| Porosity (%) | A rough appraisal reservoir rock | Permeability (mD) | A rough appraisal reservoir rock |
| Gas bed | |||
| 0 - 5 | Negligible | <0.1 | Compacted |
| 5 - 10 | Poor | 10 - 0.1 | Low permeability |
| 10 - 15 | Fair | 100 - 10 | Conventional |
| 15 - 20 | Good | ||
| 20 - 25 | Very good | ||
| >25 | Excellent |