Primary emissions and secondary formation of volatile organic compounds from natural gas production in five major U.S. shale plays

Monday, 15 December 2014: 9:00 AM
Jessica Gilman1, Brian M Lerner2, Carsten Warneke3, Martin Graus4, Rui Lui1,4, Abigail Koss5, Bin Yuan3, Shane M Murphy6, Sergio Luiz Alvarez7, Barry L Lefer8, Kyung-Eun Min9, Steven S Brown10, James M Roberts11, Hans Dieter Osthoff12, Courtney Dyan Hatch13, Jeff Peischl14, Thomas B Ryerson15 and Joost A De Gouw16, (1)NOAA ESRL, Boulder, CO, United States, (2)NOAA, Earth System Research La, Boulder, CO, United States, (3)NOAA Boulder, Boulder, CO, United States, (4)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (5)University of Colorado at Boulder, Boulder, CO, United States, (6)University of Wyoming, Laramie, WY, United States, (7)University of Houston, Houston, TX, United States, (8)University of Houston, Earth and Atmospheric Sciences, Houston, TX, United States, (9)NOAA, Boulder, CO, United States, (10)NOAA Earth System Research Lab, Chemical Sciences Division, Boulder, CO, United States, (11)NOAA/ESRL, Boulder, CO, United States, (12)University of Calgary, Chemistry, Calgary, AB, Canada, (13)Hendrix College, Conway, AR, United States, (14)NOAA ESRL Chemical Sciences Division, Boulder, CO, United States, Boulder, CO, United States, (15)NOAA Chemical Sciences Divisio, Boulder, CO, United States, (16)NOAA Earth System Research Lab, Boulder, CO, United States
According to the U.S. Energy and Information Administration (EIA), domestic production of natural gas from shale formations is currently at the highest levels in U.S. history. Shale gas production may also result in the production of natural gas plant liquids (NGPLs) such as ethane and propane as well as natural gas condensate composed of a complex mixture of non-methane hydrocarbons containing more than ~5 carbon atoms (e.g., hexane, cyclohexane, and benzene). The amounts of natural gas liquids and condensate produced depends on the particular reservoir. The source signature of primary emissions of hydrocarbons to the atmosphere within each shale play will therefore depend on the composition of the raw natural gas as well as the industrial processes and equipment used to extract, separate, store, and transport the raw materials. Characterizing the primary emissions of VOCs from natural gas production is critical to assessing the local and regional atmospheric impacts such as the photochemical formation of ozone and secondary formation of organic aerosol.

This study utilizes ground-based measurements of a full suite of volatile organic compounds (VOCs) in two western U.S. basins, the Uintah (2012-2014 winter measurements only) and Denver-Julesburg (winter 2011 and summer 2012), and airborne measurements over the Haynesville, Fayetteville, and Marcellus shale basins (summer 2013). By comparing the observed VOC to propane enhancement ratios, we show that each basin has a unique VOC source signature associated with oil and natural gas operations. Of the shale basins studied, the Uintah basin had the largest overall VOC to propane enhancement ratios while the Marcellus had the lowest. For the western basins, we will compare the composition of oxygenated VOCs produced from photochemical oxidation of VOC precursors and contrast the oxygenated VOC mixture to a “typical” summertime urban VOC mixture. The relative roles of alkanes, alkenes, aromatics, and cycloalkanes as precursors for C2-C6 aldehydes and ketones, and C3-C4 alkyl nitrates will be investigated.