40 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



In this particular model the vertical hue represents 

 the plumb line from the derrick floor. The curved line 

 is an accurate representation 

 of the course of the drill 

 hole through the formations. 

 The model was made by- 

 drilling holes through sheets 

 of glass in the surveyed posi- 

 tions of the hole at differ- 

 ent depths. A black cord 

 threaded through these holes 

 represents the well. 



The Sperry-Sun Well Sur- 

 veying Company of Philadel- 

 phia also employs an attrac- 

 tive and useful method of 

 depicting deviation. They 



Fig. 18. 

 Fig. 18. — Thurmann's borehole model. 



Fig. 19. 



Fig. 19.— Glass model of the Chanslor-Canfield, Midway Oil Co.'s No. 96 

 Olinda oil well in the FuUerton, Calif., Field, showing the course of a very deep 

 borehole. {After Anderson.) 



project the surface position of the borehole on to the 

 lowest depth model plane as the center of deviation 

 coordinates. From this axis the relative displacements 

 are plotted at their respective depths (Fig. 19a). The 



