Interplay Between Permeability Retardation and Capillary Trapping of Rising Carbon Dioxide in Storage Reservoirs
Bibliographic record
Abstract
Summary The main objective of this work is to understand, by analytical and numerical study, how permeability retardation interacts with capillary-barrier trapping to cause accumulation as carbon dioxide (CO2) migrates upward in saline aquifers during geological sequestration. The study is of one-dimensional (1D) two-phase (CO2 and water) countercurrent flow. The analytical model describes CO2 buoyant migration and accumulation at a “flow-barrier zone” (low permeability) above a “flow-path zone” (high permeability). The relative importance of permeability retardation and capillary trapping is examined under different magnitudes of buoyant-source fluxes and porous-media properties. In the limiting case of zero capillary pressure, the model equation is solved using the method of characteristics (MOC). Permeability-retarded accumulation, induced by the permeability difference between the flow path and the barrier zone, is illustrated through CO2-saturation profiles and time/distance diagrams. Capillary trapping is subsequently accounted for by graphically incorporating a capillary pressure curve and capillary-threshold effect. Results demonstrate that the accumulation contributions from both the permeability hindrance and capillary trapping are convolved at sufficiently large fluxes. At a given time, the total CO2 accumulated by permeability hindrance is greater than that accumulated by capillary trapping, but the former approaches the latter at large time. The low-permeability zone need not be completely impermeable for accumulation to occur. We demonstrate that considering only capillary trapping understates the amount of CO2 accumulated beneath low-permeability structures during significant periods of a sequestration operation.
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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 | 0.001 | 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 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".