Miscellaneous Subsurface Methods 



625 



bound waters, and these in turn may introduce a considerable error in core- 

 saturation determinations. 



Another appreciable limitation of coring results from the fact that it 

 is usually very expensive and causes marked increases in over-all well, 

 costs when it must be used. The development of more economical methods 

 to evaluate subsurface formations accurately as well as to find ways to 

 reduce coring costs would be a major contribution to the oil industry. 



APPLICATION OF DIPMETER SURVEYS 

 E. F. STRATTON and R. G. HAMILTON 



The SP (spontaneous-potential) dipmeter was described^ several 

 years ago as a means for determining the direction and magnitude of 

 formation dip in situ. This instrument was designed to record simultan- 

 eously three SP curves of known orientation, 120° apart along three gen- 

 eratrices of a well bore. Each curve fixes thus one point on a bedding 

 surface and the position of the surface can be determined (fig. 325) by the 

 displacement between the curves. 



electrode electrode electrode 

 HI #2 #3 



ELtCTROD£3 



Poaifion of 

 ^\ Electrode 



Photoclinometer Picture 



MagriBt-ic North 



Figure 325. Basic principles of dipmeter. 



Doll, H. G., The SP Dipmeter: Am. Inst. Min. Met. Eng. Tech. Pub. 1547, Jan. 1943. 



