Abstract
Underground hydrogen storage (UHS) is a distinguished method for reducing anthropogenic greenhouse gases (GHGs) and meeting global energy demand. One of the important parameters for subsurface storage of gas is rock-fluid interfacial tension (gamma rock-fluid) as gas injection and production rate, spread and flow in porous media, storage capacity, and containment security can be derived by this parameter. However, it is impossible to experimentally measure gamma rock-fluid. Moreover, gamma rock-fluid data for rock/H2/water systems in various shales, evaporite, and basaltic formations at geo-storage conditions are scarce in the literature. Thus, advancing and receding contact angles data were used to theoretically compute it at various pressures, temperatures, and shale-TOC by the combination of Young's equation and Neumann's equation of state. For all the rocks evaluated in this study, it was found that gamma rock-gas decreased with pressure, temperature, and shale-TOC. Also, gamma rock-water decreased with temperature but increased with shale-TOC, assuming that it remained constant with pressure. Thus, this work provides a deep understanding of wetting characteristics at various rock/H2/water systems, leading to a better investigation of hydrogen storage beneath shales, evaporite, and basaltic formations.