Effect of cyclic hysteretic multiphase flow on underground hydrogen storage: A numerical investigation

Abstract

Hydrogen storage in subsurface geological formation is a complex process requiring information at multiple scales for successful understanding and implementation. While some laboratory investigations and pore-scale studies showed evidence of hydrogen and water cyclic hysteresis, field-scale underground hydrogen storage considering the cyclic hysteretic effect received little or no attention and thus remains poorly understood. This is particularly important due to the fact that an underground hydrogen storage project typically involves repeated cycles of hydrogen injection and withdrawal. In this work, numerical simulations were performed to examine the impact of the cyclic hysteretic effect on the dynamics of hydrogen saturation and the associated efficiency of storage and withdrawal cycles. The results indicate that the cyclic hysteretic effect impedes the injected hydrogen distribution in the formation and results in a greater ultimate hydrogen recovery factor during subsequent withdrawal phases (∼77%). However, the accumulated hydrogen in the formation top will, in turn, increase the formation pressure. The impact of capillary pressure and H2 dissolution in brine were also investigated. The results suggest that capillary pressure and dissolution could alter the hydrogen saturation distribution while depicting a negligible effect on the ultimate hydrogen recovery factor. It was found that the loss of hydrogen due to dissolution can be compensated by avoiding more significant residual trapping in our study.