Large-scale measurement campaigns of fugitive and vented emissions in British Columbia, Alberta, and Saskatchewan: Patterns and Opportunities
Prof. David Risk
Aggressive reductions of methane, a potent greenhouse gas, have been proposed for Canada’s oil and gas sector. Few large-scale measurement studies have been conducted to confirm a baseline. This study used a vehicle-based gas measurement system to measure fugitive and vented gas emissions across a number of oil and gas developments in Canada including: Lloydminster, Alberta (heavy oil); Peace River, Alberta (oil sands); Medicine Hat, Alberta (conventional gas); Fort St John, British Columbia (Montney tight gas); Midale, Saskatchewan (conventional oil); and Viewfield, Saskatchewan (Bakken tight oil). We recorded methane, carbon dioxide, hydrogen sulphide, ethane, and methane isotopic signature in real-time at 1-2 Hz over multi-week field campaigns, during which we made measurements downwind of over 5,000 active or suspended wells and facilities, in triplicate. Plumes that met strict geochemical criteria were attributed to nearby infrastructure via back-trajectory analysis. For ~1000 persistent emitters, we determined emissions severity using an AERMOD-system gaussian plume model. Methane was slightly elevated in most developments, with notably larger observed enhancements in Lloydminster. Emission frequency (incidence) ranged from as low as 25% of infrastructure per development, up to almost 70% (again in Lloydminster). Average emission severity per piece of infrastructure differed across developments by a factor of ~2, which was somewhat less than we expected. In each development, some prolific “super-emitters” were present, with the top-ranking 5-10% of sources emitting ~50% of the total volume. This study shows that emission mitigation needs will differ across developments, but that in all of them super-emitters would seem to offer low-hanging fruit. This study also shows how measurement at large scales is feasible using industry-standard air pollutant monitoring principles, that could be extended to methane to help decrease measurement and screening costs.
E. Atherton, D. Risk, C. Fougere, M. Lavoie, A. Marshall, J. Werring, J.P. Williams, C. Minions (2017) Mobile measurement of methane emissions from natural gas developments in Northeastern British Columbia, Canada, Atmospheric Chemistry and Physics, 17:12405-12420. (doi: 10.5194/acp-17-12405-2017)