Measurement of Relative Permeability of Coal to Gas and Water
Bibliographic record
Abstract
ABSTRACT Relative permeability of coal to gas and water is an important variable in coalbed methane reservoir development as it is required for reserve estimation and field production planning. In this study, gas-water relative permeability of two coal samples: Grande Prairie (GP) and Goldsource (GS) were determined by the Johnson-Bossler-Naumann (JBN) method, which is widely used for petroleum reservoir rocks. An experimental apparatus was designed, built, tested, and commissioned for various two-phase gas-water relative permeability measurements. The gas phases used were helium, methane, and carbon dioxide in this order of adsorbing strength on coal and the water phase used was formation brine. Forty-eight drainage and imbibition displacement runs were carried out on the two coal samples using helium-brine, methane-brine, and carbon dioxide-brine combinations at three different operating pressures (100, 300, 400 psi) at a constant overburden pressure (800 psi), and the results were analyzed and plotted on drainage and imbibition curves. Imbibition relative permeability showed that the irreducible water saturation correlated with pressure and the absolute permeability of the coal samples changed after each experiment. The GS coal sample showed a greater two-phase flow saturation range than the Grande Prairie coal sample. In both cases, the relative permeability to gas was low and high for water. The coal samples tended to become more water-wet at higher pressures in the case of adsorbing gases, namely methane and carbon dioxide but in the case of non-adsorbing gas helium, higher pressure prevented the inflow of water into the smaller pores leading to a decrease in irreducible water saturation with an increase in pressure. The drainage experiments were highly unstable based on the Instability Number calculated. The resulting relative permeability curves showed oscillation. From this study, it was concluded that coal relative permeability to gas and water depended on the nature of gas, the operational pressure, and fluid-mineral interactions.
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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 | 0.000 |
| 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 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".