Variational Phase-Field Fracture Approach in Reactive Porous Media

Abstract

We present a comprehensive model to simulate fracture nucleation and propagation in porous media, incorporating chemical reactions. This model integrates three main processes: fluid flow in porous media, reactive transport, and the mechanical deformation of fractured porous media using a variational phase-field approach. To account for chemical reactions, we use the geochemical package PHREEQC, coupled with a finite-element transport solver (OpenGeoSys), to model reactions in both thermodynamic equilibrium and kinetically, considering changes in porosity. To represent chemical damage, we introduce a variable that ranges from intact material to fully damaged material. This variable accounts for changes in porosity as a result of chemical reactions, separate from the mechanical damage represented by the phase-field variable. We test our model through various examples to showcase its ability to capture fracture nucleation and propagation driven by chemical reactions. Our model is implemented within the open-source finite element framework OpenGeoSys.