Department of Civil Engineering and Applied Mechanics, McGill University, Montreal H3A 0G4, Canada.
Environ Sci Technol. 2021 Jan 5;55(1):563-570. doi: 10.1021/acs.est.0c04265. Epub 2020 Dec 15.
Abandoned oil and gas wells are one of the most uncertain sources of methane emissions into the atmosphere. To reduce these uncertainties and improve emission estimates, we geospatially and statistically analyze 598 direct methane emission measurements from abandoned oil and gas wells and aggregate well counts from regional databases for the United States (U.S.) and Canada. We estimate the number of abandoned wells to be at least 4,000,000 wells for the U.S. and at least 370,000 for Canada. Methane emission factors range from 1.8 × 10 g/h to 48 g/h per well depending on the plugging status, well type, and region, with the overall average at 6.0 g/h. We find that annual methane emissions from abandoned wells are underestimated by 150% in Canada and by 20% in the U.S. Even with the inclusion of two to three times more measurement data than used in current inventory estimates, we find that abandoned wells remain the most uncertain methane source in the U.S. and become the most uncertain source in Canada. Understanding methane emissions from abandoned oil and gas wells can provide critical insights into broader environmental impacts of abandoned wells, which are rapidly growing in number around the world.
废弃油井和天然气井是大气中甲烷排放最不确定的来源之一。为了减少这些不确定性并提高排放估算的准确性，我们对来自美国和加拿大的 598 个废弃油井和天然气井的直接甲烷排放测量数据进行了地理空间和统计分析，并汇总了区域数据库中的井数。我们估计，美国至少有 400 万口废弃油井，加拿大至少有 37 万口。甲烷排放因子取决于封堵状态、井类型和地区，范围从每口井 1.8×10 g/h 到 48 g/h，平均值为 6.0 g/h。我们发现，加拿大废弃油井和天然气井的甲烷年排放量被低估了 150%，美国则被低估了 20%。即使将当前清单估算中使用的数据增加两到三倍，我们发现废弃油井和天然气井仍然是美国最不确定的甲烷排放源，在加拿大则成为最不确定的排放源。了解废弃油井和天然气井的甲烷排放情况，可以为更广泛的废弃油井对环境的影响提供重要的见解，因为全球废弃油井的数量正在迅速增加。
