Waterflooding Experiments with X-ray CT Imaging
Bibliographic record
Abstract
Abstract Three experiments have been performed, injecting brine and polymer into a sand pack saturated with heavy oil. Each experiment was imaged with time lapse X-ray CT. The first two experiments, conducted in a medical scanner with a resolution of 350 μm, suggested important features below the scale of spatial resolution. The last experiment, performed in a synchrotron beamline with a resolution of 4.3 μm, provided a view of oil/water interactions on the scale of individual pores. Conventional theory holds that waterflooding is unstable with respect to the development of fingers, which push the oil ahead of them. "Sweep efficiency" can be improved by increasing the water viscosity with polymer, which reduces the mobility ratio and stabilizes the front. Waterflooding has been applied successfully to heavy oil, but the detailed mechanisms of recovery are not well understood. Breakthrough of water occurs quickly at the producer; most oil production occurs at high water cuts over a long period of time. The most striking feature of the medical scans was the absence of distinct fingers of high water saturation. The only identifiable, compact "front" consisted of saturation changes of 20% or less. Moreover, breakthrough occurred long before the front reached the production end of the pack. More surprisingly, water saturation was observed to increase everywhere throughout each experiment. The inference was that fingering, if present, was occurring at a scale below that of the resolution. The synchrotron scans did not reveal the expected pore scale fingering, but instead showed evidence of water transport entirely in wetting films. Residual blobs of connate water were observed to grow throughout, but never linked up to form fully water-saturated paths. The mechanism of oil mobilization was also quite different from the traditional picture. There was no scale at which oil was pushed ahead of a water front. Instead, isolated droplets of immobile water swelled, fed by films of water on the grain surfaces. These results do not rule out an eventual transition to a more conventional picture; only a few pore volumes were injected. But the path to that state may be different from what is usually assumed.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".