Analysis of influencing factors of injection and production of underground hydrogen storage in aquifer

Underground hydrogen storage in aquifers is a novel approach to address the regional dispersion and volatility of renewable energy, enabling large-scale H2 storage. The selection of injection and production schemes determines the safe operation and operational efficiency of underground hydrogen storage. Given the limited research on factors influencing the hydrogen storage capacity of underground aquifers and the inadequate analysis of hydrogen migration during injection and production, this study developed an underground aquifer model using numerical simulation methods to investigate these issues. To ensure injection safety, the capillary pressure of the model caprock was calculated prior to numerical simulation. The maximum initial injection flow rate was then determined using a trial-and-error method, ensuring that the capillary pressure threshold was not exceeded. Through simulation, it is observed that peak pressure in the top well area of the reservoir typically occurs at two critical moments: first, when H2 from the bottom of the well initially reaches the cap rock, and second, when the increasing plume thickness causes the top pressure of the reservoir to approach its critical value. Through the implementation of a segmentation injection strategy and adjustment of the injection rate, the maximum storage capacity of the model over a fixed 24-month period is determined to be 0.270 Mt.