A coupled phase-field and reactive-transport framework for fracture propagation in poroelastic media

Abstract

We present a novel approach to model hydro-chemo-mechanical responses in rock formations subject to fracture propagation within chemically active rock formations. The framework developed integrates the mechanisms of reactive transport, fluid flow and transport in porous media, and phasefield modelling of fracture propagation in poroelastic media. The solution approach integrates the geochemical package PHREEQC with a finite-element open-source platform, FEniCs. The PHREEQC solver is used to calculate the localized chemical reaction, including solid dissolution/precipitation. The resulting solid weakening by chemical damage is estimated from the reaction-induced porosity change. The proposed coupled model was verified with previous numerical results and applied to a synthetic case exhibiting hydraulic fracturing enhanced with chemical damage. Simulation results suggest that mechanical failure could be accelerated in the presence of ongoing chemical processes due to rock weakening and porosity changes, allowing the nucleation, growth, and development of fractures.Modeling the chemo-mechanical responses in porous media is of interest to several disciplines in engineering and science, including underground storage of carbon dioxide (CO 2 ) in reactive rock formations 1-5 , CO 2 injection for enhanced oil and gas recovery [6][7][8][9] , well stimulation 10 , concrete durability [11][12][13][14] , geothermal recovery [15][16][17] , and long term storage of hazardous waste [18][19][20] , among others. The physical and chemical processes involved govern mineral formations, such as dissolution and precipitation in metamorphic and sedimentary rocks and the resulting reaction-driven fracture propagation. Proper modeling of the impact of mineral reactions and the associated mechanical response of subsurface rocks is, therefore, crucial [21][22][23][24][25] .Various modeling approaches have been proposed in the literature to simulate the complex dynamics of mechanical failure, particularly fracture propagation combined with other fluid/rock processes such as diffusion, advection, and chemical reactions in rock formations [21][22][23] . For a fluid-solid system, fractures provide hydraulic pathways for fluid flow, allowing the progress of the reaction front. Bringedal et al. 26 proposed a model for dissolution and precipitation in porous media using an evolving interface between the fluid and solid, where physical and chemical properties vary smoothly. This diffusive fluid-solid interface models the transition between the fluid and the mineral phases. According to Bringedal et al. 26 , the solution of the second-order Allen-Cahnlike partial differential equation defines the dissolution and precipitation profile in the system. Schuler et al. 23 developed a chemo-mechanical phase-field model to study dissolution-assisted fracture development. Ogata et al. 22 developed a fluid flow and mass transport model for rock fractures using a coupled thermal-hydraulicmechanical-chemical framework. The proposed formulation requires introduc...

A Methodology for Optimizing the Calibration and Validation of Reactive Transport Models for Cement-Based Materials

“…Noteworthy is the development of reactive transport (RT) models to simulate changes in cement-based materials due to transport and chemical interaction between the initial material and ionic or gaseous species from the surrounding environment [2]. The application of RT models is gaining interest in the cement and concrete community [3][4][5][6][7][8][9], a process driven by continued development and improved capabilities of RT model [6,8,[10][11][12][13][14], as well as the development of thermodynamic databases for cement-based materials, [15][16][17][18][19].…”