A review on phase-field modeling of hydraulic fracturing

Motivated by the successful implementation of the phase-field method (PFM) to simulate complicated fracture patterns at moderate computational costs in solid materials, many research groups have started since 2012 applying the PFM to model hydraulic fracturing, especially that occurs in porous geomaterials. These research works have contributed to the development of the PFM from different perspectives, especially in connection with the mathematical formulations of the hydro-mechanical processes and the numerical algorithms to solve the emerging coupled problems. In this regard, the underlying paper aims to review the significant scientific works that utilized the PFM to model fracturing caused mainly by fluid injection in a certain porous domain and, less common, by fluid extraction (e.g., drying) from a certain porous domain. This includes reviewing different approaches for deriving the phase-field evolution formulation (e.g. Ginzburg–Landau approach, thermodynamically consistent approaches, and microforce-based approach) and reviewing several formulations for the stiffness degradation function and that of the crack driving force. Besides, the paper will go through several methods to estimate the crack aperture width, in addition to reviewing different numerical approaches and implementations. The paper will be concluded by presenting a number of open topics and challenges to be addressed in future works.