ESRV and Production Optimization for the Naturally Fractured Keshen Tight Gas Reservoir
The economic gas production in Keshen deep reservoir (7000–8038 m), located in the Tarim basin, as one of the largest gas resources in the north-west China, depends on the optimization of Effective Stimulated Reservoir Volume (ESRV), which was investigated through numerical simulations based on the match of fracture properties and reservoir capabilities under high pressure (>116 MPa) and high temperature (160–170 °C) in this study. An integrated multiphysical model, which couples gas flow with mechanical deformation and describes the gas flow interaction between the matrix, natural fractures and hydraulic fractures, was developed to optimize the ESRV and predict the production. Controlling factors of the ultimate gas recovery were analysed, and the impacts of pressure-dependent permeability of matrix and fracture systems on gas recovery were indicated through two case studies. Results show that if the impacts of effective stress on porosity and permeability were neglected, natural fracture spacing and permeability were the predominant factors affecting the ultimate gas recovery, whereas the half-length of the primary hydraulic fractures and the spacing of the secondary-fracture networks were more important for enhancing gas recovery due to the permeability sensitivity to the effective stress. This study improves the understanding of gas flow interaction among the matrix, natural fractures and hydraulic fractures in tight gas reservoir.
KeywordsESRV and production optimization Keshen Tight gas Natural fracture Stress-dependent permeability
This work is supported by the National Natural Science Foundation of China (Grant No. 51604286), Science Foundation of China University of Petroleum, Beijing (No. 2462014YJRC015, No. 2462016YJRC036), Foundation of State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing (No. PRP/indep-3-1707).
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