Assessment of CO2/shale interfacial tension

Abstract

Caprocks/CO2 interfacial tension (γsc) is an essential parameter that helps to provide insights into the interaction between CO2and caprocks. Lower values of γsc suggest stronger CO2- caprocks interaction (lower CO2capacity is inferred) and vice versa. Rocks/CO2 interfacial tension also explains why different minerals have different wettability to CO2 at the same pressure and temperature. Two caprock samples acquired from a potential CO2 storage site in New South Wales in Australia were used in this work. All the laboratory measurements were conducted at varying pressure from 5 MPa to 20 MPa and a temperature of 343 K. Our findings suggest that solid/CO2 interfacial tension (γsc) in caprocks is highly dependent on total organic carbon (TOC) percentage, pressure, and quartz content. γsc in sample-2 of higher TOC and quartz (TOC =0.11 wt%, quartz = 62%) is lower than γsc in sample-1 of lower TOC and quartz (TOC =0.081 wt%, quartz = 31%. The higher percentage of TOC and quartz increases the hydrophobic sites available in the sample, allowing stronger affinity towards CO2. Lower interfacial tension implies a stronger affinity of CO2 towards caprock surface (the high chance that CO2 will enter through caprocks and causes leakage). Therefore, it can be inferred that high TOC caprocks offer a lower CO2 trapping integrity, hence reducing their CO2 storage capacity. A remarkable relationship between solid/CO2 interfacial tension and CO2 density–which is easy to determine – at different pressures (up to 20 MPa) and 343 K temperature was also demonstrated in this work. This insight can significantly enhance Carbon Geosequestration processes' fundamental understanding.

RAS ID

38792

Document Type

Journal Article

Date of Publication

2021

Volume

627

School

School of Engineering

Copyright

subscription content

Publisher

Elsevier

Comments

Al-Yaseri, A., Abdulelah, H., Yekeen, N., Ali, M., Negash, B. M., & Zhang, Y. (2021). Assessment of CO2/shale interfacial tension. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 627, article 127118. https://doi.org/10.1016/j.colsurfa.2021.127118

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Link to publisher version (DOI)

10.1016/j.colsurfa.2021.127118