Methane Venting at Cold Heavy Oil Production with Sand (CHOPS) Facilities Is Significantly Underreported and Led by High-Emitting Wells with Low or Negative Value

• Published in: Environmental science & technology Vol. 57; no. 8; pp. 3021 - 3030
• Main Authors: Festa-Bianchet, Simon A, Tyner, David R, Seymour, Scott P, Johnson, Matthew R
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 28.02.2023
• Subjects: Aerial surveys; Air Pollutants - analysis; Airborne sensing; Aircraft; Canada; Emission analysis; Emission inventories; Emission measurements; Emissions; Gas venting; Lidar; Methane; Methane - analysis; Mitigation; Natural Gas - analysis; Oil; Oil and Gas Fields; Petroleum production; Sand; Wells; Canada; venting; carbon pricing; spectroscopy; LiDAR; methane; marginal wells; heavy oil; emissions; unsteady
• DOI: 10.1021/acs.est.2c06255
• ISSN: 0013-936X

Cold Heavy Oil Production with or without Sand, CHOP(S), facilities produce a significant portion of Canada's conventional oil. Methane venting from single-well CHOPS facilities in Saskatchewan, Canada was measured (i) using Bridger Photonics' airborne Gas Mapping LiDAR (GML) at 962 sites and (ii) on-site using an optical mass flux meter (VentX), ultrasonic flow meter, and QOGI camera at 11 sites. The strong correlation between ground measurements and airborne GML supported subsequent detailed analysis of the aerial data and to our knowledge is the first study to directly test the ability of airplane surveys to accurately reproduce mean emission rates of unsteady sources. Actual methane venting was found to be nearly four times greater than the industry-reported levels used in emission inventories, with ∼80% of all emissions attributed to casing gas venting. Further analysis of site-total emissions revealed potential gaps in regulations, with 14% of sites appearing to exceed regulated limits while accounting for 61% of measured methane emissions. Finally, the concept of marginal wells was adapted to consider the inferred cost of methane emissions under current carbon pricing. Results suggest that almost a third of all methane is emitted from environmentally marginal wells, where the inferred methane cost negates the value of the oil produced. Overall, the present results illustrate the importance of independent monitoring, reporting, and verification (MRV) to ensure accuracy in reporting and regulatory compliance, and to ensure mitigation targets are not foiled by a collection of disproportionately high-emitting sites.