Experimental Study of Displacement Flows in a Vertical Eccentric Annulus
Bibliographic record
Abstract
Abstract Primary cementing is an essential part in constructing an oil or gas well. Leakage occurs due to a poor seal of the cement in the annulus, which may be caused either during or after placement. Key in controlling leakage is to ensure the integrity of the surface casing, which is primarily vertical. This paper addresses the underlying fluid mechanics that may affect cement placement in vertical casings. We present results of miscible Newtonian displacement flow experiments carried out in a dimensionally scaled laboratory set-up. The experimental set-up has been described in detail (Renteria and Frigaard, J. Fluid Mech, 905, 2020) [1], and used previously in horizontal orientation. We use the same annular flow loop but in vertical configuration. The effects of density difference, viscosity ratio and eccentricity of the annulus have been studied. We find that the eccentricity is always dominant in affecting the displacement, and the narrow side view gives us more detail of residual layers. The buoyancy number and Reynolds number are key factors that affect the stability of the whole process. Large buoyancy number and small Reynolds number lead to stable interface and less dispersion. The residual layer at the narrow side can be removed out to a degree, under significant density difference and at lower flow rates. However, the viscosity ratio appears to play only a secondary role in vertical displacement flows. Our future directions will use the present experiments for comparison with 2D and 3D models, and we then aim to extend the experimental program to shear-thinning non-Newtonian fluids.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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 teacher head, 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".