The impact of thermal transport on reactive THMC model for carbon capture and storage

Abstract

Addressing current limitations in Thermo-Hydro-Mechanical-Chemical (THMC) models is crucial for accurately simulating complex physical and chemical interactions in carbon capture and storage (CCS) processes. This paper presents a new fully coupled THMC model, specifically focusing on investigating thermo-chemo coupling (dissolution) effects for CCS applications. The model is a further extension of the mixture coupling theory, which incorporates entropy and mass balance equations, phenomenological equations, and Maxwell's relations to describe the intricate coupling between mechanical, hydraulic, chemical, and thermal properties. The model considers a two-phase flow, liquid and supercritical. By deriving new coupling terms from the phenomenological equations, the model provides capacity to account for energy losses due to friction between the two phases, along with energy losses arising from the transport of the solute and the evolution of porosity/permeability. Furthermore, the model incorporates an additional coupling term in the mechanical equation to represent the chemical dissolution effect on volumetric strain relief. Two terms added in the liquid equation account for the friction of newly dissolved minerals particles on liquid transport and the effects of porosity changes on liquid flow through dissolution. Finally, Thermal transport coupling is integrated into the model, as it is a crucial part of CCS applications. Numerical results demonstrate that increasing temperature significantly decreases porosity due to thermal expansion, but thermal energy triggers chemical dissolution which in the long run increases both porosity and permeability. Chemical dissolution has the most significant incremental effect on porosity over time, while thermal expansion has the greatest impact until thermal equilibrium is reached, with the direct impacts of pressure and strain on porosity falling in between. This research presents a comprehensive coupling framework that accounts for two-phase friction, the dissolution process, and changing permeability, which gives it potential utility in the planning process for CCS applications.