510 



Subsurface Geologic Methods 



drawn, a full-gauge bit is used to proceed with further drilling. This type 



of whipstock was developed to save rig time. The time and expense of 



making a round trip to ream the "rathole" is considerable in deep wells. 



The Eastman knuckle joint is a mechanical deflecting tool of simple 



(1) (2) (3) (4) 



Figure 241. Operation of Eastman full-gauge whipstock. 



construction, which has been used with very successful results for a num- 

 ber of years. It has certain advantages over the removable whipstock. As 

 provision is made to circulate through the tool, sand bridges in the well 

 may be removed when necessary. No pin is present in the knuckle joint, 

 which may shear prematurely. The danger of sticking a removable whip- 

 stock in the hole from cuttings settling out of the mud is much greater 



