Methane Emissions from Process Equipment at Natural Gas Production Sites in the United States: Liquid Unloadings

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• 作者：David T. Allen ; David W. Sullivan ; Daniel Zavala-Araiza ; Adam P. Pacsi ; Matthew Harrison ; Kindal Keen ; Matthew P. Fraser ; A. Daniel Hill ; Brian K. Lamb ; Robert F. Sawyer ; John H. Seinfeld
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：January 6, 2015
• 年：2015
• 卷：49
• 期：1
• 页码：641-648
• 全文大小：354K
• ISSN：1520-5851

文摘

Methane emissions from liquid unloadings were measured at 107 wells in natural gas production regions throughout the United States. Liquid unloadings clear wells of accumulated liquids to increase production, employing a variety of liquid lifting mechanisms. In this work, wells with and without plunger lifts were sampled. Most wells without plunger lifts unload less than 10 times per year with emissions averaging 21鈥?00鈥?5鈥?00 scf methane (0.4鈥?.7 Mg) per event (95% confidence limits of 10鈥?00鈥?0鈥?00 scf/event). For wells with plunger lifts, emissions averaged 1000鈥?0鈥?00 scf methane (0.02鈥?.2 Mg) per event (95% confidence limits of 500鈥?2鈥?00 scf/event). Some wells with plunger lifts are automatically triggered and unload thousands of times per year and these wells account for the majority of the emissions from all wells with liquid unloadings. If the data collected in this work are assumed to be representative of national populations, the data suggest that the central estimate of emissions from unloadings (270 Gg/yr, 95% confidence range of 190鈥?00 Gg) are within a few percent of the emissions estimated in the EPA 2012 Greenhouse Gas National Emission Inventory (released in 2014), with emissions dominated by wells with high frequencies of unloadings.