iTOUGH2-EOS7C model used to analyze multiphase flow and underpressured shale at the Bruce Nuclear Site, Ontario, Canada
Bibliographic record
Abstract
Hydraulic testing and long-term monitoring have revealed significant overpressures and dramatic underpressures in Paleozoic shales and carbonates at the Bruce nuclear site on the eastern flank of the Michigan basin near Tiverton, Ontario. Although several lines of evidence from both laboratory and field studies suggest that a small amount of gas phase methane could be present in the shale, previous studies examining causal linkages between gas phase and the underpressure have been inconclusive. To better elucidate processes in such a system, we simulated multiphase flow in a highly simplified 1-D representaion of the site using iTOUGH2-EOS7C. Specifically, we examined the effects of various factors, including geologic heterogeneity as well as different boundary and initial conditions, on the evolution of gas phase methane and gas- and water-phase pressures within the system. Heterogeneity observed in core samples was represented using three stratigraphic regions with distinctly different capillary pressure characteristics and, in one case, a few thin, distinct zones. Significant underpressure occurred only when gas pressures set as an initial conditions required it, and even in this case the underpressure was geologically short-lived. We conclude that the presence of multiple fluid phases alone is unlikely to explain the underpressure at the site and suggest that the influence of gas-phase methane on pore water flow is minimal. This is consistent with prior conceptualizations of the underpressured section at the site as a thick aquiclude, in which solute transport occurs extremely slowly, bounded by aquifers of significantly higher permeability.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 0.001 |
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".