Feasibility of hydrogen storage in depleted shale gas reservoir: A numerical investigation

Due to the low operation cost, high containment security, and large storage capacity, depleted shale gas reservoirs are considered as promising options for large-scale hydrogen storage. However, its feasibility has not been systematically examined yet. It is still unknown about whether the deliverability (injection/withdrawal) capacity could meet the energy supply/demand and how the depletion time, cushion gas selection, injection/withdrawal strategy will influence the performance of this scenario. Therefore, we present a numerical compositional modelling investigation on hydrogen storage in a partially depleted Fuling shale gas reservoir in China. The results demonstrated that: 1) a high injection/withdrawal capacity could be achieved through a single shale play pad in the area of interest as approximately 5.4 x 108 Sm3 hydrogen could be stored and 3 x 108 Sm3 could be recovered in each cycle (equal to 0.54 TWh of power output). 2) CH4 production is inhibited once hydrogen storage project is performed, an early depletion time could significantly reduce CH4 production but slightly improve H2 withdrawal. 3) Cushion gas injection is beneficial to reducing H2 loss and enhancing 2.8% H2 recovery, while the main drawback of this operational measure is an increase in capital cost in gas separation due to lower H2 purity in the produced gas. This work demonstrates that shale gas reservoir is a promising candidate for hydrogen storage, which is beneficial to the implementation of large-scale hydrogen economy and the operation of hydrogen supply chain.