Effect of relative permeability hysteresis on plume dynamics, wellbore flow regime, and storage efficiency in underground hydrogen storage

Hydrogen storage in porous geological formations can potentially provide large-scale, seasonal storage of energy. This study investigates the effect of relative permeability hysteresis on the storage processes, particularly addressing the effects on the dynamics of the hydrogen plume, on the two-phase flow regime in the wellbore, and on the storage operations. Numerical simulations of the underground hydrogen storage processes are conducted for scenarios which account for and which ignore hysteresis. The hysteretic constitutive relationships used are based on two independent, experimentally derived datasets from literature. In scenarios that account for hysteresis, the hydrogen plume is less mobile and the hydrogen mass is more dispersed than in scenarios without hysteresis. In addition, hysteresis leads to increased brine upconing and influx into the production borehole. A simple analysis of the two-phase flow regime in the borehole provides an estimate of the required minimum flow rate to ensure annular flow. Though different, both hysteretic constitutive relationships used in this study yield the same trend. All the effects of hysteresis mentioned above are detrimental for hydrogen recovery and tend to be more significant in the first few storage cycles. Operationally, these problems could be addressed by providing for a rest period between injection and production that is long enough to let the hydrogen plume accumulate near the well and potentially by the use of a cushion gas. • Analysed effects of relative permeability hysteresis in underground hydrogen storage. • Hysteresis reduces hydrogen recovery especially in initial storage cycles. • Hysteresis reduces mobility of the hydrogen plume and increases its spread and extent. • Hysteresis increases brine upconing and affects the wellbore flow regime.