Development of Tensile Hoop Stress during Horizontal Directional Drilling through Sand
Bibliographic record
Abstract
Although horizontal directional drilling has become commonplace, there are problems associated with high drilling mud pressures causing hydraulic fracture leakage of mud out into the environment. Initiation of tensile fracture is examined here, using finite- element analysis to represent the sand material and the annulus of filtercake that forms around the borehole. The analyses examine the soil response as mud pressures are increased, including shear failure in the sand material and the cohesive filtercake layer. The study identifies the initial geostatic stress conditions and the drilling fluid pressures that initiate tensile stresses in the filtercake. The effects of filtercake thickness, borehole depth, and the location of the maximum tensile stresses are studied. Significant discrepancies are found relative to limits currently used in the industry. Tensile fracture may be responsible for some mud loss, but simple use of drilling mud pressures that prevent tensile circumferential stress may be overly conservative.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".