Investigating the aging behavior of HNBR seal elements in high-pressure high-temperature wellbore environments exposed to H <sub>2</sub> S and CO <sub>2</sub>
Bibliographic record
Abstract
Widely employed as a seal element in the oil and gas industry, understanding the aging behavior of Hydrogenated Nitrile Butadiene Rubber (HNBR) is crucial for both theoretical and practical advancements. This study investigates the degradation mechanisms of peroxide-cured HNBR compounds exposed to H2S and CO2 in a simulated environment at elevated pressure and temperature. Prior to accelerated aging, the mechanical properties and chemical structure of the samples were evaluated . Subsequently, the compounds were subjected to harsh aging conditions in Hc-A (5% vol. H2S and 20% vol. CO2) and Hc-B (20% vol. H2S and 5% vol. CO2) environments at high-pressure/high-temperature (HPHT) conditions of 6.9 MPa and 121°C, respectively. Fourier-transform infrared (FTIR) spectroscopy revealed significant changes in the molecular structure of the aged HNBR samples, resulting in increased swelling, reduced density of -C≡N groups and double bonds, additive migration, and a weakened reinforcing effect of carbon black. Furthermore, the study observed notable changes in the mechanical properties, including increased mass, volume, and elongation at break, but decreased hardness, modulus, ultimate tensile strength, and compression set compared to virgin samples. Notably, the results highlight the dominant influence of CO2 in the simultaneous sour gas immersion test on the structure-property relationship of the aged HNBR samples.
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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 | 0.000 | 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) | 0.001 | 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".