CHEYENNE, Wyo. (AP) - Workers at a blown oil well in eastern Wyoming took advantage of changing winds Friday to plug the well with mud and end a powerful, three-day eruption of potentially explosive natural gas.
The operation to stem the air pollution - not to mention the risk of an explosion at a multimillion-dollar drilling rig - began at about 9:30 a.m. By 11 a.m. the flow of gas had stopped, according to Tom Doll, supervisor of the Wyoming Oil and Gas Conservation Commission.
Workers continued to pump mud down the well throughout the day but were wrapping up toward the evening. Meanwhile, cleanup of spilled oil-based drilling mud got under way.
The well belonged to Oklahoma City-based Chesapeake Energy. It just recently was drilled and extended more than three miles vertically and horizontally under the rolling prairie.
Houston-based well control company Boots & Coots and parent company Halliburton pumped mud down the well bore through steel lines.
The blowout happened Tuesday afternoon. Methane gas roared from the ground at the drilling site five miles northeast of Douglas, population 6,100. The nearest home is over a mile away.
The blowout pushed drilling mud to the surface, and clouds of gas blurred the horizon. Authorities issued an evacuation advisory to 67 people in homes within two and a half miles of the well, and 50 people heeded it.
Nobody was hurt.
Fickle winds delayed work to bring the well under control. Workers staged equipment near the well Wednesday, but the shifting winds blew gas over the equipment that night. Wind patterns remained unfavorable Thursday.
On Friday, westerly winds enabled workers to re-approach the well.
The blowout happened as crews installed steel casing into the well, which had been drilled to a vertical and horizontal distance of almost 18,000 feet. The well targeted the Niobrara Shale underlying eastern Wyoming, northern Colorado and western Nebraska.
Drilling into the Niobrara has picked up over the past couple of years by companies using the latest methods for horizontal drilling and hydraulic fracturing. Hydraulic fracturing, or fracking, involves pumping large amounts of pressurized water mixed with fine sand and chemicals into wells to create fractures.
Nearly all new oil wells in Wyoming are fracked, but fracking had not yet taken place at the Chesapeake well.