Modeling and assessment of CO2 geological storage in the Eastern Deccan Basalt of India

In this study, the CO2 carbonatization potential of the Deccan basalt formation in Eastern India is evaluated by establishing a hydro-chemical field-scale model based on the geological, hydrological, and geochemical parameter of the basalt in the Mandla lobe. The reliable initial mineral thermodynamic parameters are obtained by validating the laboratory scale experiment of CO2-water-basalt reaction with a numerical method. Over 50% of injected carbon mineralized within 140 days for the Deccan basalt in the Mandla lobe, and the majority of CO2 is sequestered as ankerite, siderite, and calcite, which occupy a percent of 65%, 28%, and 7%, respectively. Clay minerals, including smectite and chlorite, are important secondary minerals contributing to the process of CO2 storage in the basaltic reservoir. Clay precipitation can promote the dissolution of silica- and aluminum-rich plagioclase and release Ca2+ to enhance the carbonatization of CO2 to Ca carbonates but competes for Fe2+ and Mg2+ from siderite and magnesite. Clay precipitation also impacts the CO2 carbonatization efficiency by changing the basalt conductivity. CO2 carbonatization efficiency was found to increase with the reduction of injection rate. However, slow flow rate can increase the pore clogging risk and induce large pressure build-up. This is the first field-scale assessment of CO2 mineralization potential of the Deccan basalt, which is one of the largest terrestrial flood basalt formations in the world. The results can provide valuable information and scientific support for India and global carbon mitigation.