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On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site

[Image: see text] Understanding methane emissions from the natural gas supply chain continues to be of interest. Previous studies identified that measurements are skewed due to “super-emitters”, and recently, researchers identified temporal variability as another contributor to discrepancies among s...

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Autores principales: Johnson, Derek, Heltzel, Robert
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8190792/
https://www.ncbi.nlm.nih.gov/pubmed/34124443
http://dx.doi.org/10.1021/acsomega.1c00874
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author Johnson, Derek
Heltzel, Robert
author_facet Johnson, Derek
Heltzel, Robert
author_sort Johnson, Derek
collection PubMed
description [Image: see text] Understanding methane emissions from the natural gas supply chain continues to be of interest. Previous studies identified that measurements are skewed due to “super-emitters”, and recently, researchers identified temporal variability as another contributor to discrepancies among studies. We focused on the latter by performing 17 methane audits at a single production site over 4 years, from 2016 to 2020. Source detection was similar to Method 21 but augmented with accurate methane mass rate quantification. Audit results varied from ∼78 g/h to over 43 kg/h with a mean emissions rate of 4.2 kg/h and a geometric mean of 821 g/h. Such high variability sheds light that even quarterly measurement programs will likely yield highly variable results. Total emissions were typically dominated by those from the produced water storage tank. Of 213 sources quantified, a single tank measurement represented 60% of the cumulative emission rate. Measurements were separated into four categories: wellheads (n = 78), tank (n = 17), enclosed gas process units (n = 31), and others (n = 97). Each subgroup of measurements was skewed and fat-tailed, with the skewness ranging from 2.4 to 5.7 and kurtosis values ranging from 6.5 to 33.7. Analyses found no significant correlations between methane emissions and temperature, whole gas production, or water production. Since measurement results were highly variable and daily production values were known, we completed a Monte Carlo analysis to estimate average throughput-normalized methane emissions which yielded an estimate of 0.093 ± 0.013%.
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spelling pubmed-81907922021-06-11 On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site Johnson, Derek Heltzel, Robert ACS Omega [Image: see text] Understanding methane emissions from the natural gas supply chain continues to be of interest. Previous studies identified that measurements are skewed due to “super-emitters”, and recently, researchers identified temporal variability as another contributor to discrepancies among studies. We focused on the latter by performing 17 methane audits at a single production site over 4 years, from 2016 to 2020. Source detection was similar to Method 21 but augmented with accurate methane mass rate quantification. Audit results varied from ∼78 g/h to over 43 kg/h with a mean emissions rate of 4.2 kg/h and a geometric mean of 821 g/h. Such high variability sheds light that even quarterly measurement programs will likely yield highly variable results. Total emissions were typically dominated by those from the produced water storage tank. Of 213 sources quantified, a single tank measurement represented 60% of the cumulative emission rate. Measurements were separated into four categories: wellheads (n = 78), tank (n = 17), enclosed gas process units (n = 31), and others (n = 97). Each subgroup of measurements was skewed and fat-tailed, with the skewness ranging from 2.4 to 5.7 and kurtosis values ranging from 6.5 to 33.7. Analyses found no significant correlations between methane emissions and temperature, whole gas production, or water production. Since measurement results were highly variable and daily production values were known, we completed a Monte Carlo analysis to estimate average throughput-normalized methane emissions which yielded an estimate of 0.093 ± 0.013%. American Chemical Society 2021-05-27 /pmc/articles/PMC8190792/ /pubmed/34124443 http://dx.doi.org/10.1021/acsomega.1c00874 Text en © 2021 The Authors. Published by American Chemical Society Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Johnson, Derek
Heltzel, Robert
On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site
title On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site
title_full On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site
title_fullStr On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site
title_full_unstemmed On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site
title_short On the Long-Term Temporal Variations in Methane Emissions from an Unconventional Natural Gas Well Site
title_sort on the long-term temporal variations in methane emissions from an unconventional natural gas well site
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8190792/
https://www.ncbi.nlm.nih.gov/pubmed/34124443
http://dx.doi.org/10.1021/acsomega.1c00874
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