Reconciliation of Ground and Airborne Measurements of Methane Emissions from Oil and Gas Production

[This work was presented at AGU Fall Meeting 2023.]
Our emissions model constrained by downwind (Tracer flux/OTM 33a) methane measurements of oil and gas (O&G) production sites in the Denver-Julesburg (DJ) Basin reveals a basin flux estimate of 8.3 (95% CI: 5.7, 14.5) tons CH4/hr, which is consistent with the EPA Greenhouse Gas Reporting Program (GHGRP) inventory and a recent aircraft mass balance study. We find that the average production site in the DJ emits 1.43 kg CH4/hr and 30% of total production emissions come from the highest 5% of emitting sites, those emitting greater than 4.3 kg CH4/hr. Combining state O&G production records with these measurements, we observe a basin averaged production-normalized emission rate of 0.36% (95% CI: +/- 0.09%), an order of magnitude lower than previous findings. Finally, CarbonMapper GAO surveys showed that high-emission events, point sources emitting greater than 10 kg CH4/hr, contribute 16% of the total upstream O&G methane emissions in the DJ basin. Although, operator records matching GAO plumes to known maintenance and pre-production events show that the contribution from fugitive high-emission events is 3.3%.