648 



Subsurface Geologic Methods 



The interfitting teeth previously discussed; the twisting-tearing and 

 chipping-crushing action of long, penetrating, chisel-shaped teeth; a safe 

 thickness of cone shell; a strong bearing; all are carefully balanced to 

 provide a long-life bit and a fast rate of penetration. 



Medium-Hard Formation Bits 

 The OSQ-2 Tricone 



Although most soft to medium-hard formations may be drilled eco- 

 nomically with one of the OSC series of tricone bits, there are strata en- 

 countered having hardness and abrasive characteristics that require a rock- 



FiGURE 344. Hughes 9-inch type OSQ-2 tricone bit. 



bit design to give a longer cutting life without a marked reduction in drill- 

 ing speed. 



The OSQ-2 rock bit (fig. 344) is of a special design for drilling for- 

 mations on the harder side of medium such as packed sands, anhydrite, 

 medium-hard lime, and the harder shales, which respond best to twisting, 

 tearing, chipping, and crushing actions as the cutter teeth penetrate. The 

 OSQ-2 bit has these actions on the formation. The cone axes, as in the 

 OSC series, are offset to provide additional twisting-tearing action. The 

 cutter teeth are spaced apart comparable to the OSC, but no portion of any 

 tooth is removed, thereby providing more cutting teeth to insure longer 

 life and greater footage per bit in harder formations. The cutting struc- 

 ture and action on bottom have been properly adjusted for a good pene- 



