Reservoir characterization of fairways in a tight light oil play of the Upper Cretaceous Cardium Formation, west Pembina, Alberta, Canada
Bibliographic record
Abstract
Abstract Shallow-marine reservoirs of the Upper Cretaceous Cardium Formation contain one of the largest light oil accumulations in Canada, which have been exploited since the 1950s. Since 2008, multistage fractured horizontal wells have revived this play. This study presents a reservoir characterization of the offshore to shoreface unconventional reservoirs of the Cardium Formation in the halo play along the western margin of the legacy Pembina oil pool in central Alberta. Although permeability of these facies is too low to achieve economic production from vertical wells, they were the main carrier beds forming the migration pathway for charging the updip conventional reservoirs in the Pembina field. Three reservoir facies are present in the west Pembina study area: bioturbated muddy sandstones, interbedded sandstones and mudstones, and hummocky cross-stratified sandstones. Shoreface sandstones are relatively thin in the halo play area; thus, significant production in the horizontal wells is attributed to the thin sandstone beds and bioturbated muddy sandstone reservoir facies. To characterize these unconventional, heterogenous reservoirs, traditional reservoir evaluation techniques are integrated with computerized tomography scanning to better evaluate reservoir properties and flow pathways. Cutoffs of 90 gamma-ray API units, 6% porosity, and 0.075-md permeability were used to create a series of reservoir property maps. These detailed maps show the most prospective area of the halo play is a 4-km (2.5-mi)-wide zone immediately to the west of the legacy west Pembina Pool boundary. This lateral heterogeneity with narrow sweet spot fairways explains the significant production variability in these shallow-marine reservoirs.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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 teacher head, 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".