Investigation of Effect of Equivalent Diameter Definitions on Determination of Pressure Losses of Non-Newtonian Fluids in Annuli
Notice bibliographique
Résumé
Abstract Accurate estimation of pressure losses associated with fluid flow in annuli is essential to achieve better bottom hole pressure control in drilling operations. Control of formation pressures and optimization of hydraulic programs can be obtained only if the pressure losses in the circulation system are precisely known. One of the major challenges in determining actual annular pressure losses is that the non-Newtonian fluid flow in annular conduit is much more complex than pipe flow. Many investigators proposed different equivalent diameter concepts to link annular flow to well defined pipe flow. In this study, effect of using various equivalent diameter definitions together with three widely used rheological models is analyzed for different annular conditions. The study is aimed to show how pressure losses vary as rheological model and equivalent diameter definitions are coupled. The effects of the ration between inner and outer radius and the effect of flow rate on the accuracy of equivalent diameters are shown in the study as well. It is important to note that, based on the complexity of wellbore configuration, different equivalent diameter definitions might result in more accurate calculations for different parts of the system. This study provides guidelines to predict frictional losses with higher accuracy. Introduction While drilling fluid is circulated in the annulus, it exerts additional pressure on the wellbore. If frictional pressure losses in the annulus are not determined accurately, the equivalent circulating density (ECD) calculations will also be incorrect increasing the chances of having well control problems. Determination of pressure losses in annulus is harder due to the complexity of the geometry compared to regular circular geometry present in pipe flow. Depending on the clearance between wellbore (or casing inner diameter) and pipe outer diameter, and also on the flow rate required to carry cuttings effectively, flow might be in turbulent or laminar regime. Several authors analyzed the non- Newtonian flow in annular conduits and suggested either empirical or analytical solutions. However, disagreement between calculated and measured pressure losses, due to the complex nature of non-Newtonian fluids, still exists today. Fredrickson and Bird1 have derived an analytical expression to determine frictional pressure losses in annulus for Power Law rheological model. Their approach gives reasonable results when inner to outer radii ratios are more than 0.5. Kozicki, Chou and Tiu2 determined a relation between maximum velocity and pressure loss for Power Law fluids flowing in ducts of arbitrary cross-sections under laminar flow conditions. Zamora and Lord3 proposed a new numerical and graphical technique to determine pressure losses of non-Newtonian fluids in pipes and annuli. The model is valid for Bingham Plastic, Power Law and Yield Power Law rheological models. Langlinais, Bourgoyne and Holden4 compared actual annular pressure losses obtained from two wells with theoretical calculations. They found out that pressure losses are more sensitive to the definition of annular gap compared to rheological model.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,005 | 0,004 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».