Capillary processes increase salt precipitation during CO2 injection in saline formations

Kelly, Helena L.; Mathias, Simon A.

Abstract

An important attraction of saline formations for CO2 storage is that their high salinity renders their associated brine unlikely to be identified as a potential water resource in the future. However, high salinity can lead to dissolved salt precipitating around injection wells, resulting in loss of injectivity and well deterioration. Earlier numerical simulations have revealed that salt precipitation becomes more problematic at lower injection rates. This article presents a new similarity solution, which is used to study the relationship between capillary pressure and salt precipitation around CO2 injection wells in saline formations. Mathematical analysis reveals that the process is strongly controlled by a dimensionless capillary number, which represents the ratio of the CO2 injection rate to the product of the CO2 mobility and air-entry pressure of the porous medium. Low injection rates lead to low capillary numbers, which in turn are found to lead to large volume fractions of precipitated salt around the injection well. For one example studied, reducing the CO2 injection rate by 94 % led to a tenfold increase in the volume fraction of precipitated salt around the injection well.

Citation

Kelly, H. L., & Mathias, S. A. (2018). Capillary processes increase salt precipitation during CO2 injection in saline formations. Journal of Fluid Mechanics, 852, 398-421. https://doi.org/10.1017/jfm.2018.540

• Journal Article Type: Article
• Acceptance Date: Jul 1, 2018
• Online Publication Date: Aug 7, 2018
• Publication Date: Oct 1, 2018
• Deposit Date: Jun 29, 2018
• Publicly Available Date: Feb 7, 2019
• Journal: Journal of Fluid Mechanics
• Print ISSN: 0022-1120
• Electronic ISSN: 1469-7645
• Publisher: Cambridge University Press
• Peer Reviewed: Peer Reviewed
• Volume: 852
• Pages: 398-421
• DOI: https://doi.org/10.1017/jfm.2018.540
• Public URL: https://durham-repository.worktribe.com/output/1322837