Hydrodynamics of Off-Bottom Plug Placements in Deviated Wells
Bibliographic record
Abstract
Abstract Wellbores come in various shapes, from vertical to deviated and horizontal configurations. Deviated or horizontal wells typically involve a vertical drilling phase before shifting towards the target direction. As oil and gas production becomes economically unviable, well abandonment is common, involving the deployment of multiple cement plugs. The off-bottom plugs, located above the lowermost plug, are strategically placed in the vertical or least deviated sections of the well. We consider a representative 2D model for the early stages of cement placement, where slurry is injected from a concentric injector with the well, and explore the influence of well inclination on the placement process. In vertical wells, the injected fluid forms a central finger below the injector. However, in highly deviated wells, the fluid slumps towards one side of the casing walls. The transition between these two flow regimes occurs through a monotonic change with the inclination angle. In all cases, the buoyancy-driven flow is disrupted, resulting in a mixed layer below the injector, and the accumulation of the injected fluid above it. While the accumulated fluid remains primarily unmixed with wellbore fluids in vertical wells, intermittent mixing occurs in deviated wells. The frequency and magnitude of this mixing change non-monotonically with the inclination angle.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".