There are large numbers of brine-extracted caverns which can be reconstructed as the nature gas storage in the exploited salt mine.

In order to speed up the construction of gas storage in the Yangtze River Delta and guarantee the stable operation of long-distance gas pipeline in the project of transporting gas from the west to the east,the institute studies the feasibility of 15 brine-extracted caverns in the chosen site.

To build gas storage on the basis of development and utilization of the formed old salt cavern in salt mine is a kind of fast and effective technique (except for accelerating the construction of the new cavern).

Bypassing the cavity bottom of Chang 5# Well,bore hole of Chang 5# Well successfully butts old cavity of Chang 1# Well and realizes brine extraction,which enhances the output and quality of brine by a large margin and increase ore recovery rate.

In drilling of directional-butted brine extraction well,saturated brine(edible salt)is not only the important guarantee for increasing the extraction rate of rock salt core and ensuring the quality of well struc-ture but also the safeguard against drilling accident in well caused by the oversize diameter in rock salt stra-tum.

During the operation of the salt cavern gas storage, the salt bed around the salt cavern will generate variation of stresses because of strata pressure and internal pressures of the salt caverns.

With the development of Gas Transmitting From West to East Project and natural gas industry,large numbers of gas storage will be built in China,so it is important to analyze the stability of salt cavern.