Abstract: To investigate the flow in porous media-stress coupling mechanism during gas production from the fractured zone of shale-gas horizontal wells and the spatiotemporal evolution of pore pressure and in-situ stress,a finite-element coupled simulation method based on a refined geological model was established.By embedding fracture surfaces into geological grids and using a three-dimensional property interpolation function,this method accurately maps multiscale fractures onto finite-element grids.On this basis,a fluid-solid coupling model considering non-Darcy flow and the dynamic evolution of porosity and permeability was constructed.According to the model,a production-history matching method was established using gradient descent of the error between simulated and actual pressures of production wells.With the Well X platform in the Luzhou Block,Sichuan,as an example,the coupled responses of pore pressure and stress under gas-production drive and the influence of the fracture system were analyzed on the basis of dynamic calibration of initial pore pressure and permeability and production-history matching.The results show that the average relative error of history matching was 4.6%,indicating that the model accurately reflects actual production performance.During short-term gas production over 82 d,the near-wellbore pore pressure decreased by approximately 1.5 MPa,and the effective stress increased correspondingly by approximately 0.9 MPa.The near-wellbore pressure-depletion funnel and stress-concentration zone expanded outward synchronously,with the affected range mainly confined within 50 m of the well.The decrease in pore pressure and the volumetric strain of the rock led to slow reductions in porosity and permeability,with decreases of less than 0.5%,indicating that short-term production had limited effects on reservoir physical properties.As preferential seepage pathways,the fracture system accelerated pressure propagation and simultaneously formed stress concentration in the mechanical response,causing fluid-solid coupling to exhibit pronounced anisotropy and heterogeneity.The results provide a quantitative research tool for engineering issues such as productivity evaluation,interwell interference analysis,and casing-integrity assessment in shale-gas development.

Key words: shale gas, horizontal well, fractured zone, flow in porous media-stress coupling, fracture, pore pressure, finite-element method