Assessing interfacial interactions in mixed H2-CO2 aqueous systems for geological gas storage

Author Identifier (ORCID)

A. Keshavarz: https://orcid.org/0000-0002-8091-961X

Abstract

Underground hydrogen storage (UHS) offers a viable solution for large-scale hydrogen storage, yet understanding the interfacial interactions that govern gas mobility and trapping remains critical. This study investigates the interfacial tension (IFT) behaviour of H2–CO2–brine systems under reservoir-relevant conditions, focusing on the effects of temperature (20–80°C), pressure (10–100 bar), salinity, and gas composition. Using experimental methods, gas–water IFT values were measured in both distilled water and formation brine environments. Results show that IFT trends vary with aqueous composition and gas type: IFT increases with temperature in pure H2–water systems but decreases in brine due to salt-induced weakening of cohesive forces. CO2-containing mixtures exhibit a pronounced pressure-dependent reduction in IFT, linked to greater gas solubility and molecular interactions. Salinity also consistently reduces IFT via the salting-out effect. The study highlights the role of CO2 as a cushion gas, which enhances hydrogen injectivity by lowering IFT and minimizing capillary trapping. Nonlinear IFT responses at high CO2 concentrations further emphasize the complexity of multiphase interactions in porous media. These findings improve the fundamental understanding of interfacial behaviour in subsurface hydrogen storage and inform the design of more effective UHS and CO2 sequestration strategies.

Keywords

Underground hydrogen storage, interfacial tension, CO₂–H₂ mixtures, brine systems, reservoir conditions, multiphase flow

Document Type

Conference Proceeding

Date of Publication

1-1-2025

Publication Title

Sixth EAGE Global Energy Transition Conference & Exhibition (GET 2025)

Publisher

European Association of Geoscientists and Engineers

School

School of Engineering

Comments

Esfandiari, H., Safari, A., Hassanpouryouzband, A., Haghighi, M., Keshavarz, A., Zeinijahromi, A., & Keykhosravi, A. (2025). Assessing interfacial interactions in mixed H2-CO2 aqueous systems for geological gas storage. Sixth EAGE Global Energy Transition Conference & Exhibition (GET 2025), 2025, 1–5. https://doi.org/10.3997/2214-4609.202521037

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Link to publisher version (DOI)

10.3997/2214-4609.202521037