Developing a better understanding of methane emissions patterns and inventories across major Canadian energy developments

Canadian governments have pledged to cut energy sector methane emissions 40-45% below 2012 levels by 2025. Site-level measurements of methane will guide reduction efforts and confirm the success of new regulation. However, available data are still sparse, and current reported inventories are disputed due to the discrepancies between industry-reported inventories and those derived from measurement studies. In this study, we pooled and analyzed fugitive and vented methane measurements from nearly 10,000 well pads in Canada to examine emission trends across developments, infrastructure types, and to derive a measurement-based bottom up inventory. Measurements were contributed by academia, industry, regulators, and NGOs, using a variety of measurement methodologies including vehicle-based, gaussian dispersion, OGI, aircraft, and tracer release. Methane measurements were aggregated to a total site-level value as some of the methodologies could not discriminate between vented and fugitive emissions. Unexpectedly, measurements revealed that, in some cases, infrastructurally simple sites had higher emissions than complex sites, despite having fewer components with potential to emit. This is likely due to a combination of factors such as maintenance frequency, and likelihood of onsite gas use, flaring, or conservation. Additionally, this finding highlights that individual component counts are not always a good predictor of emissions, and that other factors may be equally important. That said, we determined that scaling up facility-level measurements introduces less uncertainty in bottom-up inventory estimates compared to scaling component measurements/emission factors. Lastly, measurements suggest that inactive (suspended and abandoned) sites do sometimes emit methane, but unfortunately the number of available measurements is still rather low. Inventory estimates that incorporate inactive sites are measurably different because of the large inactive site count (>35% of Alberta wells are inactive), but more measurements are needed to better understand their contribution to the energy sector's greenhouse gas footprint.