PIPESIM- Fluid Calibration

Fluid Calibration

Black oil fluid properties (also known as PVT properties) are predicted by correlations developed by fitting experimental fluid data with mathematical models. Various correlations have been developed over the years based on experimental data sets covering a range of fluid Properties.

The PIPESIM Help system describes the range of fluid properties used to develop each correlation, which helps you select the most appropriate correlation for your fluid. For more information, refer to Black oil Correlations. Correlations. The default correlations in PIPESIM are based on the overall accuracy of the correlations, as applied to a broad range of fluids. To increase the accuracy of fluid property calculations, PIPESIM provides functionality to match PVT fluid properties with laboratory data. Calibration of these properties can greatly increase the accuracy of the correlations over the range of pressures and temperatures for the system being modeled.

For example, calibration of the bubble point pressure can result in the initial appearance of gas at a depth, hundreds or even thousands of feet shallower or deeper than in an uncalibrated model. This will result in a significantly different mixture fluid density and, thus, a vastly different elevational pressure gradient.

Likewise, calibration of the fluid viscosity can drastically improve the calculation of the frictional pressure gradient, especially in heavy oils and emulsions. If the calibration data is omitted, PIPESIM calibrates on the basis of oil and gas gravity alone, resulting in a loss of accuracy. After the calibration is performed, a calibration factor is calculated as the ratio of the measured value to the value calculated calculat ed by the selected correlation for the th e PVT property.

The calibration method available in PIPESIM 2014.1 is Single Point Calibration. Single Point Calibration

In many cases, actual measured values for PVT properties show a variance from the values calculated using the correlations. When this occurs, it is useful to calibrate the property using the measured value. PIPESIM can use the known data for the property to calculate a calibration constant Kc; Kc = Measured Property @(P,T)/Calculated Property @(P,T)

This calibration constant is used to modify all subsequent calculations of the property in question, as below: Calibrated value = Kc * (Predicted value) Task 4: Calibrate PVT Data

Do the following: 1. Access the Fluid editor either through the Completions tab of the Well editor or from the Fluid Manager on the Home tab. 2. Select the Viscosity tab and enter the measured dead oil viscosity data as below. Also, change the undersaturated oil viscosity correlation and the emulsion viscosity method to Bergman & Sutton and Brinkman respectively. Production Rate 8,840 stb/d Flowing BHP 2,495 psia Flowing WHT 138 degF Depth at which gas appears Between 7,082 ft and 7,199 ft 3. Select the Calibration tab and enter the additional measured PVT data shown below. The selected black oil correlations will be tuned to match this data. 4. Click Close. The fluid model is now calibrated. 5. Re-run the P/T Profile task with the same boundary conditions conditions and observe the difference in results between this calibrated model and the uncalibrated model in the previous task. M