A new source of pollution is escaping from all Bakken oil sites and regulators and operators are trying to figure out how much and what to do about it.
Lynn Helms, director of the state's Department of Mineral Resources, said the Bakken-only situation does have serious environmental implications.
The good news is that a solution may come while there are only 1,700 Bakken wells in North Dakota instead of the 10,000 there may be some day, Helms said.
The State Health Department and the Environmental Protection Agency are working with major Bakken producers to accurately measure how many tons of hydrocarbon called "volatile organic compounds," are being emitted, a number that easily could be into the tens of thousands of tons, if not higher.
The situation came to light a few months ago.
Oil producers self-reported the possibility of unusually heavy and unexpected volatile organic compound emissions coming from storage tanks on oil well sites, said Jim Semerad, who manages air quality permitting and compliance for the North Dakota Health Department.
It's assumed the numbers are so low, oil companies aren't even asked to report them on well registration forms.
Semerad said so far, even the worst case numbers haven't raised a red flag for health and ambient air quality standards, in part because wells are spread out over hundreds of square miles.
"The monitoring has been fine," he said.
Because they have wells on Fort Berthold Indian Reservation, Marathon Oil and EOG Resources, notified the federal Environmental Protection Agency that the emissions from one well may exceed 100 tons a year, which requires a federal Title V air quality operating permit.
No Bakken wells have a Title V air quality permit. Only two others do, but for hydrogen sulfide and sulfur, the emissions that smell like rotten eggs.
A VOC number more than 100 tons is generally associated with large processing sites, where a dozen or more oil or natural gas wells are gathered up mid stream, said Josh Rickard, EPA Region 8 enforcement team manager.
"That speaks to how unusual this is. It was a surprise to companies that the potential (to exceed Title V levels from one well) was even there," Rickard said.
Companies also made informal self reports to the health department.
Self-reporting helps companies reduce potential penalties while they take steps to reduce emissions.
The EPA has started formal enforcement against the companies that self-reported. Depending on what it learns, "We would start looking at enforcement across the field," Rickard said.
The state's enforcement process for self-reporting is similar and will lead to requiring VOC emission controls and imposing monetary fines, depending on the severity of the violation, Semerad said.
The vapor - which consists of light hydrocarbons, or "volatile organic compounds" - is emitted from vents on top of the storage tanks, where oil is stabilized after being separated in heater treater equipment from the natural gas that comes up with it.
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The hydrocarbon content is peculiar to Bakken oil.
"Most crudes have very little of these hydrocarbons," Helms said.
The explanation why oil from the Bakken formation and the Three Forks-Sanish - just below it - contains the hydrocarbons could lie in where it comes from.
Helms said the very deep formations are source rocks of oil. Normally, oil migrates from source rocks into pools and the hydrocarbons disappear in the process, he said.
The fix is not all that difficult, or that expensive - ranging from $50,000 to $150,000 per well - compared to the several millions it costs to drill a well.
Semerad said companies will be required to either flare the storage tank emissions, or install capture devices and add the emissions to the natural gas.
He said the department doesn't want to move too fast. If companies find it's economical to divert the VOCs to its natural gas stream, that's preferable to flaring, because it has a conservation effect as opposed to wasting it in a flare, Semerad said.
"It's an odd case. We're not sure how fast we want to move," he said.
Companies have provided VOC data, but results vary widely. Semerad said some consistent means of measuring the emissions will have to be established.
"To date, we don't know how big the exceedence is. When we know what the violation is and how significant it is, we will proceed accordingly, " Semerad said.
Brent Miller is operations manager for Whiting Oil, which has 60 Bakken wells near Parshall.
Miller said the company hired a third party to measure emissions from storage tanks at four wells of different age and production output starting next week.
He said it's important to find the root of the problem.
Miller said his company wants to know if the oil is being thoroughly separated from natural gas in the heater treater phase.
"If we just look at (storage tank) emissions and don't consider the separation issue as well, we could come to the wrong conclusion," he said.
Companies, Whiting included, are installing flare equipment on storage tanks now.
Miller said oil companies are working together. "We want to get our arms around the problem, compare notes and try to solve it quicker, without forcing by the EPA and the State Health Department," he said.
Semerad said his department is working with five major Bakken producers (Whiting, Marathon, EOG, Conoco-Phillips and Hess Corp.) to devise a remedy and will meet with an association of oil and gas producers next month to continue addressing the VOC emissions and measurements.
(Reach reporter Lauren Donovan at 701-784-5511, or email@example.com.)