Methane Emissions for Two Oil and Gas Regions of Alberta
Prof. Matthew Johnson
Methane is an important short-lived greenhouse gas that is many times more potent that carbon dioxide, especially in the near term. Reducing methane emissions is globally recognized as an important, near-term opportunity for mitigating climate change and meeting international climate commitments. The oil and gas industry is the largest sector source of methane emissions in Canada, and current federal and provincial regulatory efforts are focussed on reducing these emissions by 40-45%. However, many sources of methane in the oil and gas sector (especially so-called fugitive sources) are difficult to quantify and the national greenhouse gas inventory is consequently based on a combination of reported and estimated data. Especially important questions for the success of proposed regulations include the accuracy of the assumed baseline methane emission estimates, the accuracy and completeness of current reporting, and the nature and distribution of sources. This presentation will discuss a recent peer-reviewed study designed to directly compare “top-down” airborne methane measurements with updated region-specific “bottom-up” inventories utilizing current industry-reported flaring and venting volumes (reported data) and quantitative estimates of unreported venting and fugitive sources. For a 50 × 50 km measurement region near Red Deer, Alberta, characterized by natural gas and light oil production, measured methane fluxes were more than 17 times greater than that derived from directly reported data but consistent with our region-specific bottom-up inventory-based estimate. For a 60 × 60 km measurement region near Lloydminster, characterized by significant cold heavy oil production with sand (CHOPS), airborne measured methane fluxes were five times greater than directly reported emissions from venting and flaring and four times greater than our region-specific bottom up inventory-based estimate. The methodological comparison has implications both for understanding the accuracy and completeness of current emission reporting, and for evaluating the effectiveness of current federal and provincial regulatory efforts aimed at reducing methane emissions in this sector.
- M.R. Johnson, D.R. Tyner, S. Conley, S. Schwietzke, D. Zavala-Araiza (2017) Comparisons of Airborne Measurements and Inventory Estimates of Methane Emissions in the Alberta Upstream Oil and Gas Sector, Environmental Science & Technology, 51(21):13008-13017. (doi: 10.1021/acs.est.7b03525)