Quantifying Methane and Ethane Emissions to the Atmosphere From Central and Western U.S. Oil and Natural Gas Production Regions

Abstract

We present atmospheric measurements of methane (CH4) and ethane (C2H6) taken aboard a National Oceanic and Atmospheric Administration WP‐3D research aircraft in 2015 over oil‐ and natural gas‐producing regions of the central and western United States. We calculate emission rates from the horizontal flux of CH4 and C2H6 in the planetary boundary layer downwind of five of these oil‐ and gas‐producing regions: the Bakken in North Dakota, the Barnett in Texas, the Denver Basin in Colorado, the Eagle Ford in Texas, and the Haynesville in Texas and Louisiana. In general, we find that the enhancement of C2H6 relative to CH4 in the atmosphere is similar to their relative abundances in locally produced natural gas. For the Bakken and Barnett regions, both absolute CH4 emissions and the percentage of produced natural gas emitted to the atmosphere are consistent with previous studies. The percentage of produced natural gas emitted to the atmosphere was lower than in previous studies in the Denver Basin and the Haynesville regions, which may be due to a decrease in drilling activity, an increase in emission controls, or some combination thereof. Finally, we provide the first estimates of basin‐wide emissions from the Eagle Ford region using in situ airborne data and find C2H6 emissions to be greater than those from the Bakken region. Emissions from the Bakken and Eagle Ford regions combined account for 20% of anthropogenic C2H6 emissions in North America.

Multispecies Assessment of Factors Influencing Regional CO2 and CH4 Enhancements During the Winter 2017 ACT‐America Campaign

“…This enhancment ratio for the Mid‐Atlantic was 4.5% (Figure e): within the range of reported ratios for Mid‐Atlantic region shale plays (Marcellus, Utica) of 2–16% (Conder & Lawlor, ; Peischl et al, ) and higher than the reported 2.6–3.3% ethane: in dense urban regions (Plant et al, ). In the Southeast, this enhancement ratio was approximately 5% (Figure e), which is within the range of 2–10% reported in both Smith et al () and Peischl et al () for the Bakken and other shale plays in this region. The Midwest ethane: was 3.8% (Figure e), lower than those reported in the Bakken shale formation and Denver basins (approximately 50% and 16%, respectively; Peischl et al, ).…”

“…In the Southeast, this enhancement ratio was approximately 5% (Figure e), which is within the range of 2–10% reported in both Smith et al () and Peischl et al () for the Bakken and other shale plays in this region. The Midwest ethane: was 3.8% (Figure e), lower than those reported in the Bakken shale formation and Denver basins (approximately 50% and 16%, respectively; Peischl et al, ). This lower ratio is likely due to agricultural emissions (Figure b) but still generally higher than that found in urban areas.…”

Methane Mitigation: Methods to Reduce Emissions, on the Path to the Paris Agreement

“…Moreover, as mentioned above, drones typically have a height limit in most jurisdictions, depending on airspace classification. Karion et al (2013Karion et al ( , 2015 and Caulton et al (2014) used aircraft-based measurements to map out emissions from unconventional oil and gas fields in the United States, while Peischl et al (2015Peischl et al ( , 2018 and used aircraft equipped with a high-precision analyzer to study several major shale gas fields. Similarly, in the Netherlands, Yacovitch et al (2018) used a light aircraft equipped with a high-precision gas analyzer and flask sampling capability to determine emissions from the giant Groningen gasfield and the heavily agricultural surrounding area.…”

Separation of Methane Emissions From Agricultural and Natural Gas Sources in the Colorado Front Range

“…A few other studies that have apportioned (Peischl et al, 2018;Petron et al, 2014;Townsend-Small et al, 2016) or quantified (Eilerman et al, 2016;Fried et al, 2015;Gilman, 2017;Tzompa-Sosa et al, 2017;Yuan et al, 2017) CH 4 in the DJB study area exist, but none have attempted to source apportion CH 4 based on excess columns. These results can be used to assess how the concept of excess columns compares with results based on in situ observations.…”