Numerical study of the efficiency of underground hydrogen storage in deep saline aquifers, rock springs uplift, Wyoming

Underground hydrogen storage (UHS) is able to store a large amount of energy with efficiency, thus meeting the high demand for energy in winter. This study aims at investigating the feasibility and efficiency of UHS in the Nugget Sandstone, Rock Springs Uplift, Wyoming. The representative geological model is first constructed with the control of well logs and seismic data. Then the multiphase flow functions are well coupled into the subsurface reservoir model. Following that, based on the uncertainty of reservoir parameters, gas source accessibility, and production cost, the effects of key parameters on H2 fate within the reservoir and H2 recovery efficiency are researched. Simulation outcomes reveal that H2 dissolution into formation brine gives rise to a lower amount of trapped H2 within the reservoir but the recovery ratio is reduced by the H2 dissolution at the end. Relative permeability hysteresis can not only relieve the H2 vertical migration, but also give a wider H2 radial distribution. As the cycle proceeds, relative permeability hysteresis results in the notable enhancement in the trapped H2, leading to a reduction of the final recovery ratio from 0.86 to 0.76 when the residual gas saturation, Sgmax, ranges from 0.2 to 0.4. A slower cushion gas (CG) injection rate gives rise to a smaller final trapped H2, which accordingly results in an increase of recovery ratio. Further, the final recovery ratio changes from 0.835 to 0.846 due to an increase in working gas components from H2:CH4 = 1:1 to H2:CH4 = 3:1. The insights obtained in this study shed a light on accelerating the achievements of decarbonisation goals through the commercial-scale energy conversion and transition from conventional fossil energy and renewable energy to hydrogen.