Position of 

 *r\ Electrode 



eLCCTROD« 



electrode electrode el*ctrod« 

 *l #2 #3 



Photoc linometer Picture 



Magnetic North 



Figure 19-1. Basic principles of dipmeter. 



three SP or resistivity curves and gives the drift and azimuth of the well bore. 

 Spring guides above and below the photoclinometer-electrode assembly serve to 

 keep the device centered in the hole and to prevent it from turning. 



The curves are recorded photographically at the surface on the standard 

 electric-logging recorder. 



AREAS OF APPLICATION Those regions where the geologic section is 



primarily sand and shale, i.e., California or 

 the Gulf Coast, are best suited for the use of the SP dipmeter. The spontaneous 

 potential here in general shows sharp, well-defined anomalies at formation 

 boundaries, which give definite dip determinations. Likewise in these areas a 

 series of bedding surfaces between sand and shale can usually be found at any 

 depth in a well where a dip determination is needed. 



The resistivity dipmeter, on the other hand, has proved of utility in such 

 areas as west Texas, the Mid-continent, and the Rocky Mountains. The numerous 

 resistivity anomalies between, for example, shale and limestone found in most 



390 



