Experimental Study on the Behavior of Gas–Water Two-Phase Fluid Flow Through Rock Fractures Under Different Confining Pressures and Shear Displacements

Understanding the flow behaviors of two-phase fluids in rock mass fractures holds significant importance for the exploitation of oil and gas resources. This paper takes rock fractures with different surface roughness characteristics as its research object and conducts experiments on the gas–water seepage laws of fractures under various confining pressures and shear displacements. The results indicate that the higher the fracture surface roughness, the larger the equivalent fracture width and the higher the single-phase permeability of gas/water in the fractures. During gas–water two-phase flow, when the water phase split flow rate is high, the influence of the confining pressure and fracture surface morphology on the water phase is significantly higher than that on the gas phase. The relative permeability at the isosmotic point of the fractures increases with the increase in confining pressure and decreases with the increase in roughness. After the dislocation of shale fractures, the interphase resistance within the fractures reduces. The relative permeability of the water phase increases more significantly compared to that of the gas phase. The water phase split flow rate at the isosmotic point does not change significantly, and the relative permeability at the isosmotic point increases. This research is helpful for guiding the protection based on the conductivity capacity of the rock mass fracture network.