Numerical Investigation of Subsurface Hydrogen Storage: Impact of Cyclic Injection

The use of hydrogen (H₂) as a clean fuel has gained enormous interest in recent years. For this purpose, excess H₂ can be stored in subsurface geological formations. The underground hydrogen storage (UHS) can help to mitigate the challenges associated with seasonal variability in renewable energy production and provide a reliable source of hydrogen for future utilization. While recent studies showed that repeated hydrogen injection and production in aquifer can result in hydrogen and water cyclic hysteresis, the existing classical trapping models fail to model such phenomena in the context of hydrogen and brine. Moreover, the impact of cyclic hysteretic behavior effect received little or no attention on the reservoir scale and thus still remains poorly understood. This study conducts numerical simulations to analyze the impact of cyclic hysteresis on the efficiency of underground hydrogen storage. The results showed that the cyclic hysteresis effect will result in a shorter lateral migration of the injected H₂ and more H₂ accumulating in the vicinity of the wellbore due to the poorer hydrogen flow ability and higher critical hydrogen saturation. The accumulated hydrogen will in turn contribute to a higher hydrogen recovery factor and thus improve the efficiency of underground hydrogen storage.