Gas seep linked to nearby drilling
GSPI News Editor
Gas found seeping up along West Divide Creek south of Silt is probably coming from the same geological formation being drilled in the area, investigators have found.
Also, state regulators disclosed Monday that they were already working with the EnCana oil and gas company to rectify problems with two nearby wells when the seeping problem was discovered.
EnCana reported Monday at a meeting of Garfield County Commissioners that tests of area drinking wells so far show no detectable levels of benzene, toluene, xylene or ethylbenzene. But the company has committed to continue providing drinking water or filtering for residents and livestock in the area.
Colorado Oil and Gas Conservation Commission staff have found significant levels of benzene, which is a carcinogen, and nondangerous amounts of toluene and xylene at the seep site.
EnCana on Monday placed some charcoal-activated booms in the seep area to try to absorb the contaminants from the water.
COGCC staff members collected gas from the half-mile-long seep site and sent it to a lab in Illinois for stable isotope analysis, a sort of fingerprinting of the gas, said Debbie Baldwin, the COGCC’s environmental supervisor. That analysis found a close chemical match between the seeping gas and Williams Fork formation gas tapped by four nearby gas wells.
“This is not biological gas seeping up,” said Baldwin, referring to gas created by decomposition of organic matter.
Nor does it appear to be coming from the Wasatch geological formation. Testing is revealing that the Wasatch formation contributes to low levels of methane gas in drinking water in the area, but that gas isn’t associated with drilling projects.
Jaime Adkins, area engineer for the COGCC, said Monday the nearby Schwartz and Brown wells had not been cemented successfully, and the state was working with EnCana on getting the situation rectified before the state agency first learned of the seepage April 1.
After drilling gas wells, crews inject cement between the well casing and the outside of the hole to seal off the gap between them.
After EnCana was unable to cement off the two wells according to state permit requirements, it asked the COGCC for permission to conduct remedial work. Adkins approved it, but it wasn’t completed before the seepage occurred.
EnCana has since finished the work. However, Adkins said if the wells are the source of the gas, it could take several weeks before the seepage stops, given the distance the gas would have to travel between the wells and the seep.
Adkins said the problems EnCana had with the two wells don’t exist with most wells, and there’s little evidence of seepage associated with drilling in western Garfield County, which is focused on the Williams Fork formation found 6,000 feet underground.
“The conditions that existed surrounding this site do not exist everywhere,” he said. “This isn’t business as usual, and it wasn’t before we had any bubbles.”
Prior to discovery of the seepage, EnCana was already testing other water wells near its Garfield County drilling operations to establish baseline data for use by the COGCC.
EnCana spokesman Walt Lowry said the company also is testing water wells when it drills new gas wells.
Despite the cementing problems with the two gas wells, investigators have yet to conclusively determine the source of the seepage.
“Connecting all the dots is what we’re working on, and we may or may not be successful in doing that,” Adkins said.
Baldwin said investigators can’t trace gas back to specific wells through isotope testing.
If the leak can’t be traced, stopping it could be difficult, Adkins said.
Baldwin said investigators need to determine if the gas is traveling through a natural fracture, or up through a well bore, and possibly into a fracture near the surface.
Baldwin said the methane gas in the seep is not toxic in itself, but in high enough concentrations can suffocate and kill vegetation by displacing oxygen.
However, the discovery of the benzene caused the COGCC to immediately notify residents not to use wells for drinking, said COGCC deputy director Brian Macke.
He added, “It wouldn’t be advisable to water livestock from the creek water, at least with the level of contaminants that were found.”
The COGCC has had several calls from residents for water testing since the seepage was reported, and provides such testing when asked.
Nancy Jacobsen, who lives near the seep site, worries about other seepage that might be occurring in the area that isn’t evident because it isn’t coming up in what little water can be found in the area.
“I don’t want to get cancer in 15 years from benzene,” she said.
Macke said EnCana will conduct soil gas surveys as part of its proposed plan of action related to the seep.
Said Lowry, “We’re very concerned about the problem, obviously.”
He said EnCana would like to find the source of the seepage. In the meantime, it has stopped all drilling and drill completion operations within a two-mile radius of the seep, except remedial work or efforts to identify the source of the gas.
It also is testing 15 wells and two springs, and plans to continue doing so on a weekly basis at first, and then a monthly basis.
EnCana also plans to continue testing affected stream water, both upstream and downstream. And, it has offered to install barricades to keep wildlife away from the seep area.
Macke praised EnCana for its response to the discovery of the seep.
“They’ve been proactive and very cooperative in working through the situation with us,” he said.
He said the COGCC requires companies to develop a plan to address such problems, and EnCana began working on its plan before being asked.
The COGCC is continuing to review that plan, he said.
Jacobsen is less impressed with EnCana. She said a year ago, an EnCana officials promised county residents that such seepage wouldn’t occur.
She noted that EnCana faces no bonding requirement to cover such circumstances.
“There’s nothing in place to mitigate if this is in my well,” she said.
She doesn’t believe the gas has gotten into the well at her home, but said she wants ongoing testing to be sure.
County Commissioner Tresi Houpt shared Jacobsen’s concern over the seepage, and urged EnCana and COGCC officials to try to learn from the incident.
“This is the type of thing that homeowners for several years have been concerned about having happen. We have to figure out what we can do to keep this from happening,” Houpt said.
Contact Dennis Webb: 945-8515, ext. 516
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