AFA Documentation
AFA Documentation
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Composite Models

Introduction

In some cases, it will be necessary to consider variations in the mobility in the lateral direction. Some of the more common cases where one can observe a change in mobility are:

  • Injection of a different fluid

  • Change in saturations due an aquifer

  • Changes in saturations due to a gas cap

  • Change in lateral saturation due to production below a dew point

  • Compartments

  • Facies change

  • Rock properties

Mathematically, any change in the mobility (kh/u) and/or diffusivity (k/Φuct) could be represented by a composite system.

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Radial Composite (left) & Linear Composite (right) Systems


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Idealized Example of Radial Composite System (Porosity Decrease)

Pressure Contour Modelling of Composite Systems

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Radial Composite (left) & Linear Composite (right) Systems

Bourdet Derivatives for Radial Composite System

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See Also:

References:

  • Tang, R. W., and A. K. Ambastha. "Analysis of CO2 Pressure Transient Data With Two- and Three-Region Analytical Radial Composite Models." Paper presented at the SPE Annual Technical Conference and Exhibition, Houston, Texas, October 1988.

  • Bozorgzadeh, Manijeh, and Alain C. Gringarten. "Condensate-Bank Characterization From Well-Test Data and Fluid PVT Properties." SPE Res Eval & Eng 9 (2006): 596–611

  • Ambastha, A.K.. "Practical Aspects of Well Test Analysis Under Composite Reservoir Situations." J Can Pet Technol 34 (1995)