Analysis of Oil and Gas Ethane and Methane Emissions in the Southcentral and Eastern United States Using Four Seasons of Continuous Aircraft Ethane Measurements

Barkley, Z.; Davis, Kenneth J.; Feng, Sha; Cui, Yu Yan; Fried, Alan; Weibring, Petter; Richter, Dirk; Walega, J.; Miller, Scot M.; Eckl, Maximilian; Roiger, Anke; Fiehn, Alina; Kostinek, Julian

doi:10.1002/essoar.10505536.1

Cited by 2 publications

(10 citation statements)

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“…While many studies have examined C 2 H 6 :CH 4 ratios using specific measurement techniques (Gentner et al., 2014; Hopkins et al., 2016; Kille et al., 2019; Peischl et al., 2013, 2018; Roscioli et al., 2015; Smith et al., 2015; Wunch et al., 2016; Yacovitch et al., 2014) this study provides a unique data set allowing intercomparison between measurement techniques that are sensitive to different spatial and temporal scales. As more studies (Barkley et al., 2021; Lan et al., 2019; Tribby et al., 2022) investigate using C 2 H 6 :CH 4 and other hydrocarbon ratios to characterize basins and do methane emissions inversion, a “telescoping” approach that leverages measurements on different scales is a valuable characterization tactic. By illustrating our consistent ability to apportion sources using the C 2 H 6 :CH 4 ratio across measurement techniques and sensitivity scales, we provide a basis for future studies aiming to use satellite, other remote sensing, aircraft, and mobile in situ measurements in concert to characterize and apportion O&G emission sources.…”

Section: Discussionmentioning

confidence: 99%

“…Barkley et al. (2021) use C 2 H 6 observations convolved with a priori C 2 H 6 :CH 4 ratio maps to infer CH 4 emissions from fossil fuel operations. These C 2 H 6 :CH 4 ratio maps are spatially coarse as shown in Figure S2 of Barkley et al.…”

Section: Discussionmentioning

confidence: 99%

“…Of the fossil resources, coal contributes 5.9% and oil and gas (O&G) contribute 11.2% to the global methane budget in inventories (Saunois et al., 2020). However, some top‐down global (Schwietzke et al., 2016), national (Miller et al., 2013) and regional (Barkley et al., 2021) estimates show that fossil methane emissions may be much higher than inventories suggest. The discrepancies and uncertainties between top‐down estimates and bottom‐up inventories reinforce the importance of continued atmospheric methane monitoring and accurate accounting.…”

Section: Introductionmentioning

confidence: 99%

“…While these studies have examined C 2 H 6 :CH 4 ratios using the variety of techniques listed, we are unaware of investigations which directly compare the ability of these different measurement techniques to use C 2 H 6 :CH 4 ratios for source attribution across spatial (meter to 10's of kilometer) and temporal (seconds to hours resolution) scales. Recent top down inversion studies have used atmospheric C 2 H 6 to isolate CH 4 fossil sources (Barkely et al., 2021) by assuming constant basin wide ratios. However, basin wide C 2 H 6 :CH 4 ratios have been shown to have increased with time in some basins confounding their use in inversions (Lan et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

“…We report a stable and unique C 2 H 6 :CH 4 ratio of approximately 1.3% from the coal vent plume during all three campaigns across spatial (from meters scale for mobile transects to kilometers scale for total column measurements) and temporal (second resolution for mobile transects to minutes/hours resolution for total column measurements) scales. Both the ground‐based mobile and aircraft campaigns illustrate the highly heterogeneous and transient emissions landscape in the region, a critical issue in using C 2 H 6 to infer CH 4 emissions from O&G basins (Barkley et al., 2021; Lan et al., 2019; Tribby et al., 2022). Despite the presence of other large and fluctuating hydrocarbon sources in the SJB, we were able to isolate and identify the coal vent plume using the C 2 H 6 :CH 4 ratio in each measurement campaign.…”

Section: Introductionmentioning

confidence: 99%

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Using Multiscale Ethane/Methane Observations to Attribute Coal Mine Vent Emissions in the San Juan Basin From 2013 to 2021

et al. 2022

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Source attribution of natural gas emissions from fossil fuels in New Mexico's San Juan Basin (SJB) is challenging due to source heterogeneity and emissions transience. We demonstrate that ethane (C2H6) to methane (CH4) mixing ratios can identify and separate sources over different scales using various measurement techniques. We report simultaneous CH4 and C2H6 observations near a coal mine vent and oil and gas (O&G) emission sources using ground‐based in situ measurements in 2020/2021. During these campaigns, we observed a stable coal vent C2H6:CH4 ratio of 1.28% ± 0.11%, discernibly different than nearby O&G source ratios ranging from 0.9% to 16.8%. We analyze airborne observations of the SJB taken in 2014/2015 that exhibit similar coal vent ratios and further show the region's heterogeneity. We identify episodic O&G sources, including a gas plant source detected in 2014/2015 that is absent in our 2020/2021 data. We examine total column observations of C2H6 and CH4 made in 2013 with a solar spectrometer and find a C2H6:CH4 ratio of 1.3% ± 0.4% for the coal vent. The stable and unique coal vent ratio relative to other O&G sources in the region is used to demonstrate that consistent attribution is possible using various measurement methods at multiple scales across many years. Finally, we demonstrate that using C2H6 as a proxy for fossil CH4 inversions can inform detailed basin‐scale inversions, provided we understand source specific changes in the C2H6:CH4 ratio like we report in the SJB.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Using Multiscale Ethane/Methane Observations to Attribute Coal Mine Vent Emissions in the San Juan Basin From 2013 to 2021

et al. 2022

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Quantification of Oil and Gas Methane Emissions in the Delaware and Marcellus Basins Using a Network of Continuous Tower-Based Measurements

Barkley

Davis

Miles

et al. 2022

Preprint

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Abstract. According to the United States Environmental Protection Agency (US EPA), emissions from oil and gas infrastructure contribute 30 % of all anthropogenic methane (CH4) emissions in the US. Studies in the last decade have shown emissions from this sector to be substantially larger than bottom-up assessments, including the EPA inventory, highlighting both an increased importance of methane emissions from the oil and gas sector towards their overall climatological impact, and the need for independent monitoring of these emissions. In this study we present continuous monitoring of regional methane emissions from two oil and gas basins using tower-based observing networks. Continuous methane measurements were taken at 4 tower sites in the northeastern Marcellus basin from May 2015 through December 2016, and 5 tower sites in the Delaware basin in the western Permian from March 2020 through April 2022. These measurements, an atmospheric transport model, and prior emission fields, are combined using an atmospheric inversion to estimate monthly methane emissions in the two regions. This study finds the mean overall emission rate from the Delaware basin during the measurement period to be 146–210 Mg CH4 h-1 (energy-normalized loss rate of 1.1–1.5 %, gas-normalized rate of 2.5–3.5 %). Strong temporal variability in the emissions was present, with the lowest emission rates occurring during the onset of the COVID-19 pandemic. In the Marcellus, this study finds the overall mean emission rate to be 19–28 Mg CH4 h-1 (gas-normalized loss rate of 0.30–0.45 %), with relative consistency in the emission rate over time. These totals align with aircraft top-down estimates from the same time periods. In both basins, the tower network was able to constrain monthly flux estimates within ±20 % uncertainty in the Delaware and ±24 % uncertainty in the Marcellus. The results from this study demonstrate the ability to monitor emissions continuously and detect changes in the emissions field, even in a basin with relatively small emissions and complex background conditions.

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Analysis of Oil and Gas Ethane and Methane Emissions in the Southcentral and Eastern United States Using Four Seasons of Continuous Aircraft Ethane Measurements

Cited by 2 publications

References 50 publications

Using Multiscale Ethane/Methane Observations to Attribute Coal Mine Vent Emissions in the San Juan Basin From 2013 to 2021

Using Multiscale Ethane/Methane Observations to Attribute Coal Mine Vent Emissions in the San Juan Basin From 2013 to 2021

Quantification of Oil and Gas Methane Emissions in the Delaware and Marcellus Basins Using a Network of Continuous Tower-Based Measurements

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