Numerical Study of Deformation Properties and Permeability of Sedimentary Rock in the Compression Failure Process Using the Discrete Element Method

Abstract

Deformation properties and permeability of sedimentary rock in the compression failure process was numerically studied using the distinct element method. Elastic tensors were estimated using the finite element method (D^fem) and the method assuming the affine deformation (D^affine). Permeabilities were estimated using the effective medium approximation and the fluid flow network. In agreement with the experimental results, the linear stress-strain relation under low differential stress and the nonlinear inelastic stress-strain relation near peak differential stress level were observed in the simulations. The change of D^fem was relatively small in the linear elastic region, then D^fem evidently changed and became anisotropic after the peak strength. On the other hand D^affine didnot varied significantly compared with D^fem but also became anisotropic. After peak strength inelastic deformation was the dominant deformation process. The permeability estimated using the effective medium approximation was increased after the failure. The permeability estimated using the fluid flow network exhibited anisotropy. The anisotropy of the elastic tensors and the permeability estimated from the fluid flow network could be attributed to the structural change of the rock model due to differential stress.