Three-dimensional FE Model for Pipeline in Permafrost with Thermosyphon Protection
Notice bibliographique
Résumé
Abstract Permafrost presents one of the key challenges to development of oil and gas reserves in both onshore and near-shore Arctic fields. The settlement due to permafrost thawing has been observed for warm foundations and pipelines. Such settlement is considered a severe threat to the integrity of these foundations and pipelines. Further, large-scale permafrost degradation due to the thermal interference with warm foundations and pipelines may potentially lead to major environmental issues, which may take hundreds of years to recover. As one of the most effective approachs to protect the permafrost from thawing, two-phase closed thermosyphons have been employed in many Arctic projects. The thermosyphons' response as a "thermo-diode" is the key to this technology. However, due to the complex nature of the fluid flow and heat transfer processes within the thermosyphon, simulating a thermosyphon with CFD methods in the engineering design could be overwhelming and unpractical. This paper presents a finite element (FE) model that can be used in the geothermal analysis of the permafrost, taking into account the external thermal interference and the effect of thermosyphons. An anisotropic conduction model of the thermosyphon is implemented to simplify the thermal-fluid processes within the thermosyphon, and reduce the computational cost. The developed model can be used to optimize the design of new infrastructures and pipelines in the permafrost, as well as to assess how thermosyphons work as a mitigation method in existing projects that are affected by permafrost thawing. Introduction to permafrost Permafrost is ground at or below the freezing point of water (0°C or 32°F) for two or more successive years. It is a very common geographic phenomenon in the North. Most permafrost of the Northern Hemisphere is distributed in Russia (80% of Siberia), Alaska (80%), Canada (50%), Greenland (81%), China (22%) and northern Europe. Recently, there is an increasing interest in the research of Arctic offshore permafrost because of the difficulties it poses for offshore oil development. For Arctic offshore projects, permafrost typically exists in shallow waters and at shore crossing. The challenge of constructing a pipeline in the permafrost is two-fold. One is to design the pipeline in a way that is affordable and stable over its working period; the other is to eliminate or limit the impact of the pipeline to the fragile arctic environment. Thaw settlement is considered the most direct problem related to warm pipeline buried in permafrost. With the heat released from the pipeline, the surrounding permafrost may gradually thaw over years of operation. Depending on the amount of heat released from the pipe, the soil type and the distribution of massive ice in the permafrost, differential settlement is likely to occur. In areas, the pipeline may be no longer supported vertically and may be, in effect, bearing the weight of soil on its top. This causes the pipeline to deflect into the void created by settlement and induces strains in the pipe wall, which could result in over stress and even damage of the pipeline.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,003 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,007 | 0,001 |
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 source (Gemma direct ou Codex distillé), 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 ».