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.