Numerical Modeling of Mineral Dissolution in Acidic Environments: A Step Towards Advancing CCS Applications

Carbon capture and storage (CCS) has emerged as a key strategy in mitigating anthropogenic greenhouse gas emissions. By capturing CO₂ from industrial sources and storing it in deep geological formations, CCS offers a pathway to reduce atmospheric CO₂ concentrations. The success of CCS relies on understanding fluid-mineral interactions, reactive transport processes, and the long-term stability of geological storage systems. This study investigates mineral dissolution in acidic environments using numerical simulations as a foundation for reactive transport modeling in geological systems. The research focuses on developing and validating computational methods that can accurately predict the behavior of minerals exposed to acidic conditions, similar to those encountered in CO₂ storage scenarios. In this study, ANSYS Fluent was employed to simulate the dissolution of calcite (CaCO₃), serving as a representative mineral for the methodology due to its abundance in potential storage formations and well-documented reaction kinetics. The numerical setup comprises a rectangular domain with a centrally positioned circular mineral sample, allowing detailed observation of dissolution patterns and fluid flow characteristics. The fluid enters the domain with a defined H⁺ ion concentration, triggering a chemical reaction, CaCO₃(s) + H⁺ → Ca²⁺ + HCO₃^-. The simulation incorporates multiple physical and chemical processes, including advection, diffusion, and surface reactions. A comprehensive mesh sensitivity analysis ensures numerical accuracy and solution independence. The study evaluates the spatial and temporal evolution of ion concentration distributions and reaction rates. The numerical results are verified and validated against numerical and experimental data from the literature. The developed methodology includes a detailed consideration of boundary conditions, numerical schemes, and convergence criteria. While focused on calcite, the framework is adaptable to other minerals and reaction systems. The research addresses common challenges in numerical modeling of dissolution processes, such as handling moving boundaries and accurately representing reaction kinetics. The results provide insights into the fundamental mechanisms controlling mineral dissolution under acidic conditions. Analyzing concentration profiles and reaction rates helps identify rate-limiting steps and optimal conditions for dissolution processes. These findings directly impact understanding the porosity and permeability evolution in geological formations exposed to CO₂ rich fluids. This study establishes a foundation for more complex investigations involving multiphase systems and geological storage scenarios. The methodology can be extended to study various aspects of CCS implementation, from reservoir-scale simulations to detailed analysis of wellbore integrity. By advancing our understanding of fluid-mineral interactions and providing validated numerical tools, this research contributes to developing effective storage systems and risk minimization strategies, ultimately supporting CCS's role in global greenhouse gas reduction efforts.