Construction simulating and controlling of the two-well-vertical(TWV) salt caverns with gas blanket

Abstract

The two-well-vertical (TWV) cavern-constructing with gas blanket technology is an important alternative to the single-well (SW) with oil blanket technology. This technology has the advantages of achieving larger cavern volume, clean brine, great water flow rate, and high economic benefits. Promoting and developing its theory and technology will help the future development of salt mining and cavern construction for energy storage in China, as it is in the initial stage. In this paper, a visualized physical simulation platform of water dissolving of the TWV caverns with gas blanket was established, and large size salt rock blocks were used to simulate the constructing process of salt caverns. The similarity ratios of size, flow rate, and time between prototype and model were calculated by using the similarity theory and dimensional analysis. A series of physical simulation tests of water-dissolving caverns were carried out, that the research factors including the two-well-spacing, flow rate, and gas/oil blanket. The results show that: (1) The water flow rate can be increased to 200–400 m3/h by increasing the two-well-spacing when using the TWV technology, which is 2–4 times that of the single-well. (2) It is found that 30–40 m is the optimal size for the two-well-spacing, and the two-well-space is much larger than 40 m may exist risks of roof instability. (3) During the initial stage of cavern construction, it will obtain a smaller lateral solution angle and an ideal cavern bottom groove shape with gas blanket. After the cavern construction is finished, it also will obtain better cavern shape, larger cavern volume and clean brine by comparing with oil blanket. So, the technology of the TWV cavern construction with gas blanket is promising for brine leaching and energy storage cavern construction and it is also worth further study.