IADC

WOB

(KN/mm)

RPM

(r/min)

Applicable Formations

114/116/117

0.3~0.75

180~60

Very soft formations with low compressive strength and high drillability, such as clay, mudstone, chalk, etc.

124/126/127

0.3~0.85

180~60

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

134/135/136/137

 0.3~0.95

150~60

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

214/215/216/217

0.35~0.95

150~60

Medium formations with high compress strength, such as medium soft shale, hard gypsum , medium soft limestone, medium soft sandstone, soft formation with harder interbed, etc.

227

  0.35~0.95

150~50

Medium hard formations with high compressive strength, such as abrasive shale, limestone, sandstone, dolomite, hard gypsum, marble,etc

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