Experimental evaluation of interactions in supercritical CO₂/water/rock minerals system under geologic CO₂ sequestration conditions

The hydrothermal autoclave experiments were conducted to simulate the interactions in the scCO₂/water/rock minerals (quartz, biotite and granite) reaction systems using a Hastelloy C reaction cell at 100 °C. The dissolution characteristics of rock minerals and their surface texture alternation after hydrothermal treatment were examined by ICP-AES and SEM/EDX investigation, respectively. The results suggested that the hydrolysis of plagioclase phase should be mainly responsible for the elements dissolved from the Iidate granite samples. The dissolution was encouraged by the introduction of CO₂ in the water/granite system, and generated an unknown aluminosilicate. No distinct chemical alternations occurred in the water-free scCO₂/granite system, which indicated that rock minerals should be chemically stable in the water-free scCO₂ fluids under the current mild experimental conditions. Both the highest concentration of Ca existing in the scCO₂/vapor/granite system and the SEM observation results of calcite deposit, suggested that a meaningful CO₂ minerals trapping process should be potential in the CO₂-rich field during a short physicochemical interaction period.