Experimental Study on the Sweep Patterns of CO<sub>2</sub> Flooding in Reservoirs with Interlayer Heterogeneity
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide CO 2 flooding is widely applied in low-permeability reservoirs due to its good injectivity, miscibility with crude oil, and ability to diminish the interfacial tension and viscosity between oil and gas. However, strongly heterogeneous reservoirs can lead to phenomena such as fingering and gravity override during the displacement process, which significantly reduce the sweep area. To address this, this study systematically investigates the mechanisms influencing CO 2 miscible flooding sweep efficiency under interlayer heterogeneity using a 2D, three-layer, equally thick, heterogeneous visualized physical model. The study compares oil displacement efficiency under three injection-production strategies: sequential activation of high-, medium-, and low-permeability layers, simultaneous activation, and accelerated flooding (1.0 mL/min). High-speed imaging technology is used for real-time monitoring of the CO 2 front migration, revealing the dynamic coupling mechanism of gravity segregation and mass transfer. Experimental results show that at low injection rates (0.1 mL/min), gravity override leads to early gas cap formation at the top of the high-permeability layer, restricting the gas-phase sweep area. In contrast, high injection rates (1.0 mL/min) enhance horizontal displacement forces, suppressing override and increasing the sweep area in the high-permeability layer. Additionally, the migration of CO 2 from the low-permeability layer to the medium-permeability layer intensifies under gravity segregation, and its recovery is strongly influenced by injection rates. The simultaneous activation strategy significantly improves recovery in the medium-permeability layer through synergistic vertical mass transfer and horizontal pressure difference, achieving a total recovery of 85.47%, making it the optimal injection-production strategy. This study provides a theoretical basis for optimizing CO 2 flooding in interlayer heterogeneous reservoirs, emphasizing the critical role of injection-production rates and interlayer coupling effects on sweep efficiency.
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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 | 0.000 |
| 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".