Pit wall and core expressions of intra-point bar erosional surfaces in McMurray Formation point bars, Fort Hills Mine, Alberta, Canada
Bibliographic record
Abstract
Abstract At the Fort Hills open-pit mine in Northern Alberta, Canada, bitumen is extracted from sandstone of the Lower Cretaceous McMurray Formation. The main reservoir unit comprises 30 m thick point bars that are interpreted as the deposits of large, tidally influenced rivers. Intra-point bar erosion surfaces were interpreted in the deposits using detailed photographic evidence from the pit walls of the mine, and core and wireline well log data from nearby wells. In the mine walls, the surfaces are represented by a discontinuity that separates older, more shallow-dipping inclined heterolithic stratification (IHS) from younger, more steeply dipping IHS. Core and wireline logs show a predictable succession of strata across the discontinuity, which can be identified by: an abrupt change in facies that may coincide with a significant decrease in mudstone bioturbation intensity or complete lack of bioturbation; an abrupt increase in bed thickness; a change in bedding dip magnitude and azimuth; a change in grain size or grain size trend; a succession with uncharacteristically low or high angle of dip depending on where the well intersects the intra-point bar erosion surface; and/or the presence of sandstone beds interbedded with mudstone-clast breccia in the upper parts of the point bar succession. The presence of intra-point bar erosion surfaces in a reservoir exploited via steam-assisted gravity drainage (SAGD) could affect steam chamber development and/or fluid drainage, depending on the lithology of the units underlying and overlying the discontinuity. The results of this study will help geoscientists map point bar bodies in the subsurface, plan primary SAGD well pairs, predict SAGD reservoir performance, and understand steam conformance in wells.
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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 | 0.002 | 0.002 |
| 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".