Experimental and modeling assessment of geochemical processes in CO₂ storage within saline aquifers

Abstract

The combustion of fossil fuels accounts for over 85% of global energy supply and is a major source of CO₂ emissions. Geological storage in mature reservoirs and deep saline aquifers is a promising mitigation strategy for reducing greenhouse gas emissions. The Paraná Basin (South America) and the Gondwana Damodar and Son-Mahanadi basins (India) present suitable conditions, with porous sandstone reservoirs sealed by impermeable caprocks. This study investigates CO₂–brine–rock interactions in a synthetic saline aquifer under high pressure (25–200 bar) and temperature (50–100 °C) for 24–96 h. The laboratory experiments in a hydrodynamic reactor revealed precipitation of carbonate minerals, confirmed by XRD. PHREEQC modeling predicted the formation of calcite, dolomite, magnesite, siderite, and dawsonite, with a marked decrease in the concentrations of brine ions. The results effectively establish that CO₂–brine interactions promote mineral trapping, providing insights into long-term CO₂ stabilization in saline aquifers.