Mystery of SAGD Casing Gas Corrosivity and Corrosion Mitigation Strategy
Bibliographic record
Abstract
Abstract In the steam-assisted gravity drainage (SAGD) process, casing gas from the producers consists of a mixture of produced gas and carry-over steam. The produced gas contains approximately 15% CO2 and 0.6% H2S with temperatures up to 180°C. For the corrosivity of casing gas, CO2 corrosion modelling predicts a corrosion rate (CR) of 600 mpy (15 mm/y). Mackinawite corrosion modelling predicts a rate of 270 mpy (6.75 mm/y). The results from both corrosion models predicts that the casing gas should be severely corrosive under these conditions. However, results from corrosion coupon (CC) and probe monitoring in the associated pipelines indicated low to moderate general and pitting CRs at the higher temperatures with the CR increasing as the temperature was lowered. A corrosion product analysis supported that a passivation film of pyrrhotite and magnetite had formed at temperatures above 90°C. Also, the more tenacious siderite is formed at temperatures higher than 90°C, contributing to the corrosion protection. The corrosion caused by the casing gas was aggravated further by the injection of inhibited methanol for freeze protection purposes. A corrosion mitigation program was implemented that included regular pigging, the application of a corrosion inhibitor, a corrosion mechanism study, CR monitoring and a non-destructive examination program. The program was effective in reducing the CR and the operational reliability of the pipeline was maintained. This paper discusses a proposed passivation mechanism that explains the lower than expected corrosion rates based upon the research results of peers. It also details the additional corrosion mitigation program that effectively reduced corrosion to acceptable rates.
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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".