Isotopic fingerprinting of fugitive methane and CO2 from the Western Canada Sedimentary Basin (WCSB): Data documentation and impact
Bibliographic record
Abstract
The general public, industry and regulators seek information about both intentional and unintentional greenhouse gas (GHG) emissions from energy wells. Minimizing these emissions may be one of the easiest steps to reaching reduction targets. ẟ13C is a common tool used to assess sources of atmospheric methane. Here we report and map the isotopic composition of 1280 production gases from energy wells in the Western Canada Sedimentary Basin (WCSB), which mark the ẟ13C of downstream GHG emissions in the production and transmission network. The WCSB is a worldwide recognized hydrocarbon producer, with more than 450,000 energy wells drilled only in Alberta. Produced methane ẟ13C ranges from -70‰ (VPDB – biogenic source) to -23‰ (VPDB – over mature shale) averaging, -47.2‰. Many of the currently producing, shut-in and abandoned wells also emit fugitive gas through surface casings (SCVF) and soil/ground migration (GM). Their ẟ13C of the fugitive gases usually indicates a shallower source than the production target (average SCVF ẟ13Cmethane= - 55.6 ‰, GM ẟ13Cmethane= - 58.0 ‰, and average SCVF ẟ13CO2= - 55.6 ‰, GM ẟ13 ẟ13CO2= -15.8 ‰). Mapping (isoscapes) of isotope values from 2800 SCVF, and 1800 GM gases sampled across WCSB, show that geology and topography constrain the source of leaks. The spatial distribution and wide range of ẟ13C of fugitive methane across the WCSB provide insights and data to climate modellers seeking to attribute atmospheric methane sources but is also relevant for mitigation of emissions as well as informing regulators.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.004 | 0.008 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".