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

Abstract

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.

A New Technique for Airborne Measurements to Quantify Methane Emissions Over a Wide Range: Implementation and Validation

“…Thus, each of the sources shown in Figure 12 had a 355 unique and consistent C 2 H 6 ratio which can be used to characterize and differentiate multiple sources based on this percentage. This is in agreement with the findings of Meyer et al (2022).…”

“…While the MIRA Pico is highly sensitive with a large dynamic range ( 20 ppb < χ CH4 < 4000 ppm) (MIRAManual2019; Meyer et al (2022); Follansbee et al ( 2024)), there are observable levels of semi-periodic drift in the measured mixing ratios for both hydrocarbons at the ppb level. This effect is especially noticeable for χ C2H6 , partly because ambient mixing ratios for C 2 H 6 are generally 100× smaller than CH 4 .…”

“…Hodnebrog et al (2018);Kutcherov and Krayushkin (2010);Glasby (2006); NAS2018;Forster et al (2007);Hansen et al (2000);Meyer et al (2022)). …”

European Climate Policy in the Context of the Problem of Methane Emissions from Coal Mines in Poland

“…Governments, environmental organizations, and industries are increasingly recognizing the importance of reducing methane emissions to combat climate change. Implementing methane capture technologies in coal mines represents a tangible and effective step towards achieving these environmental goals [69][70][71][72].…”

A Wellbore Pressure Control Method for Two-Layer Coal Seam Gas Coproduction Wells

“…Areas of vertical distribution with multiple potential production layers are currently discovered in the Ordos Basin, Qinshui Basin, Eastern Yunnan and western Guizhou in China [4][5][6][7][8]. Similar areas are also found in the United States, Australia and Canada, such as the San Juan Basin [9,10], Black Warrior Basin [11,12], Powder River Basin [13,14], Horseshoe Canyon Basin [15,16], and Bowen-Surat Basin [17,18].…”