Numerical Simulation of Water‐Rock Reaction for CO ₂ Sequestration in Sandstone Reservoir

ABSTRACT

Climate change represents one of the most pressing global challenges facing humanity. Under the framework of the national climate change strategy, Carbon Capture, Utilization, and Storage (CCUS) is currently regarded as the only viable technology capable of achieving large‐scale, near‐zero‐emission utilization of fossil energy, thereby contributing significantly to the carbon neutrality goal of China. In this study, the brine layer of the Jilin Oilfield was selected as the research target, and numerical simulation of CO ₂ ‐formation water‐rock reactions was conducted using the TOUGHREACT software. The effects of CO ₂ injection on reservoir fluid pH, mineral transformation, and ion concentrations in formation water were systematically analyzed. The simulation results indicate that both dissolution and precipitation reactions occurred simultaneously in the acidic CO ₂ solution, with the pH of the formation water stabilizing at approximately 4.8. Overall, the reaction system exhibited a tendency for magnesite, montmorillonite, kaolinite, illite, and dolomite to precipitate, while albite, chlorite, and calcite were prone to dissolution. Different mineral assemblages were generated at various stages of the reaction process. The dissolution of CO ₂ increased rock porosity and permeability. However, the magnitude of these changes was relatively minor, exerting little influence on the CO ₂ injection capacity. The findings of this study provide valuable experimental references and theoretical support for CO ₂ sequestration in saline aquifers of the Jilin Oilfield.