States of in-situ stress in the Duvernay East Shale Basin and Willesden Green of Alberta, Canada: variable in-situ stress states effect fault stability
Bibliographic record
Abstract
Induced earthquakes in some areas of the Duvernay Formations (i.e., of areas near the city of Red Deer and Fox Creek) due to Hydraulic fracturing (HF) operations nearby and seismic quiescence of the other areas (of a similar level of HF activities) warrants geomechanical investigations. Here, we start by quantitatively constraining the magnitudes and orientations of minimum ( S h ), maximum ( S H ) horizontal stresses, vertical stress ( S V ) utilizing both borehole measurements and earthquake’s focal-mechanism (FM) solutions for a study area where a newly emerging swarm of HF induced earthquakes are reported (near the city of Red Deer, Canada). The apparent pore pressures ( P P ) are also assessed through several transient well testing results targeting the unconventional reservoirs. This knowledge allows the fault stabilities for the high-profile HF induced Red Deer ( M L 4.2/ M W 3.8) earthquake to be assessed. The N-S (or E-W) aligned fault, revealed by the FM solution, appears to be stable at a hydrostatic fluid pressure but unstable when fluid pressure is increased to the level of ambient unconventional reservoir pore pressures. The slip-tendency of the faults in the region studied is assessed by calculating the required fluid pressures to activate hypothetical faults; we find that the HF-induced clusters geographically overlap with the zones of higher susceptibility. High ambient pore pressure does not correlate with high susceptibility, and large deviatoric stress is needed to cause HF-induced earthquakes.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".