Overpressure detection from geophysical, drilling and well testing data for petroleum exploration wells in the Beaufort-Mackenzie Basin, Yukon and Northwest Territories
Bibliographic record
Abstract
A comprehensive database consisting of geophysical data, drilling mud weights, and subsurface temperature, and formation pressure measurements was compiled and utilized to detect the depth to top of overpressure for the petroleum exploration wells in the Beaufort-Mackenzie Basin. One hundred and fifty-two depths to the top of overpressure were determined for 112 wells by using geophysical methods, supplemented with drilling and geothermal data. The majority of overpressure picks were confirmed using measured pore fluid pressure data. An additional 36 wells are believed to be too shallow to have penetrated an underlying overpressured zone. Composite plots for each well are presented graphically with wireline logs, well seismic velocities, mud weights, and borehole temperatures to illustrate the geophysical, drilling and geothermal responses and their correlations with well testing data, thus providing multi-parameter evidence for an integrated interpretation of overpressure distribution. Overpressure interpretations were ranked based on the availability and quality of the various types of data, as well as the reliability of the different methods used. Among the geophysical data that are good indicators of overpressure occurrences, shale sonic transit-time (and transformed porosity) and continuous sonic velocity are preferred because of the abundance of these data and the sensitivity of rock acoustic properties to porosity and stress. Mud weights provide an upper estimate of in situ pore pressure because of the need to approximately balance formation pressures during drilling; interpretations based on mud weights are mostly consistent with the results from geophysical data and measured fluid pressures from well tests. The interpreted depth to the top of overpressure varies from <1000 to over 4500 m (GL/SL) and is largely confined to undercompacted sediments in the central-northern delta and offshore areas. Overpressure occurs predominantly within the Paleogene Aklak, Taglu, Richards, and Kugmallit sequences, but can reach the base of the Plio-Pleistocene Iperk Sequence in wells on the outer shelf in the deep-water region of the Beaufort Sea. Our refined interpretations of overpressure occurrence in exploration wells provide key control points for more detailed mapping and modelling of overpressures in the basin.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.004 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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 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".