Pressure Dependent Permeability of Tight Rocks
Bibliographic record
Abstract
Abstract According to Terzaghi's principle, the effective stress σ' is related to the total stress σ and the pore pressure Pp by the relationship σ' = σ - Pp. In a typical reservoir depletion scenario, the pore pressure decreases under constant total stress, and as a result, the effective stress increases. The increase of the effective stress has a negative impact on permeability due to rock compaction, while the decrease in pore pressure enhances the apparent permeability because of the gas slippage effect. In tight gas reservoirs, since the slippage effect is no longer negligible, the pressure dependency of the permeability is very complicated. In this paper, we used three samples from the Montney tight gas siltstone reservoir in western Canada, whose absolute permeabilities range from in the order of 10-4 mD to 10-3 mD. Permeability measurements under different pressure conditions using both the unsteady state pressure decay and the pressure pulse decay methods were carried out. Based on the measured data, permeability was modeled as a function of reservoir pressure. Using this function, we carried out reservoir simulations and examined the impact of pressure dependence of permeability on the gas recovery process from a tight gas reservoir.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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".