CHEYENNE, Wyo. (AP) -- A gas blowout prompted more than 60 residents to evacuate their homes by Wednesday amid fear of an explosion at an oil well being drilled into the Niobrara Shale formation in Wyoming.
Natural gas began spewing into the air Tuesday from the well about 10 miles northeast of the town of Douglas. Witnesses told television station KCWY-TV that the roar of escaping gas could be heard six miles away.
Authorities were concerned about the possibility of an explosion or fire before the spewing gas could be plugged. No workers were injured.
"I'm hoping this thing doesn't catch on fire because they have a good chance of salvaging the rig and the well bore," said Tom Doll, supervisor of the Wyoming Oil and Gas Conservation Commission, which oversees oil and gas drilling in the state.
The rate of gas leaking was diminishing Wednesday and officials were optimistic that workers with the Houston-based well control company Boots & Coots might soon be able to plug the well with drilling mud, Doll said.
Air samples around the well were normal but the company asked about 80 residents who live within 2.5 miles to voluntarily evacuate, said officials of the Chesapeake well.
"We have our specialized equipment in there," company spokeswoman Kelsey Campbell said. "They are in there are working to contain the well."
The leak occurred after the well had been drilled and while steel casing was being installed down the well hole. Oil-based drilling mud spewed from the ground, along with the gas, but was mostly being contained to the drilling site, according to Chesapeake.
An oil and gas commission inspector happened to be at Trinidad 223 rig hours before the blowout occurred.
"If there was something that was odd in terms of the activity, he would have known about it," Doll said. "There was nothing going on outside of the normal routine."
The Niobrara Shale is a deep oil-bearing formation beneath eastern Wyoming, northeastern Colorado and western Nebraska where drilling has increased over the past two years.
The Chesapeake well had been drilled to its full depth and length of close to 18,000 feet vertically and horizontally, Doll said.