A41Q-01
Estimates of Methane and Ethane Emissions from the Barnett Shale Using Atmospheric Measurements

Thursday, 17 December 2015: 08:00
3012 (Moscone West)
Anna Karion1,2, Colm Sweeney3, Eric A Kort4, Paul B Shepson5, Stephen A Conley6, Thomas Lauvaux7, Kenneth J Davis7, Aijun Deng7, David Richard Lyon8 and Mackenzie Lynn Smith4, (1)NOAA/Earth System Research Lab, Boulder, CO, United States, (2)National Institute of Standards and Technology Gaithersburg, Gaithersburg, MD, United States, (3)NOAA Boulder, ESRL, Boulder, CO, United States, (4)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (5)Purdue University, West Lafayette, IN, United States, (6)University of California Davis, Davis, CA, United States, (7)Pennsylvania State University Main Campus, University Park, PA, United States, (8)University of Arkansas, Environmental Dynamics, Fayetteville, AR, United States
Abstract:
Recent development of horizontal drilling technology and advances in hydraulic fracturing techniques by the oil and gas industry have dramatically increased onshore U.S. natural gas and oil production in the last several years. The primary component of natural gas is methane (CH4), a powerful greenhouse gas; therefore, natural gas leakage into the atmosphere affects its climate impact.

We present estimates of regional methane (CH4) and ethane (C2H6) emissions from oil and natural gas operations in the Barnett Shale, Texas, made in March and October 2013 as part of the Environmental Defense Fund’s Barnett Coordinated Campaign. The Barnett is one of the largest production basins in the United States, with 8% of total U.S. natural gas production, and thus, our results represent a crucial step toward determining the greenhouse gas footprint of U.S. onshore natural gas production. Using a mass balance approach on eight different flight days the total CH4 emissions for the region are estimated to be 76 ± 13x 103 kg/hr, or 0.66 ± 0.11 Tg CH4 /yr; (95% CI). Repeated mass balance flights in the same basin on eight different days and two seasons demonstrate the consistency of the mass balance approach. On the basis of airborne C2H6 and CH4 measurements, we find 71-85% of the observed CH4 emissions quantified in the Barnett Shale are derived from fossil sources. The average C2H6 flux was 6.6 ± 0.2 x 103 kg/hr and consistent across six days in spring and fall of 2013. This result is the first demonstration of this approach for C2H6.

We estimate that 60±11x103 kg CH4/hr (95% CI) are emitted by natural gas and oil operations, including production, processing, and distribution in the urban areas of Dallas and Fort Worth. This estimate is significantly higher than emissions reported by the EDGAR inventory or by industry to EPA’s Greenhouse Gas Reporting Program.

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