State health officials said Monday that oil, natural gas and water that spilled into a lined pit after a weekend rupture at a North Dakota oil well had been contained.
Crews were working Monday to stop the leak at the Whiting Petroleum Corp. well about eight miles northwest of New Town. The well was shut down after a valve near the wellhead failed on Saturday, causing the leak, said Jack Ekstrom, a spokesman for the Denver-based company.
"The thing has calmed down," Ekstrom said Monday. "There's no guarantees obviously, but we think it will be over by the end of today."
Ekstrom said the liquids are totally contained and being hauled to a disposal facility. The leak has caused no environmental damage, he said.
North Dakota Health Department officials confirmed that all of the liquid was held within the site, with the help of some temporary dike work.
"It's all good news," said Dennis Fewless, director of water quality for the state Health Department.
Workers were evacuated from the remote site on Saturday, company officials said. There were no injuries reported.
About 50 to 70 barrels of fluid per hour was flowing into the pit immediately after the failure, but that rate had declined by 75 percent by Monday morning, Ekstrom said. The fluid was 90 percent water and 10 percent oil and natural gas, he said. About 5,630 barrels of water and 420 barrels of oil had been hauled from the site by early Monday.
Officials have not determined what caused the wellhead to fail, Ekstrom said.
"We haven't been able to get close enough yet to say anything, other than it failed," he said. "It may have ruptured, it may have broken. All we can say now is that it was somehow demised."
Whiting Petroleum operates wells in several states, including North Dakota, Oklahoma and Texas. Its largest projects are in the Bakken and Three Forks-Sanish formations in western North Dakota, company officials said.
The well, known by the company as Roggenbuck 14-25H, uses horizontal drilling and hydraulic fracturing, a process that breaks open oil-bearing rock with pressurized fluid and sand.
"It is a typical Bakken and Sanish field well. We have drilled in excess of 80 or 90 of these," Ekstrom said.