Green hydrogen storage capacity estimations in depleted gas reservoirs

Green hydrogen is poised to play a crucial role in the transition to renewable energy sources. It acts as a versatile energy storage carrier, helping to balance supply and demand. However, storing hydrogen presents significant challenges, as current technologies can only handle limited volumes. One promising solution involves injecting hydrogen into depleted oil & gas reservoirs, where it can be stored and later extracted when needed. This study explores this approach using the material balance method, which estimates the volumes within a reservoir. It is applied to a depleted natural gas system supported by an aquifer, taking into account pressure and flow rate histories. As the natural gas production rate increases, the hydrogen storage capacity also rises preventing the water to invade in the reservoir. For example, at a reference pressure of 2000 psi, there is no hydrogen storage capacity at a flow rate of 10 MMMCF/day, whereas a storage capacity of 314 BSCF is observed at a flow rate of 1000 MMMCF/day. These insights highlight the potential of utilising depleted reservoirs for hydrogen storage, offering a feasible path to overcoming the current limitations in hydrogen storage technology.