Evaluation of Potential for Salt Cavern Gas Storage and Integration of Brine Extraction: Cavern Utilization, Yangtze River Delta Region

The Yangtze River delta region of China consumes a large amount of natural gas, but the current gas storage facilities of this region can provide only 19.6 × 108 m3 of natural gas for use, which will be far less than the required gas storage volume of 66.8 × 108 m3 in 2030. The reason is due to lacking suitable underground gas storage space. To meet the space demands of underground gas storage (UGS) in the Yangtze River Delta region, the feasibilities of UGS construction in salt formations including depth of mines, thickness of salt strata, distance to pipelines, and geologic safety of the salt mines are evaluated. The representative blocks of Huai’an salt mine and Fengxian salt mine are suggested as potential sites for UGS construction. To promote UGS construction operation quickly and economically, utilizing the existing caverns can be considered firstly. The evaluation indicates that the existing caverns can store about 12.91 × 108 m3 natural gas for UGS with a cavern utilization rate of 30%. To satisfy the space for residual gas storage, the idea of “integration of brine extraction and cavern utilization” is put forward; that is, salt mining enterprises carefully control the usability of newly increased cavern volume during brine extraction. The forecast shows that about 36.9% of the newly increased cavern volume is sufficient to meet the residual cavern demand of UGS to fulfill a gas store volume of 34.3 × 108 m3 in 2030 in the Yangtze River delta. This research provides an effective method to solve the space need for UGS in the Yangtze River delta; simultaneously, it also presents win–win cooperation for the utilization of abandoned caverns and energy storage.