Pore‐scale trapping of supercritical CO₂ and the role of grain wettability and shape

The capillary trapping of supercritical CO 2 (s‐CO 2 ) is postulated to comprise up to 90% of permanently trapped CO 2 injected during geologic sequestration. Successive s‐CO 2 /brine flooding experiments under reservoir conditions showed that water‐wet rounded beads trapped 15% of injected s‐CO 2 both as clusters and as individual ganglia, whereas CO 2 ‐wet beads trapped only 2% of the injected s‐CO 2 as minute pockets in pore constrictions. Angular water‐wet grains trapped 20% of the CO 2 but flow was affected by preferential flow. Thus, capillary trapping is a viable mechanism for the permanent CO 2 storage, but its success is constrained by the media wettability.