Cementing Horizontal Wells: Complete Zonal Isolation Without Casing Rotation
Bibliographic record
Abstract
Abstract There is a common perception that displacing mud in horizontal wellbores is made ineffective by large density differences due to stratification of the fluid layers along the annulus. Hence the industry commonly employs methods such as casing rotation to move fluids around the annulus. Whilst such methods may be effective, they are not always necessary. Using a mathematical model of the process, we show that even with large density differences it is still possible to have a steadily advancing displacement front that displaces mud all around the annulus without casing rotation. The conditions when this is possible depend on the fluid rheologies, flow rate and hole geometry, but not the density difference. These conditions are easily quantified. Although density difference does not enter into the criteria for an effective displacement, the length of the interface along the wellbore does scale with the density difference. This means that, provided one is able to tolerate additional fluid volumes, we are able to effectively displace the mud even using fluids with large density differences. This new understanding of the displacement fluid mechanics opens up new opportunities for cementing difficult horizontal wells, (e.g. slimhole), where casing rotation is not possible.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".