A correlation for the matrix-driven increase in hydraulic permeability of rough-walled fractures

Fractured porous media models often underestimate fracture permeability by neglecting the contribution of matrix-driven fluid pathways, relying instead on slip boundary conditions to account for matrix influence. Previous studies have demonstrated that such fluid pathways through permeable matrix regions can significantly affect fracture flow and enhance fracture permeability, a phenomenon that is not captured by conventional models that are based solely on slip boundary conditions. In this study, we develop an empirical correction to upscaled fracture permeability that incorporates the effect of matrix flow. We quantify the increase in fracture permeability through numerical simulations of a discrete fracture-matrix (DFM) system with varying matrix permeability. Our results reveal a substantial increase in apparent fracture permeability, which cannot be captured by traditional models based on impermeable walls. The empirical correction is validated by applying it to a fracture network system, demonstrating its robustness in both single-fracture and network-scale settings. This study emphasizes the necessity of accounting for matrix flow when estimating fracture permeability, ensuring more accurate predictions for exploiting fractured porous media.