Creating Measurement-Based Oil and Gas Sector Methane Inventories using Source-Resolved Aerial Surveys

AbstractWe present a new framework for incorporating aerial measurements into comprehensive oil and gas sector methane inventories that achieves robust, independent quantification of measurement and sample size uncertainties, while providing timely source-level insights beyond what is possible in current official inventories. This “hybrid” inventory combines top-down, multi-pass aerial measurements with bottom-up estimates of unmeasured sources leveraging continuous probability of detection and quantification models for a chosen aerial technology. Notably, the combined Monte Carlo and “mirror-match” bootstrapping technique explicitly considers skewed source distributions and finite facility populations that have not been previously addressed. The protocol is demonstrated to produce a comprehensive upstream oil and gas sector methane inventory for British Columbia, Canada, which while approximately 1.7 times higher than the most recent official bottom-up inventory, reveals a lower methane intensity of produced natural gas (< 0.5%) than comparable estimates for several other regions. Finally, the developed method and data are used to upper bound the potential influence of source variability/intermittency on the overall inventory, directly addressing an open question in the literature. Results demonstrate that even for an extreme case, variability/intermittency effects can be addressed by sample size and survey design and have a minor impact on overall inventory uncertainty.