2609 Elucidation of gas trapping mechanism in two-phase flow in porous rocks using micro-focus X ray CT
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To utilize aquifers without proven seal structures as CO_2 storage reservoir, CO_2 should be trapped by residual gas trapping and solubility trapping as well as physical trapping by cap-rock. We investigated the mechanism of the residual gas trapping from a microscopic point of view by means of micro-focus X-ray CT. First, we imaged trapped air bubbles in a Berea sandstone chip after spontaneous imbibition. Next, distributions of trapped bubbles in Berea sandstone were imaged in core-flooding. With a packed bed of glass beads, the effects of capillary number and the injected water volume are discussed. The trapped bubbles consist of two-type; one occupies the center of pore with a pore-scale size and the other has a pore-network scale size.
