Bridging Detection Gaps in Oil and Gas Methane Inventories: Integrating Vehicle-Based to Aerial-Based and OGI Surveys

Methane emissions from the upstream oil and gas sector are a significant contributor to global methane emissions. Optical gas imaging (OGI) is widely used in regulatory leak-detection and repair (LDAR) programs in this sector, yet recent studies have found that OGI identifies only a fraction of site-level emissions compared to aerial-based measurement methods. There is a growing need for technological intercomparisons to better understand the strengths and limitations of different measurement methods in real-world field conditions, to inform their application in both LDAR and emission inventory development. In this study we compared vehicle-based, aerial-based, and quantitative OGI measurements at 302 sites in the Sundre region in Alberta, Canada. The vehicle-based system had the highest detection frequencies at 70% followed by aerial-based at 28% and OGI at only 12%. The vehicle-based system (0.017–32.2 kg/h) was also more sensitive than OGI (0.17–29.6 kg/h) and aerial-based (0.28–41 kg/h), capturing 72% of the emissions < 1kg/h, far more than the other methods, while aerial-based measurements identified higher total site-level emissions, particularly from site with many tall sources. Using a measurement-based inventory incorporating all three technologies, we found that each technology on its own is likely to underestimate total emissions – most significantly OGI at 29% of the total inventory, followed by vehicle-based (44%) and aerial-based (66%). These findings suggest that OGI misses a substantial fraction of emitting sites and total emissions. While this technology is valuable for identifying specific leaking components, it is less effective for site-level screening or for filling gaps in the low-level emission distribution. Aerial-based surveys similarly miss the low end of the emission distribution but are more effective at detecting and quantifying emissions from tall sources. Compared to OGI, the vehicle-based system was both more effective at finding emitting sites across a broader emission range and considerably faster, positioning it as a strong candidate for bridging the gap between component-level and aerial methane monitoring.