Oil and gas industry leaders are pushing back today against an EPA draft report that linked hydraulic fracturing with water contamination in Wyoming by insisting that what happened in that state is light years away from drilling being done in Texas, New York and other parts of the country.
In its draft report yesterday, the Environmental Protection Agency said it had discovered synthetic chemicals associated with gas production and hydraulic fracturing fluids inside deep water wells in Pavillion, Wyo.
It was the first time a federal agency had linked water contamination with the hydraulic fracturing process, which involves blasting mixtures of water, sand and chemicals deep underground to break up dense shale rock and unlock trapped oil and natural gas.
But energy analysts and regulators say the study is fundamentally flawed — making a hypothetical case that contamination can be pinned on fracturing, instead of a causal one. And they stress that the kind of drilling done at the gas field in west central Wyoming is far different than the work happening elsewhere in the U.S.
In Pavillion, fracturing took place both in and below the drinking water aquifer and very close to drinking water wells — conditions that the EPA noted are not common elsewhere. Some of the 169 gas production wells in the area were fractured at points just 1,220 feet below the ground.
By contrast, in South Texas, energy companies are extracting natural gas from the Eagle Ford shale formation at depths ranging from 4,000 to 14,000 feet below the surface. In that region, the gas-rich shale is separated from the aquifers above it by thousands of feet of dense rock.
That’s true in other parts of the country, too.
Nationwide, most shale formations are far deeper than aquifers that typically contain potable water only to depths of about 600 to 700 feet. For instance, the gas-producing zone of the Barnett shale lies at around 8,000 feet. In the Marcellus shale that stretches across Pennsylvania and New York, the gas-rich region is generally 6,500 feet down.
Analysts at the Houston-based energy investment bank Tudor Pickering Holt stressed that “the proximity of gas zones to the aquifer” in Pavillion, Wyo., is “not common in modern plays.” And they noted that the Wyoming drilling was a “unique situation” with the gas reservoir just below the fresh water aquifer.
The issues there likely stem from surface casing in wells not being set deep enough and therefore not extending throughout the aquifer that extended down at least 250 feet in Pavillion, said TPH analyst Dave Pursell. Casing, meanwhile, was typically set at just 150 to 175 feet, leaving some of the well surface inadequately isolated from the aquifer.
These aren’t “best practices,” Pursell said. “I can’t defend a shallow well that doesn’t have surface casing across an aquifer zone. That is a level of protection that is critical to drinking water, particularly in an instance where you know the reservoir is in close proximity to the aquifer.”
The risk is that “if you have a leak in your production casing, you’ve created an avenue for communication between the reservoir and the aquifer,” Pursell noted.
If the possible contamination in Wyoming is ultimately traced back to poor well design and inadequate casing, it could spur industry to speed up its development of new and better standards governing those issues, Pursell said.
Kevin Book, an analyst with ClearView Energy in Washington, D.C., predicted that gas producers and oilfield service companies will continue to highlight how well design and fracturing techniques vary from state to state.
“Well designs vary with basin characteristics,” Book noted, “and the important question is whether a well provides a sufficient barrier between a hydrocarbon bearing formation and surrounding water resources.”
Regulators and producers in Texas already are highlighting the distinctions between what happened in Wyoming and the kind of drilling and fracturing taking place in the Lone Star State.
Elizabeth Ames Jones, the chairman of the Railroad Commission that regulates oil and gas production in the state noted that “the geology of Texas is different.”
“Hydraulic fracturing does not go on close to the surface here and it would be impossible to migrate up from miles below the earth to a water table,” she said. “”We have stringent rules on well construction and extra precautions must be taken near water tables. There is no reason to apply this EPA finding in Wyoming — regardless of what the results end up proving to be — in Texas.”
Jones also said the different geologies of Wyoming and Texas are fresh evidence that state-based regulation of hydraulic fracturing is best. “This is exactly why one size oversight does not fit all,” she said.
But Les Shephard, head of the Sustainable Energy Research Institute at the University of Texas at San Antonio, said it is unwise to rule out contamination from ever occurring in Texas because of the depth of the shale rock formations energy companies are tapping.
There is a problem with using words like “impossible” or “never,” when data later shows contamination may have occurred, Shephard said. The result is “you find that you’ve lost a lot of credibility,” Shephard said.
Tracy Idell Hamilton of the San Antonio Express-News contributed to this report.