Geomechanics evolution integrated with hydraulic fractures, heterogeneity and anisotropy during shale gas depletion

Abstract

Due to reservoir depletion, the reservoir geomechanical parameters, such as stresses, permeability, are changing during shale gas production. A coupled flow-geomechanics model was built to investigate time-lapse geomechanical responses in production before infill well placement of Sichuan Basin shale gas reservoir. In the modelling, hydraulic fractures were simulated from microseismic data and mapped from a geological model to build the flow model. An interface code was improved to build the geomechanical model properties from the geological model, as well as communicates the data between finite difference grids in the reservoir simulator and finite element grids in the geomechanical simulator. In addition, the anisotropy of physical properties and rock mechanical properties was integrated in the flow model and the geomechanical model. Stress-dependent porosity and permeability models were embedded as well. Case studies show that stress evolution and re-orientation are affected by both the trajectory and fractures of producing wells, as well as the heterogeneity of geomechanical properties. Besides, the effect of parallel wells production should be taken into consideration based on the wells-spacing.