A computational framework based on explicit local chemical equilibrium for coupled chemo-hydro-mechanical effects on fluid-infiltrating porous media

Conventionally, a finite element framework for coupled hydro-mechanical-chemical processes in porous media adopts simplified chemical reactions, which consider superficial chemical effects of complicated multiphysics mechanisms. This paper presents a novel computational framework for geochemistry of reactive multi-component systems to explicitly capture the mineral dissolution/precipitation of saturated porous media. The resultant of this framework can be applied in oil recovery engineering and used to simulate the production scenarios. The model is also fundamental for studying on creep behaviors from the view of the coupling effects between hydro-geochemistry. In particular, a complete chemistry system of Image 1 is considered, including intra-aqueous chemical reactions and kinetic rate-limiting chemical reactions. Besides, an algorithm is proposed such that the complete chemistry system is scalable for various chemical reactions and is easily incorporated into existing finite element frameworks for hydro-mechanical processes of porous media. This complete chemistry system is implemented to establish a local chemical equilibrium. The geochemical reactive transport equations are then sequentially coupled with the balance laws such that coupling among fluid advection-diffusion, solid deformation, chemical concentration advection-diffusion, intra-aqueous chemical reaction, and kinetic rate-limiting chemical reaction can be simulated. Phenomenological relations for porosity and permeability changes with mineral saturation in solutions are employed. We first verify the proposed framework to capture the advection-diffusion of different chemical species under steady-state and transient conditions. Then a consolidation problem under the chemical reactions is presented to further demonstrate the capabilities of the proposed computational framework.