Feasibility analysis of a single-well retreating horizontal cavern for natural gas storage in bedded salt rock

Abstract

Compared with vertical storage, horizontal storage in bedded salt rock deposits is reasonable and scientific for large-capacity gas storage and for avoiding the risk of interlayer and interfacial oil and gas leaks. The single-well retreating horizontal (SWRH) leaching method is introduced in this paper. After calculating similarity ratios, a physical similarity simulation experiment was conducted for inferring the cavern shape. A numerical model was developed based on the inferred cavern shape, and the stability of the SWRH cavern was analysed. Reasonable values of the cycle frequency and the roof and floor salt layers’ thicknesses were determined. The effects of the pillar width and asynchronous internal gas pressure between adjacent caverns were analysed. The results show that the SWRH cavern satisfies the safety requirements of bedded salt rock districts over the entire design lifetime. A cyclic frequency that is too low and asynchronous internal gas pressure are not conducive to the stability and reliability of the cavern. To ensure stability, the thicknesses of the roof and floor salt rock layers of the horizontal cavern should exceed 16 m and 6 m, respectively. This study opens new vistas for constructing horizontal gas-storage systems in bedded salt rock.