Propagation law of fractures in deep shale gas reservoirs considering the influence of interlayers and interfaces.

This article focuses on investigating the propagation behavior of hydraulic fractures in deep shale reservoirs, particularly under the influence of interlayers and interfaces with varying mechanical properties. Using a three-dimensional discrete lattice method, the study simulates fracture propagation considering factors such as interlayer thickness, interface tensile strength, friction angle, cohesion, and dilation angle, based on geological parameters from the southern Sichuan Basin. Results indicate that both interlayers and interfaces impede vertical fracture propagation, with shear failure predominantly occurring at interfaces and tensile failure in the surrounding matrix. The ability of fractures to penetrate interfaces increases with higher tensile strength, friction angle, and cohesion but decreases as the dilation angle grows, with large dilation angles completely blocking fracture penetration. These findings provide theoretical insights for optimizing hydraulic fracturing operations by controlling fracture height and layer-crossing, thereby enhancing reservoir stimulation efficiency.