New WVU Study Looks at Methane in Water Supplies
A new research study is on the way in West Virginia that tackles the question of “Is there methane in the water supply? And if so, how did it get there?” One of the charges often leveled at shale gas drilling is that it causes a migration of methane (natural gas) into water supplies. Perhaps the most famous case in recent years is that of Dimock, Pennsylvania (see MDN stories about Dimock).
A researcher from West Virginia University is conducting a new study by sampling and analyzing water samples in the Monongahela River watershed to determine if there’s methane in local water supplies, with an eye to determining how it got there if it is there.
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.
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.*
*WVNS Channel 59 News (Oct 4, 2011) – WVU Researcher to Map Methane Sources in Monongahela-Area Drinking Water