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Combined effects of CO2 adsorption-induced swelling and dehydration-induced shrinkage on caprock sealing efficiency

Citation

Shang, X and Wang, J and Wang, H and Wang, X, Combined effects of CO2 adsorption-induced swelling and dehydration-induced shrinkage on caprock sealing efficiency, International Journal of Environmental Research and Public Health, 19, (21) Article 14574. ISSN 1660-4601 (2022) [Refereed Article]


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© 2022 by the authors. This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License, (https://creativecommons.org/licenses/by/4.0/)

DOI: doi:10.3390/ijerph192114574

Abstract

Carbon dioxide (CO2) may infiltrate into the caprock and displace brine water in the caprock layer. This causes two effects: one is the caprock swelling induced by the CO2 adsorption and the other is the caprock dehydration and shrinkage due to CO2–brine water two-phase flow. The competition of these two effects challenges the caprock sealing efficiency. To study the evolution mechanism of the caprock properties, a numerical model is first proposed to investigate the combined effects of CO2 adsorption-induced expansion and dehydration-induced shrinkage on the caprock sealing efficiency. In this model, the caprock matrix is fully saturated by brine water in its initial state and the fracture network has only a brine water–CO2 two-phase flow. With the diffusion of CO2 from the fractures into the caprock matrix, the CO2 sorption and matrix dehydration can alter the permeability of the caprock and affect the entry capillary pressure. Second, this numerical model is validated with a breakthrough test. The effects of the two-phase flow on the water saturation, CO2 adsorption on the swelling strain, and dehydration on the shrinkage strain are studied, respectively. Third, the permeability evolution mechanism in the CO2–brine water mixed zone is investigated. The effect of dehydration on the penetration depth is also analyzed. It is found that both the shale matrix dehydration and CO2 sorption-induced swelling can significantly alter the sealing efficiency of the fractured caprock.

Item Details

Item Type:Refereed Article
Keywords:CO2 geological sequestration, brine water-CO2 two-phase flow, matrix dehydration, caprock swelling, permeability evolution
Research Division:Engineering
Research Group:Fluid mechanics and thermal engineering
Research Field:Geophysical and environmental fluid flows
Objective Division:Energy
Objective Group:Environmentally sustainable energy activities
Objective Field:Environmentally sustainable energy activities not elsewhere classified
UTAS Author:Wang, X (Professor Xiaolin Wang)
ID Code:154179
Year Published:2022
Deposited By:Engineering
Deposited On:2022-11-07
Last Modified:2023-01-10
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