The Optimization of Infill Well Fracturing Using an Integrated Numerical Simulation Method of Fracturing and Production Processes

Abstract

Abstract New wells are continuously drilled to improve the recovery of shale gas reservoirs. Production processes of parent wells will induce stress changes in the reservoir and then affect infill wells’ fracturing design. In this paper, we employed an integrated numerical method to simulate the hydraulic fracturing and production processes with single one method, thus the fracturing scheme of the infill well can be optimized. The integrated numerical method is based on the finite element method (FEM), which is named as the discontinuous discrete fracture method (DDFM). The DDFM can be used with conventional finite element mesh, which is perfectly compatible with the discrete fracture model (DFM). The fully coupled solution of DDFM is validated by two problems, including Mandel problem's analytical solution and the numerical solutions of the single fracture propagation. When predict the shale gas production, a new diffusion equation is modified to describe the shale gas flow, and the simulation results showed a good agreement with the field data. At last, this paper takes an infill well construction in a shale gas reservoir in south China as an example. The hydraulic fractures of parent wells are interpreted from micro-seismic data and described with DFM to reduce the computational cost. Then the infill well's hydraulic fractures are described using DDFM. After simulating the production process of two parent wells, we get the current formation pressure and stress state. Aims at obtaining the maximum profit of the whole well region, by comparing the gas production of different fracturing schemes, we can choose the optimal fracturing scheme of the infill well.