Dynamic evaluation of microscopic damage and fluid flow behavior in reservoir shale under deviatoric stress

This study presented a three-dimensional reconstruction method for digital shale cores in detail and examined the impact of deviatoric stress on the microscopic damage and fluid flow behavior in reservoir shale under deviatoric stress. In particular, this paper investigated the distribution of damage, deformation, and stress in shale under different deviatoric stresses. In addition, the characteristics of fluid velocity and pressure distribution under deviatoric stress and permeability evolution were discussed. The results showed that: (1) The deformation and damage in digital cores increased with the deviatoric stress, and the pore area will be more affected by deviatoric stress than the matrix area. (2) The fluid velocity distribution varies significantly between the matrix and the pore area, and the flaky connected fracture will aggravate this difference. (3) The fluid velocities of digital cores D1 and D2 decreased first and then increased with the increase of the deviatoric stress. (4) The permeability of digital cores D1 and D2, as the deviatoric stress increased, initially decreased due to rock deformation but subsequently increased due to the increasing damage.