.25, RMS error is defined as:

RMS error =

Page 160/264



CONFIDENTIAL Figure 12.2: Schlumberger VX29 oil flowrate vs. ASRC reference oil flowrate 2500 +/- 10% relative error SLB-VX29: all points SLB-VX29: limited operating envelope 2000


500

0 0

500

1000

1500

2000

2500


Figure 12.3: Schlumberger VX29 oil flowrate error vs. ASRC reference GVF 50 +/- 10% relative error SLB-VX29: all points

40

SLB-VX29: limited operating envelope limited operating envelope


-50 0

20

40

60

80

100

Reference GVF (%)


Page 161/264

CONFIDENTIAL Figure 12.4: Schlumberger VX29 oil flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 12.5: Schlumberger VX29 water flowrate vs. ASRC reference water flowrate 2500 +/- 10% relative error SLB-VX29: all points SLB-VX29: limited operating envelope 2000


500

0 0

500

1000

1500

2000

2500


Page 162/264


CONFIDENTIAL Figure 12.6: Schlumberger VX29 water flowrate error vs. ASRC reference GVF 50 +/- 10% relative error SLB-VX29: all points

40

SLB-VX29: limited operating envelope



-40

-50 0

10

20

30

40

50

60

70

80

90

100

90

100

Reference GVF (%)

Figure 12.7: Schlumberger VX29 water flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

Reference GVF (%)


Page 163/264

CONFIDENTIAL Figure 12.8: Schlumberger VX29 liquid flowrate vs. ASRC reference liquid flowrate 3500 +/- 5% relative error SLB-VX29: all points SLB-VX29: limited operating envelope

3000


2500


500

0 0

500

1000

1500

2000

2500

3000

3500


Figure 12.9: Schlumberger VX29 liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error SLB-VX29: all points

40



-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 164/264


CONFIDENTIAL Figure 12.10: Schlumberger VX29 liquid flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 12.11: Schlumberger VX29 gas flowrate vs. ASRC reference gas flowrate 8.0 +/- 10% relative error SLB-VX29: all points 7.0


6.0


1.0

0.0 0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0



Page 165/264

CONFIDENTIAL Figure 12.12: Schlumberger VX29 gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error SLB-VX29: all points

40


) 30 e c n e r e 20 f e r o t e 10 v i t a l e r 0 % ( r o r r -10 e e t a r w-20 o l f s a G-30 -40

-50 0

10

20

30

40

50

60

70

80

90

100

90

100

Reference GVF (%)

Figure 12.13: Schlumberger VX29 gas flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

Reference GVF (%)

Page 166/264


CONFIDENTIAL Figure 12.14: Schlumberger VX29 water cut vs. ASRC reference water cut 100 +/- 5% absolute error SLB-VX29: all points SLB-VX29: limited operating envelope 80

60

) % ( t u c r e 40 t a w r e t e M 20

0 0

10

20

30

40

50

60

70

80

90

100

90

100

-20


Figure 12.15: Schlumberger VX29 water cut error vs. ASRC reference GVF 25 +/- 5% absolute error SLB-VX29: all points

20




-20

-25 0

10

20

30

40

50

60

70

80

Reference GVF (%)


Page 167/264

CONFIDENTIAL Figure 12.16: Schlumberger VX29 water cut error vs. ASRC reference GVF and water cut 100

90

80

70

Watercut error


< -25% -25% to -10% -10% to -5% -5% to +5% +5% to +10% +10% to +25% > +25%

30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 12.17: Schlumberger VX29 GVF vs. ASRC reference GVF 100 +/- 5% absolute error SLB-VX29: all points

90


80

70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)

Page 168/264


CONFIDENTIAL Figure 12.18: Schlumberger VX29 GVF error vs. ASRC reference GVF 15 +/- 5% absolute error SLB-VX29: all points SLB-VX29: limited operating envelope 10



-15 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 12.19: Schlumberger VX29 GVF error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

Reference GVF (%)


Page 169/264

CONFIDENTIAL Figure 12.20: Schlumberger VX29 GOR vs. ASRC reference GOR 1.0E+05 +/- 10% absolute error SLB-VX29: all points SLB-VX29: limited operating envelope

1.0E+04


1.0E+03

1.0E+02 1.0E+02

1.0E+03

1.0E+04

1.0E+05

Meter GOR (scf/stb)

Figure 12.21: Schlumberger VX29 GOR error vs. ASRC reference GVF 50 +/- 10% absolute error SLB-VX29: all points

40


30


-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 170/264


CONFIDENTIAL Figure 12.22: Schlumberger VX29 GOR error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 12.23: Schlumberger VX29 statistics

100 Oil

Water

Gas

Liquid

90

80


70

60

50

40

30

20

10

0 < -50

-50 to -25

-25 to -10

-10 to +10

+10 to +25

+25 to +50

> +50

Error band


Page 171/264

CONFIDENTIAL Figure 12.24: Schlumberger VX29 cumulative curves

100

90

80



10


0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Figure 12.25: Schlumberger VX29 cumulative curves

100

90

80


RMS error GOR

0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Page 172/264


CONFIDENTIAL 12.4





RMS repeatability =


The repeatability results are shown in Figure 12.26. This figure is included for completeness in the report, but may give a misleading impression of the repeatability as the same well properties were not necessarily used for each repeat test of a well. A better representation of the VX29 meter repeatability is given in the following Section for the reprocessed meter data, and can be seen in Figure 12.51. Figures in brackets exclude well V-106. Table 12.4: Repeatability results for the four m ultiphase flow meters


SLB




3.3 (3.1)

6.3 (5.5)

6.5 (5.9)

Figure 12.26: Schlumberger VX29 repeatability 16 Liquid 14

Gas Water cut

12

RMS

) 10 % ( y t i l i b 8 a t a e p e R 6

4

2

0 V03

V101

V102

V103

V106

V107


V107

V108

V109

V113

V117

V202

Average

Page 173/264

CONFIDENTIAL Table 12.5: Schlumberger VX29 test results (accuracy)

CONFIDENTIAL Table 12.6: Schlumberger VX29 test results (repeatability)

CONFIDENTIAL 12.5

Test results after reprocessing with correct well profile data (accuracy)

The test results for the Schlumberger VX29 multiphase flow meter after reprocessing with the correct well profile data are shown in Figure 12.27 to Figure 12.50. Several types of graphs are used to demonstrate the measurement accuracy of the meter. Figure 12.27 shows the oil flowrate from the multiphase flow meter plotted against the oil flowrate from the ASRC test separator reference. For perfect agreement between the multiphase flow meter and the test separator reference, the points would lie on the solid diagonal line. The dashed diagonal lines show a ±10% deviation from the reference values. Figure 12.28 shows the percentage error in the oil flowrate measurement from the multiphase flow meter (relative to the test separator reference) plotted against the gas volume fraction. This comparison is used because normally the GVF has the biggest influence on multiphase flow meter uncertainty, and can be seen to be true in this case as the oil flowrate errors increase with GVF. Figure 12.29 shows the error in the oil flowrate measurement plotted against water cut and GVF. The error is represented by a different coloured point depending whether it is < 10% (green), <25% (blue), < 50% (red) or >50% (black). Clearly the ideal multiphase flow measurement behaviour would be to have entirely green points on this plot. These plots can be useful to isolate any separate influence of water cut on the measurement, compared to the stronger trends with GVF. Similar plots are given for water flowrate, liquid flowrate, gas flowrate, water cut , GVF and GOR. For flowrates and GOR the errors are evaluated as relative percentage errors: Relative error = (Meter reading – reference reading) / Reference reading while for water cut and GVF the errors are expressed as absolute deviations, Absolute error = Meter reading – reference reading Figure 12.48 shows the flowrate errors as a histogram in bands of ±10%, 25%, 50% and > 50% errors. In Figure 12.49 and Figure 12.50 the cumulative error plotted in the yaxis is the proportion of test points giving an error less than or equal to the value on the x-axis. For example on Figure 12.49, 41% of test points had an oil flowrate error within ±10%. For the curve in Figure 12.50, RMS error is defined as:

RMS error =

Page 176/264



CONFIDENTIAL Figure 12.27: Schlumberger VX29 (reprocessed) oil flowrate vs. ASRC reference oil flowrate 2500 +/- 10% relative error SLB-VX29 Reprocessed: all points SLB-VX29 Reprocessed: limited operating envelope 2000


500

0 0

500

1000

1500

2000

2500


Figure 12.28: Schlumberger VX29 (reprocessed) oil flowrate error vs. ASRC reference GVF 50 +/- 10% relative error SLB-VX29 Reprocessed: all points

40

SLB-VX29 Reprocessed: limited operating envelope limited operating envelope


-50 0

20

40

60

80

100

Reference GVF (%)


Page 177/264

CONFIDENTIAL Figure 12.29: Schlumberger VX29 (reprocessed) oil flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 12.30: Schlumberger VX29 (reprocessed) water flowrate vs. ASRC reference water flowrate 2500 +/- 10% relative error SLB-VX29 Reprocessed: all points SLB-VX29 Reprocessed: limited operating envelope 2000


500

0 0

500

1000

1500

2000

2500


Page 178/264


CONFIDENTIAL Figure 12.31: Schlumberger VX29 (reprocessed) water flowrate error vs. ASRC reference GVF 50 +/- 10% relative error SLB-VX29 Reprocessed: all points

40




-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 12.32: Schlumberger VX29 (reprocessed) water flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


Page 179/264

CONFIDENTIAL Figure 12.33: Schlumberger VX29 (reprocessed) liquid flowrate vs. ASRC reference liquid flowrate 3500 +/- 5% relative error SLB-VX29 Reprocessed: all points SLB-VX29 Reprocessed: limited operating envelope

3000


2500


500

0 0

500

1000

1500

2000

2500

3000

3500


Figure 12.34: Schlumberger VX29 (reprocessed) liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error SLB-VX29 Reprocessed: all points

40



-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 180/264


CONFIDENTIAL Figure 12.35: Schlumberger VX29 (reprocessed) liquid flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 12.36: Schlumberger VX29 (reprocessed) gas flowrate vs. ASRC reference gas flowrate 9.0 +/- 10% relative error SLB-VX29 Reprocessed: all points

8.0

SLB-VX29 Reprocessed: limited operating envelope 7.0

) d / f 6.0 c s M M ( e 5.0 t a r w o l f 4.0 s a g r e t 3.0 e M 2.0

1.0

0.0 0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0



Page 181/264

CONFIDENTIAL Figure 12.37: Schlumberger VX29 (reprocessed) gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error SLB-VX29 Reprocessed: all points

40



0


-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 12.38: Schlumberger VX29 (reprocessed) gas flowrate error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 182/264


CONFIDENTIAL Figure 12.39: Schlumberger VX29 (reprocessed) water cut vs. ASRC reference water cut 100 +/- 5% absolute error SLB-VX29 Reprocessed: all points SLB-VX29 Reprocessed: limited operating envelope 80

60

) % ( t u c r e 40 t a w r e t e M 20

0 0

10

20

30

40

50

60

70

80

90

100

-20


Figure 12.40: Schlumberger VX29 (reprocessed) water cut error vs. ASRC reference GVF 25 +/- 5% absolute error SLB-VX29 Reprocessed: all points

20




-20

-25 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


Page 183/264

CONFIDENTIAL Figure 12.41: Schlumberger VX29 (reprocessed) water cut error vs. ASRC reference GVF and water cut 100

90

80

70

Watercut error


< -25% -25% to -10% -10% to -5% -5% to +5% +5% to +10% +10% to +25% > +25%

30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

90

100

Reference GVF (%)

Figure 12.42: Schlumberger VX29 (reprocessed) GVF vs. ASRC reference GVF 100 +/- 5% absolute error SLB-VX29 Reprocessed: all points

90


80

70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

70

80

Reference GVF (%)

Page 184/264


CONFIDENTIAL Figure 12.43: Schlumberger VX29 (reprocessed) GVF error vs. ASRC reference GVF 15 +/- 5% absolute error SLB-VX29 Reprocessed: all points SLB-VX29 Reprocessed: limited operating envelope 10



-15 0

10

20

30

40

50

60

70

80

90

100

90

100

Reference GVF (%)

Figure 12.44: Schlumberger VX29 (reprocessed) GVF error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

Reference GVF (%)


Page 185/264

CONFIDENTIAL Figure 12.45: Schlumberger VX29 (reprocessed) GOR vs. ASRC reference GVF 1.0E+05 +/- 10% absolute error SLB-VX29 Reprocessed: all points SLB-VX29 Reprocessed: limited operating envelope

1.0E+04


1.0E+03

1.0E+02 1.0E+02

1.0E+03

1.0E+04

1.0E+05

Meter GOR (scf/stb)

Figure 12.46: Schlumberger VX29 (reprocessed) GOR error vs. ASRC reference GVF 50 +/- 10% absolute error SLB-VX29 Reprocessed: all points

40


30


-40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 186/264


CONFIDENTIAL Figure 12.47: Schlumberger VX29 (reprocessed) GOR error vs. ASRC reference GVF and water cut 100

90

80

70



30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Figure 12.48: Schlumberger VX29 (reprocessed) statistics

100 Oil

Water

Gas

Liquid

90

80


70

60

50

40

30

20

10

0 < -50

-50 to -25

-25 to -10

-10 to +10

+10 to +25

+25 to +50

> +50

Error band


Page 187/264

CONFIDENTIAL Figure 12.49: Schlumberger VX29 (reprocessed) cumulative curves

100

90

80



10


0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Figure 12.50: Schlumberger VX29 (reprocessed) cumulative curves

100

90

80


RMS error GOR

0 0

5

10

15

20

25

30

35

40

45

50

Error value (%)

Page 188/264


CONFIDENTIAL 12.6

Test results after (repeatability)

reprocessing

with

correct

well

profile

data




RMS repeatability =


The repeatability results are shown in Figure 12.51. This figure shows much better repeatability for the reprocessed data than for the raw data shown in F igure 12.26. Figures in brackets exclude well V-106. Table 12.7: Repeatability results for the four m ultiphase flow meters


SLB (reprocessed)




3.1 (2.9)

4.7 (4.3)

5.5 (5.0)

Figure 12.51: Schlumberger VX29 (reprocessed) repeatability 18 Liquid 16

Gas Water cut

14

RMS

12

) % ( y 10 t i l i b a t a e 8 p e R 6

4

2

0 V03

V101

V102

V103

V106

V107


V107

V108

V109

V113

V117

V202

Average

Page 189/264

CONFIDENTIAL Table 12.8: Schlumberger VX29 reprocessed test results (accuracy)

CONFIDENTIAL Table 12.9: Schlumberger VX29 reprocessed test results (repeatability)

CONFIDENTIAL

12.7

Comparison of raw and reprocessed data

Figure 12.52 to Figure 12.63 show a comparison of the Schlumberger multiphase flow meter test results before and after reprocessing for the correct well profiles (calibrations). These generally show that an improvement with measurement accuracy is achieved by reprocessing, as would be expected. This is of course consistent with the improvement in overall measurement statistics shown in Table 12.1 to Table 12.3. The measurement errors still increase with GVF, which shows that calibration is not the principal source of measurement error at high GVF.

Page 192/264


CONFIDENTIAL

Figure 12.52: Schlumberger VX29 oil flowrate vs. ASRC reference oil flowrate 2500 +/- 10% relative error VX29, Prudhoe Bay 2003 VX29, GPB, 2003, Reprocessed 2000


500

0 0

500

1000

1500

2000

2500


Figure 12.53: Schlumberger VX29 oil flowrate error vs. ASRC reference GVF 50 +/- 10% relative error 40



-50 0

20

40

60

80

100

Reference GVF (%)


Page 193/264

CONFIDENTIAL

Figure 12.54: Schlumberger VX29 water flowrate vs. ASRC reference water flowrate 2500 +/- 10% relative error VX29, Prudhoe Bay 2003 VX29, GPB, 2003, Reprocessed 2000


500

0 0

500

1000

1500

2000

2500


Figure 12.55: Schlumberger VX29 water flowrate error vs. ASRC reference GVF 50 +/- 10% relative error 40


) e 30 c n e r e f e r 20 o t e v i t 10 a l e r % ( 0 r o r r e -10 e t a r w-20 o l f r e t a -30 W -40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 194/264


CONFIDENTIAL

Figure 12.56: Schlumberger VX29 liquid flowrate vs. ASRC reference liquid flowrate 3500 +/- 5% relative error VX29, Prudhoe Bay 2003 3000


) 2500 d / b t s ( e t 2000 a r w o l f d i u 1500 q i l r e t e M 1000

500

0 0

500

1000

1500

2000

2500

3000

3500


Figure 12.57: Schlumberger VX29 liquid flowrate error vs. ASRC reference GVF 50 +/- 5% relative error 40


) e c n e r 30 e f e r o 20 t e v i t a 10 l e r


% ( r 0 o r r e e t -10 a r w o l f -20 d i u q i l l -30 a t o T -40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


Page 195/264

CONFIDENTIAL

Figure 12.58: Schlumberger VX29 gas flowrate vs. ASRC reference gas flowrate 9.0 +/- 10% relative error VX29, Prudhoe Bay 2003

8.0

VX29, GPB, 2003, Reprocessed 7.0

) d / f 6.0 c s M M ( e 5.0 t a r w o l f 4.0 s a g r e t e 3.0 M 2.0

1.0

0.0 0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0


Figure 12.59: Schlumberger VX29 gas flowrate error vs. ASRC reference GVF 50 +/- 10% relative error 40


) e 30 c n e r e 20 f e r o t e 10 v i t a l e r 0 % ( r o r r -10 e e t a r w-20 o l f s a G-30 -40

-50 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)

Page 196/264


CONFIDENTIAL

Figure 12.60: Schlumberger VX29 water cut vs. ASRC reference water cut 100 +/- 5% absolute error VX29, Prudhoe Bay 2003 VX29, GPB, 2003, Reprocessed

80

60

) % ( t u c r e 40 t a w r e t e M 20

0 0

10

20

30

40

50

60

70

80

90

100

90

100

-20


Figure 12.61: Schlumberger VX29 water cut error vs. ASRC reference GVF 25 +/- 5% absolute error 20


) e 15 c n e r e f 10 e r m o r 5 f e t u l o s 0 b a % ( r -5 o r r e t u -10 c r e t a W-15 -20

-25 0

10

20

30

40

50

60

70

80

Reference GVF (%)


Page 197/264

CONFIDENTIAL

Figure 12.62: Schlumberger VX29 GVF vs. ASRC reference GVF 100 +/- 5% absolute error 90


80

70

) 60 % ( F V G 50 r e t e M 40 30

20

10

0 0

10

20

30

40

50

60

70

80

90

100

80

90

100

Reference GVF (%)

Figure 12.63: Schlumberger VX29 GVF error vs. ASRC reference GVF 15 +/- 5% absolute error VX29, Prudhoe Bay 2003 VX29, GPB, 2003, Reprocessed

10

) e c n e r e f 5 e r m o r f e t u 0 l o s b a % ( r o -5 r r e F V G -10

-15 0

10

20

30

40

50

60

70

Reference GVF (%)

Page 198/264


CONFIDENTIAL

Figure 12.64: Schlumberger VX29 GOR vs. ASRC reference GOR 1.0E+05 +/- 5% absolute error VX29, Prudhoe Bay 2003 VX29, GPB, 2003, Reprocessed

1.0E+04


1.0E+03

1.0E+02 1.0E+02

1.0E+03

1.0E+04

1.0E+05

Reference GOR (scf/stb)

Figure 12.65: Schlumberger VX29 GOR error vs. ASRC reference GVF 25 +/- 5% absolute error 20


15


-20

-25 0

10

20

30

40

50

60

70

80

90

100

Reference GVF (%)


Page 199/264

CONFIDENTIAL

Page 200/264


CONFIDENTIAL

13

REFERENCE DATA QUALITY

Data was recorded from the ASRC reference system at 1 minute intervals throughout the tests. For each test the oil, water, liquid and gas rates and the water cut were plotted against time and the most appropriate portion of the data was selected for the test period. This information is shown in Figure 13.4 to Figure 13.49. These figures show oil, water and liquid flowrates in stb/d and gas rates in Macfd (thousand ft 3 per day, at line conditions) For each test the statistical confidence of liquid rate, gas rate and water cut was calculated using the CONFIDENCE function in Excel (evaluated for a 95% confidence level), divided by the mean flowrate. The results are shown in Figure 13.1 to Figure 13.3. A line has been shown on these figures to indicate ‘slug flow’ which refers to tests with unsteady flowrates.

Figure 13.1: ASRC reference liquid rate statistical confidence 16

e 14 c n e d i f n 12 o c l ) a e c t 10 i t a s r i t f a o t s % 8 e e t v a r i t a l d i e 6 u ( r q i l e c 4 n e r e f e 2 R 0

SLUG FLOW

3 0 V

1 0 1 V

1 0 1 V

2 0 1 V

2 0 1 V

3 0 1 V

6 0 1 V

6 0 1 V

6 0 1 V

6 0 1 V

7 0 1 V

7 0 1 V

7 0 1 V

8 0 1 V

8 0 1 V

8 0 1 V

9 0 1 V

9 0 1 V

3 1 1 V

7 1 1 V

7 1 1 V

1 0 2 V

2 0 2 V

Well test


Page 201/264

CONFIDENTIAL

Figure 13.2: ASRC reference ga s rate statistical confidence

8

e 7 c n e d i 6 f n o c l ) e a t c a 5 i t r s f i t o a t % s 4 e e v t i a r t a s l e a ( r 3 g e c n 2 e r e f e R 1

0

SLUG FLOW

3 0 V

1 0 1 V

1 0 1 V

2 0 1 V

2 0 1 V

3 0 1 V

6 0 1 V

6 0 1 V

6 0 1 V

6 0 1 V

7 0 1 V

7 0 1 V

7 0 1 V

8 0 1 V

8 0 1 V

8 0 1 V

9 0 1 V

9 0 1 V

3 1 1 V

7 1 1 V

7 1 1 V

1 0 2 V

2 0 2 V

7 1 1 V

1 0 2 V

2 0 2 V

Well test

Figure 13.3: ASRC reference water cut statistical confidence 2.5%

e c n e 2.0% d i f n o c l a c i t 1.5% s i t a t s t u c r 1.0% e t a w e c n e r 0.5% e f e R

0.0%

SLUG FLOW

3 0 V

1 0 1 V

1 0 1 V

2 0 1 V

2 0 1 V

3 0 1 V

6 0 1 V

6 0 1 V

6 0 1 V

6 0 1 V

7 0 1 V

7 0 1 V

7 0 1 V

8 0 1 V

8 0 1 V

8 0 1 V

9 0 1 V

9 0 1 V

3 1 1 V

7 1 1 V

Well test

Page 202/264


CONFIDENTIAL

Figure 13.4: V03 2003-09-12 3500

100% Oil rate Water rate

90%

Liquid rate

3000

Gas rate Oil 1/2 hour

80%

Oil 1 hour Water cut

2500

Valid test period

70%

60% 2000 50% 1500 40%

30%

1000

20% 500 10%

0 04:48

0% 07:12

09:36

12:00

14:24

16:48

19:12

21:36

Figure 13.5: V03 2003-09-21 2500


90%

Liquid rate Gas rate Oil 1/2 hour

2000

80%

Oil 1 hour Water cut Valid test period

70%

1500

60%

50%

1000

40%

30%

500

20%

10%

0 07:12

0% 09:36

12:00

14:24


16:48

19:12

21:36

00:00

Page 203/264

CONFIDENTIAL

Figure 13.6: V101 2003-09-09 2000


1800

90%


1600

80%


1400

70%

1200

60%

1000

50%

800

40%

600

30%

400

20%

200

10%

0 21:36

0% 22:48

00:00

01:12

02:24

03:36

04:48

06:00

07:12

08:24

Figure 13.7: V101 2003-09-15 3000


90%

Liquid rate Gas rate

2500

Oil 1/2 hour

80%


70% 2000 60%

1500

50%

40% 1000 30%

20% 500 10%

0 04:19

Page 204/264

0% 04:48

05:16

05:45

06:14

06:43

07:12

07:40

08:09

08:38


CONFIDENTIAL

Figure 13.8: V101 2003-09-28 5000


4500

90%


4000

80%


3500

70%

3000

60%

2500

50%

2000

40%

1500

30%

1000

20%

500

10%

0 03:36

0% 04:48

06:00

07:12

08:24

09:36

10:48

12:00

13:12

14:24

15:36

Figure 13.9: V102 2003-09-05 3500

25%

Oil rate Water rate Liquid rate 3000


20%

Oil 1 hour Water cut 2500

Valid test period

15% 2000

1500 10%

1000

5% 500

0 16:48

0% 18:00

19:12

20:24


21:36

22:48

00:00

01:12

Page 205/264

CONFIDENTIAL

Figure 13.10: V102 2003-09-08 4500

25%

Oil rate Water rate 4000


3500

20%


3000 15% 2500

2000 10% 1500

1000 5%

500

0 21:36

0% 22:48

00:00

01:12

02:24

03:36

04:48

06:00

07:12

Figure 13.11: V102 2003-09-13 3000


90%


2500

Oil 1/2 hour

80%


70% 2000 60%

1500

50%

40% 1000 30%

20% 500 10%

0 02:24

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04:48

07:12

09:36

12:00

14:24

16:48

0% 19:12


CONFIDENTIAL

Figure 13.12: V102 2003-09-24 4500


4000

90%


3500

80%


70% 3000 60% 2500 50% 2000 40% 1500 30% 1000

20%

500

10%

0 12:00

0% 12:28

12:57

13:26

13:55

14:24

14:52

15:21

15:50

16:19

Figure 13.13: V103 2003-09-09 3500

100%


90%


80%

Oil 1 hour 2500

Water cut 70%

Valid test period

60% 2000 50% 1500 40%

30%

1000

20% 500 10%

0 07:12

0% 08:24

09:36

10:48


12:00

13:12

14:24

15:36

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Figure 13.14: V103 2003-09-13 3000

100%

Oil rate Water rate

90%


2500

80%

Oil 1/2 hour Oil 1 hour Water cut

70%

Valid test period

2000

60%

1500

50%

40% 1000 30%

20% 500 10%

0

0%

16:48

19:12

21:36

00:00

02:24

04:48

07:12

09:36

12:00

14:24

Figure 13.15: V103 2003-09-24 12000


90%


10000

Oil 1/2 hour

80%


70% 8000 60%

6000

50%

40% 4000 30%

20% 2000 10%

0 15:36

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16:48

18:00

19:12

20:24

21:36

0% 22:48


CONFIDENTIAL

Figure 13.16: V106 2003-09-05 700

100%

Oil rate Water rate

90%

Liquid rate 600


80%


500

Valid test period

70%

60% 400 50% 300 40%

30%

200

20% 100 10%

0

0%

09:36

10:48

12:00

13:12

14:24

15:36

16:48

18:00

Figure 13.17: V106 2003-09-07 1400

25%


Liquid rate Gas rate 20%

Oil 1/2 hour Oil 1 hour 1000

Water cut Valid test period 15%

800

600 10%

400

5% 200

0 10:48

0% 12:00

13:12

14:24

15:36


16:48

18:00

19:12

20:24

21:36

22:48

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Figure 13.18: V106 2003-09-14 3000

100%

Oil rate Water rate

90%

Liquid rate 2500


80%


70%

Valid test period

60%

1500

50%

40% 1000 30%

20% 500 10%

0 12:00

0% 14:24

16:48

19:12

21:36

00:00

02:24

04:48

07:12

Figure 13.19: V106 2003-09-28 2500


90%


2000

80%


70%

1500

60%

50%

1000

40%

30%

500

20%

10%

0 13:12

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14:24

15:36

16:48

18:00

19:12

20:24

21:36

22:48

00:00

0% 01:12


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Figure 13.20: V106 2003-09-29A 1000


900

90%


800

80%


700

70%

600

60%

500

50%

400

40%

300

30%

200

20%

100

10%

0 01:12

0% 02:24

03:36

04:48

06:00

07:12

08:24

09:36

10:48

Figure 13.21: V106 2003-09-29B 900


800

90%


700

80%


70% 600 60% 500 50% 400 40% 300 30% 200

20%

100

10%

0 09:36

0% 10:48

12:00

13:12

14:24


15:36

16:48

18:00

19:12

20:24

21:36

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CONFIDENTIAL

Figure 13.22: V106 2003-09-30B 5000


4500

90%


4000

80%


3500

70%

3000

60%

2500

50%

2000

40%

1500

30%

1000

20%

500

10%

0 19:12

0% 21:36

00:00

02:24

04:48

07:12

09:36

12:00

14:24

Figure 13.23: V106 2003-09-30A 5000


4500

90%


4000

80%


3500

70%

3000

60%

2500

50%

2000

40%

1500

30%

1000

20%

500

10%

0 19:12

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0% 21:36

00:00

02:24

04:48

07:12

09:36

12:00

14:24


CONFIDENTIAL

Figure 13.24: V107 2003-09-09 3500


90%

Liquid rate

3000


80%


2500

Valid test period

70%

60% 2000 50% 1500 40%

30%

1000

20% 500 10%

0 14:24

0% 15:36

16:48

18:00

19:12

20:24

21:36

22:48

Figure 13.25: V107 2003-09-15 3000


90%


2500

Oil 1/2 hour

80%


70% 2000 60%

1500

50%

40% 1000 30%

20% 500 10%

0 12:00

0% 14:24

16:48

19:12


21:36

00:00

02:24

04:48

07:12

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CONFIDENTIAL

Figure 13.26: V107 2003-09-22A 10000


9000

90%


8000

80%


7000

70%

6000

60%

5000

50%

4000

40%

3000

30%

2000

20%

1000

10%

0 12:00

0% 13:12

14:24

15:36

16:48

18:00

19:12

20:24

21:36

22:48

00:00

Figure 13.27: V107 2003-09-22B 10000


9000

90%


8000

80%


7000

70%

6000

60%

5000

50%

4000

40%

3000

30%

2000

20%

1000

10%

0 12:00

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0% 13:12

14:24

15:36

16:48

18:00

19:12

20:24

21:36

22:48

00:00


CONFIDENTIAL

Figure 13.28: V107 2003-09-24 7000

100% Oil rate Water rate Liquid rate

6000

Gas rate

80%


5000

Valid test period

60%

4000 40% 3000

20% 2000

0% 1000

0

-20%

06:00

07:12

08:24

09:36

10:48

12:00

13:12

Figure 13.29: V108 2003-09-009 1800

100%


90%


1400

Oil 1/2 hour

80%


1200

70%

Valid test period

60% 1000 50% 800 40% 600 30% 400

20%

200

10%

0 21:36

0% 22:48

00:00

01:12

02:24


03:36

04:48

06:00

07:12

08:24

09:36

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CONFIDENTIAL

Figure 13.30: V108 2003-09-16 2500


90%


2000

80%


70%

1500

60%

50%

1000

40%

30%

500

20%

10%

0 06:00

0% 07:12

08:24

09:36

10:48

12:00

13:12

14:24

15:36

Figure 13.31: V108 2003-09-18 2500


90%


2000

80%


70%

1500

60%

50%

1000

40%

30%

500

20%

10%

0 19:12

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0% 21:36

00:00

02:24

04:48

07:12

09:36

12:00

14:24

16:48


CONFIDENTIAL

Figure 13.32: V108 2003-09-22A 1600


1400

90%


80%

Oil 1 hour

1200

Water cut Valid test period

70% 1000 60%

800

50%

40% 600 30% 400 20% 200 10%

0 22:48

0% 00:00

01:12

02:24

03:36

04:48

06:00

07:12

08:24

09:36

Figure 13.33: V108 2003-09-22B 1600


1400

90%


80%

Oil 1 hour

1200


70% 1000 60%

800

50%

40% 600 30% 400 20% 200 10%

0 22:48

0% 00:00

01:12

02:24

03:36


04:48

06:00

07:12

08:24

09:36

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CONFIDENTIAL

Figure 13.34: V108 2003-09-22C 1600


1400

90%


80%

Oil 1 hour

1200


70% 1000 60%

800

50%

40% 600 30% 400 20% 200 10%

0 22:48

0% 00:00

01:12

02:24

03:36

04:48

06:00

07:12

08:24

09:36

Figure 13.35: V109 2003-09-10 1800


1600

90%


1400

80%


70% 1200 60% 1000 50% 800 40% 600 30% 400

20%

200

10%

0 08:24

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0% 09:36

10:48

12:00

13:12

14:24

15:36


CONFIDENTIAL

Figure 13.36: V109 2003-09-19 3500


90%

Liquid rate

3000


80%


2500

Valid test period

70%

60% 2000 50% 1500 40%

30%

1000

20% 500 10%

0 16:48

0% 19:12

21:36

00:00

02:24

04:48

07:12

09:36

12:00

Figure 13.37: V109 2003-09-23A 2000


1800

90%


1600

80%


1400

70%

1200

60%

1000

50%

800

40%

600

30%

400

20%

200

10%

0 19:12

0% 20:24

21:36

22:48

00:00


01:12

02:24

03:36

04:48

06:00

07:12

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Figure 13.38: V109 2003-09-23B 2000


1800

90%


1600

80%


1400

70%

1200

60%

1000

50%

800

40%

600

30%

400

20%

200

10%

0 19:12

0% 20:24

21:36

22:48

00:00

01:12

02:24

03:36

04:48

06:00

07:12

Figure 13.39: V113 2003-09-10 1200

25%

Oil rate Water rate Liquid rate 1000


20%


Valid test period

15%

600

10% 400

5% 200

0 14:24

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0% 15:36

16:48

18:00

19:12

20:24

21:36

22:48


CONFIDENTIAL

Figure 13.40: V113 2003-09-22 1600


1400

90%


80%

Oil 1 hour

1200


70% 1000 60%

800

50%

40% 600 30% 400 20% 200 10%

0 00:00

0% 01:12

02:24

03:36

04:48

06:00

07:12

08:24

Figure 13.41: V113 2003-09-27 1800


1600

90%


1400

80%


70% 1200 60% 1000 50% 800 40% 600 30% 400

20%

200

10%

0 12:00

0% 14:24

16:48

19:12


21:36

00:00

02:24

04:48

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Figure 13.42: V117 2003-09-06 4000

100%


90%


3000

80%


70%

Valid test period 2500

60%

2000

50%

40% 1500 30% 1000 20% 500 10%

0

0%

00:00

01:12

02:24

03:36

04:48

06:00

07:12

Figure 13.43: V117 2003-09-08A 4500

100%


90%


3500

80%


3000

70%

Valid test period

60% 2500 50% 2000 40% 1500 30%

1000

20%

500

10%

0 06:00

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0% 07:12

08:24

09:36

10:48

12:00

13:12

14:24

15:36


CONFIDENTIAL

Figure 13.44: V117 2003-09-08B 4500

100%


90%


3500

80%


3000

70%

Valid test period

60% 2500 50% 2000 40% 1500 30% 1000 20%

500

10%

0 06:00

0% 07:12

08:24

09:36

10:48

12:00

13:12

14:24

15:36

Figure 13.45: V117 2003-09-24 4000


3500

90%


80%

Oil 1 hour

3000


70% 2500 60%

2000

50%

40% 1500 30% 1000 20% 500 10%

0 21:36

22:48

00:00

01:12


02:24

03:36

04:48

0% 06:00

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CONFIDENTIAL

Figure 13.46: V201 2003-09-26 4000


3500

90%


80%

Oil 1 hour

3000


70% 2500 60%

2000

50%

40% 1500 30% 1000 20% 500 10%

0 21:36

0% 00:00

02:24

04:48

07:12

09:36

12:00

14:24

Figure 13.47: V202 2003-09-10 1600


1400

90%


80%

Oil 1 hour

1200


70% 1000 60%

800

50%

40% 600 30% 400 20% 200 10%

0 21:36

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0% 22:48

00:00

01:12

02:24

03:36

04:48

06:00


CONFIDENTIAL

Figure 13.48: V202 2003-10-01 1800


1600

90%


1400

80%


70% 1200 60% 1000 50% 800 40% 600 30% 400

20%

200

10%

0

0%

20:24

21:36

22:48

00:00

01:12

02:24

03:36

Figure 13.49: V202 2003-09-30 1400


90%

Liquid rate

1200


80%


1000

Valid test period

70%

60% 800 50% 600 40%

30%

400

20% 200 10%

0 12:00

0% 13:12

14:24

15:36


16:48

18:00

19:12

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21:36

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CONFIDENTIAL

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CONFIDENTIAL

14

PROJECT DOCUMENTATION

14.1

Calibration procedures – phase 1

The following installation requirements and start-up procedures were discussed with representatives of Agar, FMC, and SLB on 08/27/03. Roxar was not available for this meeting, but the pre-test calibration and data format sections were discussed with Roxar by teleconference between Brady/Mehdizadeh/Smith and Roxar on 08/26/03. These procedures will be used during the 2-day of preliminary tests, called Phase 1 of the program. The procedures may be revised before the full test program, called Phase 2 will get underway. 1 4.1 .1 I n s t a l l a t i o n : m et er s eq u e n c e a n d o r i en t a t i o n i n t h e l o op

SLB (skid) – FMC (vertical up, 90’ elbow in/out) – Roxar ( vertical up, 90’ elbow in/out) – Agar (skid) – ASRC. Agar requires dry instrument air @ 80 psig for the operation of the diverter valve. ASRC will provide instrument air for Agar. 1 4.1 .2 I n s t a l l a t i o n : el e ct r i c a l p o w e r o u t l et f o r t h e l a b

ASRC to provide 110-volt electrical outlets for vendors as follows: Schlumberger FMC Roxar Agar Mehdizadeh

2 outlets 3 3 3 1

1 4.1 .3 I n s t a l l a t i o n : em p t y ch a m b er a n d p r essu r e t e st

Upon completion of mechanical work and loop clean up: Roxar meter will require 30- minute empty chamber tests. Schlumberger, FMC, and Agar do not need empty chamber test. All meters and the loop will be subjected to pressure test with diesel @ 1000psig after empty chamber test by Roxar is competed. Agar requires flushing meter with lake water for 5 minutes.


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1 4.1 .4 P r e-t est c a l i b r a t i o n / v er i f i c a t i o n

Well fluid calibration to be conducted for density, permittivity, and conductivity: Table 14.1: Meter fluid property calibration re quirements

Vendor Oil:

SLB 30 cc per well

Density Permittivity Produced Water:

Y N 30 cc per well

Density Conductivity

Y N

FMC 3 litres per horizon N Y 3 litres per horizon Y Y

Roxar 3 litres per horizon Y Y 3 litres per horizon Y Y

Agar Not required N N Not required N N

Bruce Smith will provide to all vendors density data on produced water from all wells except V-201. Well fluid samples gathered from the wells for these calibrations will be saved and tagged in 5 gallon cans and marked for storage. Flow test: after installation in the loop, all meters will be subjected to flowrates of 8000 and 1500 bbl/d for 5 minutes at each rate, to calibrate Venturi and PD meters. HB&R or Little Red will supply the 200 bbl of water for this step. The loop and meters will be flushed by diesel after the flow test. 1 4.1 .5 P r el i m i n a r y w e l l t est s

These tests will be conducted so that vendors can check the performance of the meters under dynamic flow conditions and make appropriate revisions to their meters. This phase is expected to last 2 days. Each test will last for 4 hours, including purge time. ASRC will provide water cut data at 30-minute intervals. Well test data will be provided by ASRC at the end of each test. Agar will take water cut samples at own meter for calibration/verification and provide the data to Mehdizadeh. ASRC will drain the test separator between each well test. This step is expected to need approximately 30 minutes. Table 14.2: Wells to be used for preliminary well tests

Well V-106 V-102 V-117

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Liquid bbl/day 600 2600 3000

Gas MMscf/day 2.7 2.5 5.0

Water cut % 30 9 60

Formation GOR scf/stb 500 457 460


CONFIDENTIAL

All test results will be compared with ASRC data and vendors will be permitted to make documented adjustment to their meters. Each vendor will have access to their own test data. Adjustment to the meters will be documented and will be included in each vendor’s calibration procedure. 14.2

Roxar installation and start up procedures

The following installation requirements and start-up procedures were discussed with representatives of Roxar on 09/11/03. These installation and start up and procedures are different from the procedures used by other vendors. The previous procedures had to be revised since Roxar is joining the test campaign at a late date. These procedures will be used during the dynamic fluid calibration stage, currently referred to as phase 4. The procedures may be revised before the full test program, called phase 5 gets underway. 1 4.2 .1 I n s t a l l a t i o n : m et er s eq u e n c e a n d o r i en t a t i o n i n t h e l o op

The Roxar meter is installed in vertical up position with 90° elbow in/out. 1 4.2 .2 I n s t a l l a t i o n : el e ct r i c a l p o w e r o u t l et f o r t h e l a b

Roxar would have access to 3 outlets 14.2.3 Installation

Since the Roxar meter is already installed in the loop, the following procedures will be used: • • • •

•

Initial check of the data acquisition computer will be done at Price Pad. Layout of electrical and power lines to the meter can be performed at the site without hot work permit - no power. Install 110/24V converter in the lab trailer at the site. Install gamma ray source on the meter. Transportation of the nuclear source to the site and radiation survey to be conducted by Roxar (Slavko Tosic). This survey will be checked by ASRC and will be coordinated with Mike Schwemley (HSE). Report submitted to HSE. Obtain hot work permit to power up and check instruments.

1 4.2 .4 P r e-t est c a l i b r a t i o n / v er i f i c a t i o n

Well fluid calibration to be conducted for density, permittivity, and conductivity. Fluid density and water density data gathered by Schlumberger has been given to Roxar. Bruce Smith has provided density data on produced water from all wells except V-201. The following procedures will be provided to prepare the loop for the dynamic well test:


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CONFIDENTIAL

• • • •

•

Depressurise and purge the loop with diesel to clean the current content. Allow one hour for fluid to drain from the meter into the U part of the loop. Use vacuum truck to suction the line dry. Allow 2 hours for Roxar to conduct empty cavity test Fill the loop with dry crude. Allow 2 hours for Roxar to conduct permittivity tests. Pressurize the loop with water to 1000 psig and check for leaks. During this step allow 30 minutes for Roxar to perform gamma calibration with water in the loop. Begin dynamic fluid well tests if the loop integrity is OK in the above step.

1 4.2 .5 D y n a m i c f l u i d w el l t est s

These tests will be conducted so that Roxar can check the performance of the meters under dynamic flow conditions and make appropriate revisions to their meters. This phase is expected to last 2 days. Well V-102 will be tested and the ASRC and periodic water cut data will be given to Roxar at the end of the test. Any adjustment to the Roxar meter will be documented and will be included in their calibration procedure. Roxar will be asked to sign the ‘Set-up and calibration’ document to declare the Roxar meter available for normal testing and compliance evaluation. Roxar will also provide a short procedure for set-up, start, stop, and down loading of the data to be used after Roxar has left the premises.

14.3

Vendor requirements: Agar MPFM-401

The following procedures come as additional to the instruction in the user manual. The following are the major items in the start up. 1.

Before powering up MPFM, check that the power to the MPFM and DAS is within ±10% of the nominal specified power.

2.

Check and/or terminate wiring between MPFM and DAS.

3.

Verify that a strainer is installed upstream of the MPFM and that it has the proper basket.

4.

Verify that 90 psi ±10 psi pneumatic dry gas/air is supplied to the MPFM.

5.

Before applying any fluid or pressure, power-up the MPFM and DAS. Booting of DAS computer will launch MPFM software in DAS.

6.

Check for error messages. Record and acknowledge any errors.

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CONFIDENTIAL

7.

Go to General Data screen. 7.1 7.2 7.3

7.4 7.5 7.6 7.7 7.8 8.

Go to the RDC Data screen: 8.1 8.2

9.

Verify RDC communication by ensuring that the counter of RDC communication errors is 0. Verify PAMS/OWM communication by ensuring that the counter of OWM communication errors is 0. Check the stream and ambient temperature read normal. They should be close to each other unless the MPFM is under direct sunlight in which case stream temperature will be some degrees higher. Check that all the pressure transmitters read normal. Check that PD meter reads zero. Check that Long Phase reads more than Short Phase. Check that both Long and Short amplitudes are negative and Long Amp is more negative than the Short Amp. Check the ID sensor reads between 0.5 and 0.8 mA.

Check that the vortex flow reads zero. Check that the absolute pressure vp0 reads normal and very close to p0.

Go to PAMS Data screen: 9.1 9.2

Check that the cycle is more than 15. Check the PAMS temperature reads Normal.

10.

Check valve configuration of the MPFM

11.

Check operation of the 301 valve including fail safe mode.

12.

Check operation of the 401 Valve including fail safe mode.

13.

Check output of pressure transmitters. Calibrate as required.

14.

Perform calibration Calibration).

15.

Perform zero dry check and zero trim if required for each pressure transmitter.

16.

Purge the 301-loop transducers line with DOW CORNING 550 silicon oil. (See user manual).

17.

Purge the 401-loop transducers line with process gas or air (see user manual).

of

RDC

analogue


to

digital

conversion

(Electronic

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CONFIDENTIAL

18.

Verify in the Pressure Transducer screen that the full scale (FS) errors do not exceed 0.2% (P1, P4 and P6) or 0.1% (P2, P3, P5, VP1, VP2). Write down all the numbers in the Static Test-Air form.

19.

Check PAMS calibration using Agar microwave attenuation kit.

20.

Perform self-verification: 20.1 Connect required pump, piping, hoses and valves required to supply and control flow rate of water or very low viscosity oil (viscosity less the 2cP) through the MPFM. 20.2 Select Self-Verification screen and follow on screen instructions: 20.2.1 Adjust flow rate to about 80% of the PD meter maximum flow rate. Ensure that no gas is present. Wait for stabilized flow rate. 20.2.2 Collect High Flow data by pressing key H 20.2.3 Wait for the countdown to reach zero. Write down the final values into the High Flow SVT log form. If the High Flow portion of the SVT is not passed a message will appear indicating so. In that case repeat sections 13 to 18 of this procedure. If the High flow portion of SVT is successful a message will appear indicating so and you can proceed to the next step. 20.2.4 Perform Low Flow SVT. 20.2.5 Adjust flow rate between 10 and 20% of the PD meter Full Scale. Ensure that no gas is present. Wait for stabilized flow rate. 20.2.6 Start collecting Low Flow data by pressing key L. 20.2.7 Wait for the countdown to reach zero. Write down the all the final values into the Low Flow SVT log form and sign it. If the Low Flow portion of the SVT is not passed a message will appear indicating so. In that case, proceed to check PD meter for internal leakage or PD signal generation and processing failures. 20.2.8 Change screen to General Data and verify that the water cut value is close to 100%. 20.2.9 Verify that the ID value is more than 2.0 mA. 20.2.10 Write down ambient and stream temperatures and pressures (P0 and VP0) in the SVT log form. 20.2.11 Complete and sign the SVT log sheet. 20.2.12 Stop flow.

21.

Check the configuration following the user manual instruction. Pay attention specifically to the 401 Parameters and to the Fluid properties parameters. Modify these values as required according to the particular application.

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22.

Perform valve set-up adjustments and field water cut trim as follows: 22.1 Valve adjustments: 22.1.1 Flow the most severe slugging well and adjust Over spin delay, Cycles to return valves to normal state , Time Constant error and Span Control. 22.1.2 Flow the foamiest well or the lowest GVF and highest liquid in order to obtain the minimum effective 301 GVF. Adjust 401 valve GVF settings accordingly. 22.2 Field water cut trim (some or all of these steps can be performed with the same wells as in the previous section): 22.2.1 Flow a dry well to collect oil samples and simultaneous diagnostics data to perform oil field trim. 22.2.2 Flow the well with the highest water content. Collect emulsion samples and simultaneous diagnostics data. Determine the water content of the samples and use information to perform water field trim. 22.2.3 Flow a well with intermediate oil continuous water content. Collect emulsion samples and simultaneous diagnostics data. Determine the water content of the samples and use information to perform oil continuous field span adjustment. 22.2.4 Flow a well with intermediate water continuous water content. Collect emulsion samples and simultaneous diagnostics data. Determine the water content of the samples and use information to perform water continuous field span adjustment.

14.4

Vendor requirements: FMC Flowsys

1 4.4 .1 I n s t a l l a t i o n

The TopFlow multiphase meter should be installed vertically upwards. The first change in orientation downstream of the meter should be of elbow type. TopFlow multiphase meter always installed vertically upwards. The TopFlow meter was installed at BP V-Pad with a T-piece upstream of the meter and an elbow downstream of the meter. An 8-pair electrical cable was ran into the lab trailer and connected to a computer interface enclosure. The computer interface enclosure is connected to a industrial PC where the user interface software is ran. The computer interface enclosure and the PC including monitor require 100-240VAC power supply. The PC is powered through a UPS.


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1 4.4 .2 I n p u t p a r a m et er s

The TopFlow multiphase meter requires the following parameters as input: • • • • •

Oil Density Water Density Gas Density Water Conductivity or Water Salinity, required only for water-continuous flow high water cuts) Oil Permittivity (also called Dielectric constant), required only for oil-continuous flow (low water cuts)

Oil Density

The Oil Density is needed at operating conditions. If the Oil Density is not easily available at operating conditions, the Oil Density can be given at stock tank conditions and/or as API gravity. Document received from BP gave the specific gravity at 60°F for some historical well tests/samples. The most recent one for the wells at V-Pad is given below: Table 14.3: Oil property data from BP

Well name

V03 V101 V102 V103 V106 V107 V108 V109 V113 V117 V201 V202

Oil density (g/cm3) 0.8944 0.9047

Test temp °F 60 60

0.9165 0.9053 0.9076 0.9285 0.9066

60 60 60 60 60

Schlumberger took samples of each individual well and the results were to be shared with the other participants. The Schlumberger values confirmed the values received from BP. FMC/Flowsys took samples of three wells V03, V117 and V201. The results of the oil density values for these samples are shown in Table 14.4.

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Table 14.4: Oil properties measured by FMC

Well name

V03 V101 V102 V103 V106 V107 V108 V109 V113 V117 V201 V202

Oil density (API) 27.3

Test temp °F 60

26.1 22.8

60 60

The variations in the given oil densities for the individual wells were not significant and one average oil density is used by the meter. The oil density was set as 0.904g/cm3 for all wells. The oil density is automatically corrected for changes in operating temperature and pressure. Water Density

Water density is required. Document received from BP gave the specific gravity of the brine at 60°F for some historical well tests/samples. The most recent one for the wells at the V-Pad is given below: Table 14.5: Water property data from BP

Well name V03 V101 V102 V103 V106 V107 V108 V109 V113 V117 V201 V202

Water density (g/cm3) 1.0133 1.0176

Test temp °F 60 60

1.0193 1.0201 1.0200 1.1096 1.0202

60 60 60 60 60

1.0219

60


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Schlumberger was allowed to take samples of each individual well and the results were to be shared with the other participants. The Schlumberger data was very similar to the BP data, but reported at slightly higher temperatures. FMC/Flowsys took samples of three wells V03, V117 and V201. The results of the water density values for these samples are shown below: Table 14.6: Water properties measured by FMC

Well name V03 V101 V102 V103 V106 V107 V108 V109 V113 V117 V201 V202

Water density (g/cm3) 1.0156

Test temp °F 60

1.0202

60

An average water density of 1.02044 g/cm 3 is used for all wells at V-Pad. The water density is automatically corrected for changes in operating temperature and pressure.

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Gas Density

The Gas specific gravity is required. Table 14.7: Gas property data from BP

Well name V03 V101 V102 V103 V106 V107 V108 V109 V113 V117 V201 V202 V-Pad average

Gas s.g.

0.7272

0.7484

0.6916

0.722

Table 14.8: Gas property data from Schlumberger

Well name V03 V101 V102 V103 V106 V107 V108 V109 V113 V117 V201 V202 V-Pad average


Gas s.g. 0.738 0.714 0.723 0.720 0.736 0.744 0.716 0.704 0.707 0.645 0.754 0.668 0.714

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Water Conductivity / Salinity

If the water conductivity or salinity is not known, the water conductivity or water salinity can be measured by the Flowsys meter by filling it with water from the well. No brine was available to fill the meter. Salinity/conductivity was estimated based on the water density. The salinity/conductivity is ONLY included in the Flowsys set of equations at water-continuous flow, i.e. high water cuts. None of the wells at V-Pad is expected to be water-continuous unless a high amount of water is injected at the well head. Oil Permittivity / Dielectric Constant

The oil permittivity is not normally measured by the oil field operators. It is acceptable to use a default value for the oil permittivity of Heavy oil 2.35; Medium oil 2.25; Light oil/condensate 2.15. If there is an opportunity to measure the oil permittivity, the performance of the Flowsys meter can be slightly improved. The oil permittivity can be measured by the Flowsys multiphase meter by filling the meter with crude oil. About 2 litres of crude is needed to fill up the 3-inch meter. FMC took samples from three wells V03, V117 and V201. The samples were stabilised overnight and the top portion of the samples were filled into the Flowsys meter to measure the permittivity of the samples. Since the samples also included produced water, the samples had to be analysed at the BP laboratory to determine the water content. Based on this water content, FMC calculated the individual permittivity of the three samples. The water cut values received from the BP lab did not match very well with the Flowsys measurement when the same samples were filled into the meter. The difference was about 2 to 5%. The Flowsys measurement with diesel filled meter corresponded very well with the theoretical value of the diesel permittivity and therefore the meter readings are considered correct. The water cut readings received from the lab was disregarded and a calculated theoretical value of the permittivity was considered to be more accurate and therefore used for all wells at V-Pad. Therefore the laboratory results of the samples were not used to calibrate the meter. Fluid properties summary

It is recommended that the available density data for historical routine well samples are used for setting up the fluid properties of the Flowsys meter. No specific samples are required for the TopFlow meter as long as density data is available from historical samples. It is not recommended to take samples of the wells to determine the permittivity for future installations at BP Alaska.

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1 4.4 .3 P a n d D P t r a n s m i t t er

If the transmitter is positioned lower than the Venturi tappings and temperatures below 32°F are expected, the tubing must be filled with an anti-freeze liquid to avoid icing. If the transmitter is positioned higher than the Venturi tappings, no anti-freeze liquid is required. The transmitter on the BP Alaska unit is located lower than the venture tappings. The tubing of the dp transmitter were therefore flushed and filled with a glycol based liquid to avoid icing in the tubing and transmitter cells. The density of the glycol based liquid is taken into account by the meter. An estimated density of the glycol based fluid of 0.980g/cm 3 is used. If there is a leakage in the Venturi tubing or the equalizer valve has been opened, the tubing must be re-filled with an anti-freeze liquid.

14.5

Vendor requirements: Schlumberger

1 4.5 .1 G a s S a m p l i n g

Equipment

Ranarex gas gravity meter 5 000 psi gas sampling bottle – 1 litre Procedure

Connect the gas-sampling bottle to the gas line of the separator. Fill and purge the bottle 3 times. Fill the bottle and connect it to the Ranarex. Flow the gas through the Ranarex maintaining the floating ball to the expected gravity. Wait for the needle to stabilize before the reading. Then take the reading. Flush the gas left in the bottle. Then re-do the process. If the reading is the same then the data is validated. Else redo again.


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1 4.5 .2 A t m o sp h e r i c l i q u i d sa m p l i n g

If sampling from the oil line of the separator, flush the separator and wait enough to ensure the integrity of the fluid. Protect the place from any spill. Flush the sampling port. Then start to sample. 1 4.5 .3 P r o cessi n g l i q u i d s a m p l es

Pure Oil

In our case the choice went up to the Heating process. B a s i c c en t r i f u g i n g

Pour the sample in one centrifuge glass. Balance the pure crude with another sample. This sample has to be cut by 50% oil base diluents (Xylene, Super, Toluene, etc.) and few drops of emulsion breaker. Spin the sample. Spin until you reach the same water-cut on both tubes. Spin 5 minutes more and cross check the readings remain the same. If it is the case then the centrifuging is finished. Apply the same time to the rest if the sample. At the end take a sample of the oil and mix it with oil base diluents and few drop of emulsion breaker and spin it to check for water contamination. E m u l si o n b r ea k er a n d h ea t

According with the laboratory the fraction of emulsion breaker to set into the sample, e.g. for 1 litre sample, 10ml of W54 emulsion breaker. Heat the sample to 60 °C / 140 °F until complete separation is done. At the end take a sample of the oil, mix it with oil base diluents add few drop of emulsion breaker and spin it to check for water contamination. After the oil in situ set an oil/water mixture in the meter (same procedure as the oil in situ but with a mix of oil and water where the BSW has been checked) and start the reading. The BSW measured with the PhaseWatcher must match the BSW and the GVF must be equal to 0%. Look at the triangle and ensure the measured point is well on the oil/water line.

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Pure Water Centrifuging

Use the same procedure as basic oil centrifuging. With a syringe or a pipette extract the water from the sample. C en t r i f u g i n g a n d oi l b a se d i l u en t s

Fill the centrifuge glasses with 50% of oil base diluents to break the emulsion. Use the same procedure as basic oil centrifuging. With a syringe or a pipette extract the water from the sample. C en t r i f u g i n g , oi l b a se d i l u en t s a n d em u l s i on b r ea k er

Fill the centrifuge glasses with 50% of oil base diluents and few small drops of emulsion breaker. Use the same procedure as basic oil centrifuging. With a syringe or a pipette extract the water from the sample. After the water in situ set an oil/water mixture in the meter (same procedure as the oil in situ but with a mix of oil and water where the BSW has been checked) and start the reading. The BSW measured with the PhaseWatcher must match the BSW and the GVF must be equal to 0%. Look at the triangle and ensure the measured point is well on the oil/water line. BSW and mixture sample for BSW check with the meter

The sample must be homogenous. If not shake it vigorously. Fill one centrifuge glass with 50% oil base diluents, oil and few drops of emulsion breaker. Save 100ml of sample. Then fill the second centrifuge glasses as per the first one. Spin it. The two readings should be the same. If not, homogenise the sample and re-do the procedure again. Viscosity

Try to measure the oil viscosity to a temperature as close as possible to the flowing temperature. For BSW between 40% to 60% quality check the mixture viscosity and set the phase inversion to fit the readings.


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15

PROJECT CONSULTANT’S DAILY REPORTS

15.1

August 31 st, 2003

1 5 .1 . 1 S a f e t y

0600 Safety meeting at ASRC unit #1: pad operation has not commenced yet. Multiphase Metering Team meetings were held at 7:00 and 19:00. Reviewed status of each vendor. FMC calibration complete. SLB calibration to be completed this evening, fluid samples to BP lab, waiting for the results. SLB completed analysis of fluid samples taken by FMC/SLB. Agar, SLB, and FMC meters are on location. Roxar meter, without gamma source, is also on location. 1 5.1 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)

None. 1 5.1 .3 L o op a n d m et e r s t a t u s

FMC meter taken to location. commenced.

Groundwork and transportation of loop components

1 5.1 .4 O t h er p e r t i n en t ev en t s

None. 1 5.1 .5 D a t a t a k en a n d t r a n s m i t t ed

None. 1 5 .1 .6 W el l s u sed i n t h e t e st s

None.


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15.2

September 1st, 2003

1 5 .2 . 1 S a f e t y

0600 Safety meeting at ASRC unit # 1. Safety meeting was conducted at the ASRC trailer on V-Pad by ASRC and pad operator. Sign in/out procedure is in place at the ASRC trailer for all personnel working on the project. 1 5.2 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)


All meters are installed. SLB requires 12 to 24 hours of additional calibration time. Start-up procedures will be changed to get electrical hook up before leak check to allow SLB to finish open cavity calibration. Agar to perform in situ calibration and all vendors to complete electrical checks. Well fluid analysis by SLB completed and density, gas s.g. data was distributed to vendors. The data will be used to develop well profiles for the phase 1 tests as follow: Agar (1), FMC (3), SLB (12). Each vendor will prepare a one-page training manual for the operator training to include start-up, shutdown, restart and data downloads. Phase 1 tests will begin with well V-106 when the test loop is completed. A technical audit of ASRC test separator will be conducted on September 3rd. 1 5.2 .4 O t h er p e r t i n en t ev en t s

None. 1 5.2 .5 D a t a t a k en a n d t r a n s m i t t ed

Crude and produced water density and gas s.g. provides to all vendors from SLB sample analysis and BP (Bruce Smith) well data. 1 5 .2 .6 W el l s u sed i n t h e t e st s

None.

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15.3

September 3rd, 2003

1 5 .3 . 1 S a f e t y

0600 Safety meeting at ASRC unit # 1: check in/out by all personnel at ASRC, no recalls. Hasebe and Mehdizadeh witnessed a source and background radiation check conducted by SLB on SLB meter. Report prepared by SLB to given to Hasebe for the project file. Hasebe will check with BP Safety to ensure these steps meet BP requirements. Safety engineer from ASRC is to conduct independent radiation survey on the SLB meter tomorrow. 1 5.3 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)

None 1 5.3 .3 L o op a n d m et e r s t a t u s

Lab in place, electrical power available, and vendors have installed all meter computers. ASRC well testing, tanks and associated equipment in place. Test loop and return line completed and connected to the header. FMC has completed the pretest checkout. Agar has also completed the pre-test check out except for the air supply to the diverter valve, to be completed this evening. SLB has been conducting open cavity tests to be completed this evening. All meters, ASRC test separator, and loop components are expected to be ready for leak check tomorrow. Plan for September 4th is to conduct a walk-through of the test facility and perform pressure integrity and leak test at 1000 psig. A flow rate test, per previously established test procedure will then be performed. 1 5.3 .4 O t h er p e r t i n en t ev en t s

Maureen Johnson, BP HSE management, and ASRC management visited the test facility. MPU operations personnel invited to attend walk-through tomorrow. 1 5.3 .5 D a t a t a k en a n d t r a n s m i t t ed


None.


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15.4

September 4th, 2003

1 5 .4 . 1 S a f e t y

0600 Safety meeting at ASRC unit # 1: safety walk-through and orientation was conducted by Jim Moore and ASRC, prior to leak check for vendors, ASRC and VECO personnel. 1 5.4 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)


Vendors conducted an audit of the ASRC test separator and verified the equipment to be used. Audit is documented and signed by vendors for the project file. Conducted a leak check on the loop. Corrected leaks with Agar (3) and FMC(1) in preparation for the flowrate tests per the Phase 1 procedures, i.e. flow rate up to 7300 bbl/d and down to 1500 bbl/d. All vendors checked out OK on rates and accumulated flow for 21 minutes was 71.7 (tank) vs. 69.5 for all meters and ASRC. About ±2 bbl variation looks good. Following the flowrate tests the loop was purged with 30 bbl of diesel and is ready for the well flow to begin tomorrow. Agar had to drain the gas loop and FMC had to charge the pressure transducer reservoir with glycol in preparation for the well tests. Well tests will commence starting at 6:00am tomorrow. 1 5.4 .4 O t h er p e r t i n en t ev en t s

New day pad operator (Larry) was given orientation of the test facility. Mark O’Malley from Milne Point visited the site. 1 5.4 .5 D a t a t a k en a n d t r a n s m i t t ed

Flowrates on water tests. 1 5 .4 .6 W el l s u sed i n t h e t e st s

None.

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15.5

September 7th, 2003

1 5 .5 . 1 S a f e t y

0600 Safety meeting at ASRC unit # 1: safety orientation for the crew and vendors was held on September 6th prior to well tests. Tool box meeting on waste disposal was conducted on September 7th. 1 5.5 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)


Phase 1 tests on wells V-102, V-106, and V-117 completed and a preliminary summary and comparison with ASRC tests was emailed to Bruce Smith for distribution. Raw data from vendors was collated and will be sent to Bruce Smith via pouch mail. Met with vendors to plan for additional tests. ASRC results were shared with each vendor. Vendors have had a chance to adjust their meters. Will repeat Phase 1 tests with wells 102,106, and 117 to check for improvements. Wells 106 and 117 are being flowed to tank for more accurate liquid measurement. The repeat tests are expected to be complete tomorrow. Will spend tomorrow afternoon to evaluate the data and plan Phase 2. Each vendor has prepared training sessions for 4 operating personnel to be conducted on September 7th at 8:00 am. VECO completed the rig up of tents over the meters. 1 5.5 .4 O t h er p e r t i n en t ev en t s

Artie Soria from L-Pad visited the site. 1 5.5 .5 D a t a t a k en a n d t r a n s m i t t ed

Phase 1 tests data and preliminary summary. 1 5 .5 .6 W el l s u sed i n t h e t e st s

V-102, 106 and 117


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15.6

September 11th, 2003

1 5 .6 . 1 S a f e t y

Safety meeting at ASRC unit # 1: site orientation and ATP training for Roxar (Stig Froyen and Slavko Tosic) and Andrew Hall were held on September 11 th. Roxar and Andrew Hall also completed HSE and vehicle driving safety orientations. 1 5.6 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)

None 1 5.6 .3 L o op a n d m et e r s t a t u s

Completed tests on wells 101, 103, 107, 108, 109, and 113. Andrew Hall is in the process of conducting analysis and summarising the test results. Well tests were halted before well 202 could be tested due to ESD at the V-Pad. The 202 well tests will resume as soon as the situation in V-Pad is normalised. All data and pictures taken up to September 8th, except Agar tests on 102, 106 and 117, has been loaded on the server under the “Multiphase Field Test” by Hasebe. The missing Agar data is available on diskette and will be loaded with the next batch. SLB has informed the project team that unless they get more accurate gas composition data, by chromatography from current sample from each well, their results will be inaccurate for wells with GVF higher than 95%, which includes most of the wells on VPad. We currently do not have up-to-date chromatography results on all wells. SLB is to submit a document to describe the desired accuracy of the gas composition and implication on the performance of the meter if such gas composition accuracy is not available. Roxar team is on site minus the gamma source, power cable, data cable, and 110/24V converter needed in the data acquisition computer. Site personnel are working to provide these items to Roxar. A procedure for Roxar meter set up and calibration was developed and will be used to proceed with Roxar tests when the equipment and gamma source are ready to go.

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1 5.6 .4 O t h er p e r t i n en t ev en t s

ESD on the well pad stopped the well tests. 1 5.6 .5 D a t a t a k en a n d t r a n s m i t t ed

Data up to September 8th. 1 5 .6 .6 W el l s u sed i n t h e t e st s

V-102, 103, 107, 108, 109, and 113.


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15.7


1 5 .7 . 1 S a f e t y

Safety meeting at ASRC unit # 1: held as per schedule. 1 5.7 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)


Completed well tests 202, 03, 102, 103, 106 and 101 (partial). SLB has provided a table on the sensitivity of the meter for wells 117 and 106 fluids. The data shows that the SLB meter is very sensitive to CO2 content of the gas, e.g. 10% CO2 content results in 18% to 20% inaccuracy in the oil rate for 106 and 117 wells. This implies that we have to supply accurate gas content data for individual wells as the CO2 content can vary from 5% to 11% in V-Pad wells. SLB has also indicated that the issue of poor initial calibration due to oil film on the gamma ray window has to be resolved. But this can be done at the end of project and data will then be post processed. Roxar has checked out the flow computer. It works and was transported to the site. Gamma source is expected to arrive here tomorrow. Roxar has also laid out the power and communication cables. Hot work connections to be done when the source gets here. The temperature transmitter on the FMC meter has stopped working. The problem was reported to FMC and they provided diagnostic and repair procedure. Repair will be done during the hot work permit needed for the Roxar meter. We will continue to acquire data and will correct it later for temperature. 3-inch pipe will replace the current 2-inch return line. Installation will take place on September 15th following shutdown of the loop. 1 5.7 .4 O t h er p e r t i n en t ev en t s

Andrew Hall and Roxar personnel briefed Randy Selman on the status of Roxar meter on September 13th.

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1 5.7 .5 D a t a t a k en a n d t r a n s m i t t ed

Write access to the “Multiphase Field Test” folder on the server is not available to Mehdizadeh/Hall. Will continue pouch mailing the data. The folder now contains all documents and data up to September 8 th. 1 5 .7 .6 W el l s u sed i n t h e t e st s

V-03, 101 (1 hour), 102, 103, 106 and 202.


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15.8


1 5 .8 . 1 S a f e t y

Safety: radiation survey was conducted at the site for the Roxar source. The ASRC safety inspector will audit the survey and the results will be submitted to HSE tomorrow before we start testing the Roxar meter. 1 5.8 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)


Completed well test 108 but the test was stopped after 6 hours in order to shut down the loop and complete the Roxar meter installation. Roxar source arrived and installed. All hot work on the Roxar meter was completed. Roxar meter calibration will be initiated at 9:00 am tomorrow per the procedure developed previously. Andrew Hall has completed the collation and analysis of all data up to September 16 th. The data and graphs have been loaded into the group file server. The 2-inch to 3-inch’ pipe conversion on the return line was completed. Well tests 107 and 108 were conducted with the new 3-inch return line. 1 5.8 .4 O t h er p e r t i n en t ev en t s

Andrew Hall has completed his tour of duty and returned to Anchorage. Hall will brief Bruce Smith on the status of data analysis and final report on September 17 th. 1 5.8 .5 D a t a t a k en a n d t r a n s m i t t ed

Write access to the “Multiphase Field Test” folder on the server is now available to Mehdizadeh and will be used to load the current data. 1 5 .8 .6 W el l s u sed i n t h e t e st s

V-107 and 108.

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15.9


1 5 .9 . 1 S a f e t y

Radiation survey conducted on the Roxar source at the site by Roxar and ASRC was submitted to Mike Schwemley. A leak in the Agar meter developed during the water flush procedure for the Roxar meter. Ice blockage on the discharge line to the tank resulted in a high pressure peak in the test loop exposing the Agar meter to pressures above its ANSI rating pressure. About ½ bbl of test water due to the leak was contained within the bermed area and vacuumed out. A pressure protection document and training roster on this incident is prepared by Hasebe and distributed to ASRC personnel and posted at the site for future flushing operations. 1 5.9 .2 E n v i r o n m en t a l i ssu es ( sp i l l s, r el ea s es, i n j u r i es)

About ½ bbl of lake water, all contained, with no release to gravel pad or tundra. 1 5.9 .3 L o op a n d m et e r s t a t u s

Completed the diesel flush portion of the Roxar meter calibration. The calibration procedure was aborted due to the leak in the Agar meter and will be resumed on September 18th. A bypass loop was built around the Agar meter and pressure tested. Calibration of the Roxar meter will continue and should be completed on September 18th. The repair to the Agar meter is to be finished by September 19 th by Agar personnel travelling to the slope today and the meter will be put back in the loop at that time. This shut-down has also allowed SLB to change the gamma ray counter on their meter, which had developed instability. Due to fore-mentioned activities, we could not conduct any well tests. 1 5.9 .4 O t h er p e r t i n en t ev en t s

Eric Ward visited the site on September 18 th and was briefed on the status of the testing, reviewed the operation of the ASRC test separator, and looked at the multiphase data we have generated up to now. 1 5.9 .5 D a t a t a k en a n d t r a n s m i t t ed


V-108.


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15.10 September 21st, 2003 15.10.1

Safety

Safety: during the pressure test of the Agar meter on 20th September, the strainer flanges began to leak. ASRC shut down the pump, depressurised the system and prepared to tighten the flange. Before re-torquing the flange, it was decided to sweep the line with dry gas. During the gas sweep, mist of diesel fluid was released from the flange. The diesel mist came in contact with the ground, outside the containment area. ASRC immediately notified the pad operator, his immediate supervisor and the environmental personnel. Environmental visited the site, inspected the area and determined the incident to be a spot clean up. 1 5.1 0.2

E n v i r o n m en t a l i ssu e s ( sp i l l s, r el ea s es, i n j u r i es)

Diesel mist in contact with the ground. Spot clean up. 1 5.1 0.3

L o op a n d m et e r st a t u s

Completed the calibration of the Roxar meter. The Roxar personnel made final adjustment and declared meter ready for performance compliance phase. Repair to the Agar meter was also completed. After initial leak check, the strainer leaked and was removed per Agar instruction. The meter was pressure tested to 1000 psig and passed the leak check. Agar meter was then installed into the loop; the entire loop pressure tested to 1000 psig and put on-line. For the first time we have all four meters in the loop producing measurement data. Test of well 109 was completed and well 03 is ongoing and will be completed tonight. Will start on well 113 next. 1 5.1 0.4

O t h er p e r t i n e n t ev en t s

Mehdizadeh prepared graphs on wells 107, 108, and 109. Wendy Baumeister suggests these wells as candidates for gas optimisation study in the next phase. The graphs will be used to discuss gas optimisation procedure with Baumeister. Roxar and Agar personnel have completed their work and departed for Anchorage. 1 5.1 0.5

D a t a t a k en a n d t r a n sm i t t ed

Data from wells 109 and 108 downloaded to the group file. 1 5 .1 0 .6

W el l s u sed i n t h e t e st s

V-03 and 108.

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15.11 September 23rd, 2003 15.11.1

Safety

No safety related incident. 1 5.1 1.2


None. 1 5.1 1.3


Completed tests on wells 113 and 03. Both wells were also tank tested. Completed gas optimisation tests on wells 107 and 108. Testing on 109 was stopped due to compressor failure at ASRC trailer. Testing to resume tonight, after the portable compressor is hooked up to the ASRC. 1 5.1 1.4


Other pertinent events: Bruce Weiler visited the test site and was briefed on the status of the project. Work on well 201 progressing and the well may be ready for testing after the scheduled Pad ESD. 1 5.1 1.5


Data from gas optimisation phase on wells 107 and 108 was processed and will be loaded to the group file tomorrow. 1 5 .1 1 .6


V-107 and 108.


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CONFIDENTIAL

15.12 September 25th, 2003 15.12.1

Safety

Met with ASRC personnel on September 24th to review the recent “Communication Protocol for the Three Phase Metering Project” developed by Hasebe. This protocol emphasizes the need for both written and oral communication to the GPB Field Team Lead for all activities associated with the test program. 1 5.1 2.2


None. 1 5.1 2.3


Completed tests wells 109, 107, 103, and 117. All wells were tank strapped to obtain liquid measurements. The test loop was shut down on September 25th at 6:00 am due to the Pad ESD. The loop was depressurised, flushed, and filled with methanol to protect meters from cold weather during the anticipated 2-day ESD. 1 5.1 2.4


The following people visited the test facility and were briefed on the multiphase testing programme: Jane Williamson (AOGCC) Mike Hanus (ExxonMobil) Mike Mullaly (ExxonMobil) Ryan Dunn (ConocoPhillips) Dudley Platt (DOR) Jessie Carr (BP, well optimisation engineer) 1 5.1 2.5


Data from wells 102, 103, 107, 108, 109, and 117 was loaded to the group file. Prepared a list of all tests conducted up to date and each meter’s time in the loop. This list will be used as the index to collate and process data for each meter. The list is also loaded into the group file. 1 5 .1 2 .6


V-102, 103, 107, 108, 109 and 117.

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CONFIDENTIAL

15.13 September 28th, 2003 15.13.1

Safety

No incident. 1 5.1 3.2


None. 1 5.1 3.3


Resumed testing of well 201 after the Pad ESD was lifted on 26th September. Purging of the line with well 201 was initiated at 9:00 PM on 26 th September and the well was put on test at 3:00 AM on 27 th September. Sample water cut from the ASRC separator was above 99%. It became apparent that 201 was not quite ready for test. Gas from the pad was injected to test loop header in order to move the stream through the ASRC and pad separators. This caused high GVF in the test loop. All multiphase meters read water cut values well below the samples. The L-Pad shut down at 8:45 causing pressure drop in the loop and higher GVF. As a result all meters were subjected to high water cut and GVF tests. At 12:00 the gas to the loop was shut off. All meters began reading correct water cut. The test on V-201 was aborted at 13:00 and V-113 was brought in to push the liquid through the separators. Testing continued with V113 and V-101. Currently we are testing V-106 and V-202, which were previously tested without the Roxar meter in the loop, until the situation with V-201 becomes clear. 1 5.1 3.4


Mehdizadeh gave a brief overview of the project at the Bruce Weiler’s toolbox meeting on September 27th. Mehdizadeh met with Kevin Yeager and established a procedure for demobbing of the loop, starting on October 1 st. Hasebe has advised all vendors by email of the demob date and has asked them to provide instruction for rig down and disconnecting the instruments. Also Yeager is updating the expenses on AFE PBS4P2136. 1 5.1 3.5


Data from wells 201, 106, and 113. 1 5 .1 3 .6


V-106, 113 and 201.


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CONFIDENTIAL

15.14 September 30th, 2003 15.14.1

Safety

Wrote a Control Procedure for ASRC personnel to handle control and shut down during the high water cut/high gas volume fraction tests involving water injection from V-105 and gas from the pad header into V-106 stream. A review and training meeting was held with ASRC personnel prior to the test. 1 5.1 4.2


None. 1 5.1 4.3


V-201 was not available for testing during this reporting period. Testing continued with V-106 in preparation for the high water cut tests involving this well. We assessed various schemes to develop a ‘virtual’ high water cut well by injecting produced water in to the V-106 stream. Settled for injecting water from V-105 into V-106 stream through an S-riser to S-riser jumper. Also prepared procedure to adjust the GVF in the stream with gas injection from the pad header. As it turned out this was not necessary. The water injection scheme produced water cuts ranging from 45% to 95%. The high water cut tests were completed last night. The high water cut tests are the last phase of the project. With the completion of these tests the project is concluded and the demobbing of the equipment will begin on October 1 st. 1 5.1 4.4


Other pertinent events: discussed demobbing of Roxar, Agar, SLB and FMC with vendors. The assistance of the Pad operator (Charlie Geoff) and crew in rigging the water injection jumper was crucial in completing this phase of the project. 1 5.1 4.5


Data from well V-106 1 5 .1 4 .6


V-106

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CONFIDENTIAL

16

FIGURES AND TABLES

16.1

List of figures

Figure 4.1: Schematic diagram of Agar MPFM-400 series multiphase flow meter .......... ......... .......... ......... .16 Figure 4.2: Photograph of the Agar-401 multiphase flow meter at the test site............................................17 Figure 4.3: Photograph of the Flowsys multiphase flow meter at the test site..............................................18 Figure 4.4: Photograph of the Roxar MPFM 1900VI multiphase flow meter at the test site (centre meter, prior to installation of radioactive source)..............................................................................................19 Figure 4.5: Photograph of the Schlumberger multiphase flow meter at the test site. .......... .......... .......... .....20 Figure 5.1: Location of the field test site..........................................................................................................21 Figure 5.2: Schematic of multiphase flow meter installation..........................................................................22 Figure 5.3: Photograph of multiphase flow meter installation .......... .......... .......... .......... .......... .......... ........... 22 Figure 5.4: Photograph of meter protection .....................................................................................................23 Figure 5.5: Simplified ASRC Separator Schematic ........... .......... ........... .......... ........... .......... ........... ........... ....24 Figure 6.1: Agar 401 liquid flowrate error vs. ASRC reference GVF..............................................................35 Figure 6.2: Agar 401 gas flowrate error vs. ASRC reference GVF..................................................................36 Figure 6.3: Agar 401 water cut error vs. ASRC reference GVF ......... .......... .......... .......... .......... .......... ........... 36 Figure 6.4: FMC Flowsys liquid flowrate error vs. ASRC reference GVF ........... .......... .......... ........... .......... ..37 Figure 6.5: FMC Flowsys gas flowrate error....................................................................................................38 Figure 6.6: FMC Flowsys water cut error ........................................................................................................38 Figure 6.7: Roxar MPFM 1900VI liquid flowrate error vs. ASRC reference GVF .......... .......... .......... .......... .39 Figure 6.8: Roxar MPFM 1900VI gas flowrate error vs. ASRC reference GVF ......... .......... .......... ........... .....40 Figure 6.9: Roxar MPFM 1900VI water cut error vs. ASRC reference GVF .......... ........... ........... .......... ........ 40 Figure 6.10: Schlumberger VX29 (reprocessed) liquid flowrate error vs. ASRC reference GVF...................41 Figure 6.11: Schlumberger VX29 (reprocessed) gas flowrate error vs. ASRC reference GVF .......... .......... ...42 Figure 6.12: Schlumberger VX29 (reprocessed) water cut error vs. ASRC reference GVF ........... .......... ......42 Figure 6.13: Liquid flowrate repeatability for the four meters .......... .......... .......... .......... .......... .......... ........... 44 Figure 6.14: Gas flowrate repeatability for the four meters............................................................................44 Figure 6.15: Water cut repeatability for the four meters ........... .......... ........... .......... ........... .......... ........... ......45 Figure 6.16: Oil flowrate from the 4 multiphase flow meters vs. ASRC reference oil flowrate.....................46 Figure 6.17: Oil flowrate error from the 4 multiphase flow meters vs. ASRC reference GVF ......... .......... ...46 Figure 6.18: Water flowrate from the 4 multiphase flow meters vs. ASRC reference water flowrate. ......... 47 Figure 6.19: Water flowrate error from the 4 multiphase flow meters vs. ASRC reference GVF ......... ........ 47 Figure 6.20: Liquid flowrate from the 4 multiphase flow meters vs. ASRC reference liquid flowrate ......... 48 Figure 6.21: Liquid flowrate error from the 4 multiphase flow meters vs. ASRC reference GVF.................48 Figure 6.22: Gas flowrate from the 4 multiphase flow meters vs. ASRC reference gas flowrate..................49 Figure 6.23: Gas flowrate error from the 4 multiphase flow meters vs. ASRC reference GVF... .......... ........ 49 Figure 6.24: Water cut from the 4 multiphase flow meters vs. ASRC reference water cut.. .......... .......... .....50 Figure 6.25: Water cut error from the 4 multiphase flow meters vs. ASRC reference GVF..........................50 Figure 6.26: GVF from the 4 multiphase flow meters vs. ASRC reference GVF............................................51 Figure 6.27: GVF error from the 4 multiphase flow meters vs. ASRC reference GVF .......... .......... .......... ....51 Figure 6.28: GOR from the 4 multiphase flow meters vs. ASRC reference GOR...........................................52 Figure 6.29: GOR error from the 4 multiphase flow meters vs. ASRC reference GVF..................................52 Figure 6.30: Venturi pressure drop for 29mm Venturi throat ......... .......... .......... ........... .......... .......... ........... .53 Figure 7.1: Schematic of tank test installation................................................................................................55 Figure 7.2: View of the tank test location ........................................................................................................56 Figure 7.3: Schlumberger oil flowrate vs. reference oil flowrate.....................................................................59 Figure 7.4: Schlumberger oil flowrate error vs. reference GVF ......... .......... .......... .......... .......... .......... ........... 59 Figure 7.5: Schlumberger water flowrate vs. reference water flowrate..........................................................60 Figure 7.6: Schlumberger water flowrate error vs. reference GVF.................................................................60 Figure 7.7: Schlumberger liquid flowrate vs. reference liquid flowrate..........................................................61 Figure 7.8: Schlumberger liquid flowrate error vs. reference GVF.................................................................61 Figure 7.9: Schlumberger gas flowrate vs. reference gas flowrate..................................................................62 Figure 7.10: Schlumberger gas flowrate error vs. reference GVF...................................................................62 Figure 7.11: Schlumberger water cut vs. reference water cut.........................................................................63 Figure 7.12: Schlumberger water cut error vs. reference GVF .......... .......... .......... .......... .......... .......... ........... 63


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CONFIDENTIAL Figure 7.13: Schlumberger GVF vs. reference GVF ......... .......... ........... .......... .......... .......... .......... ............ ......64 Figure 7.14: Schlumberger GVF error vs. reference GVF ......... ........... .......... .......... .......... .......... .......... ......... 64 Figure 7.15: Roxar oil flowrate vs. reference oil flowrate................................................................................66 Figure 7.16: Roxar oil flowrate error vs. reference GVF .......... .......... .......... .......... .......... .......... .......... ........... 66 Figure 7.17: Roxar water flowrate vs. reference water flowrate.....................................................................67 Figure 7.18: Roxar water flowrate error vs. reference GVF ......... .......... .......... ........... .......... .......... ............ ....67 Figure 7.19: Roxar liquid flowrate vs. reference liquid flowrate.....................................................................68 Figure 7.20: Roxar liquid flowrate error vs. reference GVF............................................................................68 Figure 7.21: Roxar gas flowrate vs. reference gas flowrate.............................................................................69 Figure 7.22: Roxar gas flowrate error vs. reference GVF................................................................................69 Figure 7.23: Roxar water cut vs. reference water cut......................................................................................70 Figure 7.24: Roxar water cut error vs. reference GVF .......... .......... .......... ........... .......... .......... .......... ............ .70 Figure 7.25: Roxar GVF vs. reference GVF......................................................................................................71 Figure 7.26: Roxar GVF error vs. reference GVF ............................................................................................71 Figure 7.27: FMC oil flowrate vs. reference oil flowrate ......... .......... ........... .......... .......... .......... .......... ........... 73 Figure 7.28: FMC oil flowrate error vs. reference GVF .......... .......... .......... .......... .......... .......... .......... ............ .73 Figure 7.29: FMC water flowrate vs. reference water flowrate ......... ........... .......... .......... .......... ........... ......... 74 Figure 7.30: FMC water flowrate error vs. reference GVF..............................................................................74 Figure 7.31: FMC liquid flowrate vs. reference liquid flowrate .......... ........... .......... .......... ........... .......... ........ 75 Figure 7.32: FMC liquid flowrate error vs. reference GVF .......... .......... ........... .......... .......... ........... ........... ....75 Figure 7.33: FMC gas flowrate vs. reference gas flowrate ........... .......... .......... .......... .......... ........... ............ ....76 Figure 7.34: FMC gas flowrate error vs. reference GVF ........... .......... .......... .......... ........... .......... .......... ......... 76 Figure 7.35: FMC water cut vs. reference water cut .......... ........... .......... ........... .......... ........... .......... ........... ...77 Figure 7.36: FMC water cut error vs. reference GVF ........... ........... .......... ........... .......... ........... ........... .......... .77 Figure 7.37: FMC GVF vs. reference GVF .......................................................................................................78 Figure 7.38: FMC GVF error vs. reference GVF..............................................................................................78 Figure 7.39: Repeatability of Schlumberger VX multiphase flow meters.......................................................80 Figure 7.40: Repeatability of Roxar MPFM1900VI multiphase flow meters ......... .......... .......... .......... .......... 80 Figure 8.1: GPB well test map..........................................................................................................................82 Figure 8.2: GPB well test map, showing Agar-401 qualified operating envelope ......... .......... .......... .......... ...83 Figure 8.3: GPB well test map, showing FMC-Flowsys qualified operating envelope...................................83 Figure 8.4: GPB well test map, showing Roxar MPFM1900VI ........... .......... ........... .......... .......... ........... ........ 84 Figure 8.5: GPB well test map, showing Schlumberger VX29 qualified operating envelope ......... .......... .....84 Figure 8.6: Overall score for portable well testing (Assuming majority of wells lie in meter operating range)........................................................................................................................................................92 Figure 8.7: Overall score for well pad separator new build (Assuming majority of wells lie in meter operating range).......................................................................................................................................92 Figure 8.8: Overall score for well pad separator replacement (Assuming majority of wells lie in meter operating range).......................................................................................................................................93 Figure 8.9: Overall score for well pad separator augmentation (Assuming majority of wells lie in meter operating range).......................................................................................................................................93 Figure 8.10: Best fit to Agar and Schlumberger liquid flowrate measurement data.....................................94 Figure 9.1: Schematic diagram of Agar MPFM-400 series multiphase flow meter .......... ......... .......... ......... .97 Figure 9.2: Photograph of the Agar-401 multiphase flow meter at the test site............................................98 Figure 9.3: Agar 401 oil flowrate vs. ASRC reference oil flowrate................................................................102 Figure 9.4: Agar 401 oil flowrate error vs. ASRC reference GVF .......... .......... .......... ......... .......... .......... ......102 Figure 9.5: Agar 401 oil flowrate error vs. ASRC reference GVF and water cut .......... ......... .......... .......... ..103 Figure 9.6: Agar 401 water flowrate vs. ASRC reference water flowrate.....................................................103 Figure 9.7: Agar 401 water flowrate error vs. ASRC reference GVF............................................................104 Figure 9.8: Agar 401 water flowrate error vs. ASRC reference GVF and water cut .......... .......... .......... ......104 Figure 9.9: Agar 401 liquid flowrate vs. ASRC reference liquid flowrate.....................................................105 Figure 9.10: Agar 401 liquid flowrate error vs. ASRC reference GVF..........................................................105 Figure 9.11: Agar 401 liquid flowrate error vs. ASRC reference GVF and water cut..................................106 Figure 9.12: Agar 401 gas flowrate vs. ASRC reference gas flowrate...........................................................106 Figure 9.13: Agar 401 gas flowrate error vs. ASRC reference GVF..............................................................107 Figure 9.14: Agar 401 gas flowrate error vs. ASRC reference GVF and water cut......................................107 Figure 9.15: Agar 401 water cut vs. ASRC reference water cut....................................................................108 Figure 9.16: Agar 401 water cut error vs. ASRC reference GVF ........... ........... .......... ........... .......... ........... ..108 Figure 9.17: Agar 401 water cut error vs. ASRC reference GVF and water cut .......... .......... ........... ........... 109

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CONFIDENTIAL Figure 9.18: Agar 401 GVF vs. ASRC reference GVF....................................................................................109 Figure 9.19: Agar 401 GVF error vs. ASRC reference GVF .......... ........... .......... ........... .......... ........... ........... 110 Figure 9.20: Agar 401 GVF error vs. ASRC reference GVF and water cut .......... ........... ........... ........... ....... 110 Figure 9.21: Agar 401 GOR vs. ASRC reference GOR...................................................................................111 Figure 9.22: Agar 401 GOR error vs. ASRC reference GVF..........................................................................111 Figure 9.23: Agar 401 GOR error vs. ASRC reference GVF and water cut..................................................112 Figure 9.24: Agar 401 statistics......................................................................................................................112 Figure 9.25: Agar 401 cumulative curves.......................................................................................................113 Figure 9.26: Agar 401 cumulative curves.......................................................................................................113 Figure 9.27: Agar 401 repeatability................................................................................................................114 Figure 10.1: Photograph of the Flowsys multiphase flow meter at the test site..........................................117 Figure 10.2: FMC Flowsys oil flowrate vs. ASRC reference oil flowrate .......... .......... .......... .......... ........... ...121 Figure 10.3: FMC Flowsys oil flowrate error vs. ASRC reference GVF........................................................121 Figure 10.4: FMC Flowsys oil flowrate error vs. ASRC reference GVF and water cut................................122 Figure 10.5: FMC Flowsys water flowrate vs. ASRC reference water flowrate .......... ........... .......... .......... ..122 Figure 10.6: FMC Flowsys water flowrate error vs. ASRC reference GVF ........... .......... .......... .......... ......... 123 Figure 10.7: FMC Flowsys water flowrate error vs. ASRC reference GVF and water cut .......... .......... ......123 Figure 10.8: FMC Flowsys liquid flowrate vs. ASRC reference liquid flowrate ........... .......... ........... .......... .124 Figure 10.9: FMC Flowsys liquid flowrate error vs. ASRC reference GVF ........... .......... ........... .......... ........ 124 Figure 10.10: FMC Flowsys liquid flowrate error vs. ASRC reference GVF and water cut ......... ........... ....125 Figure 10.11: FMC Flowsys gas flowrate vs. ASRC reference gas flowrate .......... .......... .......... .......... ......... 125 Figure 10.12: FMC Flowsys gas flowrate error..............................................................................................126 Figure 10.13: FMC Flowsys gas flowrate error vs. ASRC reference GVF and water cut .......... .......... ........ 126 Figure 10.14: FMC Flowsys water cut............................................................................................................127 Figure 10.15: FMC Flowsys water cut error .......... ........... .......... .......... ........... .......... .......... ........... ........... ....127 Figure 10.16: FMC Flowsys water cut error vs. ASRC reference GVF and water cut.................................128 Figure 10.17: FMC Flowsys GVF ...................................................................................................................128 Figure 10.18: FMC Flowsys GVF error ..........................................................................................................129 Figure 10.19: FMC Flowsys GVF error vs. ASRC reference GVF and water cut.........................................129 Figure 10.20: FMC Flowsys GOR ...................................................................................................................130 Figure 10.21: FMC Flowsys GOR error vs. ASRC reference GVF ........... .......... .......... .......... ........... .......... ..130 Figure 10.22: FMC Flowsys GOR ...................................................................................................................131 Figure 10.23: FMC Flowsys statistics ............................................................................................................131 Figure 10.24: FMC Flowsys cumulative curves ......... ........... .......... .......... .......... .......... ........... .......... ........... .132 Figure 10.25: FMC Flowsys cumulative curves ......... ........... .......... .......... .......... .......... ........... .......... ........... .132 Figure 10.26: FMC Flowsys repeatability ........... .......... .......... .......... ........... .......... .......... .......... ............ ........ 133 Figure 11.1: Photograph of the Roxar MPFM 1900VI multiphase flow meter at the test site (centre meter, prior to installation of radioactive source)............................................................................................137 Figure 11.2: Roxar MPFM 1900VI oil flowrate vs. ASRC reference oil flowrate ......... .......... .......... ......... ...141 Figure 11.3: Roxar MPFM 1900VI oil flowrate error vs. ASRC reference GVF .......... .......... .......... .......... ...141 Figure 11.4: Roxar MPFM 1900VI oil flowrate error vs. ASRC reference GVF and water cut ......... .......... 142 Figure 11.5: Roxar MPFM 1900VI water flowrate vs. ASRC reference water flowrate .......... .......... .......... 142 Figure 11.6: Roxar MPFM 1900VI water flowrate error vs. ASRC reference GVF......................................143 Figure 11.7: Roxar MPFM 1900VI water flowrate error vs. ASRC reference GVF and water cut..............143 Figure 11.8: Roxar MPFM 1900VI liquid flowrate vs. ASRC reference liquid flowrate .......... .......... .......... 144 Figure 11.9: Roxar MPFM 1900VI liquid flowrate error vs. ASRC reference GVF .......... .......... .......... ....... 144 Figure 11.10: Roxar MPFM 1900VI liquid flowrate error vs. ASRC reference GVF and water cut............145 Figure 11.11: Roxar MPFM 1900VI gas flowrate vs. ASRC reference gas flowrate ......... .......... .......... ....... 145 Figure 11.12: Roxar MPFM 1900VI gas flowrate error vs. ASRC reference GVF ......... .......... ......... .......... .146 Figure 11.13: Roxar MPFM 1900VI gas flowrate error vs. ASRC reference GVF and water cut................146 Figure 11.14: Roxar MPFM 1900VI water cut vs. ASRC reference water cut .......... .......... .......... ......... ......147 Figure 11.15: Roxar MPFM 1900VI water cut error vs. ASRC reference GVF............................................147 Figure 11.16: Roxar MPFM 1900VI water cut error vs. ASRC reference GVF and water cut ......... .......... .148 Figure 11.17: Roxar MPFM 1900VI GVF.......................................................................................................148 Figure 11.18: Roxar MPFM 1900VI GVF error vs. ASRC reference GVF....................................................149 Figure 11.19: Roxar MPFM 1900VI GVF error vs. ASRC reference GVF and water cut .......... .......... ........ 149 Figure 11.20: Roxar MPFM 1900VI GOR ......................................................................................................150 Figure 11.21: Roxar MPFM 1900VI GOR error vs. ASRC reference GVF....................................................150 Figure 11.22: Roxar MPFM 1900VI GOR error vs. ASRC reference GVF and water cut............................151 Figure 11.23: Roxar MPFM 1900VI statistics................................................................................................151


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CONFIDENTIAL Figure 11.24: Roxar MPFM 1900VI cumulative curves .......... ........... .......... .......... .......... .......... .......... ......... 152 Figure 11.25: Roxar MPFM 1900VI cumulative curves .......... ........... .......... .......... .......... .......... .......... ......... 152 Figure 11.26: Roxar MPFM 1900VI repeatability .........................................................................................153 Figure 12.1: Photograph of the Schlumberger multiphase flow meter at the test site .......... .......... .......... ..157 Figure 12.2: Schlumberger VX29 oil flowrate vs. ASRC reference oil flowrate............................................161 Figure 12.3: Schlumberger VX29 oil flowrate error vs. ASRC reference GVF .......... .......... .......... .......... .....161 Figure 12.4: Schlumberger VX29 oil flowrate error vs. ASRC reference GVF and water cut .......... .......... .162 Figure 12.5: Schlumberger VX29 water flowrate vs. ASRC reference water flowrate.................................162 Figure 12.6: Schlumberger VX29 water flowrate error vs. ASRC reference GVF........................................163 Figure 12.7: Schlumberger VX29 water flowrate error vs. ASRC reference GVF and water cut................163 Figure 12.8: Schlumberger VX29 liquid flowrate vs. ASRC reference liquid flowrate ........... .......... .......... .164 Figure 12.9: Schlumberger VX29 liquid flowrate error vs. ASRC reference GVF........................................164 Figure 12.10: Schlumberger VX29 liquid flowrate error vs. ASRC reference GVF and water cut..............165 Figure 12.11: Schlumberger VX29 gas flowrate vs. ASRC reference gas flowrate.......................................165 Figure 12.12: Schlumberger VX29 gas flowrate error vs. ASRC reference GVF..........................................166 Figure 12.13: Schlumberger VX29 gas flowrate error vs. ASRC reference GVF and water cut..................166 Figure 12.14: Schlumberger VX29 water cut vs. ASRC reference water cut................................................167 Figure 12.15: Schlumberger VX29 water cut error vs. ASRC reference GVF .......... .......... ........... .......... .....167 Figure 12.16: Schlumberger VX29 water cut error vs. ASRC reference GVF and water cut ........... ........... 168 Figure 12.17: Schlumberger VX29 GVF vs. ASRC reference GVF .......... .......... .......... ........... .......... .......... ..168 Figure 12.18: Schlumberger VX29 GVF error vs. ASRC reference GVF.......... .......... .......... ........... .......... ...169 Figure 12.19: Schlumberger VX29 GVF error vs. ASRC reference GVF and water cut .......... ........... ......... 169 Figure 12.20: Schlumberger VX29 GOR vs. ASRC reference GOR...............................................................170 Figure 12.21: Schlumberger VX29 GOR error vs. ASRC reference GVF......................................................170 Figure 12.22: Schlumberger VX29 GOR error vs. ASRC reference GVF and water cut..............................171 Figure 12.23: Schlumberger VX29 statistics..................................................................................................171 Figure 12.24: Schlumberger VX29 cumulative curves .......... .......... .......... ........... .......... .......... .......... ........... 172 Figure 12.25: Schlumberger VX29 cumulative curves .......... .......... .......... ........... .......... .......... .......... ........... 172 Figure 12.26: Schlumberger VX29 repeatability .......... .......... ........... .......... .......... .......... ........... ............ ....... 173 Figure 12.27: Schlumberger VX29 (reprocessed) oil flowrate vs. ASRC reference oil flowrate...................177 Figure 12.28: Schlumberger VX29 (reprocessed) oil flowrate error vs. ASRC reference GVF ......... .......... .177 Figure 12.29: Schlumberger VX29 (reprocessed) oil flowrate error vs. ASRC reference GVF and water cut ................................................................................................................................................................178 Figure 12.30: Schlumberger VX29 (reprocessed) water flowrate vs. ASRC reference water flowrate........178 Figure 12.31: Schlumberger VX29 (reprocessed) water flowrate error vs. ASRC reference GVF ......... ......179 Figure 12.32: Schlumberger VX29 (reprocessed) water flowrate error vs. ASRC reference GVF and water cut ...........................................................................................................................................................179 Figure 12.33: Schlumberger VX29 (reprocessed) liquid flowrate vs. ASRC reference liquid flowrate........180 Figure 12.34: Schlumberger VX29 (reprocessed) liquid flowrate error vs. ASRC reference GVF...............180 Figure 12.35: Schlumberger VX29 (reprocessed) liquid flowrate error vs. ASRC reference GVF and water cut ...........................................................................................................................................................181 Figure 12.36: Schlumberger VX29 (reprocessed) gas flowrate vs. ASRC reference gas flowrate................181 Figure 12.37: Schlumberger VX29 (reprocessed) gas flowrate error vs. ASRC reference GVF...................182 Figure 12.38: Schlumberger VX29 (reprocessed) gas flowrate error vs. ASRC reference GVF and water cut ................................................................................................................................................................182 Figure 12.39: Schlumberger VX29 (reprocessed) water cut vs. ASRC reference water cut.........................183 Figure 12.40: Schlumberger VX29 (reprocessed) water cut error vs. ASRC reference GVF ........... .......... ..183 Figure 12.41: Schlumberger VX29 (reprocessed) water cut error vs. ASRC refe rence GVF and water cut184 Figure 12.42: Schlumberger VX29 (reprocessed) GVF vs. ASRC reference GVF.........................................184 Figure 12.43: Schlumberger VX29 (reprocessed) GVF error vs. ASRC reference GVF .......... .......... .......... .185 Figure 12.44: Schlumberger VX29 (reprocessed) GVF error vs. ASRC reference GVF and water cut........185 Figure 12.45: Schlumberger VX29 (reprocessed) GOR vs. ASRC reference GVF .......... .......... .......... .......... 186 Figure 12.46: Schlumberger VX29 (reprocessed) GOR error vs. ASRC reference GVF...............................186 Figure 12.47: Schlumberger VX29 (reprocessed) GOR error vs. ASRC reference GVF and water cut ....... 187 Figure 12.48: Schlumberger VX29 (reprocessed) statistics .......... .......... .......... ........... .......... .......... ............ ..187 Figure 12.49: Schlumberger VX29 (reprocessed) cumulative curves............................................................188 Figure 12.50: Schlumberger VX29 (reprocessed) cumulative curves............................................................188 Figure 12.51: Schlumberger VX29 (reprocessed) repeatability.....................................................................189 Figure 12.52: Schlumberger VX29 oil flowrate vs. ASRC reference oil flowrate..........................................193

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CONFIDENTIAL Figure 12.53: Schlumberger VX29 oil flowrate error vs. ASRC reference GVF .......... ......... .......... .......... ....193 Figure 12.54: Schlumberger VX29 water flowrate vs. ASRC reference water flowrate...............................194 Figure 12.55: Schlumberger VX29 water flowrate error vs. ASRC reference GVF......................................194 Figure 12.56: Schlumberger VX29 liquid flowrate vs. ASRC reference liquid flowrate .......... .......... .......... 195 Figure 12.57: Schlumberger VX29 liquid flowrate error vs. ASRC reference GVF......................................195 Figure 12.58: Schlumberger VX29 gas flowrate vs. ASRC reference gas flowrate.......................................196 Figure 12.59: Schlumberger VX29 gas flowrate error vs. ASRC reference GVF..........................................196 Figure 12.60: Schlumberger VX29 water cut vs. ASRC reference water cut................................................197 Figure 12.61: Schlumberger VX29 water cut error vs. ASRC reference GVF .......... .......... ........... .......... .....197 Figure 12.62: Schlumberger VX29 GVF vs. ASRC reference GVF .......... .......... .......... ........... .......... .......... ..198 Figure 12.63: Schlumberger VX29 GVF error vs. ASRC reference GVF.......... .......... .......... ........... .......... ...198 Figure 12.64: Schlumberger VX29 GOR vs. ASRC reference GOR...............................................................199 Figure 12.65: Schlumberger VX29 GOR error vs. ASRC reference GVF......................................................199 Figure 13.1: ASRC reference liquid rate statistical confidence.....................................................................201 Figure 13.2: ASRC reference gas rate statistical confidence.........................................................................202 Figure 13.3: ASRC reference water cut statistical confidence ......... ........... .......... ........... .......... ........... ........ 202 Figure 13.4: V03 2003-09-12...........................................................................................................................203 Figure 13.5: V03 2003-09-21...........................................................................................................................203 Figure 13.6: V101 2003-09-09 .........................................................................................................................204 Figure 13.7: V101 2003-09-15 .........................................................................................................................204 Figure 13.8: V101 2003-09-28 .........................................................................................................................205 Figure 13.9: V102 2003-09-05 .........................................................................................................................205 Figure 13.10: V102 2003-09-08.......................................................................................................................206 Figure 13.11: V102 2003-09-13.......................................................................................................................206 Figure 13.12: V102 2003-09-24.......................................................................................................................207 Figure 13.13: V103 2003-09-09.......................................................................................................................207 Figure 13.14: V103 2003-09-13.......................................................................................................................208 Figure 13.15: V103 2003-09-24.......................................................................................................................208 Figure 13.16: V106 2003-09-05.......................................................................................................................209 Figure 13.17: V106 2003-09-07.......................................................................................................................209 Figure 13.18: V106 2003-09-14.......................................................................................................................210 Figure 13.19: V106 2003-09-28.......................................................................................................................210 Figure 13.20: V106 2003-09-29A ....................................................................................................................211 Figure 13.21: V106 2003-09-29B ....................................................................................................................211 Figure 13.22: V106 2003-09-30B ....................................................................................................................212 Figure 13.23: V106 2003-09-30A ....................................................................................................................212 Figure 13.24: V107 2003-09-09.......................................................................................................................213 Figure 13.25: V107 2003-09-15.......................................................................................................................213 Figure 13.26: V107 2003-09-22A ....................................................................................................................214 Figure 13.27: V107 2003-09-22B ....................................................................................................................214 Figure 13.28: V107 2003-09-24.......................................................................................................................215 Figure 13.29: V108 2003-09-009 .....................................................................................................................215 Figure 13.30: V108 2003-09-16.......................................................................................................................216 Figure 13.31: V108 2003-09-18.......................................................................................................................216 Figure 13.32: V108 2003-09-22A ....................................................................................................................217 Figure 13.33: V108 2003-09-22B ....................................................................................................................217 Figure 13.34: V108 2003-09-22C ....................................................................................................................218 Figure 13.35: V109 2003-09-10.......................................................................................................................218 Figure 13.36: V109 2003-09-19.......................................................................................................................219 Figure 13.37: V109 2003-09-23A ....................................................................................................................219 Figure 13.38: V109 2003-09-23B ....................................................................................................................220 Figure 13.39: V113 2003-09-10.......................................................................................................................220 Figure 13.40: V113 2003-09-22.......................................................................................................................221 Figure 13.41: V113 2003-09-27.......................................................................................................................221 Figure 13.42: V117 2003-09-06.......................................................................................................................222 Figure 13.43: V117 2003-09-08A ....................................................................................................................222 Figure 13.44: V117 2003-09-08B ....................................................................................................................223 Figure 13.45: V117 2003-09-24.......................................................................................................................223 Figure 13.46: V201 2003-09-26.......................................................................................................................224 Figure 13.47: V202 2003-09-10.......................................................................................................................224


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GPB Multiphase Meter Tests 1

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