On hydrogen wettability of basaltic rock

One of the major challenges pertaining to a full hydrogen economy is hydrogen storage in the Earth's subsurface formations, such as deep saline aquifers and depleted oil and gas reservoirs. Generally, sedimentary basins are considered for this purpose due to their potential for large-scale storage. However, basaltic formations are also in comparable proportions having voluminous volcanic rocks, vast expansions, and high thickness. We, thus, in this work, evaluate brine/hydrogen/rock wettability of the real Basalt rock samples from CarbFix site in Iceland. Wettability is one of the significant parameters that highly influences the spreading and migration of the gas (as seen for CO₂ capillary trapping investigations), interfacial area, mass transfer, and mineralization. We carried out brine/gas/Basalt three-phase contact angle measurements for some gases (CO₂, N₂, and He) under storage conditions of high temperature (323 K) and pressures (5, 10, 15, and 20 MPa). The analogy drawn from developed correlation for H₂ from the contact angle trend of He (density close to H₂ density) and empirical correlations reveals that a strong water-wetting state of Basalt can be expected for H₂. The high water-wetting state of Basalt in the presence of H₂ at storage conditions may be suitable for capillary trapping of H₂ for long term storage in Basaltic formation.