Effect of Tool Joints on Contact Force and Axial-Force Transfer in Horizontal Wellbores
Bibliographic record
Abstract
Summary An experimental study has been conducted to investigate the effect of tool joints on the buckling/post-buckling behavior of drillpipes constrained in straight horizontal wellbores. Buckling/post-buckling behavior of drillpipes has traditionally been investigated with continuous pipes. To our knowledge, this is the first time the effect of tool joints is included in such a study. The U. of Tulsa Drilling Research Projects experimental buckling facility has been used to carry out the desired experiments. Axial loads at both ends of the pipe and contact forces at the tool joints were measured. Changes in the drillpipe configuration were also investigated visually as the axial load increases. Some of the new findings of this study can be summarized as follows. Sequential occurrence of buckling/post-buckling configuration of jointed pipe is similar to that of continuous pipes, reported previously by various investigators. In other words, in both cases, the pipes buckle first laterally and then helically as the axial compressive load increased. The presence of tool joints does not affect the critical lateral (sinusoidal) buckling load significantly. However, it increases the critical load, causing helical pipe configuration (helical buckling) of approximately 20%. The use of tool joints improved the efficiency of the axial load transfer by approximately 40%. The results of this study will help to improve the design of operational parameters for drilling with jointed pipes as well as with coiled tubing (CT). In particular, improved axial-load transfer performance would allow drillers to use a higher weight on bit and, consequently, faster and possibly less costly drilling.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".