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

摘要

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.