title: Aerial Surveys of Elevated Hydrocarbon Emissions from Oil and Gas Production Sites.
abstract: Oil and gas (O&G) well pads with high hydrocarbon emission rates may disproportionally contribute to total methane and volatile organic compound (VOC) emissions from the production sector. In turn, these emissions may be missing from most bottom-up emission inventories. We performed helicopter-based infrared camera surveys of more than 8000 O&G well pads in seven U.S. basins to assess the prevalence and distribution of high-emitting hydrocarbon sources (detection threshold ∼ 1-3 g s(-1)). The proportion of sites with such high-emitting sources was 4% nationally but ranged from 1% in the Powder River (Wyoming) to 14% in the Bakken (North Dakota). Emissions were observed three times more frequently at sites in the oil-producing Bakken and oil-producing regions of mixed basins (p < 0.0001, χ(2) test). However, statistical models using basin and well pad characteristics explained 14% or less of the variance in observed emission patterns, indicating that stochastic processes dominate the occurrence of high emissions at individual sites. Over 90% of almost 500 detected sources were from tank vents and hatches. Although tank emissions may be partially attributable to flash gas, observed frequencies in most basins exceed those expected if emissions were effectively captured and controlled, demonstrating that tank emission control systems commonly underperform. Tanks represent a key mitigation opportunity for reducing methane and VOC emissions.
authors.affiliation: Environmental Defense Fund , 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States.|Environmental Dynamics Program, University of Arkansas , Fayetteville, Arkansas 72701, United States.
authors.forename: David R
authors.initials: DR
authors.lastname: Lyon
authors.affiliation: Environmental Defense Fund , 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States.
authors.forename: Ramón A
authors.initials: RA
authors.lastname: Alvarez
authors.affiliation: Environmental Defense Fund , 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Zavala-Araiza
authors.affiliation: Department of Energy Resources Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Brandt
authors.affiliation: Department of Earth System Science, Woods Institute for the Environment, and Precourt Institute for Energy, Stanford University , Stanford, California 94305, United States.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Jackson
authors.affiliation: Environmental Defense Fund , 301 Congress Avenue, Suite 1300, Austin, Texas 78701, United States.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Hamburg
mesh_terms: D000393:Air Pollutants; D006838:Hydrocarbons; D008697:Methane; D011795:Surveys and Questionnaires; D014959:Wyoming
chemical_list: D000393:Air Pollutants; D006838:Hydrocarbons; D008697:Methane