The Nature of Temporally Variable Methane Emissions at Oil and Natural Gas Operations in the Eagle Ford Basin

Thursday, 17 December 2015
Poster Hall (Moscone South)
Tegan Noel Lavoie1, Paul B Shepson1, Maria O. L. Cambaliza2, Brian H Stirm3, Stephen A Conley4, Shobhit Mehrotra4, Ian C Faloona4, Michael Mayfield5, David Richard Lyon6 and Ramon Alvarez7, (1)Purdue University, West Lafayette, IN, United States, (2)Ateneo de Manila University, Physics, Quezon City, Philippines, (3)Purdue University, Aviation Technology, West Lafayette, IN, United States, (4)University of California Davis, Davis, CA, United States, (5)Leak Surveys, Inc., Early, TX, United States, (6)University of Arkansas, Environmental Dynamics, Fayetteville, AR, United States, (7)Environmental Defense Fund, Austin, TX, United States
To understand the current state of U.S. greenhouse gas emissions from oil and gas operations, policy makers refer to national inventories and reporting programs, and therefore, it is imperative that these reports are accurate and representative. Many studies exist that investigate the reliability of current monitoring methods, however, to our knowledge the temporal variability of the magnitude and source of methane (CH4) emissions from oil and gas facilities has not been reported in the literature. We present results from a field campaign conducted in June 2014 in the Eagle Ford basin, Texas to assess the temporal variability of emissions from a variety of facilities using data obtained through four different methods. The variability of total CH4 emission rate from individual facilities was investigated by repeated measurement of emissions from five gathering facilities using two aircraft-based mass balance approaches. Basin-wide emissions variation was examined by conducting a series of eight four hour afternoon aerial surveys of two 35 x 35 km areas, with transects oriented perpendicular to the prevailing wind direction. The emission source-type and magnitude were further investigated using helicopter-based FLIR camera observations conducted repeatedly at eight oil wells, one gas well, and four gathering facilities. Results indicate a high degree of variability in day-to-day and sometimes hour-to-hour CH4 emissions magnitude. FLIR camera observations suggest that the component-level source of facility emissions is also highly variable over time, with both storage tank vent stacks and tank hatches representing important components of the observed day-to-day variability. While some emissions were due to scheduled maintenance, others appeared to occur due to faulty and/or aging equipment. Here we discuss what was learned in terms of factors that explain the observed emission rate variability.