Bibliographic record
Abstract
Summary As early as 1999, the need for industry guidelines regarding the use of coiled tubing (CT) in sour wells was recognized (Luft and Wilde 1999). Small-scale standard National Assocation of Corrosion Engineers (NACE) tests (i.e., proof-ring, C-ring, double-cantilever-beam, and slow-strain-rate tests) have been performed to evaluate the behavior of CT materials in sour environments (Cayard and Kane 1997; McCoy 2005; McCoy and Thomas 2006; Luft 2003). Although these tests evaluate the crack-resistance properties of the material in sour conditions, they do not give data regarding the low-cycle fatigue performance of CT after sour exposure that could be used for CT-string management in real operating conditions. By 2003, uniaxial low-cycle corrosion fatigue tests of short, full-body CT samples were used to evaluate the sour performance of Grade-70 and -80 materials (Luft 2003). These tests, although they considered fatigue performance, were based on uniaxial reversing loads rather than reversing bending strains, which is what occurs in CT operations. In addition to this, the need for high-strength CT materials (i.e., 90-grade and higher) in sour wells required additional knowledge regarding their sour performance. By the end of 2004, a joint-industry project (JIP) among ExxonMobil Development Company, Shell Canada Limited, and BJ Services Company was initiated to investigate the serviceability of high-strength CT in sour environments, with the main emphasis on the measurement of low-cycle bending-fatigue life after sour exposure using full-body CT samples. Some of the early results of this project were included in a previous paper (Luft et al. 2007). The present paper summarizes more than 4 years of laboratory testing aimed at establishing the effect of sour exposure on the low-cycle fatigue life of CT materials. Other aspects related to the possible CT degradation from sour exposure are also included, such as the effect of varying sour-environment severities, performance of anticracking (H2S) inhibitors, effect of prefatigue, butt- and bias- weld performance, and tensile-strength integrity. The results have led to changes in the current operating procedures regarding CT-strings management and CT-material selection criteria for sour service.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".