Numerical Simulation of CO₂ Dissolution and Mineralization Storage Considering CO₂-Water-Rock Reaction in Aquifers

CO₂ storage technology is crucial in addressing climate change by controlling the greenhouse effect. This technology involves the injection of captured CO₂ into deep saline aquifers, where it undergoes a series of reactions, such as structure binding, dissolution, and mineralization, enabling long-term storage. Typically, the CO₂ is maintained in a supercritical state, enhancing its storage efficiency. However, the efficiency can be influenced by the CO₂-water-rock reactions. Many minerals exist in rock, like calcite, dolomite, kaolinite, etc. This study introduces some chemical reactions that occur during the dissolution and mineralization of CO₂. The relationship between solubility and pressure was obtained through solubility fitting. We obtained the initial parameters of the CO₂-water-rock reaction experiment by fitting the data. These parameters can be applied to the mechanism model. This study employs the GEM module of CMG software, integrating physical parameters from the Ordos Basin's deep saline aquifers to develop a mechanism model. In this model, CO₂ injection started from the first year and continued for 20 years. This study simulated a total of 80 years of CO₂ storage. This study has elucidated how reservoir conditions and injection schemes affect the dissolution and mineralization of CO₂. This study creatively combines practical experiments and numerical simulations and uses numerical simulations to compensate for the manpower and material resources consumed in actual experiments. The research results indicate that permeability should not be too high, and an increase in porosity is beneficial for storage. As the injection rate increases, the amount of CO₂ storage increases. Top layer perforation yields lower efficiency compared to full, middle, or bottom layer perforation, with the latter providing the higher efficiency in CO₂ dissolution and mineralization. Bottom perforation is the most favorable perforation position for CO₂ storage.