Mixed-Layer Illite-Smectite Illitization under Supercritical CO2 Conditions

The long-term safe storage of CO2 in geological reservoirs requires the understanding impact on clay-rich sealing cap rocks. reactivity mixed layer illite-smectite was investigated to determine reaction pathways under conditions supercritical (scCO2) context storage. A common clay (blue marl from Guadalquivir Tertiary basin, southern Spain) tested brine scCO2 (100 bar and 35 °C) for 120 240 h. sample marl) contains calcite, quartz, illite, smectite, corresponding mixed-layer kaolinite. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses were performed. illitization observed by XRD confirmed a variation content different elements (K, Mg, Na, Ca, Fe) transformation, as well an increase specific surface (SSA) (36.1 38.1 m2/g N2, 14.5 15.4 adsorption). Furthermore, these reactions lead mineral dissolution secondary formation along CO2–water–clay intercalations source rock responsible change porosity (7.8 7.0 nm pore size). implications illitisation, destruction, precipitation processes integrity should be explored before deciding location.