Feasibility analysis of natural gas storage in the voids of sediment within salt cavern——A case study in China

Abstract

Utilizing voids in sediment to store natural gas represents a new direction for the development of salt cavern underground gas storage in China. In this study, the feasibility of natural gas storage within sediment voids was analyzed. Firstly, a device was developed to simulate the formation of sediment. The results showed that the porosity of the sediment was 52 %. Secondly, a debrining test was conducted in a sediment-filled cavern to analyze the overall volume of voids in sediment, which was determined to be 259,000 m3 through the deformation coordination relationship between compressed air, salt cavern, and brine. In addition, a pressure equilibrium equation for debrining was established, based on which the resistance of the sediment to debrining was determined to be 0.098 MPa. Finally, sediment models were established using PFC3D for particle with different morphologies, and a servo-loading program was developed based on the cpower model of salt rock creep to simulate the long-term deformation of sediment and variation of voids in sediment. 20.7 % reduction in sediment porosity after 30 years. Compared with the salt cavern deformation without sediment, the presence of sediment is beneficial to preserve the effective volume for storing natural gas in the salt cavern.