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Ohio Utica Shale

Study says drinking water wells near natural gas wells at greater risk

By Bob Downing Published: June 24, 2013

From Duke University today:

DURHAM, NC -- Homeowners living within one kilometer of shale gas wells appear to be at higher risk of having their drinking water contaminated by stray gases, according to a new Duke University-led study.

Duke scientists analyzed 141 drinking water samples from private water wells across northeastern Pennsylvania's gas-rich Marcellus shale basin. Their study documented not only higher methane concentrations in drinking water within a kilometer of shale gas drilling -- which past studies have shown -- but higher ethane and propane concentrations as well.

Methane concentrations were six times higher and ethane concentrations were 23 times higher at homes within a kilometer of a shale gas well. Propane was detected in 10 samples, all of them from homes within a kilometer of drilling.

“The methane, ethane and propane data, and new evidence from hydrocarbon and helium isotopes, all suggest that drilling has affected some homeowners' water,” said Robert B. Jackson, a professor of environmental sciences at Duke's Nicholas School of the Environment. “In a minority of cases, the gas even looks Marcellus-like, probably caused by faulty well construction.”

The ethane and propane contamination data are “new and hard to refute,” Jackson stressed. “There is no biological source of ethane and propane in the region and Marcellus gas is high in both, and higher in concentration than the Upper Devonian gas found in-between.”

The team examined which factors might explain their results, including topography, distance to gas wells and distance to geologic features. “Distance to gas wells was, by far, the most significant factor influencing gases in the drinking water we sampled,” said Jackson.

The peer-reviewed findings will appear this week in the online Early Edition of the Proceedings of the National Academy of Sciences.

Hydraulic fracturing, also called hydrofracking or fracking, involves pumping water, sand and chemicals deep underground into horizontal gas wells at high pressure to crack open hydrocarbon-rich shale and extract natural gas. Accelerated shale gas drilling and hydrofracking in recent years has fueled concerns about contamination in nearby drinking water supplies.

Two previous peer-reviewed studies by Duke scientists found direct evidence of methane contamination in water wells near shale-gas drilling sites in northeastern Pennsylvania, as well as possible connectivity between deep brines and shallow aquifers. A third study conducted with U.S. Geological Survey scientists found no evidence of drinking water contamination from shale gas production in Arkansas. None of the studies have found evidence of contamination by fracking fluids.

“Our studies demonstrate that distances from drilling sites, as well as variations in local and regional geology, play major roles in determining the possible risk of groundwater impacts from shale gas development," said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School. "As such, they must be taken into consideration before drilling begins.”

“The helium data in this study are the first from a new tool kit we've devised for identifying contamination using noble gas isotopes,” said Duke research scientist Thomas H. Darrah. “These tools allow us to identify and trace contaminants with a high degree of certainty.”

Co-authors on the new study are Nathaniel R. Warner, Adrian Down, Kaiguang Zhao and Jonathan D. Karr, all of Duke; Robert J. Poreda of the University of Rochester; and Stephen G. Osborn of California State Polytechnic University.

Duke's Nicholas School of the Environment and the Duke Center on Global Change funded the research.


“Increased Stray Gas Abundance in a Subset of Drinking Water Wells Near Marcellus Shale Gas Extraction," Robert Jackson, Avner Vengosh, Thomas Darrah, Nathaniel Warner, Adrian Down, Robert Poreda, Stephen Osborn, Kaiguang Zhao, Jonathan Karr. Proceedings of the National Academy of Sciences, Online week of June 24, 2013.

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Utica and Marcellus shale web sites

Ohio Department of Natural Resources' Division of Oil and Gas Resources Management State agency Web site.

ODNR Division of Oil and Gas Resources Management. State drilling permits. List is updated weekly.

ODNR Division of Geological Survey.

Ohio Environmental Protection Agency.

Ohio State University Extension.

Ohio Farm Bureau.

Ohio Oil and Gas Association, a Granville-based group that represents 1,500 Ohio energy-related companies.

Ohio Oil & Gas Energy Education Program.

Energy In Depth, a trade group.

Marcellus and Utica Shale Resource Center by Ohio law firm Bricker & Eckler.

Utica Shale, a compilation of Utica shale activities.

Landman Report Card, a site that looks at companies involved in gas and oil leases.FracFocus, a compilation of chemicals used in fracking individual wells as reported voluntarily by some drillers.

Chesapeake Energy Corp,the Oklahoma-based firm is the No. 1 driller in Ohio.

Rig Count Interactive Map by Baker Hughes, an energy services company.

Shale Sheet Fracking, a Youngstown Vindicator blog.

National Geographic's The Great Shale Rush.

The Ohio Environmental Council, a statewide eco-group based in Columbus.

Buckeye Forest Council.

Earthjustice, a national eco-group.

Stop Fracking Ohio.

People's Oil and Gas Collaborative-Ohio, a grass-roots group in Northeast Ohio.

Concerned Citizens of Medina County, a grass-roots group.

No Frack Ohio, a Columbus-based grass-roots group.

Fracking: Gas Drilling's Environmental Threat by ProPublica, an online journalism site.

Penn State Marcellus Center.

Pipeline, blog from Pittsburgh Post-Gazette on Marcellus shale drilling.

Allegheny Front, environmental public radio for Western Pennsylvania.