Experimental Study of Water and CO<sub>2</sub> Flooding in the Tight Main Pay Zone and Vuggy Residual Oil Zone of a Carbonate Reservoir
Bibliographic record
Abstract
In this paper, water and CO 2 flooding processes in the upper tight main pay zone (MPZ) and lower vuggy residual oil zone (ROZ) of a carbonate light oil reservoir were experimentally studied and compared. First, some carbonate reservoir rock samples from these two zones in the Steelman oilfield (Canada) were characterized using thin-section analysis and X-ray diffraction. Second, the minimum miscibility pressure (MMP) between the light crude oil and CO 2 at the actual reservoir temperature was determined. Third, a total of eight coreflood tests were conducted with the tight dolomite or vuggy limestone core plugs to examine the effects of the production pressure, CO 2 injection timing, and rock properties on the water- and CO 2 -based oil recovery processes in the two different zones. It was found that, for the CO 2 secondary flooding in the non-waterflooded tight core plugs (i.e., the MPZ), the oil recovery factor (RF) was not dramatically reduced when the production pressure was lower than the MMP. For the CO 2 flooding in the waterflooded vuggy core plugs (i.e., the ROZ), however, much less residual oil was recovered in the immiscible case than that in the miscible case, especially after CO 2 breakthrough. In comparison to waterflooding or miscible CO 2 secondary flooding alone, miscible CO 2 tertiary flooding after waterflooding was found to be the most effective method to recover the light crude oil from the tight core plugs and especially from the vuggy core plugs. Moreover, the petrographic properties of these two types of core plugs had rather different effects on the miscible CO 2 secondary flooding, whereas the miscible CO 2 tertiary flooding had similar production trends.
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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 | 0.000 |
| 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 | 0.000 |
| 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".