Mass Transfer on Multiphase Transitions in Low-Temperature Carbon-Dioxide Floods
Bibliographic record
Abstract
Summary Mixtures of reservoir oil and carbon dioxide (CO2) can exhibit complex multiphase behavior at temperatures typically less than 120°F, in which a third CO2-rich liquid (L2) phase can coexist with the oleic (L1) and gaseous (V) phases. The three-phase behavior is bounded by two types of critical endpoints (CEPs) in composition space. The lower CEP (LCEP) is a tie line in which the two liquid phases merge in the presence of the V phase, and the upper CEP (UCEP) is a tie line in which the L2 and V phases merge in the presence of the L1 phase. Slimtube tests reported in the literature show that low-temperature oil displacement by CO2 can result in the high displacement efficiency of more than 90% when three phases are present during the displacement. The nearly piston-like displacements can be quantitatively reproduced in numerical simulations when the CEP behavior is properly considered. However, it is uncertain how multicontact miscibility (MCM) is developed through the interaction of flow and three-hydrocarbon-phase behavior. This research presents a detailed analysis of mass conservation on multiphase transitions between two and three phases for the limiting three-phase flow, where the L1 phase is completely displaced by the L2 phase on the LCEP. The analysis indicates that interphase mass transfer on multiphase transitions occurs in the most-efficient way for MCM development. Simple analytical conditions derived for MCM through three phases are applied to 1D fine-scale simulations of CO2 floods by use of four and more components. Results show that the MCM conditions are nearly satisfied when the effect of numerical dispersion is small. MCM is likely developed through three hydrocarbon phases on the LCEP in the cases studied. This is consistent with analytical solutions of water and gas injection presented in the literature, in which MCM is developed on a CEP for the aqueous, V, and L1 phases. For MCM cases in this research, the L2-V two phases are present upstream of the miscible front if the composition path does not go through the UCEP tie line. However, they also can be miscible on the non-L1 edge of the UCEP tie line if the MCM composition path goes through it. Three-phase flow gradually changes to two-phase flow with varying pressure in the presence of numerical dispersion. It is shown that interphase mass transfer on multiphase transitions becomes less efficient during the change until the three-phase region completely disappears.
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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 | 0.001 |
| 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".