Enabling fractured-vuggy reservoirs for large-scale gas storage: Green hydrogen, natural gas, and carbon dioxide

Abstract

Fractured-vuggy reservoirs typically exhibit flow capacities up to ten times higher than conventional sandstone reservoirs, providing a significant advantage for Underground Gas Storage (UGS). However, their complex connectivity introduces uncertainty in gas flow pathways, leaving these potential benefits largely unexplored. To reuse this type of reservoir for UGS, we developed a flow velocity model that effectively captures the influence of multi-scale pore and fracture networks on gas flow behavior. The classified flow pathways were subsequently employed to evaluate the injection–production behavior of hydrogen, natural gas, and carbon dioxide within UGS. The results indicate that fractured-vuggy reservoirs can deliver effective peak-shaving capacity and are well-suited for UGS. Notably, hydrogen achieved a recovery factor of up to 88.5 %, and the economic analysis demonstrates that profitable storage is achievable at the current cost level of natural gas storage. The recovery factor of natural gas exceeded 92 %, yielding a net present value of $20.7 M, whereas carbon dioxide performance was highly dependent on tailored injection strategies and capture costs. This discovery suggests the potential of fractured-vuggy reservoirs for UGS and provides technical guidance for future site selection.