IADC |
WOB(kN/mm)(bit dia) |
RPM(r/min) |
Applicable Formations |
417 437 447 |
0.35--0.9 |
150--70 |
Very soft formations with low compressive strength and high drillablility ,such as clay, mudstone,chalk ,gypsum,salt, soft shale soft limestone,etc |
517 527 |
0.35--1.0 |
140--60 |
Soft formations with low compressive strength and high drillablility such asmudstone,gypsum,salt,soft shale,soft
limestone ,etc. |
537 547 |
0.45--1.0 |
120--50 |
soft to medium formations with low compressive strength ,such as medium soft shale ,medium soft limestone,medium soft limestone,medium soft sandstone,medium formation with harder and more abrasive interbeds.etc |
617 627 |
0.45--1.1 |
90--50 |
Medium hard formations with high compressive strength such as hard shale.limestone,sandstone,dolomite,etc |
637 |
0.5--1.2 |
80--40 |
Hard formations with high compressive strength,such as sandstone,limestone,dolomite,hard gypsum,marble,etc |