Benefits and Challenges Associated with CRA Injection Tubing in Corrosive Gas Wells
Bibliographic record
Abstract
Abstract The use of chemical injection (1/4" capillary) strings has gained tremendous popularity in the oilfield during the last few years. Application of these duplex stainless steel strings are now routinely used not only for corrosion chemical injection but also for injecting fresh water where downhole salt precipitation is present, as well as injection of foamer to address water loading issues. This paper describes an exhaustive investigation into the repetitive failure of these orbital welded duplex stainless steel strings due to environmental cracking in Anadarko's prolific Bossier play. Anadarko currently is very active with 12 drilling rigs running in Freestone County, Texas. The Bossier formation is encountered at a depth of 13,000 ft with a bottom hole temperature of 300 deg F. The gas stream typically contains 3% CO2, 3-5 ppm H2S, and the produced water is saturated with chlorides. Failures have occurred in numerous wells throughout the field. The paper details the root cause failure analysis investigation conducted, and the influence of well environment, tubing manufacturing process, and tubing material properties in failure. A risk-based approach was used in an attempt to predict tubing failure based on well conditions and material properties. The risk matrix was rationalized against a database of approximately 70 tubing failures. Parameters used in the risk matrix included weld type, weld and base metal hardness, and austenite/ferrite volume fraction ratios. The rationale and factors influencing replacement-tubing decisions (alternate metallurgy) to minimize the occurrence of failures is also described.
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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 | 0.003 | 0.008 |
| 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 | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| 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".