Abstract
Understanding fracture initiation and propagation from perforated wellbores is essential to designing a perforation scheme to achieve an efficient hydraulic fracture stimulation treatment. The effect of perforation design on hydraulic fracture propagation has been extensively studied using experimental and analytical methods. Because the experimental investigation of hydraulic fracture is complicated, expensive, and often returns limited results, numerical methods can be applied as an efficient way to simulate fracture propagation from perforations. An Extended Finite Element Method (XFEM) was used to develop a model to investigate the effects of various parameters on fracture propagation from a set of perforations. These parameters included perforation orientation, perforation length, stress anisotropy, and elastic properties of the formation. Fracture propagation patterns from the XFEM model were first matched against published experimental studies and exhibited good agreement. The model was then used to broaden the study of perforation effects. Results of the modeling proved the effects of perforation orientation and length on hydraulic fracture propagation pattern. Horizontal stress anisotropy and rock mechanical properties were observed to strongly influence fracture propagation. It was also observed that, when two or more perforations are positioned at different orientation angles at the same depth, a fracture tends to propagate from the less deviated perforation. In these cases, the more deviated perforation can develop a short fracture, following a propagating pattern that could be caused by stress shadowing/interference. Stress interference between two perforations positioned closely together results in either perforation breakdown or fracture propagating away from one another. The simulation results from this study offer methods to enhance perforation design for hydraulic fracture treatment, particularly in the case of high stress anisotropy and high uncertainty in a preferred fracture plane. Analyzing competing perforations suggests that a technique based on this concept can be applied when high uncertainty exists regarding the direction of the principal horizontal stresses through increasing perforation density.
Application of Extended Finite Element Method (XFEM) to Simulate Hydraulic Fracture Propagation from Oriented Perforations
