NOAA/CIRES study shows high methane levels in Uintah Basin

August 6, 2013

methane, oil and gas drilling

Uintah Basin gas field -- Utah

Uintah Basin gas field — Utah

CIRES News Release —

CIRES and NOAA scientists observe significant methane leaks in a Utah natural gas field

On a perfect winter day in Utah’s Uintah County in 2012, scientists from the Cooperative Institute for Research in Environmental Sciences (CIRES) and colleagues at the National Oceanic and Atmospheric Administration (NOAA) tested out a new way to measure methane emissions from a natural gas production field.

Their results, accepted for publication in 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 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 Vernal, Utah.

“Then the next day, the winds decreased to about 12 miles per hour, and they held very steady for hours,” Karion said.

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 Utah's Uintah Basin oil and gas fields. [Photo by Sonja Wolter, CIRES/NOAA]

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 Utah’s Uintah Basin oil and gas fields. [Photo by Sonja Wolter, CIRES/NOAA]

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 whole basin.

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.

A recent federal report estimated that methane’s leak rate, nationally, is less than 1 percent of production; another report noted 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 fields. 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 ozone pollution.

“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 years.”

CIRES is a joint institute of CU-Boulder and NOAA.

Methane emissions estimate from airborne measurements over a western United States natural gas field

Co-authors: 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.

uintah basin map

New Warnings About Methane Emissions

… As to what these studies mean for our nation as a whole, one  need is additional data — a comprehensive and consistent look at methane emissions at various locations across the country — in order to properly characterize methane across the U.S. natural gas supply system. That’s why EDF, along with close to 100 academic, research and industry partners, is working on a series of 16 studies to directly measure methane emissions across the supply chain. Together, these sixteen studies will provide the most complete national picture of methane emissions to date.

The first study, led by the University of Texas and involving nine natural gas producers, will be published in the coming weeks. The UT study is not based on emissions from a single location but on measurements from diverse regions with data collected at the actual source. Direct measurements in the UT study focus on methane lost at the well pad and other natural gas production points, and will provide insights into how effectively specific industry practices can contain methane emissions. But it won’t offer a complete picture of methane emissions across all of the natural gas system. We’ll need the entire series of studies, a project that will continue through 2014, before we can draw comprehensive conclusions about the scope of the problem and the full range of options for minimizing methane emissions.

The Uintah and Los Angeles studies tell us that methane emissions appear to be a serious problem in some regions. Additional data will tell us more about where emissions are occurring and what can be done to reduce them.  But we know enough to get started fixing the problem. There is no reason to wait.

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Read the CIRES blog — Science in Action: Air Quality Study in Utah

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