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

Abstract

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.

The Futility of Relative Methane Reduction Targets in the Absence of Measurement-Based Inventories

“…Conversely, the dominance of methane emissions from Cold Heavy Oil Production with or without Sand (CHOP­(S)) is missed or obscured in the official inventory, especially CHOP­(S) emissions via engine sheds and wellheads, which represent 38% of the measured inventory (167 kt). Not to be confused with unintended SCVFs, CHOP­(S) wells intentionally produce gas that flows to the surface through the annular space between the production casing and well bore . This gas is typically vented, either at the wellhead or via an engine shed where a portion of the gas is used to power an engine driving the hydraulic well pump and nominally should be included in reported vent volumes.…”

“…However, these reported decreases also coincided with large decreases in oil production, including a 21 and 22% drop at the same subsets of facilities operating in the two years before versus after January 1, 2020. Moreover, it is now well established that actual levels of venting in the Canadian oil and gas industry are consistently underestimated by reported data, ,,,, especially at heavy oil sites ,,, which dominate emissions in Saskatchewan. Confidence in the reported data is further eroded considering that reported volumes of gas production, venting, flaring, and fuel use must only be measured if certain annually averaged volumetric thresholds are exceeded .…”

“…This assumes that Directive PNG036 had no effect on activity-normalized venting rates. A third and fourth model augment the first two by also allowing for the possibility that some postpolicy vented gas is mis-reported as fuel use, which recent field measurements suggest could be a significant factor in underreported vent volumes . Specifically, in cases where the reported fuel use-to-oil production ratio was noted to increase after January 1, 2020, the extra fuel use is instead assumed to be mis-reported venting.…”

Creating Measurement-Based Oil and Gas Sector Methane Inventories using Source-Resolved Aerial Surveys

“…Studies in multiple jurisdictions have repeatedly found signi cant underestimation of methane emissions in o cial inventories using a range of approaches [3][4][5][6][7][8][9][10] . While proposed reasons for these discrepancies include the failure of bottom-up emission factor calculations to account for strongly skewed source distributions and "super-emitters" 8, [11][12][13][14][15] , the limited data sets behind bottom-up emission factors and associated measurement uncertainties in creating these emission factors 4,5,[16][17][18] , and potential for episodic emissions -speci cally manual liquid unloadings -to skew measurements 19 , the root of the challenge is the lack of direct measurement data in current inventories. Moreover, missing in the discussion is how quickly inventories can be expected to evolve and how quickly they will need to evolve if we are to accurately track progress toward reduction targets.…”

Creating measurement-based oil and gas sector methane inventories using source-resolved aerial surveys

“…Studies in multiple jurisdictions have repeatedly found significant underestimation of methane emissions in official inventories using a range of approaches [3][4][5][6][7][8][9][10] . Proposed reasons for these discrepancies include the failure of bottom-up emission factor calculations to account for strongly skewed source distributions and super-emitters 8,[11][12][13][14][15] ; the limited data sets behind bottom-up emission factors and associated measurement uncertainties in creating these emission factors 4,5,[16][17][18] ; and the potential for episodic emissions-specifically manual liquid unloadings-to skew measurements 19 . Ultimately, the root of these challenges is the lack of direct measurement data in current inventories.…”