CIRES, NOAA observe
significant methane leaks in a Utah natural gas field
New measurements made on one
day suggest a need for more direct data
August 5, 2013 On a perfect winter day in Utah’s Uintah County in 2012,
CIRES scientists and NOAA colleagues tested out a new way to measure methane
emissions from a natural gas production field.
Their results, accepted for
Geophysical Research Letters, constitute a proof-of-concept that could help
both researchers and regulators better determine how much of the greenhouse gas
and other air pollutants leak from oil and gas fields.
The measurements show that on one
February day in the Uintah Basin, the natural gas field leaked 6 to 12 percent
of the methane produced, on average, on February days.
“We used a mass balance technique, which means we follow an air mass as it moves
into the region and then flows out,” said Colm Sweeney, a scientist with the
Cooperative Institute for Research in Environmental Sciences (CIRES)
at the University of Colorado
Boulder, who leads the aircraft group at NOAA’s
Earth System Research
Laboratory Global Monitoring Division.
“We look at the difference in
methane between those two to determine an actual emissions rate for the region.”
CIRES, NOAA and other scientists have used this type of atmospheric mass balance
accounting technique in many other settings—to determine power plant emissions,
for example, and the atmospheric impacts of refineries and
cities, said Anna Karion, lead author of the new paper and a CIRES
atmospheric scientist who also works at NOAA.
In Utah’s Uintah Basin, on one day during a weeks-long field campaign in 2012,
weather conditions were near ideal for testing the technique in an oil and gas
field, Karion said. Late on February 2, a weather front passed through, with
high winds that swept clean the atmosphere above the Uintah Basin, south of
“Then the next day, the winds decreased to about 12 miles per hour, and they
held very steady for hours,” Karion said.
Equipment associated with natural gas
exploration and development in Utah's Uintah Basin, and the plume from a distant
power plant. A new CIRES, NOAA study finds significant methane leaks in the
basin. CREDIT: David Oonk, CIRES.
When the winds settled down on February 3, a pilot flew a single-engine Mooney
TLS aircraft, carrying sophisticated instruments for measuring methane and other
atmospheric gases, back and forth in the Uintah Basin.
The aircraft measurements let
scientists calculate the total amount of methane added to the air mass as it
transited the basin. Combining those data with precise measurements of wind
speed, made by NOAA colleagues using a
ground-based laser, scientists could calculate the methane emission for the
The team determined that methane emissions from the oil and natural gas fields
in Uintah County totaled about 55,000 kg (more than 120,000 lbs) an hour on the
day of the flight.
That emission rate is about 6 to
12 percent of the average hourly natural gas production in Uintah County during
the month of February.
federal report estimated that methane’s leak rate, nationally, is less than
1 percent of production; another
that emissions in the Uintah (“Uinta”) Basin, which produces about 1 percent of
total U.S. natural gas, may have higher emissions than typical for western gas
The Environmental Protection
Agency’s Office of Inspector General has
called for better emissions data from the natural gas sector, and this paper
is one of the first published since.
The aircraft was part of a collaborative,
multi-agency mission in the region to better understand how emissions from
fossil fuel extraction activities affect local air quality.
Methane is the primary constituent
of natural gas, and it is a potent greenhouse gas. Other components, such as
chemicals called volatile organic compounds are also emitted from oil and gas
production operations and can contribute to
Gas wells dot the landscape in the Uintah
Basin, in this Google Earth image.
“We expected methane emissions would be detectable, but we did not anticipate
levels as high as what we observed,” Sweeney said.
The aircraft flew over the oil and gas field 11 other days during the study, but
on those days, wind and other atmospheric conditions were unpredictable or
erratic making it difficult to directly estimate methane emissions.
Karion, Sweeney and their co-authors continue to analyze methane and other
emissions data gathered in Uintah Basin, in 2012 and 2013, and from recent
scientific flights through other oil and gas production regions.
Utah’s Division of Air
Quality helped to fund some of the Utah work, and Deputy Director Brock
LeBaron said that new actions already taken by the EPA and the state of Utah
will soon lessen methane emissions in the Uintah Basin.
“Our work with NOAA and CIRES indicates that high levels of volatile organic
compounds contribute to ozone pollution in the Uintah Basin,” LeBaron said.
“Our own efforts in Utah and the EPA’s oil and gas
New Source Performance Standards, designed to lessen those air quality
impacts, will also significantly cut methane emissions during the next few
A research aircraft comes in for a
landing in Vernal, Utah. Sensitive instruments aboard let CIRES and NOAA
researchers measure atmospheric levels of methane and other chemicals during
flights through the Uintah Basin oil and gas fields, in Utah. CREDIT: Sonja
CIRES is a joint institute of the National Oceanic and Atmospheric
Administration (NOAA) and the
University of Colorado
Coauthors of “Methane emissions estimate from airborne measurements over a
western United States natural gas field” are Anna Karion, Colm Sweeney,
Gabrielle Pétron, Gregory Frost, Jonathan Kofler, Ben R. Miller, Tim Newberger
and Sonja Wolter of the Cooperative Institute for Research in Environmental
Sciences at the University of Colorado Boulder; Robert Banta, Alan Brewer, Ed
Dlugokencky, Mike Hardesty, Patricia Lang, Stephen A. Montzka, Russell Schnell,
Pieter Tans, Michael Trainer and Robert Zamora of NOAA’s Earth System Research
Laboratory in Boulder, Colo.; and Stephen Conley of the University of
California, Davis. Geophysical Research Letters is a journal of the
American Geophysical Union.
- See more at: http://cires.colorado.edu/news/press/2013/methaneleaks.html