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.