New technologies for site selection and evaluation of salt-cavern underground gas storages

Abstract In order to meet the demand of constructing salt-cavern underground gas storages (UGSs) in favorable salt mines for the regions that are neither major oil and gas production zones nor major natural gas consumer markets in South China, and solve the problems of unclear conditions for selecting salt-cavern gas storage sites and of inconsistent content and depth in evaluating gas storage conditions, based on investigation and analysis of salt-cavern UGS data in China and other countries, we proposed the principles of selecting gas storage sites in combination with geology and ground surface conditions, and developed a set of technologies in evaluating construction conditions for salt-cavern gas storages. By applying the selection principles of salt-cavern UGSs, we selected and sorted some salt mines in the three major natural gas consumer markets (the Yangtze River Delta, Central–South China, and Southeast Coast of China), and evaluated the conditions of constructing a gas storage in the Huai'an salt mine with better conditions. The following findings were obtained. First, the principles of selecting gas storage sites can be applied to quickly optimize and sort the selected targets, including 6 items of geological factors such as structure, burial depth, salt-bearing layer thickness, NaCl content, top rock, and reserves, and 3 other items such as ground surface conditions, water source and brine, distance from pipeline networks. Second, the evaluation system of UGS construction conditions integrates features of structure and salt-bearing strata, tightness, firmness, dissolubility evaluation, prediction of gas storage scale, and analysis of cavity making condition. In conclusion, the new evaluation technologies can not only effectively guide the site selection and evaluation of salt-cavern UGSs but provide foundation and power support for their scheme designs, and the presented pilot proposal for utilizing thick interlayers has achieved a perfect on-site application effect. This study is of great significance for constructing UGSs in China.