The effects of geochemical reactions on CO2 sequestration in deep saline aquifers

Abstract

Deep saline aquifers are among the most promising geological formations for carbon sequestration due to their vast storage potential and long-term stability. However, CO2 injection induces significant geochemical reactions that affect injectivity. This study investigates the impact of these reactions on reservoir properties during CO2 injection, such as mineral dissolution/precipitation, pH variations, and changes in porosity and permeability. The simulation framework incorporates reaction stoichiometry modeling to quantify CO2 interactions with formation water and minerals, validated using XRF and SEM-EDS data from Field X in Southern Vietnam. The results show that CO2 injection caused some phenomena such as changes in mineral compositions and aqueous species distribution, particularly in the near-wellbore region. Minerals precipitation/dissolution release cation and HCO3-, raising pH, while silicate dissolution contributes to acidification. These reactions lead to increased permeability and porosity, affecting CO2 storage efficiency. Mineral precipitation/dissolution near the wellbore influences injectivity efficiency, emphasizing the need for accurate geochemical characterization.