Numerical simulation of underground hydrogen storage performance in aquifers

Objective With the global energy transition, the technology of underground hydrogen storage in aquifers has become a key area of research due to its significant potential for large-scale energy storage. Despite growing interest in this technology both domestically and internationally, the exploration of hydrogen flow in aquifers remains insufficient. To clarify the influence of varying injection and production rates, relative permeability hysteresis, and hydrogen blending ratios in natural gas on the performance of hydrogen storage in aquifers, this study employed the software of Computer Modelling Group (CMG) to simulate hydrogen storage in aquifers under different conditions. Methods A dynamic model was developed to simulate hydrogen storage in the aquifer under varying relative permeability hysteresis effects, with injection rates of 2.5×105 m3/d and 5×105 m3/d, production rates of 2.5×105 m3/d and 5×105 m3/d, and hydrogen blending ratios at 10% and 25%. The influence of these factors on hydrogen diffusion and storage in the aquifer was analyzed. Results Both high injection and production rates decreased the hydrogen storage performance of the aquifer. Specifically, a high injection rate reduced the volume of hydrogen stored and recovered over the same period while increasing reservoir pressure. Similarly, a high production rate decreased the volume of hydrogen recovered, leading to greater retention of hydrogen in the aquifer and an increase in reservoir pressure. The relative permeability hysteresis effect inevitably resulted in a significant reduction in hydrogen recovery, leading to hydrogen energy waste. Variations in hydrogen blending ratios had a minimal impact on storage performance. However, hydrogen blending improved gas recovery capacity compared to pure hydrogen, albeit with a higher risk of water accumulation in producing wells. Conclusion The research results provide a reference for optimizing hydrogen storage performance in aquifers and offer technical support for large-scale hydrogen storage. It is recommended to subsequently measure the relative permeability curve under more hydrogen blending ratio conditions to ensure the reliability of hydrogen-blended storage.