Use of X-ray Absorption Spectrometry to Determine Diffusion Coefficients in Low-Permeability Shale: Queenston Formation Shale
Bibliographic record
Abstract
A new spectrometric technique for measuring diffusion coefficients of Ordovician Queenston Formation shale from the Michigan Basin of southwest Ontario, Canada is presented; in this case pore diffusion coefficients (Dp) were determined for the conservative (iodide, I^-) and reactive (cesium, Cs^+) tracers in porous media. Furthermore, diffusion-reaction parameters such as Cation exchange capacity (CEC) were obtained for the reactive tracer, Cs^+ by the reactive-transport modeling. The principle of X-ray absorption spectrometry (XAS) is based on the attenuation of high atomic number of diffusive species (e.g. Cs^+and I^-) in porous media, allowing for the quantification of the resulting spatial changes. The technique employs a 1.1 mm collimated X-ray beam to resolve the tracer presence in a slice; small region of a rotating sample for a fixed time. The x-ray beam is incident on a sample of porous rock while the transmitted beam is detected on the opposite side of the sample, allowing acquisition of a transmitted X-ray energy spectrum vs intensity (counts). Additional analyses such as mineralogical studies by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) were conducted to improve the understanding of solute transport. The comparison of the data obtained by the XAS method indicating a good agreement with established radiography and other conventional diffusion methods provide an alternate approach for quantifying the diffusion coefficient of porous media.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.000 | 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".