520 



Subsurface Geologic Methods 



degrees of angle at the point at which a tool is to be set. It requires less 

 time than other orientation systems when tools are run in deep wells. The 

 drift and direction of the well at the proposed setting point must be de- 

 termined by a single-shot picture or from a multiple-shot survey. A special 

 substitute (fig. 250) containing two opposite-pole magnets is made up 

 immediately above the whipstock bit or the knuckle joint (fig. 251). This 

 orienting substitute has a tapped hole in its side, which receives the end 

 of the shear pin screwed through the back of the whipstock. The magnets 





Figure 249. Diagram of 

 Stokenbury system of 

 drill-pipe orientation. 



