Relative Permeability of Coal to Gas (Helium, Methane, and Carbon Dioxide) and Water – Results and Experimental Limitations
Bibliographic record
Abstract
Abstract Relative permeability of coal to gas and water is an important variable in coalbed methane (CBM) reservoir development as it is required for reserve estimation and field production planning. In this study, two coal samples (GP and GS) were used to determine the relative permeabilities using three gases (He, CH4 and CO2) at three different operating pressures (100, 300, 400 psi) and a constant overburden pressure of 800 psi. Both drainage and imbibition curves were obtained. Unsteady state displacements were used. The petrophysical properties of these coal samples were also measured. The very low absolute permeability of the cores (0.07 mD) required special procedures to minimize errors. The experimental results presented here showed that the relative permeabilities were typically very low for all gases and high for water. The irreducible water saturation showed correlation with the type of gas (non-adsorbable He to strongly adsorbable CO2) and pressure. It is concluded that coal relative permeability to gas and water depended on the nature of gas and the operational pressure. Relative permeability of coal changed also because of fluid-mineral interactions. It is concluded that the GP and GS samples tended to be more water-wet at higher pressures in the case of the adsorbable gases, viz. methane and carbon dioxide. However, in the case of non-adsorbing helium, higher pressure prevented the influx of water into the larger pores leading to smaller irreducible water saturation.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".