Prediction model of the in-situ sediment gradation and gas storage capacity for salt cavern hydrogen storage

Hydrogen storage in salt caverns is the optimal choice for large-scale hydrogen storage. However, significant amounts of sediment accumulate at the bottom of salt caverns in China. Utilizing the pore spaces within these sediments for storage is an inevitable approach for the future development of hydrogen storage caverns. Understanding the in-situ sediment particle size distribution and its gas storage capacity is essential to achieving this goal. This study develops a mathematical model that could accurately predict the gradation of in-situ sediment particles based on the geological characteristics of salt layers and the leaching process. The model was further used to explore the porosity distribution and gas storage capacity of sediments in actual salt mines. The results indicate that the proposed mathematical model demonstrates high accuracy. The gradation and porosity of sediments at the bottom of actual salt caverns exhibit significant heterogeneity with depth. The sediment pore reveals remarkable gas storage potential, with an overall porosity of 46.67% for the in-situ sediment body. Utilizing the sediment pores is expected to increase the available gas storage space by 28244.73 m3, leading to an expected expansion of effective storage volume by over 25.58% compared to the original capacity. This research provides a theoretical foundation for the development of large-scale hydrogen storage utilizing high-impurity, bedded salt formations in China.