Emissions of coalbed and natural gas methane from abandoned oil and gas wells in the United States

Recent work indicates that oil and gas methane (CH 4 ) inventories for the United States are underestimated. Here we present results from direct measurements of CH 4 emissions from 138 abandoned oil and gas wells, a source currently missing from inventories. Most abandoned wells do not emit CH 4 , but 6.5% of wells had measurable CH 4 emissions. Twenty‐five percent of wells we visited that had not been plugged emitted > 5 g CH 4 h −1 . Stable isotopes indicate that wells emit natural gas and/or coalbed CH 4. We estimate that abandoned wells make a small contribution (<1%) to regional CH 4 emissions in our study areas. Additional data are needed to accurately determine the contribution of abandoned wells to national CH 4 budgets, particularly measurements in other basins and better characterization of the abundance and regional distribution of high emitters.