| Â | IADC | Rock formation | WOB (KN/mm) | PRM(r/min) |
| Â | 417/427/437 | Low compressive strength, high drill-ability and extremely soft formation, like shale, clay, sandstone, conglomerate etc | 0.35~0.90 | 140~70 |
| Â | 447 | Low compressive strength, high drill-ability and soft formation, like shale, clay, sandstone, soft limestone, salt rock, plaster etc. | 0.35~1.00 | 140~60 |
|  | 517 | Low compressive strength, high drill-ability and soft formation, like shale, clay, sandstone, soft limestone, salt rock, etc. | 0.35~1.05 | 120~50 |
| Â | 527 | Soft formation with low compressive, like Low compressive strength, high drill-ability and soft formation, like shale, clay, sandstone, soft limestone, salt rock, anhydrite etc. | 0.35~1.05 | 120~50 |
| Â | 537/547 | Low compressive strength, medium hard formation with hard abrasive interlayer, like Hard shale, anhydrite, soft limestone, sandstone, dolomite with mezzanine, etc. | 0.50~1.05 | 110~40 |
| Â | 617/627 | High compressive strength, medium hard and thick hard interlayer, like hard shale, limestone, sandstone, dolomite, etc. | 0.50~1.05 | 80~40 |
| Â | 637/737 | High compressive strength, medium hard and high abrasive formation, like limestone, dolomite, sandstone, chert, etc. | 0.7~1.20 | 70~40 |
