SUMMARY:
Shale gas drilling
began in Pennsylvania
over a decade ago.
Some natural
gas companies
did not do enough
baseline well
water testing.
They would
have found
lots of methane
contamination in
home water wells
Older methane
contamination
results in
iron sulfide
in the well.
It produces water
that some folks
hauled around
in plastic jugs
and claimed
to be caused
by new fracking.
Natural gas
companies
were vulnerable
to charges
that they had
created methane
contamination
in nearby water wells,
even when the methane
existed in the well water
before fracking began
in the vicinity.
Penn State
identified
identified
a method
of determining
whether methane
contamination
of water wells is new,
and could be caused
by fracking, or is
older contamination,
unrelated to fracking.
Of the 17 samples
( out of 20,751 samples )
that came back positive
for new methane,
none came from sites
within 2,500 feet
of known problematic
gas wells.
State law holds
oil and gas
companies
responsible for
methane leaks
that affect wells
within that
2,500-foot area.
The Penn State
study is entitled
“Exploring How to Use
Groundwater Chemistry
to Identify
Migration of Methane
near Shale Gas Wells
in the Appalachian Basin”.
The study was funded
by the National Science
Foundation and USGS,
two independent institutions.
DETAILS:
"A new
testing protocol
that uses existing,
affordable water
chemistry tests
can help scientists
and regulators
detect sites
showing evidence
of new methane
gas leaks caused by
oil and gas drilling",
according to
Penn State
researchers.
They published their findings
in the journal Environmental
Science & Technology
and for the first time
made public the datasets.
"The scientists
wanted to see
what percentage
of the water wells
showed certain
chemical changes
that could indicate
new methane
contamination,
like that
which can occur
during drilling and
extraction of fossil fuels,
and not pre-existing
methane that is
commonly found
in Pennsylvania water."
Tao Wen,
a postdoctoral scholar
in the Earth and
Environmental Systems
Institute at Penn State,
said: “We found 17
out of 20,751 samples,
or about 0.08%,
that showed possible signs
of methane contamination
when those samples
were collected.”
“It’s not uncommon
to see methane
in groundwater
in the Marcellus shale
and other shale plays,”
Wen said.
“Also,
if methane
had been
in the groundwater
for a long time,
bacteria would have
reduced the iron
and sulfate.
The reduced forms
would have precipitated
as iron sulfide, or pyrite.”
"The researchers classified
low-methane samples,
where methane measured l
ess than 10 parts per million,
as low priority samples.
The other two types
not impacted by
new methane
contained high amounts
of methane and either
high salts, indicating
naturally occurring
methane not caused
by energy extraction,
or freshwater and
low sulfate levels,
meaning that
the methane
had been there
for a time."
The testing
protocol
can act as an
effective
screening
tool for methane
contamination.
“We focus on the
Marcellus shale,
but this
testing protocol
has the potential
to be applied
to other shale plays
in the United States
and other countries,”
Wen said.
Note:
Other data
gathered by the
University of Cincinnati
“found no evidence
of natural gas contamination
from recent oil and gas drilling."
Contributors to
the Penn State Study:
the Penn State Study:
Josh Woda,
a recent master’s
degree graduate
Virginia Macron,
a doctoral student ,
Department
of Geosciences;
Xianzeng Niu,
Earth and
Environmental
Systems Institute;
Zhenhui Li,
College of
Information Sciences
and Technology; and
Susan Brantley,
distinguished professor
of geosciences,
and the director
of the Earth
and Environmental
Systems Institute