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U.S. Department of Energy
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Reservoir engineering study of low-permeability Western gas sands. Final report

Technical Report ·
OSTI ID:6747341

The parameters of formation permeability, porosity, gas saturation net pay thickness, and well spacing were investigated to develop a multiple-well transient test. Long test times were found to be required for interference or pulse testing in low permeability gas reservoirs; however, well spacing has been optimized. The new type curves developed account for the length of time a well was on production prior to shut-in for the buildup test. Estimates of permeability, fracture half-length, and fracture conductivity are given by analysis of the pressure buildup using the curves. It was found that the results from Horner analysis of a vertically fractured well's pressure analysis are affected by the length of time a well produces prior to starting the buildup test. Long dimensionless flow times are needed for the Horner straight line to develop, thus requiring long flowtimes for Horner analysis of fractured wells in low permeability reservoirs. Several examples using the new curves are presented. The uniqueness study indicated that when certain parameters are accurately known through rock analysis and pressure studies, the simulations are unique. If a few key parameters are unknown and must be determined through history-matching with the simulator, uncertainty arises as to whether the solution is unique. Additional studies concerning fracture skin and wellbore storage, fracture geometry, and fracture fluid remaining in and around the fracture were performed to determine their effects on the pressure transient response and production forecast of a well. 68 figures, 10 tables.

Research Organization:
Intercomp Resource Development and Engineering, Inc., Denver, CO (USA)
DOE Contract Number:
AC19-79BC10106
OSTI ID:
6747341
Report Number(s):
DOE/BC/10106-29; ON: DE83001742
Country of Publication:
United States
Language:
English