WVU Researcher to Map Methane Sources in Monongahela-Area Drinking Water

Researcher Shikha Sharma believes that residents and researchers should be aware of what already exists in the waters — and where it came from.

The State Journal
4 October 2011
By Pam Kasey

Oil and gas operators and residents in the Marcellus shale region have become aware that drinking water can contain dissolved methane. But did it come from hydraulic fracturing, previously abandoned wells or from some other source?

Now a West Virginia University researcher is gathering data to help answer that question for aquifers in the Monongahela River watershed.

Methane in drinking water wells is an issue the gas industry is taking seriously. And with good reason. Chesapeake Energy and Cabot Oil and Gas collectively have paid $5 million in the past year to compensate Pennsylvania landowners for methane contamination of drinking water wells.

The methane could have come from a range of sources and could have been present before Marcellus activity ever began, both companies have pointed out. But without pre-drill baseline data, it’s impossible to prove.

Given that kind of liability, operators in the Marcellus region are spending 10 to 12 hours a month at roundtables and on conference calls on the topic, Marcellus Shale Coalition President and Executive Director Kathryn Klaber told The Wall Street Journal last week.

WVU’s Shikha Sharma believes that residents and researchers should be aware of what already exists in the waters — and where it came from.

An assistant professor at WVU, Sharma moved to Morgantown last year after directing a core isotope research facility at the University of Wyoming. Her main research involves the use of stable isotopes to address issues related to water and energy.

“The source of methane gas can range from active or inactive deep coal mines, landfills, gas storage fields or microbial gas generated in a shallow subsurface,” said Sharma. Abandoned oil and gas wells are another possible source.

Methane can be created in two ways, she explained: Biogenic methane forms when bacteria work on organic matter, while thermogenic methane forms when organic matter in geological formations is subjected to heat and pressure, she explained.

Because bacteria — in a landfill, say, or in a shallow coal seam — prefer easier-to-metabolize carbon-12, a lighter isotope that has six protons and only six neutrons in its nucleus, the methane they produce is isotopically light, Sharma said.

Thermogenic methane has a higher proportion of heavier carbon-13, with six protons and seven neutrons.

And while methane from different thermogenic sources might have similar isotopic signatures, researchers can look at additional measures to identify specific sources, she said: the hydrogen in the methane, the isotopic composition of associated molecules such as carbon dioxide and water, and the proportion of ethane, propane and other natural gas liquids to the methane.

So far, Sharma said, Michon Mulder, a gradate student working on the project, has taken samples from about 40 drinking water wells targeting various aquifers in the Monongahela River watershed.

The samples are undergoing analysis now for dissolved methane and a range of other parameters including sulfates, carbonates — “a whole suite of chemical constituents.”

“Once we get everything back we will try to understand what the geochemical processes are which might be happening in different aquifers of the region,” she said. “Then we’ll make GIS maps to understand the spatial variations and try to understand where the methane is coming from.”

Because Marcellus activity in the Monongahela watershed is still minimal, Sharma is hopeful that the study will provide good baseline information.

“I think having a well established baseline will benefit everyone including residents, regulatory agencies and shale gas drilling companies,” she said, by differentiating between the potential and the real impacts of hydraulic fracturing on water sources so unbiased decisions can be made.

Sharma’s research is funded by a $25,000 grant from the U.S. Geological Survey provided through the West Virginia Water Research Institute, and is being completed in collaboration with scientists in the USGS West Virginia Water Science Center in Charleston.

She has set up a laboratory at WVU where isotopes may be measured and sees it as a budding stable isotope research and teaching program on campus.