Modeling Near-Wellbore Hydraulic Fracture Complexity Using Coupled Pore Pressure Extended Finite Element Method

Understanding near-wellbore hydraulic fracture complexity is important for the design of hydraulic fracturing. This paper presents a fully coupled fluid flow and geomechanics model for predicting complex fracture propagation paths in the wellbore vicinity. The model is developed based on the coupled pore pressure extended finite-element method (XFEM). Fracture propagation, fracturing fluid flow, rock deformation, and pore fluid flow are coupled to model fracture behavior in the near-wellbore region. The influence of perforation angle and perforation length on near-wellbore fracture growth are investigated. Results show that a fracture initiated from a perforation misaligned with the direction perpendicular to the minimum field stress will finally reorient itself to that direction. But the fracture curvature resulting from fracture reorientation is highly related to the size and angle of the perforation. The results also demonstrate high dependence of fracture breakdown pressure on perforation size and location. The XFEM model proposed in this paper provides a unique tool to predict hydraulic fracture trajectory in the near-wellbore region. It can be used to aid design of various hydraulic fracturing related operations in the petroleum industry, such as fracturing stimulations, field injectivity tests, waterfloods, and produced water/cuttings re-injections.