Application of Extended Finite Element Method (XFEM) to Simulate Hydraulic Fracture Propagation from Oriented Perforations

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.

Study on Coalbed Methane Extraction Mode of Cracked Soft Coal Seam with Sectional Hydraulic Fracturing in the Rock of Coal Seam Roof

“…The level set function can be used to describe the stress singularity problem at the fracture tip, such as describing the sudden change of fracture tip stress caused by different reservoir situationsand artificial control methods for hydraulic fracturing problems and simulating the fracture tip steering and dynamic behaviours of fractures under different stress field conditions, expansion, etc. The following Westergaad function is introduced into the crack tip unit as a set function [15] , and the level set function of the crack tip is shown as follows:…”

“…Initial fractures can approximate perforations. The initial crack length is used to characterize the length of the perforation hole, and the azimuth angle of the initial crack is used to reflect the azimuth angle of the hole [16][17] . The fracture discontinuity is described using a spread function associated with the additional degrees of freedom.…”

Propagation mechanisms and parametric influence in multiple interacting hydraulic fractures: A 3‐D G/XFEM hydro‐mechanical modeling

“…A model for simulation of crack evolution in porous formation based on XFEM and cohesive crack model has been developed by Mohammadnejad and Khoei. 4 Sepehri et al 29 developed a 2-D model to analyze the effect of the orientation of the perforation on the propagation of a fracture and studied the parameters, which control the fracture evolution utilizing Abaqus's XFEM capabilities. The influence of independent variables at different fracture offsets has been studied by Abbas et al 30 based on an XFEM formulation.…”

Quantitative evaluation indexes of the spatial steering effect of directional perforation hydraulic fractures

“…Chen et al studied the optimization method of directional perforation initiation and perforation, but the influence of perforation length was not considered, and the fracture expansion path under different working conditions was not described (Chen et al, 2017). Based on the extended finite element method, Sepehri et al simulated fracture propagation under different perforation orientations and horizontal stress differences (Sepehri et al, 2015). A fluid-solid coupled model was established by Shi Jihui et al and used to study the synchronous propagation and steering of directional perforation hydraulic fractures.…”