Effects of Forward and Reverse Shear Displacements on Geometric and Hydraulic Characteristics of Single Rough Fracture by the Finite Volume Method

Abstract

AbstractShear displacement will lead to the change of rock fracture space and then affect seepage characteristics of the fracture, but for the same rock fracture, whether the spatial geometry and seepage characteristics of the fracture can be consistent under the forward and reverse shear displacements is a new question. In this paper, the 2D rough fracture profile was used to establish models of different shear displacements in the forward and reverse directions without contact zone, and the geometric distribution characteristics of the fracture space with shear displacements were analyzed. The FVM (finite volume method) was adopted to calculate and simulate the hydraulic characteristics of the relative seepage direction (forward and reverse flow) under different pressure gradients at various shear displacement models. The results showed that under the same shear displacement, the spatial geometry characteristics of forward and reverse shear displacements are consistent after the initial angle of the fracture profile is eliminated. The slope of equivalent hydraulic aperture decreases with the shear displacement, and the amplitude of the non-Darcy coefficient difference increases with the shear displacement, which are inconsistent in the forward and reverse directions, which are negatively correlated with the directional roughness of the initial fracture profile. It shows that the directional roughness inconsistency between the forward and reverse directions of fracture profile is the primary factor leading to the difference of seepage characteristic parameters under the forward and reverse shear displacements.