On the dependence of capillary entry pressure with subsurface depth in geological CO2 storage

Y. Zhou*, J. O. Heiland, D. G. Hatzignatiou, Yingfang Zhou

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

CO2 entry pressure for a specific pore geometry decreases with increasing storage site depth because the interfacial tension is reduced, and the system becomes less water-wet with depth. Few quantitative investigations on the dependency of capillary entry pressure on subsurface depth in geological CO2 storage have been reported mainly due to the absence of interfacial and wettability modeling capabilities for brine/CO2/solid systems. In this work, a workflow and methodology are proposed to quantify the dependency of capillary entry pressure with depth in geological CO2 storage. The cap-rock pore spaces are treated as straight tubes with cross-sections obtained directly from 2D SEM rock images, and the capillary entry pressure of CO2 invading these pore spaces is simulated under arbitrary uniformly-wet conditions with the use of an novel semi-analytical model. The interfacial tension between brine and CO2 is obtained as a function of the phases density difference, and the contact angle is evaluated based on the Frumkin-Derjaguin equation with the application of the DLVO theory to compute disjoining pressures isotherm curves under various storage formation conditions. Based on the developed model, the CO2 entry pressure can be computed in realistic cap-rock pore spaces extracted from 2D rock images from core samples located at various storage depths and under the appropriate pressure, temperature and brine ionic strength conditions. The dependency of brine/CO2 interfacial tension, contact angle and capillary entry pressure on CO2 storage depth and brine ionic strength is also investigated. The proposed workflow for entry pressure estimation and the relationship between capillary entry pressure and depth could enhance our understanding and improve the safety of CO2 storage. The simulated depth-dependent capillary entry pressure curves could also be incorporated into a reservoir simulation model to predict CO2 migration in the storage unit.

Original languageEnglish
Title of host publication4th EAGE CO2 Geological Storage Workshop 2014
Subtitle of host publicationDemonstrating Storage Integrity and Building Confidence in CCS
PublisherEuropean Association of Geoscientists and Engineers, EAGE
Pages34-39
Number of pages6
ISBN (Print)9781632665386
Publication statusPublished - 2014
Event4th EAGE CO2 Geological Storage Workshop 2014: Demonstrating Storage Integrity and Building Confidence in CCS - Stavanger, Norway
Duration: 22 Apr 201424 Apr 2014

Conference

Conference4th EAGE CO2 Geological Storage Workshop 2014: Demonstrating Storage Integrity and Building Confidence in CCS
CountryNorway
CityStavanger
Period22/04/1424/04/14

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  • Cite this

    Zhou, Y., Heiland, J. O., Hatzignatiou, D. G., & Zhou, Y. (2014). On the dependence of capillary entry pressure with subsurface depth in geological CO2 storage. In 4th EAGE CO2 Geological Storage Workshop 2014: Demonstrating Storage Integrity and Building Confidence in CCS (pp. 34-39). European Association of Geoscientists and Engineers, EAGE.