Assessment of reactive surface and kinetic parameters of basaltic rocks during CO2 storage

Resumo

Carbon capture and storage (CCS) is a novel technology that aims to reduce the presence of carbon dioxide from the atmosphere. This technology involves capturing CO2 from industrial sources or directly from the air, treating, transporting, and storing it in long-term safe rock formations. Basaltic rock comprises reactive minerals and glassy phases, which trap CO2 permanently through the mineralization mechanism. However, this method is complex mainly due to the rapid interaction between solid and liquid phases. The mineralization occurs at the interface between the reactive fluid and the basaltic rock surface, converting the dissolved CO2 into solid carbonate mineral that precipitates in the pores and fractures of the rock matrix. The reaction rate of a basaltic rock depends significantly on the CO2 wettability and rock-fluid interfacial interactions. However, there is limited information about the influence of the reactive surface on the reaction rate of minerals present in basalt formations. This work investigates the influence of kinetics parameters such as pH, temperature, and reactive surface area in the reaction rate of basaltic rocks. Basaltic rock dissolution and precipitation is assessed using the geochemical software PHREEQC. The proposed numerical model solves the reactive transport problem and provides feedback on the influence of the kinetics reaction parameters. The dynamics of the reactive surface during the reaction of basalt rocks is evaluated. The numerical results show the potential of basaltic rock for CO2 mineral storage as solid carbonates and identify the main factors that limit the mineralization process. Finally, this work provides a deeper understanding of CO2 mineralization that can provide valuable findings to guide Brazilian CCS projects.