Geophysical and thermal investigations of ice-rich permafrost at Parsons Lake, Northwest Territories
Notice bibliographique
Résumé
Geophysical and thermal investigations of ice-rich permafrost were performed in an area of planned hydrocarbon development at Parsons Lake, Northwest Territories. The site is owned by ConocoPhillips Canada (CPC) and ExxonMobil, and is intended to be a primary target for the Mackenzie Valley Gas Project. As a result, the Program of Energy and Research Development (PERD) funded this thesis to acquire more knowledge regarding the current and future state of permafrost at this site. Information on ground temperatures and material properties are available from boreholes extracted during the 2004 CPC drilling program. In this study, the application of ground-penetrating radar (GPR) and capacitively-coupled resistivity (CCR) to map ground ice properties was tested. Since ground ice is an important factor affecting the level of disturbance initiated by thermokarst, improving the use of geophysical tools to map its nature and extent is important. By employing techniques to determine the maximum depth of investigation, optimal smoothing factors used during the inversion of raw resistivity data were computed. Once accomplished, it was found that the observed resistivity of massive ice ranged from 25 000 to 40 000 ohm-m. Conversely, values for massive ice were more widespread and overlapped with other materials like ice-rich peat when incorrect smoothing parameters were selected. The GPR cross-sections were applied to provide more detailed information on structure and contacts between massive ice and gravelly sand deposits. It was found that CCR generates similar outputs for these types of materials. One-dimensional thermal models were constructed at previously undisturbed borehole locations. Thermal outputs were compared with the observed data, and it was found that the error during the thaw season at boreholes with near-surface mineral soils is less than 1 degree celcius at any depth. When these models were used to project maximum active layer thickness changes for the period 2011-2070, subsidence is projected to begin as early as 2058. At disturbed locations, CCR surveys conducted in winter reveal two anomalies characterized by very low resistivities (< 600 ohm-m) beneath the gravel pads. One possible explanation is the development of taliks between 2004 and 2010, and thus, future fieldwork at this site is recommended. Overall, this investigation developed a model that can be used by industry to forecast near-surface thermal regime changes under varying scenarios of climate warming.
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 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 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 ».