Static contact angle, interfacial tension, and column height measurements for underground hydrogen storage

Abstract

Geological porous media are key for large-scale hydrogen (H2) storage and production, where fluid interactions at interfaces and within rock formations are vital for effective gas containment. Although advancements have been achieved in comprehending structural trapping for estimating column height (CH), additional insights are required regarding how pore size impacts this estimation. Currently, CH estimates often consider seal rock potential, without including the capillary contribution from reservoir rock pore for structural trapping capacity assessment. This study measures the static contact angle (CA) on Wolfcamp (WC) Shale and interfacial tension (IFT) under modified drainage and imbibition conditions at temperatures of 30 and 50°C, pressures ranging from 500 to 3000 psia, and a salinity of 10 wt% sodium chloride. Subsequently, the static gas CH was calculated, accounting for contributions from the caprock pores alone and both the caprock and reservoir, to assess the structural sealing capacity of the caprock layer. The experimental procedures are comprehensively detailed in this paper. The outcome indicates that the static CA after drainage for H2)/brine/WC shale rises with pressure as the static CA after imbibition decreases. Both CAs decrease with increasing temperatures. For H2/brine systems, both drainage and imbibition IFTs decline with increasing pressure and temperature. Calculated CHs reveal that lower CAs substantially impact the gas trapping capacity beneath the caprock. In summary, this study highlights the preference for the drainage method in measuring IFT and CA to evaluate the potential structural trapping capacity of injected gas by the overlying caprock.