Numerical Investigation of Fracture Morphology Characteristics in Heterogeneous Reservoirs

Highly heterogeneous glutenite reservoirs with large amounts of gravel and weak interfaces pose a great challenge to predicting the trajectory of hydraulic fractures during the fracturing process. Based on the phase field method, a fully coupled numerical model of hydraulic fracturing is established. This paper is devoted to investigating the variation in the overall expansion pattern of hydraulic fractures in reservoirs considering randomly distributed gravel and weak interfaces. The numerical results demonstrate that the existence of gravel and a weak interface could alter the extending paths of the hydraulic fractures as well as the value of critical bifurcation injection rate. As the fracture energy of the weak interface is large enough, the hydraulic fracture tends to cross the gravel and the weak interface between the rock matrix and the gravel, forming a planar fracture. Deflection and branching of the hydraulic fracture are more likely to occur in reservoirs containing large gravels. The presented results extend the understanding of fractures propagating in heterogeneous reservoirs.