A Comparison of Plug-Derived and Probe-Derived Permeability in Cross-Bedded Sandstones of the Virgelle Member, Alberta, Canada: The Influence of Flow Directions on Probe Permeametry
Bibliographic record
Abstract
Abstract In this article we compare permeability measured on radially confined cylindrical plugs to permeabilities measured using a millimeter-scale probe tip on unconfined end-faces of the same plugs. Our investigation focuses on directional attributes of probe permeametry data as a means to understand the differences between plug-scale and probe-scale permeability magnitudes. Horizontal and vertical plug and probe flow tests were carried out on fine- to medium-grained, three-dimensional (3-D) cross-bedded sandstones collected from estuarine channel successions within the Cretaceous-age Virgelle Member at Writing-on-Stone Provincial Park, southern Alberta, Canada. The sandstones are heterogeneous in that they contain thin, discontinuous micaceous/carbonaceous laminae and apparent bedding-parallel grain-scale fabric. The resulting probe-derived permeabilities (0.4-3.5 d) are mostly higher than corresponding plug permeabilities (0.5-1.6 d), and mean probe-derived permeability anisotropy is significantly lower than that derived from plug-scale measurements, that is, plug kV/kH is less than probe-derived kV/kH. The results can be understood as a consequence of the model flow geometry of probe flow tests (Goggin et al., 1988), namely, that flow is preferentially directed parallel to the sample surface, radially outward from the probe tip. On end-faces of vertical plugs the bedding-parallel fabric further enhances flow parallel to the sample surface, and probe measurements yield reliable estimates of horizontal permeability, having magnitudes comparable to the permeability of equivalent horizontal plugs. For probe measurements on end-faces of horizontal plugs, flow paths appear to be variably confined parallel to bedding as a function of grain-scale and laminae-scale fabric, systematically yielding an overestimate of horizontal permeability (kPRH > kPLH). Interpretation of probe data in this orientation, however, is very uncertain, due to partitioning of flow paths parallel to and at angle to bedding. Significantly, almost all probe permeameter core and outcrop studies are based on measurements of this type.
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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".