Study on stability and economic evaluation of two-well-vertical salt cavern energy storage

In order to take advantage of the special layered salt rock in China, the idea of using two-well-vertical (TWV) to construct cavern was put forward, and it has been applied in some salt mines. However, at present, there is still a lack of in-depth research on the two factors that greatly affect the stability of the TWV cavern: the roof shape and working conditions. In addition, there is still a lack of targeted research on the economic rationality of con-structing caverns by TWV. Therefore, in this study, based on the cavern shape of the TWV method, salt cavern underground gas storage (UGS) model with buried depth of 1130 m was established, and numerical simulation research was conducted under different roof shapes and injection-production (IP) frequency. The simulation results show that the roof bulge will produce large deformation and is a potential unstable area. When the IP frequency increases, the risk of instability will increase to some extent. In addition, the design under different working conditions is optimized and the IP frequency and the minimum operation internal pressure (Pmin) suitable for different well spacing are put forward. Then, based on the discounted cash flow (DCF) method, the economic analysis of the proposed TWV salt cavern construction project was carried out. The internal rate of return (IRR), financial net present value, investment payback period and storage and transfer fee are evaluated, and the break-even point of the project was analyzed. Comprehensive research shows that it is feasible to use the TWV method to construct salt cavern in China.

Automated summary

Based on the application of the two-well-vertical method in China, this study conducted numerical simulation research on the influence of roof shape and working conditions on the stability of salt caverns. The optimized design parameters and economic analysis showed that using the two-well-vertical method to construct salt caverns in China is feasible.