Simulation Study of Hydraulic Fracturing Mechanism with Heterogeneous Material

Abstract

first of all, this paper intensive studies the hydraulic fracturing mechanism of heterogeneous material resultant from the seepage – damage coupling, based on which, the coupled seepage and damage effects during hydraulic fracturing is investigated, and the difficulties of hydraulic fracturing study are how to determine failure modes and breakdown pressure. By using numerically testing method, the mechanical mechanism of hydraulic fracturing under asymmetric distribution of pore pressure with three holes, including fracture patterns, stress flied distribution, initial fracturing pressure and breakdown pressure, was studied by using theFSDmodel. According to the results of this research, crack extension direction of hydraulic fracturing is influenced not only by the local pore pressure around crack tip, but also by the gradient distribution of macro pore water pressure. The fracturing direction always propagates towards the regions of higher local pore pressure and breakdown pressure decreases with the increasing of local pore pressure. These results are well aggress with the results in the experiments. This research has important theoretical and engineering value. In engineering practice, we can use the porous asymmetric hydraulic fracturing technology to control the direction of crack propagation. Keywords: hydraulic fracturing; numerical simulation; heterogeneous material; asymmetrical