Publication Date:
2017-09-26
Description:
CO 2 storage in saline aquifers is considered a potential solution for CO 2 mitigation, owing to its significant capacity and worldwide distribution capability. It is therefore becoming more important to understand the underground CO 2 /brine flow mechanisms. CO 2 migration is primarily controlled by the pore-scale subsurface flows in different saline aquifer sites with variable reservoir formation compositions and reservoir conditions. Variations occur in the state of CO 2 phase (gas versus supercritical), brine salinity, and rock wettability, under different reservoir conditions, and may result in different subsurface CO 2 /brine migration phenomena. In this study, we investigate the drainage and imbibition procedures of CO 2 and brine by injecting fluids into unconsolidated sand packs under different conditions of CO 2 phase states, brine salinity, and wettability of sand packs. The pore-scale fluid distribution is visualized using micro X - ray computed tomography (micro-CT). It is found that the phase states of CO 2 , brine salinity, and wettability have low impacts on CO 2 distribution during drainage. However, the increase in brine salinity significantly damages the connectedness of the water phase in pore structures and further decreases the CO 2 –brine interfacial areas. In addition, a pore-scale event called the droplet fragmentation of nonwetting phase is found to occur in the imbibition procedure, which is considered to be beneficial to the dissolution trapping in CO 2 geological storages. It is experimentally demonstrated that the pore structure of rock cores is a factor that significantly contributes to droplet fragmentation.
Print ISSN:
0043-1397
Electronic ISSN:
1944-7973
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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