An airborne survey has shed light on one of the most important questions in atmospheric science; how much methane leaks during oil and gas extraction? Most sites leak very little, but a few “super-emitters” release terrifying amounts of gas. The positive side of this is that plugging a small number of leaky wells should be easier than dealing with a larger number that aren't quite as bad. First, however, the companies responsible need to care.
Methane concentrations in the atmosphere have been rising rapidly since 2005 after a decade of flatness. Since methane is the second most important global warming gas, that's very bad news. Disturbingly, we know little about why – there are so many methane sources and sinks in the world that working out which ones are responsible for the recent increase has posed a challenge.
The Permian Basin is a good place to start. The Basin “Is the largest and fastest growing oil and gas producing region in the United States,” according to a paper published in Environmental Science and Technology Letters. If the fossil fuel industry, rather than say, melting permafrost, is the immediate problem, the Permian is likely to show it. With production from the area having increased more than four-fold between 2014 and 2019, methane control is becoming urgent.
Dr Daniel Cusworth of NASA's Jet Propulsion Laboratory conducted high-frequency sampling of air over the Permian, which covers much of Texas and New Mexico, in late 2019 to identify methane plumes' origins. In one small section of the Basin, 3,067 plumes were detected. Some of these proved transient, but 123 that showed up time after time were responsible for 29 percent of all emissions. Half of these were from oil and gas production, the rest from transmission and processing. Another 258 more intermittent sources accounted for another 23 percent.
Leakage was much higher than in previous studies of other American oil and gas regions, with 36 percent of the Permian plumes releasing more than 500 grams (1.1 pounds) of methane an hour into the atmosphere. More importantly, however, the “super-emitters” were releasing at least 20 times that.
The study didn't identify the nature of the leaks, and therefore how hard they would be to fix. However, co-author Riley Duren of the University of Arizona noted in a statement; “We’ve done cooperative studies with oil and gas operators in California and the Permian where they independently report that 50% of the sources we’re finding are fixable.” Considering how much rarer super-emitters were in California in the first place, the fixable proportion could be even higher in Texas. The authors note the 123 sources are responsible for 5.5 percent of all methane emissions from oil and gas production America-wide.
Considering that when methane isn't leaking into the atmosphere it's an expensive fuel, you'd think plugging leaks like this would be a higher priority.