Effects of Geometrical Irregularities on Displacement Flow in Annuli: An Experimental Approach
Bibliographic record
Abstract
Abstract Effective primary cementing is essential for ensuring well integrity, extending operational life, and mitigating environmental risks. Existing research on the displacement of drilling mud by cementing fluids (wash, spacer, slurry), has focused extensively on displacement flow in a uniform eccentric annular space between the casing and wellbore wall. Very few investigations have focused specifically on irregular wellbore geometries such as ovality, rugosity and washout sections. Eccentricity has long ago been identified as the most critical factor influencing mud removal. Experimental studies reveal that parameters like flow rates, viscosity ratios, and density ratios significantly affect displacement front stability. For instance, significant density differences (buoyancy) can stabilize highly eccentric annular displacement flows in vertical annuli. Little experimental research has been yet carried out on other irregularities. Experiments have shown that eccentricity often dominates the effects of local enlargements or obstructions, with residual fluid accumulation and localized displacement effects noted. Recent computational advances have incorporated realistic geometries derived from caliper data to better understand flow behaviors in irregular wellbores. Although caliper data is complex, much of the borehole variation is captured in a few low frequencies, prompting the question of how displacement flows respond to wavy walled geometries. This study introduces a novel experimental setup featuring a wavy annulus inspired by caliper-filtered wellbore data. The newly developed wavy annulus is designed for experiments under both concentric and eccentric configurations. Here we report preliminary results using Newtonian fluid pairs, to experiments explore displacement dynamics within this semi-sinusoidal geometry. The findings contribute to optimizing displacement flows in complex wellbore geometries, advancing primary cementing practices and raising industry awareness of these effects.
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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 | 0.000 | 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".