Beyond Heat Checking: Frictional Heating Causes Drillpipe Failure in an Extended-Reach Well
Bibliographic record
Abstract
Summary Failure of a 5-in. proprietary hole-cleaning drillpipe joint occurred during platform drilling of a North Sea extended-reach well. The joint was run in heavyweight drillpipe above the bottomhole assembly (BHA). Its failure resulted in the loss of the BHA, including high-value rotary-steerable tools, at 23,250 ft measured depth (MD). The failure occurred when the string was being rotated out through a tight spot. Topdrive stallouts and intermittent circulation were experienced. The maximum overpull applied was 50,000 lbf. The appearance of the recovered pipe indicated ductile failure, despite a zone of abnormally high hardness adjacent to the fracture. Investigation established that local frictional heating had heated the drillpipe above 1,441°F and that ductile failure had occurred when hot, although the string had not been overloaded in tension or torsion. After the rupture, the mud-flow quench hardened the hot pipe to above 572 Vickers of 10kg load Hardness (HV10) [approximately 54 Rockwell Hardness on a C scale (HRC)—Note: hardness values are given "as measured"; conversions are approximate and for information only]. "Heat checking" (i.e., downhole surface hardening of frictionally heated drillpipe) is an established phenomenon that is described in the literature. The case reported herein represents an extreme consequence of frictional heating that has important implications for the management of topdrive drilling operations.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".