In situ principal stress measurement using minifrac testing and borehole breakout analysis in the south range rocks of the Sudbury Basin, Canada
Bibliographic record
Abstract
KGHM’s Victoria project is in the south range of the Sudbury Basin in Ontario, Canada. The deposit includes mineralisation zones of nickel, copper and precious metals (platinum, palladium and gold). As a part of geomechanical data collection for mine design, a series of minifrac tests were conducted in a vertical borehole (shaft’s pilot hole) at the Victoria project. The minifrac tests were conducted in the exploration’s shaft pilot hole at depths of between 350 to 750 m. The minifrac test results and the observed borehole breakouts at depth were used to estimate the magnitude and orientation of the in situ principal stresses and correlate them to depth. The magnitude and orientation of the minimum, intermediate and maximum principal stresses were estimated using the test data. It is shown in this paper how each of these principal stresses is spatially orientated and how their magnitudes vary with depth. The minimum principal stress is expected to be sub-vertical. The intermediate and the maximum principal stresses are expected to be sub-horizontal. The kH ratio is estimated to approach 2.8 at a depth of 350 m and to substantially vary with depth, approaching 1.5 at 700 m. Below 700 m, change in the kH ratio becomes minimal and remains constant at 1.45. The intermediate principal stress shows a similar trend with depth. The kh ratio starts at 1.94 at 350 m, approaches 1.02 at 700 m and reaches a plateau of 1 at a depth below that. The estimated magnitudes of the in situ principal stresses will also be compared with the previous measurements conducted by other mine operators in the Sudbury Basin.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".