Synthesis of organic matter composition and maturation and gas data from selected deep source rock units for some wells in the Fox Creek area
Bibliographic record
Abstract
An analysis of historical and new organic matter data, as well as gas composition and isotopic ratios for deep hydrocarbon source rocks, is part of a holistic study of the potential environmental impact of unconventional hydrocarbon development in the Fox Creek area in Alberta. The goal of this activity is to use thermal maturation and gas data from deep source rocks to generate a database for the interpretation of source rocks for eventual dissolved hydrocarbons in shallow groundwater. The organic matter study consists of new petrographic observations on pellets from the Duvernay, Montney, Nordegg, and Mannville organic-rich samples. The petrography indicates that the organic matter is of marine Type II origin with one coal (Type III) sample in the Mannville Group. The organic matter reflectance measurements were taken on bitumen and converted to equivalent vitrinite reflectance values; vitrinite reflectance has been directly measured from the coal sample. The data indicate that all units reached thermal conditions for the production of hydrocarbons. The deep Duvernay Formation has the highest thermal maturity data that suggest the end of the oil window in the eastern end of the study area and the onset of the condensate zone in the western part of the study area. Rock-Eval data from publicly available wells in the GSC database were evaluated for the Duvernay, Montney, and Nordegg units. The Tmax values indicate that these units are within the hydrocarbon production zones. As with the vitrinite-equivalent data, the Duvernay Formation has reached the highest thermal maturity in the study area with values indicative of the condensate zone, the other units belong to the oil zone. Gas samples were collected in isotubes at the time of drilling. Samples were collected at various depths with some wells having only a short interval with data, while others have samples from a much longer interval. Data from 7 wells were available for our study, 6 of the wells are located at the eastern end of the study area while the last one is much further north. From gas composition (wetness ratio: C1/(C2+C3)) and delta-13C ratios of methane, the origin of the gas is thermogenic. The vertical trends of delta-13C ratios of ethane versus depth and wetness, as well as butane ratios (iC4/nC4) versus depth and wetness for wells with a longer distribution of samples, suggest partial isotopic rollover. The roll-over was not fully developed as nowhere do we see delta-13C ratios of ethane being lighter (more negative) than that delta-13C ratio of methane. This suggests, as supported by the organic matter reflectance and Rock-Eval data, that the study area never reached very high thermal conditions. The fact that significant statistical overlap of delta-13C ratios of methane and the inverted trend of delta-13C ratios for ethane challenges the use of these isotopes data for source interpretation of eventual dissolved hydrocarbons in groundwater. However, some limited data for the shallowest sampling intervals (<1500 m) in some wells suggest that more significantly different data might be present in shallower sections in the subsurface. Data from eventual shallow coals intercepted by monitoring wells to be drilled are considered critical for the interpretation of the source for eventual dissolved hydrocarbons in groundwater.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.005 | 0.007 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".