Capacity expansion method for reconstructing salt cavern into energy storage library

The invention relates to a capacity expansion method of an energy storage reservoir reconstructed from a salt cavern. The capacity expansion method comprises the following steps: designing a directional well, drilling and completing the well according to the design, discharging soluble salt, discharging brine and carrying out an air tightness test. According to the method, residual brine among salt mining residues in a salt cavern can be effectively discharged by drilling a new well to the bottom of the salt cavern, so that gaps among the salt mining residues can be effectively expanded, and the underground energy storage space is expanded; soluble salt is repeatedly washed and carried through clear water, the soluble salt is discharged to the ground, gaps between salt mining residues can be further enlarged, and the underground energy storage space is further expanded. The problem that the bottom space of the salt cavern cannot be utilized due to the fact that residual brine at the bottom of the salt cavern