Key technologies for salt-cavern underground gas storage construction and evaluation and their application

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Salt-cavern underground gas storage is technically faced with non-uniform distribution of stratified salt rocks, complex solution mining mechanism, difficult control of solution mining process, less operation safety and stability of caverns and difficult reconstruction and utilization of old caverns. In view of these technical difficulties, the design concept was fully updated based on the design experience and field practice of Jintan gas storage in Jiangsu, for purpose of maximizing salt layer utilization ratio, improving solution mining efficiency, shortening construction time and ensuring cavity safety. Based on the updated design concept, five series of key technologies were proposed in site evaluation, cavern design and control, stability assessment and storage capacity parameter design, old cavern screening and utilization, and gas storage operation and monitoring. The following results were obtained from the actual application of these key technologies to the Jintan gas storage. First, the actual drilling coincidence rate of geological program is high. Second, the cavern is morphologically coincident with the design. Third, the cavern deformation retract rate is in line with the stability evaluation result. Fourth, old caverns are successfully reconstructed and utilized. Fifth, the arrangement of the monitoring network ensures the operation safety of salt-cavern underground gas storage and makes an important contribution to the peak shaving and supply guarantee of natural gas in the Yangtze River Delta region. In conclusion, the research results provide guidance for the design and engineering implementation of salt-cavern underground gas storage construction program, as well as a theoretical and technical support for the construction of similar gas storages.