Coupled multicomponent two-phase flow and geomechanical modeling for hydrogen storage in an anticline aquifer with N₂ cushion gas injection

Hydrogen storage in aquifers utilizing nitrogen (N₂) as a cushion gas offers a promising solution for large-scale renewable energy storage. This study develops a coupled multicomponent two-phase flow and geomechanics model to evaluate the influence of operational parameters and aquifer properties on hydrogen storage performance in an anticline reservoir. Key factors analyzed include cushion gas injection amount, aquifer permeability, porosity, and thickness, hydrogen injection rate, reservoir pressure, well pressure and length. Simulation results indicate that N₂ mitigates hydrogen (H₂) dilution and suppresses formation water intrusion by increasing gas saturation near the injection well, leading to progressive increases in hydrogen recovery and a 12%–16% enhancement in gas purity over successive cycles. However, excessive cushion gas injection causes premature breakthrough, reducing purity. Higher permeability generally improves recovery but may compromise purity, while lower porosity enhances recovery at the expense of total storage capacity. Aquifer thickness moderately affects performance, and reservoir pressure and well conditions strongly influence hydrogen production rates and purity. Optimizing hydrogen storage thus requires a careful balance of cushion gas amount, reservoir properties, and operational strategies to maximize recovery while maintaining high gas quality.