Methane emissions from conventional and unconventional oil and gas production sites in southeastern Saskatchewan, Canada

Abstract

Energy development in southeastern Saskatchewan, Canada, is unique because conventional and unconventional oil and gas production is co-located. Mobile surveys are ideal for understanding emissions in this area because the overlap of production makes it difficult for airborne or satellitebased methods to differentiate emissions from each type of infrastructure. In this study, we conducted truck-based mobile surveys in the unconventional Canadian Bakken and conventional Weyburn-Midale fields to enumerate and attribute individual methane plumes, estimate methane (CH 4 ) emission rates, and compare emission vectors. We sampled downwind of 645 conventional and 289 unconventional sites, covering over 4500 km of public roads. We found that 28% of surveyed conventional sites were emitting, compared to 32% of surveyed unconventional sites. Mean emissions intensities in each development were 20 m 3 CH 4 /day per conventional site and 59 m 3 CH 4 /day per unconventional site. Emissions intensities in southeastern Saskatchewan fall on the lower range of other emissions estimates from developments in the US and Canada.

Methane emissions from upstream oil and gas production in Canada are underestimated

“…Gas concentrations (CH 4 , CO 2 , C 2 H 6 , H 2 S) were measured in real time using laser spectrometers (Picarro Inc., Santa Clara, CA, USA), (2) computational signal processing and geochemical analysis were used to distinguish oil and gas emissions from biogenic, naturally occurring sources, or other anthropogenic emissions, (3) we conducted a back-trajectory analysis to attribute emission anomalies observed on-road to specific upwind sites, (4) volumetric emissions rates were estimated via a point-source Gaussian Dispersion Model (GDM). Each of these steps, and uncertainties therein, have been explained previously 9 , 17 , 18 . Thus, only a brief overview is included in the next three subsections.…”

“…The uncertainties related to our methods of plume detection, attribution, and emission rate estimation have been previously evaluated 9 , 17 , 18 . Plume detection uncertainty (i.e.…”

“…S1) include ~ 20% of the non-oilsands producing sites in western Canada. Results from four of these campaigns have already been published 17 , 18 , but this is the first time the 6650 emission rate estimates have been aggregated. This study represents the most regionally nuanced estimate of upstream Canadian oil and gas fugitive and vented CH 4 emissions to date, and uses a much larger sample population than the ~ 300 site survey studies used by the Canadian industry to calibrate its upstream CH 4 inventory 19 .…”

“…Our measurements showed average site-level emission rates in Peace River decreased nearly three-fold from 2016 (31.5 m 3 /day/site) to 2018 (11.1 m 3 /day/site) (Table S4 ), which suggests that these new regulations are resulting in significant mitigation success in this area. Sour (H 2 S-bearing) fields are another example of regulatory success; since H 2 S is a serious health risk, sour developments like SE Saskatchewan have more restrictions on venting, which inadvertently aids in CH 4 mitigation since the gases are co-emitted 18 , 24 . SE Saskatchewan had the lowest average site-level emission rate out of all regions included in this study (Fig.…”

Methane Mitigation: Methods to Reduce Emissions, on the Path to the Paris Agreement

“…In practice, each quantification problem is different, and measuring teams have different analytical assets. Ground vehicles are appropriate and widely used for studying locally sourced plumes (e.g., Baillie et al, ) and can be supplemented with UAV (drone) grab‐bag sampling (Brownlow et al, ), or by tethered sampling tubes lifted either by UAVs (Allen et al, ), or pop‐up balloons (Steiger et al, ). Such approaches can yield 3‐D sampling for local‐scale (e.g., site‐specific) flux retrieval using mass balancing approaches to quantify fluxes accurately.…”