CASPER, Wyo. (AP) — Wyoming's top oil and gas regulator says the companies involved in a natural gas well blowout in eastern Wyoming last month won't face any fines.

Tom Doll, the state's oil and gas supervisor, tells the Casper Star-Tribune (http://bit.ly/Jb52hC ) that well owner Chesapeake Energy Corp. and drill rig owner Trinidad Drilling Ltd. won't be cited for the blowout. The mishap vented up to 2 million cubic feet of explosive gas and 31,500 gallons of drilling fluid into the air and around the drill site near Douglas.

Doll says it appears a pin that is meant to hold a key gasket tight within the well head was loose. But such mistakes aren't really addressed in state rules, even though they're costly to the companies involved and potentially dangerous to the environment and nearby residents.