Numerical modeling of CO2 sequestration into basalt at high pressure and temperature with variable brine solutions

Abstract

Mineral carbonation is a process whereby CO2 is chemically reacted with calcium and/or magnesium containing minerals to form stable carbonate minerals which needs minimal long-term monitoring. The in situ transformation mechanism involves injection of CO2 into geological formations where the temperature, pressure, and pH parameters for mineral-carbonation prevails. However, the dissolution of CO2 into formation waters depend on temperature, pressure, salinity, and buffering of pH through fluid-rock reaction, which needs numerical modeling to see the combined effect of certain variables through time. This paper presents findings from combined effect of salinity, temperature and pressure in a local geological formation, Kuantan Basalt. The models show that the amount of trapped CO2 in the selected geological formation with pure water condition and at temperature ranges from 60-150 °C is much lower than that of CO2 trapped at higher salinity geological conditions. The models also show a general decreasing amount of trapped CO2 with increasing pressure for salinity range from freshwater to 20000mg/l of NaCl. However, an increased amount of trapped CO2 with higher salinity such as the gas field of Malaysian scenario is observed. These findings may provide clues as what could happen if CO2 is sequestered into geological formations with similar mineralogical composition, similar temperature, salinity and pressure conditions.