Evaluation of CO2 solubility-trapping and mineral-trapping in microbial-mediated CO2–brine–sandstone interaction

Evaluation of CO2 solubility-trapping and mineral-trapping by microbial-mediated process was investigated by lab experiments in this study. The results verified that microbes could adapt and keep relatively high activity under extreme subsurface environment (pH < 5, temperature > 50 °C, salinity > 1.0 mol/L). When microbes mediated in the CO2–brine–sandstone interaction, the CO2 solubility-trapping was enhanced. The more biomass of microbe added, the more amount of CO2 dissolved and trapped into the water. Consequently, the corrosion of feldspars and clay minerals such as chlorite was improved in relative short-term CO2–brine–sandstone interaction, providing a favorable condition for CO2 mineral-trapping. Through SEM images and EDS analyses, secondary minerals such as transition-state calcite and crystal siderite were observed, further indicating that the microbes played a positive role in CO2 mineral trapping. As such, bioaugmentation of indigenous microbes would be a promising technology to enhance the CO2 capture and storage in such deep saline aquifer like Erdos, China.