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About Solution-Mined Caverns


Solution-mined caverns in salt are low-cost, large-volume storage facilities used for chemical feedstock. Caverns are also created when salt is dissolved to produce NaCl brine for drilling mud and other applications. Recently, solution-mined caverns have been used for disposal of oil-field wastes. Basic descriptive information on the geometry of salt is needed to site and regulate the development, use, and decommissioning of these facilities.

In Texas, 648 solution-mined caverns are currently licensed, with about 200 in bedded salt areas (Seni and others, 1995). Storage caverns are used by the chemical and petrochemical industry for storage of product and chemical feedstock. Exploration for sites for cavern development continues, with emphasis on locating suitable salt near facilities such as pipelines and industrial users. Other caverns have been created only to extract brine used by drilling and chemical industries. In addition, three salt caverns have been licensed for subsurface disposal of oil-production waste in the Midland Basin. Current regulation in Texas does not permit underground disposal of other types of industrial waste.

Salt is a unique host material for cavern development because its solubility in water permits low-cost, highly flexible, and rapid creation of caverns. Brine resulting from the mining can be sold as a product. Salt has very low permeability, making it an ideal medium for containment of stored materials. Preservation of soluble bedded salt over geologic time demonstrates the relatively inactive hydrologic setting, so that if material should leak from the cavern, transport away from the facility would generally be slow.

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Geology of Salt