Formation Selection Criteria for Volume Fracturing in Chang 7 Tight Reservoir in the Ordos Basin
Bibliographic record
Abstract
The Ordos basin possesses abundance of tight oil and it has huge commercial potential. Volume fracturing is an effective means for the exploitation of tight oil which is a significant impact by geological conditions. So far, the formation selection criteria targeting on volume fracturing of Chang 7 tight reservoir in the Ordos basin have not been established. This paper combined the experiments of rock mechanics and the fracturing simulating software Meyer, and built the selection criteria of Chang 7 tight reservoir in terms of the horizontal stress difference, the brittle index and the natural fractures. It is shown that the horizontal stress difference in Chang 7 tight reservoir is 6-12 MPa, the brittle index based on elastic parameters is 30-48, with strikingly regional natural fracture growth. The fracture geometry induced by volume fracturing is affected by the horizontal stress difference, the brittle index and the natural fracture numbers together. Complex fracture networks are likely to form in a highly naturally fractured section with the in-situ stress difference below 8 MPa and the brittle index over 40. The selection criteria is adequate for optimum formation selection and it has guide function in fieldwork which proved by field practice.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.001 | 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".