Influence of well spacing on solution mining of small-spacing dual well in salt cavern gas storages

Abstract

The occurrence of salt rock in China is generally featured with multiple interlayers and thin salt layers, which has many restrictions on the single vertical well method for solution mining. For this reason, a small-spacing dual well solution mining method was proposed to overcome the adverse geological conditions. It is essentially a dual well direct-flow brine displacement method making use of the large-sized solution mining casing to offer fast solution mining rate, short storage construction duration and high utilization rate of salt layer. Specifically, the physical model experiments, under different dual-well spacing and cavity communication modes, were conducted to explore the influence of well spacing on the final shape of cavity. The results show a small horizontal length of cavity, as a result of small well spacing, hinders the full use of the horizontal space. Whereas a larger well spacing can significantly slow down the dissolution of the cavity in the horizontal section, and further result in the irregular cavity shape. Evidently the solution mining method based on precast butted wells can provide a higher cavity-forming rate. In practical dual well solution mining projects, the dual-well spacing should be determined according to the geological conditions and engineering requirements. The research results are expected to provide reference and guidance for the cavity shape design and process parameter optimization of solution mining for small-spacing dual well in salt cavern gas storages.

Keywords

• layered salt rock
• gas storage
• dual-well solution mining
• cavity shape
• solution mining law