Geophysical and thermal investigations of ice-rich permafrost at Parsons Lake, Northwest Territories
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".