Fugitive Gas Migration in the Vadose Zone at an Experimental Field Site in the Montney Shale Gas Region
Bibliographic record
Abstract
Fugitive gas migration (GM) from compromised oil and gas wells remains a global concern. To understand environmental impacts from GM there is a need to characterize the transport and fate of fugitive gas in the vadose zone. We simulated subsurface wellbore leakage by injecting natural gas into thick unsaturated glacio-lacustrine deposits in a region of petroleum development in Western Canada. Methane and carbon dioxide effluxes were monitored and soil-gas samples were collected for molecular and stable carbon isotope analyses. A conceptual model was developed to demonstrate the physical and biogeochemical processes that control the spatial-temporal variability of GM. Methane oxidation partially attenuated natural gas; however, gas transport and fate were strongly influenced by variations in grain-size distribution and barometric pressure, resulting in episodic effluxes and lateral gas transport. To accurately detect, quantify and assess GM at oil and gas sites, adequate site characterization and continuous, spatially dense monitoring are necessary.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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".