Comprehensive feasibility study of two-well-horizontal caverns for natural gas storage in thinly-bedded salt rocks in China

Underground salt caverns provide ideal space for large-scale natural gas storage. But the current practice of constructing single-well-vertical (SWV) caverns encounter serious problems in the thinly-bedded salt rocks in China. Instead, two-well-horizontal (TWH) caverns are proposed to serve as a possible alternative for gas storage facilities. Therefore the comprehensive feasibility of the TWH-caverns as gas storage were thoroughly evaluated. First, the frame-work and criteria of feasibility evaluation of gas storage salt caverns were determined. Then the construction process and shapes of TWH-cavern were determined by physical simulation tests, and an optimum cavern shape was obtained by numerical simulation. Thirdly, the effects of mudstone interbeds, cyclic operating modes on the serviceability and safety of TWH-cavern were investigated. The cavern tightness was discussed as well. In the end, a feasibility comparison between a TWH-cavern and a SWV-cavern was made, which shows that TWH-cavern possesses better safety, higher flexibility and lower cost than SWV-cavern. Comprehensive results show that the TWH-caverns have high feasibility as gas storage in thinly-bedded salt rocks.