Pressure transient analysis for composite systems
A composite reservoir model is used to analyze well-tests from a variety of enhanced oil recovery project, geothermal reservoirs, and acidization projects. A composite reservoir is made up of two or more regions. Each region has its own rock and fluid properties. Transient pressure behavior of a well in a two-region composite reservoir has been considered extensively in the literature, and several methods have been proposed to estimate front (or discontinuity) radius, or swept volume. The study considers transient pressure derivative behavior of a well in a two-region composite reservoir to establish the applicability and the limitations of different methods to estimate front radius or swept volume. A finite-radius well with wellbore storage and skin is assumed to reduce (or inject) at a constant rate. Three outer boundary conditions are considered: infinite, closed, and constant-pressure. A study of drawdown and buildup responses has resulted in a set of correlating parameters for the pressure derivative responses, and new design and interpretation relations for well-tests in composite reservoirs. Guidelines have been presented for the applicability of different methods to estimate front radius. Dynamic phenomena, such as phase changes and multi-phase flow effects in a region near the front, can cause a sharp pressure drop at the front. Such a sharp pressure drop is modeled as a thin skin at the front in this study. An analytical solution for the transient pressure behavior of a well in a two-region composite reservoir with a skin at the front is obtained using the Laplace transformation. A thin skin at the front can explain a short duration pseudosteady short duration pseudosteady state even for small mobility and storativity contrasts. Pressure derivative behavior of a well in a homogeneous, or a three-region composite reservoir is also discussed. 93 refs., 75 figs., 11 tabs.
- Research Organization:
- Stanford Univ., CA (USA). Petroleum Research Inst.
- Sponsoring Organization:
- DOE/FE
- DOE Contract Number:
- FG22-87BC14126
- OSTI ID:
- 5496988
- Report Number(s):
- DOE/BC/14126-11; SUPRI-TR-68; ON: DE89000768
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PETROLEUM
ENHANCED RECOVERY
RESERVOIR ROCK
PRESSURE GRADIENTS
EVAPORATION
MATHEMATICAL MODELS
OIL WELLS
PRESSURE DROP
PRESSURE EFFECTS
STEAM INJECTION
SWEEP EFFICIENCY
ENERGY SOURCES
FLUID INJECTION
FOSSIL FUELS
FUELS
PHASE TRANSFORMATIONS
RECOVERY
WELLS
020300* - Petroleum- Drilling & Production