Fractured horizontal well productivity model for shale gas considering stress sensitivity, hydraulic fracture azimuth, and interference between fractures

Abstract

Productivity prediction plays an important role in the efficient and rational development of shale gas reservoirs. Current research on the productivity of multistage fractured horizontal wells in shale gas reservoirs does not consider the stress-sensitive effects of natural fractures, hydraulic fracture morphology, and seepage characteristics in the same capacity model. Therefore, we considered the adsorption, desorption, and diffusion mechanisms (pseudo-steady state and transient diffusion) of shale gas in reservoirs and the stress-sensitive effects of natural fractures based on the dual-medium seepage theory model. The finite conductivity of the hydraulic fracture and hydraulic fracture azimuth were considered in the hydraulic fracture model. The source function method was used to discretize the crack, and the hydraulic fracture model was superimposed. Finally, the two models were coupled to obtain the unstable seepage and productivity models of the multistage fractured horizontal well in a shale gas reservoir. According to the established horizontal well production model of shale gas fracturing, the production characteristic curve was calculated by programming, and the simulation results were compared with the field data of shale gas wells to verify the accuracy of the model. We used the model to analyze the effects of fracture conductivity, fracture half-length, fracture spacing, skin factor, storage ratio and leakage coefficient on productivity.