Transient Flow model and heterogeneity effect analysis for fracture networks in shale gas horizontal wells

Volume stimulation technique is currently the primary engineering approach for effectively enhancing shale gas productivity. However, in post-fracturing reservoirs, multi-media coupling is prominent, and fracture conductivity exhibits strong heterogeneity. This necessitates further characterization of heterogeneous spatial distribution of complex fractures, as well as multiple flow mechanism. This study develops a multiscale coupled matrix-fracture flow in porous media model based on the post-fracturing reservoir geometry to precisely describe production dynamics in fractured shale gas reservoirs. Heterogeneity in hydraulic fracture geometry and stimulated reservoir volume (SRV) permeability was simulated using continuous gradient functions. Analytical solutions for the multi-stage fractured shale gas reservoir model were derived through multi-linear flow model and perturbation methods. By integrating simulated annealing and particle swarm optimization algorithms, the C++ code was enhanced to achieve automated history matching and production forecasting. Results indicate that hydraulic fracture damage predominantly affects early-stage production, with near-tip fracture blocking leading to reduced overall gas production. Mid-to-late production is more significantly influenced by SRV permeability -gradual permeability variations exhibit minor impacts, whereas abrupt permeability changes substantially decrease total gas production. Based on an analysis of dynamic production data from two wells in the oilfield, this study achieves optimal matching of unknown reservoir parameters, thereby enabling reliable production performance prediction. The proposed model demonstrates high rationality and practicality in reservoir parameter inversion and shale gas well performance forecasting, providing novel insights to critical challenges in shale gas production.