Efforts to locate, measure and reduce the planet-warming methane emissions from global oil and gas operations often focus on large, concentrated sources. A growing body of research, however, suggests that, by not tracking smaller, dispersed sources, regulators, operators, and scientists are missing a significant share of the emissions problem.
Now, a new study led by scientists with the Environmental Defense Fund and published in the journal Atmospheric Chemistry and Physics finds that, of the roughly 15 million tonnes of methane coming from onshore oil and gas activities in the continental US annually, 70% comes from smaller, dispersed sources emitting less than 100 kg of methane per hour. And fully 30% of emissions are from sites releasing less than 10 kg per hour. At those rates, millions of tons of methane simply won’t show up under measurement methods not detecting those smaller sources of emissions.
The study also finds that, of the various activities, production well sites are responsible for 70% of the total regional oil and gas methane emissions. Among those well sites, between 67% and 90% of emissions originate from lower-producing sites responsible for just 10% of total oil and gas production (based on 2021 data, the latest available).
The good news is new instruments are coming online that can help. For example, MethaneSAT, developed by an EDF subsidiary with support from the Bezos Earth Fund and other donors and launched in March 2024, is specifically designed to quantify total regional emissions. It can detect large point sources as well as characterize the dominant smaller sources dispersed across large areas, mapping the full scope of emissions.
Looking Wider
Numerous studies have focused on high-emitting sites (“super-emitters”), deeming them responsible for a large fraction of total methane emissions. However, facilities emitting at lower rates and their contributions to total emissions are not well understood, especially when assessing national- and regional-level emission totals.
To get a better sense of how smaller, dispersed sources contribute to overall emissions, the study considered more than 1,900 facility-level emission rates gathered using sensitive ground-based site- and component-level measurements from 16 previous studies. The authors combine these empirical measurements with detailed infrastructure data to estimate emission rates for each individual oil and gas facility in the US, which are then used to determine emissions at the basin- and national-level.
Ground-based methods can detect emissions at 1 kg per hour or even less, but they lack the geographical reach of satellites or aircraft. The 673,940 total facilities in the measurement-based analytics developed for the study include 541,970 low-producing well sites; 121,824 non-low-production well sites; 4,431 gathering and boosting compressor stations; 2,093 transmission and storage compressor stations; 919 processing plants; and 3,153 total flare detections derived from the Visible Infrared Imaging Radiometer Suite satellite database. The overwhelming majority of these facilities were found to emit methane at rates less than 100 kg per hour, but, in aggregate, they contribute 70% of total methane emissions. For effective methane management and mitigation, these sources need to be accounted for.