Water wells near natural-gas drilling sites in eastern states are being tainted by methane linked to the drilling, a Duke University study has found.
The study, however, did not find a direct link between the water wells and the industry process of hydrofracturing, which has been targeted by some environmental groups and lawmakers.
Almost every well drilled in Colorado is “fracked,” and the process is being widely used in new oil exploration on the Front Range.
Dave Neslin, director of the Colorado Oil and Gas Commission, said he is reviewing the Duke study.
The Duke researchers found elevated levels of methane in 60 of 68 water wells sampled in five counties in Pennsylvania and New York — where a drilling boom is underway in the Marcellus shale formation.
“The frequency was the big surprise,” said Robert Jackson, director of Duke’s Center on Global Change. “We just didn’t expect to find that many wells impacted.”
Methane is not known to be toxic, but in high concentrations it can be explosive.
Industry representatives faulted the study for not having water samples before drilling occurred for comparison and for the wide area the sampling covered.
“I’m not sure you can take 68 wells over a very broad geographic area and make any statistical conclusion,” said John Conrad, a geologist who has worked for the industry.
The researchers were, however, able to document that 21 of 26 wells near active drilling sites were tainted with a type of methane that is associated with drilling and does not occur naturally.
Wells closer to drilling had higher methane concentrations.
The study found no traces of fracking fluid in the wells. The fluids — which contain trace chemicals that may be toxic — are injected into the well under pressure to fracture rock and release gas.
“The lack of fracking fluid in the wells is good news,” Jackson said.
The methane may have escaped from faulty well casings or poor cement jobs, Jackson said. The study was published Monday in the Proceedings of the National Academy of Sciences.
The Duke researchers called for tighter regulation of wells and fracking fluids.
Sherry Vargson’s water well in Bradford County, Pa., had the highest levels of methane in the study. The bubbles of methane made the water look like Alka-Seltzer was coming out of the tap, she said.
Chesapeake Energy Corp. is delivering bottled water to her house.
“I still think it can be done safely, but there are too many shortcuts being taken,” Vargson said.
Denver Post wire services contributed to this report.
Mark Jaffe: 303-954-1912 or mjaffe@denverpost.com
