Experimental Study of Carbon Dioxide Diffusion in Oil-Saturated Porous Media under Reservoir Conditions
Bibliographic record
Abstract
For both CO 2 enhanced oil recovery and CO 2 sequestration in oil reservoirs, the diffusion of injected CO 2 into oil-saturated porous media is of great significance in project design, risk assessments, economic evaluation, and performance forecast. However, the measurement of CO 2 diffusion coefficient in liquid-saturated porous media under reservoir conditions has not been well-established due to the complications caused by density-induced natural convection in the CO 2 −oil systems. This paper presented a new method for measuring the effective CO 2 diffusion coefficient in oil-saturated porous media under reservoir conditions. A core plug with the two end faces sealed was designed as the physical model for radial diffusion process. The measurement was conducted in a high-pressure diffusion cell with an oil-saturated core sample placed in the middle and the remaining void space of the cell filled by high-pressure CO 2 sample. A small-pressure decay technique was employed to record the pressure change of the gas phase during the diffusion measurement. Because the oil phase contained in the porous medium swells as CO 2 diffuses into it, the experiment essentially involves both diffusion and swelling-induced convection. To describe these processes involved in the measurement, a mathematical model along with numerical solutions was derived. The effective diffusion coefficient was determined by matching the experimental pressure decay curve with the corresponding mathematical model. The proposed method was demonstrated for oil-saturated Berea core samples at pressures ranging from 2.2 to 6.5 MPa. The measured pressure decay curves showed good agreement with the mathematical predictions using the best-fitted effective diffusion coefficients. The derived method can be readily implemented in laboratories that can handle high-pressure fluids; thus, this study provides a tool for studying CO 2 diffusion in oil-saturated porous rocks.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".