Bibliographic record
Abstract
The diffusion coefficient of vaporized solvents in bitumen is an essential parameter in the design and performance evaluation of solvent-assisted thermal recovery methods. The reported measurements of solvent diffusion coefficient are relatively scarce, especially at the high temperatures. In this study, a new constant-pressure experimental technique for one-dimensional diffusion tests, which accounts for the bitumen swelling and density change, was developed. The experimental rig enables measurement of diffusion coefficient of vaporized solvents in bitumen at high temperatures encountered in solvent-assisted thermal recovery methods. The technique involves accurate monitoring of the swelling height during isothermal and isobaric dissolution of a vaporized solvent in a liquid column of the oil. Several analytical and numerical models have been reported as forward models for estimation of diffusion coefficient from experimental data based on various assumptions. However, an important physical mechanism, the swelling-induced advective transport has not been considered in the previous studies. In this study, an analytical model is developed to determine the molecular diffusion coefficient of gaseous solvents into the bitumen, including the swelling effect, density change and advective transport. The required experimental data for determining the diffusion coefficient with this analytical model are the swelling height (gas-liquid interface movement) with time, during the dissolution of a gaseous solvent at constant pressure and temperature in a liquid column. The diffusion coefficients of propane, butane, pentane, hexane and heptane, were measured at temperatures varying from 90 C to 195 C. A modified correlation of diffusion coefficient with bitumen viscosity and solvent-bitumen mixture viscosity was developed based on the experimental results from this study and reported data from other studies. The new correlation provides a simple and reliable estimation of the diffusion coefficient of vaporized solvents in heavy oils and bitumen.
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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 | 0.001 |
| 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 | 0.001 |
| 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".