Salt caverns have good stability and air-tightness

and thus are ideal places for storage of natural gas

oil

hydrogen

etc. The oil blanket used in the conventional salt caverns created by solution mining has problems such as poor dissolution inhibition effect and heavy oil contamination

which cannot meet the requirements of green mine construction. As a substitute

gas blanket has attracted much attention. However

its application is hindered due to great difficulty in control

and the complex geological conditions of salt rock strata in China. To this end

the characteristics of gas blanket control at different cavern construction stages were analyzed first

and then the methods for predicting the thickness of gas blanket and calculating the gas injection amount at different stages were proposed based on the analysis of the pressure balance at the gas-liquid interface. Combined with an example of a well in the groove construction period

the recommended thickness of gas blanket and its fluctuation range were given

and the variation law of the gas blanket thickness and the gas injection amount with the cavern construction progress was proved. Finally

the key problems related to the application of gas blanket were discussed. The results showed that the gas blanket thickness is mainly controlled during the groove construction and roof formation periods

and the gas-liquid interface position is mainly controlled during the cavern construction and cavern repair periods. It is suggested that the average gas blanket thickness during the groove construction period should not be less than 0.3 m. The thickness of gas blanket fluctuates rapidly at the beginning of the groove construction period

and thus a larger gas blanket thickness should be set up and the nitrogen should be replenished in time. Then the gas blanket thickness tends to be stable

and the gas replenishment interval can be gradually extended. With the increase of cavern construction time

the single gas replenishment volume becomes larger and larger

and the cumulative gas replenishment volume increases linearly as a whole. During cavern construction

the wellhead gas pressure and the gas pressure at the gas-liquid interface increase first and then decrease linearly

and the wellhead gas pressure change shall be monitored in real time. The cost of gas blanket is close to that of oil blanket

but the environmental benefits are significant

and the discharged nitrogen and wellhead gas injection facilities can be reused to save costs. The position of gas-liquid interface should be monitored on site in real time by combining optical fiber monitoring and neutron logging.