KILLDEER, N.D. - Support crews were able to "kill" a breached oil well 2½ miles southwest of Killdeer on Thursday afternoon following a blowout Wednesday morning, and officials say water sources are currently not in danger.
A similar instance with a related company took place nearly two years ago, prompting a tightening of state restrictions.
During a hydraulic fracturing phase - a process using intense pressure and fluids to break through rock to reach oil - a mechanical failure caused a breach in the oil well's casing.
The pressure blew through two steel pipes surrounded by cement and oil, gas and liquids began erupting from the well head.
After support crews reached the bottom of the oil well with coil tubing at about 3:30 p.m. Thursday, they began pumping cement to permanently plug the well, said Lynn Helms, director of the state Department of Mineral Resources.
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"The well is completely dead ... we are very happy to be at that stage of things," Helms said.
When the oil well was drilled, it intersected the Killdeer aquifer, and it is still unknown at what depth the well casing breach occurred.
Officials hope to know by today.
"We thought we might bump into it when we were running this tubing in the well, but we did not," Helms said.
Based on the well's activity, it is believed the breach occurred "well above 300 feet," Helms said.
Hydraulic fracturing fluid contained about 10 chemicals, some of which are toxic in pure form, but the concentrations in which they were being pumped were not, Helms said.
Dennis Fewless, director of the Department of Health's water quality division, said officials do not see any immediate concern for those using the aquifer, including the city of Killdeer.
Fewless said aquifer mapping shows a division at the oil well location, where it then flows south.
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Andrew Nygren, hydrologist at the state water commission, said the aquifer north of Highway 200 flows toward Killdeer, naturally discharging in Spring Creek.
Northwest of Killdeer the aquifer flows southeast from the Killdeer Mountains.
The aquifer's location south of Highway 200 flows into Lake Ilo.
"The movement of water in groundwater systems is much slower than in surface water systems," Nygren said in an e-mail. "Natural flow rates of ground water in the Killdeer aquifer are probably on the order of 10 to 15 feet per year."
Officials will work with the oil company and its consultants in drilling more monitoring wells to keep track of any movement off the site, Fewless said.
To check the aquifer's present water quality and obtain baseline data, the state health department was collecting samples from individual area farm wells, two Killdeer city wells, and industrial and state water commission monitoring wells on Thursday, Fewless said.
The samples were sent to Bismarck and will undergo a broad range of tests slated to commence today, he added.
"Once the site is stabilized, we will be evaluating the soil where they were containing the oil and saltwater on site," Fewless said. "That will be determined how much of that needs to be removed."
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Dunn County has experienced a similar oil well incident in the past.
The breached and now plugged well, dubbed Franchuk 44-20, is operated by Encore Operating LP, according to the North Dakota Oil and Gas Division's website.
Denbury Resources Inc. purchased Encore earlier this year, said Ryan Jacob, Denbury HSE field operations manager who was on-site Wednesday.
Encore operated a well in Dunn County in November 2008, and while Helms says the company did not violate regulations, the well "worried" the state's oil and gas division enough to result in new rules, he said.
"We had not required that they pressure test the casing before they pump the frac job," Helms said.
This week's incident may prompt further review.
"We will certainly sit down after we've got the remediation under way and take a look at our rules and see if we need to make some changes," Helms said.
Lisa Call writes for The Dickinson Press
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