Understanding Long-Term Solute Transport in Sedimentary Basins: Simulating Brine Migration in the Alberta Basin. Final Report
Bibliographic record
Abstract
Mass transport in deep sedimentary basins places important controls on ore formation, petroleum migration, CO2 sequestration, and geochemical reactions that affect petroleum reservoir quality, but large-scale transport in this type of setting remains poorly understood. This lack of knowledge is highlighted in the resource-rich Alberta Basin, where geochemical and hydrogeologic studies have suggested residence times ranging from hundreds of millions of years to less than 5 My, respectively. Here we developed new hydrogeologic models that were constrained by geochemical observations to reconcile these two very different estimates. The models account for variable-density fluid flow, heat transport, solute transport, sediment deposition and erosion, sediment compressibility, and dissolution of salt deposits, including Cl/Br systematics. Prior interpretations of Cl/Br ratios in the Alberta Basin concluded that the brines were derived from evaporatively-concentrated brines that were subsequently diluted by seawater and freshwater; models presented here show that halite dissolution must have contributed strongly as well, which implies significantly greater rates of mass transport. This result confirms that Cl/Br ratios are subject to significant non-uniqueness and thus do not provide good independent indicators of the origin of brines. Salinity and Cl/Br ratios provided valuable new constraints for basin-scale models, however. Sensitivity studies revealed that permeabilities obtained from core- and field-scale tests were appropriate for basin-scale models, despite the differences in scale between the tests and the models. Simulations of groundwater age show that the residence time of porefluids in much of the basin is less than 100 My. Groundwater age increases with depth and approaches 200 My in the deepest part of the basin, but brines are significantly younger than their host rocks throughout the basin.
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".