Abstract

The injection of CO₂ into carbonate reservoirs for long-term sequestration induces complex geochemical and geomechanical interactions at the pore scale, influencing storage capacity and reservoir integrity. This study presents a combined numerical and experimental approach to evaluating these interactions, focusing on mineral dissolution, precipitation, and their impact on permeability and mechanical stability. Laboratory-scale experiments using high-pressure flow cells and microfluidic devices simulate CO₂-brine-rock interactions under reservoir conditions. Advanced imaging techniques, including X-ray micro-computed tomography (µCT) and scanning electron microscopy (SEM), provide insights into pore-scale alterations and reaction dynamics. Complementing the experimental analysis, a numerical model incorporating reactive transport equations and geomechanical coupling is developed to predict dissolution patterns, permeability evolution, and rock strength variations. The Lattice Boltzmann Method (LBM) and Finite Volume Method (FVM) are employed to simulate multiphase flow and mineralogical changes over time. Model calibration with experimental data ensures accuracy in representing key processes such as acid-induced pore enlargement, precipitation of secondary minerals, and stress redistribution in the rock matrix. Results reveal that CO₂ injection leads to significant heterogeneities in pore structure, enhancing permeability in some regions while inducing mechanical weakening in others. These highlight the dual impact of CO₂ sequestration in carbonate formations: improved injectivity but potential risks to reservoir stability. Understanding these dynamics is crucial for optimizing storage strategies and mitigating leakage risks. This contributes to advancing predictive models for subsurface CO₂ sequestration, supporting the safe and efficient implementation of carbon capture and storage (CCS) technologies. Future research should refine upscaling methodologies and incorporate real-time monitoring techniques for improved assessment of CO₂ behavior in geological formations.