Experimental investigation of CO2-brine-rock interactions at elevated temperature and pressure: Implications for CO2 sequestration in deep-saline aquifers

Experiments showed that the solubility of CO2 is enhanced in brine in the presence of limestone by 9% at 25 °C and 6% at 120 °C and 200 bar relative to the brine itself. The solubility of CO2 is enhanced also in brine in the presence of arkosic sandstone by 5% at 120 °C and 300 bar. The storage of CO2 in limestone aquifers is limited to only ionic and hydraulic trapping. However, brine reacted with supercritical CO2 and arkose yielded fixation and sequestration of CO2 in carbonate mineral phases. Brine desiccation was observed in all experiments containing a discrete CO2 phase, promoting porosity-reducing precipitation reactions in aquifers near saturation with mineral phases.