Numerical Investigation of Hydraulic Fracturing in a Heterogeneous Rock Mass Based on Peridynamics

In this paper, the effect of micro heterogeneity of rocks on hydraulic fracture propagation is studied using a peridynamics-based numerical model. We quantitatively examine the propagation mechanism of a single fracture in heterogeneous media. The influence of in-situ stress and fracturing fluid parameters on the fracture morphology, rock failure mode, and injection pressure are explored. We found that in-situ stress distribution and fracturing fluid parameters can significantly affect the occurrence of shear failure in the heterogeneous rock mass, and the rock heterogeneity can lead to increased injection pressure and elevated pressure oscillation. Finally, we investigate the creation of fracture networks in the heterogeneous rock mass and the simulation results show that heterogeneity can significantly increase the density and complexity of fracture networks. Highlights A new hydraulic fracturing model based on peridynamics (PD) is proposed to simulate the generation of hydraulic fracture network in heterogeneous model. The problems of PD in predicting shear failure and calculating friction are solved. A model characterizing the fracture geometric characteristics is established, and the influence of micro heterogeneity of rock mass on the generated fractures is studied. More shearing fractures are generated in heterogeneous rock relative to homogeneous rocks, and cause the rise of fracturing fluid pressure.