Experimental Investigation of Heavy over Light Fluid Mix Phenomena in Vertical Wells
Bibliographic record
Abstract
The Heavy over Light (HOL) solution, invented by Reelwell, is a main feature of the Reelwell Drilling Method (RDM) and has the potential to improve the capability to drill through challenging pressure zones. This solution can reduce torque and drag and enable Managed Gradient Drilling (MGD) operations to be performed with little to no wellhead pressure. MGD is an advanced version of Managed Pressure Drilling (MPD) and can provide a constant downhole pressure gradient.\nThe RDM solution is comprised of using a dual drill string for improved downhole pressure measurement and control. This solution utilizes a passive heavy fluid in the well annulus and an active light fluid for cleaning the well. The MGD performance depends the ability to control the mixing zone between these two fluids during the operations.\nThe HOL solution in the horizontal sections was verified by Reelwell in a test well in Canada\nin 2016, but the vertical section still remains to be investigated and verified.\nThis thesis presents a thorough investigation of the HOL mixing zone in the vertical section of experimental wells. Experiments with different fluid properties and various well diameters has been conducted and the relation between these parameters and the mixing zone length is presented.\nThe experimental result showed that both the clearance between the well and the drill string and the lower shear yield stress (LSYS) of the light fluid have effects on the mixing zone length.\nThis is also confirmed by theory. Critical values for Δρ, ΔPV and for the viscoelastic ratio, (𝐻�𝐺�′ − 𝐿�𝐺�′)⁄(𝐻�𝐺�′′ − 𝐿�𝐺�′′), where the mixing zone is short and stable below these values, have been observed. In addition, the mixing zone as a function of a correlation factor is presented and multivariate regression models have been developed. Finally, it is shown good comparison between the models and the experimental data. For further work, it would be preferable to perform a greater amount of experiments with larger well diameters and longer well pipes.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.001 | 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".