Hannah Daley, Russell R. Dickerson, Philip R. Stratton, Hao He, Xinrong Ren, Abigail R. Koss, Alan Brewer, Sunil Baidar, Benjamin Hmiel, D. Bon, Gordon Pierce, P. Weibring, Dirk Richter, J. Walega, Mercy Ngulat, Arthur Santos, Anna L. Hodshire, Timothy Vaughn, Daniel Zimmerle, Alan Fried
Abstract Despite a 2.1‐fold increase in oil and gas (O&G) production from 2012 to 2021 in the Wattenberg Field (WF) area of the Denver‐Julesburg Basin (DJB), total methane (CH4) emissions have remained unchanged within measurement uncertainties (26.0 ± 6.8 t/hr in 2012, 24.0 ± 5 t/hr in 2015, and 21.4 ± 5.7 t/hr in 2021), while ethane (C 2 H 6 ) emissions have decreased by a factor of 2.7 since 2015, from 7.0 ± 1.1 to 2.6 ± 0.9 t/hr in 2021. We present airborne mass flux measurements of CH 4 and C 2 H 6 quantifying total emissions, their variability, and primary sources—O&G versus concentrated animal feeding operations (CAFOs). Based on four mass balance flights in September and October 2021, total CH 4 and C 2 H 6 emissions showed significant day‐to‐day variability, with standard deviations of 23% and 32%, respectively. Combining in situ and LiDAR measurements with a 3‐km atmospheric model improves our understanding of the reliability of flux determination. Using C 2 H 6 and vapor‐phase acetic acid (CH 3 COOH) as tracers, we attribute 63 ± 11% of CH 4 emissions to O&G. Emission intensities (EIs), calculated as thermogenic (TG‐ CH 4 ) and C 2 H 6 emissions per barrel of oil equivalent (BOE), show a declining trend, with TG‐ CH 4 EIs decreasing at an average annual rate of 4.4% from May 2012 to October 2021 and C 2 H 6 EIs declining at an average annual rate of 10.8% from April 2015 to October 2021. C 2 H 6 EIs fell at more than twice the rate of TG‐ CH 4 EIs.