Study of the Non-Equilibrium PVT Properties of Methane- and Propane-Heavy Oil Systems
Bibliographic record
Abstract
Abstract The non-equilibrium properties of foamy oil flow are essential to better understand CSI processes in thin heavy oil reservoirs. In this paper, non-equilibrium PVT constant composition expansion (CCE) measurement of typical Canada heavy oils saturated with methane and propane respectively has been conducted. The PVT properties were tested under typical heavy oil reservoir temperature 20°C to show the non-equilibrium that different saturation pressures presented at a fixed temperature. For equilibrium tests (a magnetic stirrer stirring the heavy oil-solvent mixture at the bottom of the PVT cell), an equilibrium bubble point pressure was achieved at 76psi and 270psi for propane and methane, respectively. The initial onset pressures of the non-equilibrium tests were slightly above the equilibrium bubble point pressures. For non-equilibrium tests, Supersaturation tests and Smooth Pressure Decline tests were conducted on propane-based live oil, while only Smooth Pressure Decline tests were conducted on methane-based live oil. For Supersaturation tests, a sudden pressure drop deviated from the equilibrium bubble point pressure was applied. For Smooth Pressure Decline tests, pressure was declined almost linearly with time. Tests were used to simulate the porous media condition where there is no stirring movement and the first visible free gas appearance was observed to record the foamy oil single phase volume expansion peak before free gas forms continuously. All CCE tests phenomenally recorded different saturation pressures (inflection pressure points) at various pressure decline rates at a fixed temperature. For propane-based supersaturation tests, pressure deviation from equilibrium bubble point at 6psi and 26psi led to a pseudo bubble point at 50psi and 41psi, respectively, and they led to a different time of reaching the volume peak at 23 hours and 11 hours, respectively. For propane-based smooth pressure decline tests, pressure decline rate 0.04psi/min, 0.11psi/min, 0.263psi/min and 0.386psi/min yielded pseudo bubble pressure at 53psi, 56psi, 59psi and 60psi, respectively. For methane-based smooth pressure decline tests, pressure decline rate 0.149psi/min, 0.442psi/min, 0.856psi/min, 0.937psi/min, 2.046psi/min and 3.363psi/min yielded the pseudo bubble point pressure at 214psi, 170psi, 156psi, 110psi, 75psi and 65psi, respectively. In addition, the in-situ density was measured with different pressure decline rates and it was found that for propane-based live oil, pressure decline rate 0.04psi/min yielded the lowest live oil density 0.83g/cm3 at the lowest pseudo bubble point pressure 57psi, while the highest pressure decline yielded a relatively low density at 0.835g/cm3 at the highest pseudo bubble point pressure 63psi. Also, the higher level supersaturation test yielded a lower density at a much lower pseudo bubble point pressure about 40psi compared with that of the lower supersaturation level test at 52psi. For methane-based tests, higher the pressure decline rate was, lower the densities of the solvent-heavy oil systems at lower pseudo bubble point pressures were the results.
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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 | 0.000 |
| 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".