Method of rapidly abandoning large, cavities washed-out in rock salt

Abstract From the Canadian patent

After they have been washed out cavities (4) in rock salt, contain a large quantity of brine (8) at a temperature which is lower than the temperature of the surrounding formation (2). This means that the cavity cannot be sealed quickly because the brine will expand progressively as it heats up. The method of the invention serves to shorten the time period between the end of working the cavity for salt and being able to abandon the cavity finally from about 30 years to about 2 years. The method consists in injecting quantities of a mixture (12) into the cavity (4), the mixture being of greater density than brine (8) and being capable of setting, with equivalent quantities of brine (8) being …