Characteristics of oil–water two phase flow in anisotropic porous media with intrinsic fractures considering stress sensitivity

Pore-scale coupling between multiphase flow and matrix deformation is fundamental to the management of fractured reservoirs. Yet most studies overlook intrinsic (non-throughgoing) fractures and anisotropic pore architectures, both of which govern flow behavior and stress sensitivity at the pore scale. Here, we combine controlled core-flood experiments with a strongly coupled numerical framework to close this gap. Experimentally, we fabricate cores with prescribed intrinsic-fracture length, aperture, and orientation, and measure directional permeability and stress-sensitivity hysteresis under systematic variations of confining and inlet pressures. Numerically, we reconstruct anisotropic porous media using an improved quadtree stochastic growth scheme and couple incompressible Navier–Stokes and Cahn–Hilliard phase-field formulations to linear elasticity to simulate two-phase displacement with fluid–structure interaction. Validated against experiments, the model shows that intrinsic fractures reorganize dominant flow paths, accelerate breakthrough, and promote channeling. Deformation is strongly anisotropic: stresses localize at pore throats and fracture tips. Increasing inlet pressure enlarges the swept region and drives the fracture opening from nearly parallel to tapered, amplifying the dominant-channel effect; overburden compresses the matrix and produces a stress-shielding response around fractures. As fractures interconnect, the iso-permeability point shifts to lower water saturation and residual oil accumulates along fracture flanks. Permeability anisotropy maps onto fracture geometry: length primarily enhances the horizontal component, whereas aperture more strongly affects the vertical component. The integrated framework clarifies how microstructural evolution controls flow-path development and displacement efficiency, providing guidance for optimizing development of naturally fractured, low-permeability reservoirs.