Method for expansion of mature brine wells in salt domes

A method for mining a salt dome under the Earth's surface wherein the salt dome includes a mature brine well including an existing casing extending from the surface into an upper cavern, an insoluble deposit at a bottom of the upper cavern, and optionally, a sump for holding the insoluble deposit in whole or in part, the method comprising an initial drilling operation comprising the steps of:

• (1) removing existing seal fluids followed by removing existing hanging strings from the mature brine well;
• (2) determining from past and present sonars the top of, depth of, and volume of the insoluble deposit as it relates to the original total depth of the upper cavern;
• (3) providing a drill casing with a drillable drill bit and sufficient length to penetrate the insoluble deposit and penetrate into a portion of the salt dome which underlies the mature brine well;
• (4) rotating the casing to drill through the insoluble deposit into the portion of the salt dome which underlies the mature brine well;
• (5) providing the drill casing string with seal packer(s) to be placed in the portion of the salt dome which underlies the mature brine well;
• (6) replenishing seal fluid in the upper cavern through the drill casing and then setting the packers;
• (7) passing a drill bit on a second drill string through the drill casing to a bottom end of the drill casing;
• (8) drilling through the drillable drill bit into the portion of the salt dome which underlies the mature brine well;
• (9) drilling into the portion of the salt dome which underlies the mature brine well to a pre-determined total depth (“TD”);
• and
• (10) mining the salt at the TD to form a lower salt cavern.