At several times in the geologic past, thick layers of rock salt have formed in various basins of the world, including the North Sea, northwestern Germany, and along the shores of the Caspian Sea in southern Russia. Once buried, the salt becomes bouyant and begins to move upwards through much denser sediments, forming large pillars and domes of salt. Of all the world's salt basins, perhaps the most spectacular array of salt structures occurs along the U.S. Gulf Coast.

The salt domes of Louisiana and Texas provide excellent opportunities for natural gas storage. The location allows excess production to be stored near the points of supply.  To produce storage facilities, operators leach caverns in the salt structures.  Although these caverns are of modest size, gas can be injected into and withdrawn from the field at very high rates because the gas does not have to travel through the tortuous passageways of a rock matrix.

One prime concern in salt cavern storage is preserving the structural integrity of the cavern. Each cavern must reserve a minimum gas volume that serves to support the structure. Removal of too much gas can lead to collapse.  A  study of improved salt cavern design, sponsored by NETL, indicated that minimum pressures in most existing salt cavern storage facilities could be lowered by 10% without compromising cavern stability. Extrapolating these results across the industry could potentially result in a 17 billion cubic foot increase in working gas capacities, with no changes to existing infrastructure.

In the northeastern U.S., subsurface salt deposits are too thin to have formed mobile intrusive structures. Storage in these bedded salts is possible, but currently not economic due to the high costs of disposing of the leached brine. NETL is looking at ways to encourage industry investment in northeastern salt storage by chilling the gas to temperatures of –20^oF (–29^oC) before injection. Chilled gas allows operators to dramatically reduce the size of the cavern needed (and the amount of brine to be handled) without sacrificing stored gas volume. Ongoing work will test the impacts that this chilling would have on the structure and stability of the salt itself.