Permeability evolution of localised failure sandstone

Permeability, a crucial factor in assessing porous reservoir rock quality, can be influenced by localised deformation such as fractures, shear bands, or compaction bands. Considering the arbitrary occurrence of these bands and the need to investigate the permeability difference between the overall specimen and within the localised zone, existing literature lacks a quantitative measure for such complexity. This study proposes a numerical concept that focuses on the permeability-stress connection across multiple levels from macroscopic to grain-scale bridging via the localised band, referred to as mesoscale. This framework integrates breakage mechanics into a dual-scale continuum model, tracking the permeability evolution of Bentheim sandstone under triaxial compression. The key feature lies in the link from stress to grain size distribution, due to breakage mechanics, that governs the constitutive responses, including macro, inside and outside of the localisation zone, produced from the dual-scale model following traction equilibrium condition. The successful outcome should capture the permeability inside the localisation band that is significantly lower compared to that of the outer bulk. The achievement provides insight into how important a correct mechanism of small details can influence the overall material behaviour while opening possible studies on many other material quantities while respecting the fundamental mechanics at multiple scales.