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

The transition to a low-carbon energy future has shifted the global focus on hydrogen (H2) as a clean energy carrier, especially its role in blue ammonia production. H2 storage in aboveground tanks presents several challenges, including high material costs, limited capacity, safety concerns due to flammability, and high pressure. Underground H2 storage (UHS) systems in depleted gas reservoirs address the limitations of the aboveground system, utilizing existing gas field infrastructure to store massive H2 volumes. Qatar has a vast number of gas reservoirs located in the North Field, presenting a strategic opportunity for UHS implementations in the future blue ammonia production plant. This study assesses the technical feasibility of using UHS for a partially depleted gas reservoir located in the North Field, utilizing QASR simulation software. The novelty of this work lies in its focus on partially depleted gas reservoirs, unlike most studies which consider fully depleted reservoirs, and its regional focus on Qatar’s North Field, offering valuable insights specific to this strategic area. The simulation model included three different scenarios: a base case with no base gas (cushion gas), and two scenarios using nitrogen (N2) and carbon dioxide (CO2) as cushion gases, injecting them before the H2 injection. Simulation results have shown that the scenario with no cushion gas injection yields the lowest H2 recovery factor (RF), with an RF of 69.6%. In contrast, using cushion gases (CO2 or N2) enhances H2 recovery by maintaining reservoir pressure and enhancing system flow stability. Thus, the study has investigated the possibility of storing massive amounts of H2 in a partially depleted gas reservoir and highlighted the importance of studying different cushion gas types and compositions for an optimal UHS system with the highest possible H2 RF.