Resolving Differences Between Core and Welltest Permeability in Basal Colorado Sandstones, Canada: The Role of Rock Heterogeneity, Relative Permeability and Formation Damage
Bibliographic record
Abstract
Abstract Welltest permeabilities are about 1 to 3 orders of magnitude lower than average core permeabilities from the same well for gas bearing Cretaceous Basal Colorado channel sandstones in south-eastern Alberta, Canada. The large differences coupled with local anomalously poor production from rock with high core permeabilities have raised uncertainty in both geologic and engineering communities regarding the reliability and representativeness of welltest and core permeabilities, respectively. Differences between core and welltest permeabilities are related to the core analyses, sampling and averaging techniques, and welltest interpretation procedures. Core absolute permeabilities are optimistic in part due to the effects of clay dehydration, rock decompaction, biased oversampling of high permeability intervals, and absence of relative permeability effects. Welltest effective permeabilities have been underestimated for gas wells producing minor amounts of water by wrongly assuming single phase gas flow in permeability calculations. The sum of these features creates the large differences between core and welltest permeability.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".