Start-up of Gelled Waxy Crude Oil Pipelines: A New Analytical Relation to Predict the Restart Pressure
Bibliographic record
Abstract
Abstract In this paper, we investigate the problem of the start up of gelled waxy crude oil flows in a pipeline. Waxy crude oils are deemed to be weakly compressible, thixotropic and viscoplastic material. In severe situations, the waxy crude oil is fully gelled in the pipeline and the main issue concerning the restart of waxy crude oils relies on the estimation of the minimum pressure required at the pipe inlet. The objective of this study is to examine the possibility that the flow can restart for a pressure drop below the value predicted by the conservative relation Δp=4τyL/D, where τy denotes the yield stress, L the pipe length and D the pipe diameter, thanks to the combined effects of compressibility and thixotropy. Using a 1.5D numerical model, we evidence that there exists situations where, though the pressure drop is below the theoretical minimum pressure drop 4τyL/D, the flow restarts thanks to the combined effects of thixotropic and compressibility. From a parametric survey, we derived a new analytical relation able to predict more accurately the minimum pressure required to restart pipelines filled with a gelled waxy crude oil. This relation accounts for not only viscoplastic effects but also for compressibility and thixotropic effects.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".