| Sand type | Permeability class | Permeability description | Porosity class | ||
| Low (<7%) | Medium (7% - 15%) | High (15% - 25%) | |||
| Very tight | Very low (<0.1 mD) | Non-effective | |||
| Very tight to tight | Very low-low | Non-effective | EF2 | ||
| Tight | Low (0.1 - 1 mD) | Poorly connected | EF6 | EF1 | |
| Tight to sub-tight | Low-moderately low | Poorly to moderately connected | EF4 | ||
| Sub-tight | Moderately low (1 - 10 mD) | Poorly to moderately connected | EF5 | EF3 | |