A simulation study of underground hydrogen storage (UHS) in a partially depleted gas reservoir: A case study for the North Field, Qatar

The transition towards a low-carbon energy future has increased global interest in hydrogen (H2) as a clean energy carrier, particularly for blue ammonia production. However, aboveground H2 storage presents several challenges, including high material costs, limited storage capacity, safety concerns associated with flammability, and high operating pressures. Underground H2 storage in depleted gas reservoirs offers a promising alternative by utilizing existing gas-field infrastructure. This study assesses the technical feasibility of underground H2 storage in a representative partially depleted gas reservoir of Qatar's North Field using QASR compositional reservoir simulation. Three storage scenarios were evaluated: a base case without cushion gas and two cases employing nitrogen (N2) and carbon dioxide (CO2) as cushion gases prior to H2 injection. By investigating cushion-gas selection in a representative partially depleted reservoir, the study provides engineering insights into the influence of cushion gas on reservoir pressure support, H2 recovery, and storage performance under the investigated operating conditions. The simulation results showed that the no-cushion scenario yielded the lowest H2 recovery factor of 69.6%, whereas the use of cushion gases improved H2 recovery by maintaining reservoir pressure and promoting more efficient gas displacement. Overall, the findings demonstrate the technical feasibility of underground H2 storage in partially depleted gas reservoirs and provide reservoir-specific engineering insights that support the evaluation of cushion-gas selection for future underground H2 storage applications.