Pore-scale insights into the role of micro fractures on permeability of fractured porous media

Abstract: Fractures play a critical role in governing fluid flow within subsurface energy systems, including oil and gas production, geologic carbon sequestration, and underground hydrogen storage. This study investigated the impact of pore-scale fractures on fluid flow and permeability in fractured porous media. The analysis focused on a single fracture embedded within a porous medium. Fluid flow was simulated using the lattice Boltzmann method, and the effects of fracture length, width, and orientation angle on permeability were systematically examined. Results showed that increasing both fracture length and width enhanced permeability. Additionally, fractures oriented more closely to the flow direction (i.e., smaller orientation angles) resulted in higher permeability. Interestingly, when the orientation angle approached 90{\deg}, the presence of a fracture could reduce the overall permeability of the porous medium. A critical orientation angle was identified, beyond which the fracture decreased permeability; this critical angle was found to increase with fracture width. Permeability tensors were also fitted to determine the critical angle and quantify the influence of fracture width on the critical orientation angle. These findings provide new insights into the role of microfractures in controlling permeability, with important implications for subsurface energy systems.