Pore pressure cohesive zone modelling of complex hydraulic fracture propagation in a permeable medium

Abstract

A pore pressure cohesive zone method (PCZM) is proposed to simulate the complex hydraulic fracturing process in a permeable poroelastic medium. A shared node scheme of the cohesive elements is developed to consider the arbitrary fracture propagation and fluid flow at the intersection. The fracture propagation is based on a bilinear cohesive law, while the tangential flow within the fracture is controlled by the lubrication equation. The fluid leak-off within the cohesive element is calculated according to the distribution of pressure. Three models are given to verify the capability of the PCZM in simulating the complex fracturing process. The effects of the approaching angle, cementing strength, in situ stress and natural fracture on the fracture geometry are investigated. These studies indicate that the proposed PCZM can accurately predict complex hydraulic fractures (HFs) and provide a useful way to study HF mechanisms.