Abstract
Aggressive reductions of oil and gas sector methane, a potent greenhouse gas, have been proposed in Canada. Few large-scale measurement studies have been conducted to confirm a baseline. This study used a vehicle-based gas monitoring system to measure fugitive and vented gas emissions across Lloydminster (heavy oil), Peace River (heavy oil/bitumen), and Medicine Hat (conventional gas) developments in Alberta, Canada. Four gases (CO2, CH4, H2S, C2H6), and isotopic δ13CCH4 were recorded in real-time at 1 Hz over a six-week field campaign. We sampled 1,299 well pads, containing 2,670 unique wells and facilities, in triplicate. Geochemical emission signatures of fossil fuel-sourced plumes were identified and attributed to nearby, upwind oil and gas well pads, and a point-source gaussian plume dispersion model was used to quantify emissions rates. Our analysis focused exclusively on well pads where emissions were detected >50% of the time when sampled downwind. Emission occurrences and rates were highest in Lloydminster, where 40.8% of sampled well pads were estimated to be emitting methane-rich gas above our minimum detection limits (m = 9.73 m3d–1). Of the well pads we found to be persistently emitting in Lloydminster, an estimated 40.2% (95% CI: 32.2%–49.4%) emitted above the venting threshold in which emissions mitigation under federal regulations would be required. As a result of measured emissions being larger than those reported in government inventories, this study suggests government estimates of infrastructure affected by incoming regulations may be conservative. Comparing emission intensities with available Canadian-based research suggests good general agreement between studies, regardless of the measurement methodology used for detection and quantification. This study also demonstrates the effectiveness in applying a gaussian dispersion model to continuous mobile-sourced emissions data as a first-order leak detection and repair screening methodology for meeting regulatory compliance.
Highlights
Methane is a short-lived greenhouse gas with a radiative heating potential 28–34 times that of carbon dioxide over a 100-year timespan, and is the main constituent of energy sector emissions (Rella et al, 2015; Gasser et al, 2017)
U.S studies have shown that inventory estimates based on emission factors tend to show downward bias (Miller et al, 2013; Allen, 2014; Brandt et al, 2014), and that emissions from U.S developments are higher than previous Environmental Protection Agency (EPA) estimates (Katzenstein et al, 2003; Karion et al, 2013; Miller et al, 2013; Pétron et al, 2014; Peischl et al, 2016)
In many developments, measured emissions are higher than emission factor-based inventory estimates, though discrepancies are development specific (Atherton et al, 2017; Johnson et al, 2017; Zavala-Araiza et al, 2018)
Summary
Methane is a short-lived greenhouse gas with a radiative heating potential 28–34 times that of carbon dioxide over a 100-year timespan, and is the main constituent of energy sector emissions (Rella et al, 2015; Gasser et al, 2017). Methane is emitted during flaring, venting (reported and unreported), fugitive leakage, combustion, storage and handling losses, and accidental releases (Canadian Association of Petroleum Producers, 2004). U.S studies have shown that inventory estimates based on emission factors tend to show downward bias (Miller et al, 2013; Allen, 2014; Brandt et al, 2014), and that emissions from U.S developments are higher than previous Environmental Protection Agency (EPA) estimates (Katzenstein et al, 2003; Karion et al, 2013; Miller et al, 2013; Pétron et al, 2014; Peischl et al, 2016). Alvarez et al (2018) estimates that measured emissions from the U.S oil and natural gas supply chain are ~60% higher than current EPA inventory estimates.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
