IADC

WOB

(KN/mm)

RPM

(r/min)

Applicable Formations

517/537

0.4~1.0

120~60

Soft formations with low compressive strength and high drillability, such as mudstone, gypsum, salt, soft limestone, etc.

617

0.45~1.1

90~50

Medium hard formation with high compress 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.

117/127

0.35~0.9

150~70

Soft to medium formations with low compressive strength , such as medium soft shale, hard gypsum, medium soft limestone, medium soft sandstone, soft formation with harder interbed, etc.

Note: The upper limits of WOB and RPM in above table should not be used simultaneously.