Abstract
CO 2 injection into subsurface reservoirs is an effective method for CO 2 storage and higher geological resources recovery in low-permeability reservoirs. However, substantial CO 2 coproduction during conventional CO 2 flooding limits storage efficiency. In this study, a natural amphiphilic molecule (ARGS) is introduced to enhance oil recovery and CO 2 storage by regulating CO 2 -oil–water-rock interfacial and mass-transfer properties under saline conditions, achieving a 9.7% increase in oil recovery compared with conventional CO 2 -enhanced oil recovery (CO 2 -EOR) and a CO 2 storage ratio of up to 85% simultaneously. Under high-salinity formation-water conditions, ARGS increased CO 2 solubility by 4-fold and reduced the interfacial tension of the CO 2 -formation water system by 36%. At the water–rock interface, ARGS shifted pore-surface wettability from neutral-wet to water-wet. During ARGS-assisted CO 2 injection, oil displacement efficiency in micro- and mesopores increased by 10%–15%, expanding the CO 2 sweep range and providing more pore space for CO 2 storage. By enhancing the water-wetness of pore walls, ARGS increased CO 2 flow resistance and consequently promoted both dissolved and trapped CO 2 storage. Ultimately, the proportion of dissolved CO 2 can reach 70%. This study provides an environmentally friendly approach for the efficient CO 2 geological storage and utilization in low-permeability reservoirs.