Influence of Overlying Layers of Loose and Dense Sand or Gravel on the Drilling Mud Pressure Causing Mud Loss from Horizontal Boreholes
Bibliographic record
Abstract
Stability of horizontal boreholes under the pressure of drilling mud is a key consideration during horizontal directional drilling. Based on the successful application of experimental and numerical studies in uniform sand undertaken by the authors, an experimental study was carried out to investigate the relationship between the maximum measured mud pressure Pmax and influence of sand layers (i.e., a dense sand layer covered by different thicknesses of loose sand or dense sandy gravel). Mud pressure histories from experiments involving boreholes in stratified deposits were explored for the first time. A numerical study was also conducted, and the numerical results were close to the Pmax values observed in the tests. Earth pressure sensors were buried near the boreholes and the measured data were also compared to the results of numerical solutions. For the system involving an overlying layer of dense sandy gravel, it was conservative to use the Pmax calculation for uniform granular layers. However, for the system involving an overlying layer of loose sand, a reduction factor needed to be added; this was developed from a parametric study. Ground surface failure was less dramatic for these layered systems than seen previously for uniform sand.
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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 | 0.000 | 0.000 |
| 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) | 0.001 | 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".