Experimental investigation of the sealing capacity of generic clay-rich caprocks

► Generic caprocks were analyzed with respect to their sealing efficiency. ► He and CO2 breakthrough experiments were conducted on water saturated samples. ► Viscous gas flow was detected for rel. high permeable rocks (>10−20 m2). ► No capillary breakthrough was detected for rocks with permeabilities <10−21 m2. ► Exposure of the samples with CO2 did not result in detectable mineral alterations.