Numerical investigation of hydraulic fracture propagation in a layered reservoir using the cohesive zone method

Complex hydraulic fractures are often reported in layered formations as the existence of a geological discontinuity. A seepage-stress-damage coupled finite element model was built to study the hydraulic fracture propagation behavior of the X5 sandstone and shale layered reservoir in the western Sichuan basin. The cohesive zone method (CZM) based on damage mechanics was used to simulate hydraulic fracture initiation and propagation. The influence of geologic parameters and fracturing execution parameters on hydraulic fracture morphology were studied. The results show that hydraulic fractures are mainly penetrating the interface and extending along the interface to generate a branched fracture, while others are forming normal bi-wing fractures.