| Sweet spots type | Main controlling factors | Parameter | Level | ||
| I | II | III | |||
| Geological sweet spot | Reservoir property | TOC, % | >3.0 | 3.0 - 2.0 | <2.0 |
| Porosity, % | >4.0 | 4.0 - 2.0 | <2.0 | ||
| Gas saturation, % | ≥60 | 60 - 50 | 50 - 40 | ||
| Engineering sweet spot | Drilling conditions | Collapse pressure | <1.7 | 1.7 - 1.8 | >1.8 |
| Rock drillability | 1 - 3 | 4 - 6 | 7 - 8 | ||
| Fracturing quality | Young’s modulus, Gpa | >30 | 30 - 20 | <20 | |
| Poisson’s ratio | <0.2 | 0.2 - 0.25 | >0.25 | ||
| Brittleness index, % | >60 | 60 - 40 | <40 | ||
| Stress difference coefficient | 0 - 0.3 | 0.3 - 0.5 | >0.5 | ||