Rig move risk assessment

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MINIMIZING MINI MI NIMI MIZI ZING NG RIS R RISKS ISKS KS FOR FOR JAC J JACK ACKK--UP -UP UP RIGS RIGS

Presented by: S. Douglas Devoy

MatthewsDaniel Houston, Texas

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PRELOADING HAS PROVEN TO POSE THE GREATEST RISK DURING THE FINAL JACK-UP RIGS SUSTAIN PUNCH-THROUGHS STAGES OF THE RIG MOVE! IN ALL AREAS OF THE WORLD

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Definition of Preloading of JackJack-Up Rig

volumes of salt water into designated  , overall weight of the rig.

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Definition of Preloading of JackJack-Up Rig

spud cans penetrating deeper into the  adequate strength to support the rig.

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Rig Preloading on Location

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Risk Mitigation Measures For Preloading Location Approval 

Detailed Geotechnical Analysis / Punch--Through Study Punch

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Recommendations for Preloading Air Gap

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Recommendations for Close Monitoring of Leg Loads and Penetrations

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Recommendation for Action if Penetrations are Different than Predicted

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Preloading Risk Level Assessment ecommen a on or r ap ur ng re oa ng

Special Caution

Normal to Maximum Air Gap

ax mum -

Minimal Air Gap

Maximum 0-2’

Extreme Caution 0’ Air Gap or Draft

o o xcee Draft

o

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Rig Arrives on Location Initial Penetrations Taken ’

m te o s n ormat on . . . Generic Location Approval . . . No Preloading Program. . .

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Maximum preload water onboard Even penetrations on all 3 legs

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Dump preload water Rig jacked back to 5’ air gap

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Near end of preloading cycle Legs at even penetration ’

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Jack Up Rig PunchPunch-Through Middle East

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Information Developed Prior to Rig Move

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Detailed Soils Anal sis conducted b Geotechnical Expert

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Punch--Through Predicted Punch

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Preload in Water Recommended

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Rig Move Plan Agreed Prior to Siting 1. Preload in Water to 100% 2. Followed by Preload at Minimal Air Gap to 100%

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Findings  Le 

Penetration Curve showed ‘ unchunch-throu h’

Initial penetrations were different than predicted vs. an c pa e

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-

First stage of preload conducted at draft with no settlement of legs ’

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f

f

Port leg punchpunch-through occurred at 91% preload

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Failure in System

A

v Superseded by Rig Mover

Preloadin Conducted at 5’ Air Ga

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Lessons Learned parties engaged in preloading operation. 

It is important to keep accurate measurements f

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When the soils do not behave as Leg Penetration

urve predicts, EXTREME

aution

is advised. Lower air gap = less damage.

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Accurate Measurement of Spud Can oa an Penetration

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Case Study Estimated unc Through 5

r

ap

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ecommen at ons to

e uce

s

ur ng re oa ng

Utilize JRC Scope of Work for Rig Moves

Punch--Through Risk and Recommended Punch