Analysis of Fracture Network Response to Fluid Injection

Abstract

Geothermal as well as oil and gas are often produced from “designed” or naturally fractured reservoirs. Numerical modeling is usually required to predict and control behavior of fractures under complex processes, and often the DDM has shown to be an effective approach. In order to predict behavior of large-scale natural fracture networks using DDM an approximation technique such as fast multipole method can be used to efficiently calculate the interaction between fractures in optimal time of within O(N), where N is number of unknown. Differences of flow conditions in the reservoir carry potential change of a joint to slip or micro-earthquake (MEQ) when the shear stress surpasses a failure criterion. In this paper, Fast Multipole Displacement Discontinuity Method (FMDDM) is employed to simulate flow and micro-earthquake (MEQ) in a stochastic fracture network. Stress and displacement fields subjected to induced pressure by injection and production are calculated and joint deformation and the potential for MEQ is assessed using slip weakening conditions and a failure criterion. Expectedly, the orientation of a fracture with respect to the stress field plays an important on its slip and concomitant seismicity.