Phase‐field modeling of rate‐dependent fluid‐driven fracture initiation and propagation

Abstract

The rate‐dependent behavior associated with deformation and fracturing of materials, such as natural rocks, poses significant challenges for modeling. In addition to the complications of the viscoelastic response, the speed of fracture propagation reflects micromechanical mechanisms in the fracture process zone (FPZ). In order to represent these complicated behaviors, a thermodynamically consistent, rate‐dependent fracture model is required. Based on rigorous thermodynamic principles, we derive a rate‐dependent phase‐field mechanical model coupled with single‐phase fluid flow in both the matrix and the fracture. The model is guaranteed to satisfy energy conservation during fracture propagation. The system of equations is solved using the introduced solution procedure and a novel preconditioner that accounts for the complex fluid–structure interaction. The proposed phase‐field model is tested against several benchmark problems on solid‐fluid coupling, fluid‐driven fracture propagation and rate‐dependent viscoelastic deformation. The model serves as a strong basis for investigating rate‐dependent fracturing experiments and for making predictions of material behaviors under new conditions.

Chemical and Reactive Transport Processes Associated with Hydraulic Fracturing of Unconventional Oil/Gas Shales

“…An assumption common to many of these models is that fractures are embedded in an infinite homogeneous porous medium . A common approach consists of integrating a near-fracture tip model , for representing the small-scale tip dynamics into a macroscopic model for hydraulic fracture propagation. , Other modeling approaches utilize cohesive methods that only consider the fracturing process at the crack tip, , multiscale methods that provide a hierarchical approach to represent certain physical processes at different levels of fidelity, , discrete numerical methods such as boundary element methods, , or extended finite element methods, , meshfree methods, , phase-field methods, − and discrete element methods . Another more recent development is peridynamics as a promising approach for modeling hydraulic fracturing problems, which enables the simultaneous prediction of crack initiation and propagation in the rock matrix.…”