Multifractal evolution of shale fracture and pore structures under uniaxial compression

The evolution of fracture–pore structures critically controls the mechanical stability and permeability of shale reservoirs. To clarify their coupled behavior during stress-induced failure, we investigate the multifractal evolution of fractures and pores in shale under uniaxial compression using digital rock reconstruction and discrete element modeling. The proposed fracture-damage framework reproduces fracture nucleation, propagation, and coalescence, and reveals a strong correspondence between energy conversion and damage development. Multifractal analyses show that pore heterogeneity primarily governs the fractal characteristics at the early loading stage, whereas fracture growth becomes increasingly dominant after peak stress; meanwhile, the multifractal parameters of fractures and pores evolve in broadly consistent trends. Together with the simulated porosity and permeability responses, these fractal descriptors capture the progressive reorganization of flow pathways during loading. Overall, this work provides a quantitative structure–property link between fracture activity, pore complexity, and transport evolution in shale, offering mechanistic insights for reservoir failure interpretation and stability evaluation.