Take cheap inert gas as cushion gas of gas storage with salt caves

As the west-east gas delivering starts, it is necessary to build gas storages which are the matching facilities of the long gas transmission pipeline in the areas of Yangtze delta. With comparison of storage-building positions, the salt beds located in Jingtan salt mine of Jiangsu province are regarded as the optical target to build the gas storage in the areas of Yangtze delta. The cushion gas volume of the gas storage with salt caves changes with variation of the gas storage depth and the operating pressure. By estimation, the cushion gas volume of Jingtan gas storage with salt caves will accounts for about 33% of the total volume of the storage. If taking natural gas as the cushion gas as usual, the cushion gas cost will accounts for 28.5% of the total cost of the gas storage for the group storages, which can deliver 17 × 103 m3/a. of working gas. If taking cheaper inert gas as the cushion gas, 16.7% of the total investment can be saved. The article introduces the experience of substituting inert gas for natural gas in gas storages of France, and makes technical and economical discussion on substituting natural gas with cheaper nitrogen as cushion gas for jingtan gas storage with salt caves.