EDITOR’S NOTE: This story was updated at 11:56 a.m. Friday April 27, 2012.
Natural gas is no longer venting from the Combs Ranch Unit 29-33-70 1H well north of Douglas as of 11:05 a.m. today (Friday), according to a state official.
Well control specialists Boots & Coots and oilfield services company Halliburton had initiated well-plugging efforts at 9:25 a.m. today at the Chesapeake Energy (NYSE:CHK) drilling location 10 miles north of Douglas, according to the Wyoming Oil and Gas Conservation Commission (WOGCC). The well had been venting gas since a blowout on Tuesday afternoon.
Chesapeake is one of several operators testing the Niobrara and other deep formations in the southern Powder River Basin for shale oil potential. The rig is owned by Canadian-based Trinidad Drilling (TSX:TDG).
“At 11:05 am April 27 OGCC field inspector reported that pumping of drilling mud continues into the Combs Ranch well and that the natural gas venting to the atmosphere as ceased, approximately 68 hours after the loss of well control and venting of natural gas occurred,” commission supervisor Tom Doll said in a prepared statement this morning. ” I will get another report before 2:00 pm today confirming the time venting ceased and the duration. It is expected by then that the well capacity should be filled with drilling mud.”
No workers were injured in Tuesday’s blowout, according to company officials. The incident occurred at about 4 p.m. Tuesday as a crew was installing steel casing. Venting occurred at the mouth of the well below the rig. According to Chesapeake, the well also spewed oil-based drilling mud, which is mostly contained on location.
Well control specialists Boots & Coots (a division of Halliburton) was on location and prepared to implement plugging operations on Thursday morning, but had to delay the operation due to variable wind conditions that day, Chesapeake spokeswoman Kelsey Campbell told WyoFile. No local fire crews are on hand, said Converse County Emergency Management coordinator Russ Dalgarn, because Boots & Coots is prepared to fight a fire if there is an ignition.
Approximately 50 of the 70 residents living within a 2.5 mile radius of the Chesapeake well had voluntarily evacuated their homes on Tuesday evening. Some have returned to their homes since, however. Campbell said on Thursday that the company was still offering to pay for evacuees to stay at local hotels.
Random air quality testing — performed by Chesapeake — within the 2.5 mile radius of the venting well indicates no human health risk, according to Campbell. She said Chesapeake called for the voluntary evacuation out of an abundance of caution.
Chesapeake officials are not saying how much gas vented from the well or what constituents — besides natural gas — were vented.
A spokesman for the Wyoming Department of Environmental Quality (DEQ) said the agency stands ready to help conduct air quality monitoring in the area if requested by Chesapeake, but so far DEQ is relying on Chesapeake to provide most all information about the blowout. According to state officials, primary jurisdiction of the well blowout response lies with the Wyoming Oil and Gas Conservation Commission.
Doll had said that the rate of venting from the well is yet to be determined. Public health officials are relying on the commission and Chesapeake itself for any information.
“At this time, we do not have specific information on that blowout near Douglas regarding emissions,” Wyoming Department of Health spokeswoman Kim Deti told WyoFile via email on Thursday. “We wouldn’t expect to have such information unless the agencies responsible for monitoring indicate to us that a public health problem may exist due to emissions. We are aware of the situation and have been in contact with local health representatives. As always, we will watch for evidence of a public health concern.”
The last major well blowout in Wyoming was in August 2006 in the Line Creek subdivision near the tiny town of Clark in northern Wyoming. Gas escaped a wellbore and migrated through the ground and vented at the surface at a distance away from the drilling rig. That blowout forced the evacuation of approximately 25 nearby residents. The well, owned by Windsor Energy Group LLC, vented for several days before it was successfully plugged.
According to a follow-up investigation, the Crosby 25-3 gas well blowout spewed an estimated 97 tons of volatile organic compounds, 2 tons of benzene, toluene, ethyl benzene, xylene, 101 tons of methane (a potent greenhouse gas), and 43 tons of ethane.
Deb Thomas was one of the residents who had to evacuate her home because of the Crosby well blowout in 2006. Thomas is now coordinator for the Clark Resource Council.
“Those who are living in close proximity should know what they’re being exposed to,” Thomas told WyoFile. “And anybody with health concerns — asthma or other respiratory difficulties — I would think that it’s important to know what exposures there are.”
Wyoming’s unconventional oil play
Any blowout is extremely dangerous, especially if there’s an ignition. There are occasional “kicks” of gas in the wellbore during the drilling process. But full blowouts are relatively rare in the industry these days.
Jimmy Goolsby is a longtime Wyoming geologist, and managing partner with Casper-based Goolsby, Finley & Associates LLC. He said today’s drilling technology and blowout prevention (BOP) equipment is highly sophisticated.
“I hate to see anyone make it sound as though this sort of thing could happen anytime, anywhere,” Goolsby told WyoFile. “We drill a lot of wells and this doesn’t happen often at all.”
Chesapeake’s Combs Ranch Unit 29-33-70 1H was drilled vertically approximately 11,500 feet, then drilled horizontally for several thousand feet targeting the Niobrara formation, according to WOGCC data.
Although there was a mineral lease rush on the Niobrara in southeast Wyoming two years ago, most of the action to prove up shale oil in the state so far has been in the central-eastern portion of Wyoming known as the southern Powder River Basin. Here, operators are sinking wells into the Mowry, Sussex, Shannon and Niobrara formations.
“You get both oil and gas with these wells in the southern Powder River Basin. One of the reasons the southern Powder River Basin is hot right now is because it’s primarily oil,” said Goolsby. “Most everything we’re drilling in the southern Powder River Basin is what we’re calling over-pressured. So we’re dealing with something that, at one time, was very dangerous.”
However, the pressures that operators must control are not out of the ordinary, said Goolsby. The industry has managed higher pressures in formations in the Wind River Basin for decades, for example.
Goolsby said that it’s normal for wells in the southern Powder River Basin to flow with natural gas after first being drilled. It isn’t until hydraulic fracturing — or “fracking — and other completion techniques are performed that oil begins to flow in larger volumes.
Contact Dustin Bleizeffer at 307-577-6069 or firstname.lastname@example.org.
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