Methane Emissions from Hydraulically Fractured Natural Gas Developments in Northeastern British Columbia

If we are to attain the recent North American goals to reduce methane (CH4) emissions, we must understand emission patterns across developments of different types. In this study we quantified the incidence of CH4 emissions from unconventional natural gas infrastructure accessing the Montney play in British Columbia, Canada. We used mobile surveying to collect CH4 and CO2 measurements over 11,000 km of survey campaigns. Our routes brought us past more than 1600 unique well pads and facilities, and we repeated the six routes 7-10 times during summer (2015) and winter (2016) to explore temporal variability. Well pads and facilities were considered probable emission sources only if they were upwind by 500 m or less from the survey vehicle, and on-road concentrations were in excess of local background. In the summer campaigns we found that 47% of individual active production wells emitted CH4-rich plumes, and most of them emitted persistently across repeat surveys. Older infrastructure tended to emit more frequently (per unit), with comparable severity to younger infrastructure in terms of measured excess concentrations on-road. About 26% of abandoned wells were also found to be emitting. Extrapolating our emission incidence values across all abandoned oil and gas infrastructure in the BC portion of the Montney, we estimate that there are more than 550 abandoned wells in this area that could be emitting CH4-rich plumes. The results of this study suggest that analyzing emitting infrastructure by ages and operational differences can help delineate emission trends. Considering the recent industry downturn, our results also highlight the importance of focusing emission reduction efforts on abandoned and suspended infrastructure, as well as active. This is the first bottom-up monitoring study of fugitive emissions in the Canadian energy sector, and the results can be used to inform policy development to reduce energy-related emissions.