Abstract: MicroCT analysis of mineral phases, total and effective porosity in the Abenaki Formation, Scotian Shelf offshore eastern Canada
Bibliographic record
Abstract
Ongoing research on petroleum reservoirs offshore Nova Scotia includes analyses of carbonate material from the Abenaki Formation utilizing MicroComputed X-ray Tomography (microCT) a non-invasive procedure for imaging the internal structure of opaque objects. This method records spatial variations in the X-ray attenuation coefficient caused by mineralogical and porosity variations in a rock. The large differences between the attenuation of X-rays by solids, relative to that of air (i.e. pore space), ultimately permits the imaging and quantification of interparticle-, intraparticleand fracture-porosity in a sample. To date 22 core fragments from 6 wells, namely Panuke H08, Panuke IA/1, Demascota G-32, Acadia K-62, Margaree F-70 and Albatross B-13, have been sampled in the form of small plugs approximately 11 mm in diameter. A variety of carbonate textures have been sampled in order to identify limitations and error ranges under differing analytical conditions using a Skyscan 1072 MicroCT scanner, with spatial resolution of approximately 10 μm. Textures include intercrystalline limestone with pinpoint vugs, stylolites, inclusions and fractures (H-08), intercrystalline limestone to dolomitic limestone with vugs (Panuke IA/1), intercrystalline limestone to dolomitic limestone having pinpoint vugs (G-32), intercrystalline dolomitic limestone with vugs in association with horizontal fracturing, oolites, pisolites and sporadic stylolites (K-62), intercrystalline limestone to dolomitic limestone with vugs, with sporadic fractures and stylolites (F-70) and pelloidal, oolitic lime grainstone, with intercrystalline pore cement (B-13). With reference to effective porosity, preliminary analysis of sample plug 12 from Panuke H-08 with bulk porosity of ~8% shows an average of 4.44% effective porosity. This means that approximately 50% of the total pore space (for this sample) that are sufficiently interconnected to provide conduits for fluid movement. Carbonate samples tend to have a limited number of mineral phases present. This leads to the additional possibility of quantifying each phase by recognition of discrete grey-scale values. Preliminary microCT scans of a hydrothermal dolomite were undertaken at relatively low X-ray energy (< 100 keV). At such energies the photoelectric effect is primarily responsible for attenuation and the attenuation coefficient is a function of the effective atomic number (Zeff), with attenuation increasing
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".