No salt domes in Oklahoma. They're all along the Gulf Coast -- TX, Louisiana, MS, AL. The salt in the mid-continent is called "bedded salt" and exists in stratas interspersed with other minerals--not used for storage.
http://www.solutionmining.org/cmsFiles/Files/BriefHistory.pdf
FYI: there was a incident in Brad, TX on Friday @ 0200 that is similar but maybe different.
On Thursday, a drilling rig hit an unexpected gas pocket. The excessive gas was burned off until a heavier drilling mud was pumped into the hole to kill the well. As they were testing the new zone, gas begain to erupt from the ground away from the rig (a hundred yards or so). Around 2 am Friday morning the gas exploded a few hundred yards from the rig and blew a hole over a hundreds yards across and 60 feet deep. As of this morning, gas is still burning in the crater.
Speculation is that when the gas pocket as hit, gas had flown into a oil zone that was tapped back in the 20's or 30's and filled this zone. When the well was killed, weight required to kill the well was well below the older zone and continued to build up. They guess that rocks banging into each other caused heat/sparks to ignite the gas.
Many wells from the 20's or so were not properly cemented & cased and even worse when they were plugged IF they were plugged. Some were just capped at the top of the casing. Gas can easily migrate through the old bore and out on the ground.
My dad said that there were also some old salt caverns from the 50's in that area that were abandoned. They had been used to store waste gas. Abandoned caverns were supposed to be filled with brine.