Baseline soil gas characterization at a pilot CO2 injection site in Alberta, Canada
Bibliographic record
Abstract
A baseline soil gas characterisation was performed on the upper 2.0 m of the CO2 and CH4 soil gas system at CMC’s Containment and Monitoring Institute, a geological CO2 storage field research station. Part of this characterisation was to investigate potential gas migration (GM) at the site’s infrastructure (wells and boreholes). Constant depth soil gas surveys following the endorsed methods outlined in the Alberta Energy Regulator's (2016) Directive-020 guideline were performed at six new wells, five legacy boreholes and three background locations at the site. Additionally, multi-level soil gas sampling surveys were conducted at four new wells and three background locations. Soil gas samples were analysed for CO2, N2, O2, CH4, ẟ13CCO2, and ẟ13CCH4. Soil gas surveys were conducted in the spring, summer and fall in 2017 and 2018. Additionally, SCVF was investigated at three new wells on site. The baseline soil gas characterisation concluded soil gas methane was likely sourced from the atmosphere and that there was no detectable GM present in the soil surrounding any of the site’s ground penetrations. However, GM was confirmed at one well during previous sampling in 2016, but its duration lasted less than one year. SCVF composed principally of methane (i.e. 7.4% to 97.3%) measured at three wells, was predominantly of biogenic origins with minor contributions from immature thermogenic methane. The SCVF at all three wells was sourced from the same zone, 195 m – 200 m bgs. The GM from the one well was noted as being of the same origins and source depth as the SCVF. The CO2 soil gas baseline conditions at the site demonstrated the CO2 was naturally sourced predominantly from biological respiration with minor inputs from methane oxidation. The baseline assessment found no evidence of exogenous CO2 in the soil gas system. Spatial (horizontal and vertical) and temporal (seasonal) variation in [CO2] and ẟ13CCO2 values across the site was demonstrated to be statistically significant. Ultimately, the baseline soil gas characterisation will be used to compare against future surveys to determine if CO2 leakage has occurred from the CO2 storage reservoir and migrated into the shallow vadose zone.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".