Evaluating Fitness-for-Purpose of Coiled Tubing for Underbalanced Drilling of Sour Wells
Bibliographic record
Abstract
Abstract A multi-year joint industry program (JIP) has been completed involving an experimental testing program to evaluate the fitness-for-purpose of high-strength low-alloy steel coiled tubing (CT) in under-balanced drilling of sour oil and gas wells. The primary focus is the cold-worked material response to sour well conditions when subjecting the tubing to multiple cycles of plastic tension and compression strains in the range of 2% to 3%. The material performance and/or degradation parameters measured include low-cycle corrosion-fatigue (LCCF) life, critical stress corrosion cracking (SCC) stress intensity factor, KISCC, total plastic strain to failure, normalized fracture strain, sulfide stress cracking (SSC) and hydrogen induced cracking (HIC). Laboratory tests performed under the auspices of the JIP, consisted of low-cycle, axial-straining corrosion-fatigue with full body CT specimens submerged in aqueous H2S, H2S/CO2 varying pH, SSC corrosion inhibitors and NACE standard solution specified for determining the relative propensity for HIC and SSC. Various other testing was performed unilaterally by individual JIP sponsors, including double cantilever beam (DCB) and slow strain rate testing (SSRT). Coiled tubing samples comprised the 70 ksi and 80 ksi yield strength grades, pre-fatigued with varying exposure duration to the corrosive environment. The assessment for suitability of CT in under-balanced drilling of sour wells, was made on basis of the various performance results and failure modes obtained in the laboratory testing. These results are also intended to further the development of industry operational guidelines and coiled tubing material selection for under-balanced drilling of sour wells.
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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".