Enhancing hydrogen recovery and carbon sequestration efficiency in natural hydrogen reservoirs through CO2 injection: An experimental and simulation study

Natural hydrogen reservoirs formed through serpentinization offer significant potential as clean energy resources. However, their efficient exploitation is challenged by water invasion during pressure depletion, which can severely reduce hydrogen production efficiency. This study proposes a strategy using carbon dioxide (CO2) injection to enhance hydrogen recovery and mitigate water encroachment. A comprehensive approach combining experimental studies, molecular dynamics simulations, and reservoir modeling was employed to assess the impact of CO2 injection. Interfacial tension measurements showed that CO2/H2 gas mixtures significantly reduce interfacial tension with water compared to pure hydrogen, helping to minimize water invasion. Core flooding experiments demonstrated that CO2 injection stabilizes hydrogen production by suppressing water output. Molecular simulations revealed that CO2 preferentially adsorbs onto dolomite surfaces, forming a CO2-rich layer that acts as a barrier to water encroachment. The findings suggest that an optimal CO2 injection rate effectively enhances hydrogen recovery while also providing CO2 sequestration benefits, offering dual environmental advantages. This research provides new methods for the sustainable development of natural hydrogen reservoirs and contributes to reducing carbon emissions, supporting the transition to a low-carbon energy future.