期刊
INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL
卷 19, 期 -, 页码 160-173出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.ijggc.2013.08.020
关键词
Permeability heterogeneity; Convective mixing; Density-driven; Dissolution flux; CO2 storage
类别
资金
- US Department of Energy (DOE) [DE-EE0002764]
- National Science Foundation (NSF) [CHE-1230691]
- George and Orpha Gibson endowment for the Hydrogeology and Geofluids research group in the Department of Earth Sciences at the University of Minnesota
- Division Of Earth Sciences
- Directorate For Geosciences [1230691] Funding Source: National Science Foundation
Permanence and security of carbon dioxide (CO2) in geologic formations requires dissolution of CO2 into brine, which slightly increases the brine density. Previous studies have shown that this small increase in brine density induces convective currents, which greatly enhances the mixing efficiency and thus CO2 storage capacity and rate in the brine. Density-driven convection, in turn, is known to be largely dominated by permeability heterogeneity. This study explores the relationship between the process of density-driven convection and the permeability heterogeneity of an aquifer during CO2 dissolution storage, using high-resolution numerical simulations. While the porosity is kept constant, the heterogeneity of the aquifer is introduced through a spatially varying permeability field, characterized by the Dykstra-Parsons coefficient and the correlation length. Depending on the concentration profile of dissolved CO2, we classify the convective finger patterns as dispersive, preferential, and unbiased fingering. Our results indicate that the transition between unbiased and both preferential and dispersive fingering is mainly governed by the Dykstra-Parsons coefficient, whereas the transition between preferential and dispersive fingering is controlled by the permeability correlation length. Furthermore, we find that the CO2 dissolution flux at the top boundary will reach a time-independent steady state. Although this flux strongly correlates with permeability distribution, it generally increases with the permeability heterogeneity when the correlation length is less than the system size. (C) 2013 Elsevier Ltd. All rights reserved.
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