Numerical simulation of hydraulic fracturing process in heterogeneous rocks under different confining pressures

Abstract

Hydraulic fracture is the classical coupling action of seepage-damage and it is so important to understand the hydraulic fracture mechanisms that we can deal with the problems of rock seepage stability, such as dam instability and water outburst. On the heterogeneous characteristics of rock at microscopic level, a numerical model, which couples the seepage and the failure process, is developed to study hydraulic fracturing phenomenon in permeable and heterogeneous rocks. In this model, material is discretized into a large number of elements with the same size and different mechanical and permeable parameters in order to represent heterogeneity of the rock. A coupling analysis of seepage and damage under hydraulic fracturing on the rock is performed to simulate the fracture process of rock. The numerical analyses indicate that this model is capable of simulating the heterogeneous distribution of stress and permeability of rock subjected to hydraulic fracturing under different confining pressure. The modeling results suggest that the fracture initiation and propagation, the roughness of fracture path and the breakdown pressure are influenced considerably by the heterogeneity of the rock, and the numerical results can agree well with the relevant experimental data.