Engineering Analysis of Coiled Tubing Failure in a Gas Well with Hydrate Plugging
Bibliographic record
Abstract
Abstract Failures provide an opportunity to revisit the existing practices and make necessary improvements in the way operations are designed and executed. Hydrate plug formation in certain operating conditions pose a well-recognized operational hazard. Water can form solid crystalline structure around gas molecules when favorable conditions exist. Very few hydrate formation incidents have been reported in open literature hence limiting the understanding of this subject. One such incident occurred in Northern Alberta where a coiled tubing string became stuck due to hydrate plug formation in the well bore. Although the coiled tubing operations have become increasingly safer yet the challenging production environment results in greater intervention risks than ever. Coiled tubing failures occurring as a result of operating in these conditions enable us to learn valuable lessons which must be shared with the industry to raise general awareness and reduce industry-wide failures. During this operation, coiled tubing was run for retrieving bridge plug in a 3400m (11155ft) gas well. Restrictions were encountered during the operation, however; coiled tubing safely reached the desired depth. The plug was retrieved successfully but the coiled tubing became stuck close to surface. The pipe was freed up after several attempts and pulled inside the riser section. It was discovered that the pipe had been catastrophically buckled after the risers were opened on surface. The paper evaluates different failure scenarios in an attempt to analyze the factors that may have been responsible for pipe failure in the given operating conditions while describing the engineering analysis, investigation conducted and lessons learned from it. The paper gives an insight into hydrate prevention techniques in order to avoid stuck pipe conditions hence preventing failures during intervention operations.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".