Analysis and Correlations of Viscous Fingering in Low-Tension Polymer Flooding in Heavy Oil Reservoirs
Bibliographic record
Abstract
Low-tension polymer flooding (LTPF) can be an alternative for improving the recovery from some problematic heavy oil reservoirs, especially thin formations, where thermal methods face some challenges. A major technical challenge in LTPF is that a fingered displacement front may occur. Therefore, it is important to predict the nature of instability, to avoid viscous fingering, or, where it is inevitable, to be capable of including it as an additional factor in modeling displacement. Previous experiments of viscous fingering in immiscible displacements have been conducted in the presence of high permeabilities and linear displacement schemes. The question is whether previous findings are valid in displacement schemes similar to oil-field patterns (e.g., five-spot) in which one should deal with varying velocity profiles from injector(s) to producer(s). Hence, the effect of dispersion caused by varying velocity profiles has not been tested completely on viscous fingering. To help understand viscous fingering in LTPF in heavy oil reservoirs and to overcome the aforementioned limitations, we conducted experiments in relatively low-permeability, one-quarter, five-spot patterns. Foremost parameters, including oil recoveries at different times to breakthrough, pressure drops, cumulative saturation profiles, mean local saturations, finger lengths and widths, the dynamic level of bypassing, the dynamic population of fingers, the rate of growth of the population of fingers, and the number frequency of the fingers, were measured. We have correlated some of these parameters with the displacement time and front position. In summary, three distinct regions were identified for the viscous fingering patterns: onset of fingering, spreading phase, and end of sideways growth. The results also show that the finger width is comparable with the pore size and the fingerlike instabilities exist both in front of and behind the unstable front. Furthermore, the dynamic population of the macrofingers is well correlated with the square root of the time, and the profile of mean local oil saturation versus traveled distance is almost linear. Finally, the sharpest increase in the rate of growth of the finger population versus dimensionless pressure drop is accompanied with the sharpest pressure drop occurring at the onset of fingering and axial finger propagation during the early stages. A subsequent relatively uniform trend of the pressure drop versus time occurs during the spreading phase. Analysis of the experimentally observed fingering patterns of LTPF in this study is the most detailed interpretation performed to date, which provides new insight into the onset of fingering and finger development.
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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 | 0.001 | 0.001 |
| 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".