Fracture path interaction of two adjacent perforations subjected to different injection rate increments

Abstract

During the fracturing of shale gas reservoirs, the injection rate and its variation affect the fracture propagation path and fracture connectivity between two adjacent perforations. To reveal the interaction mechanism of injection rate change on hydraulic fracture propagation of adjacent perforations, an extended finite element method (XFEM) was employed for simulating the fracture propagation and interactions between adjacent hydraulic fractures under different injection rate increments. Considering the heterogeneity of rock minerals and based on the results of shale mineral composition analysis via X-ray diffraction (XRD), a code segment was written in Python to establish a computational network model with a random distribution of different material properties. Acoustic emission (AE) data extraction and fracture location during the process of fracture propagation were realised using MATLAB programming. Simulation results revealed that the closer the injection rate increments in adjacent perforations, the greater the compressive stress between the perforations. Variations in the pressure difference and fracture width difference between the two perforations dynamically reflect their interactions; both anisotropy and stress shadow determine the fracture propagation path. This study provides a good technical basis for fracture design optimisation.