developed with John Cagle in April 1954. Since that time two methods have 

 been published (Prescott, 1955; DeWitte, 1956). 



Although the service companies running dipmeter have heretofore made 

 the interpretations, the advent of the continuous dipmeter makes it very desirable 

 for the geologist to do his own calculations. By making a considerable number 

 of determinations, a geologist can localize a fault or unconformity. 



Figure 25-9 is a diagrammatic drawing of dipmeter curves. Besides the 

 three formation curves, the continuous dipmeter log carries curves giving the 

 following information: magnetic azimuth of electrode I, the north or south com- 

 ponent of well deflection, the east or west component of well deflection, and 

 usually the diameter of the hole. The hole may be quite irregular because of 

 mud cake on porous zones and caving in soft or fractured zones. The hole 

 calipers may fail to reach the wall of the hole in spots, and this may be one 

 source of error. 



DIPMETER CALCULATIONS 



FIELD 



Figure 25-10. Form used in making dipmeter calculations. 



Interpretation of Dipmeter Records (6) 



Figure 25-10 is a convenient form used in making dipmeter calculations. 

 The example shown will be carried through to indicate the methods used. The 

 student will find more detail in the references. 



The several companies who run electric logs have different ways of pre- 

 senting the necessary information. It is advisable to consult the particular com- 

 pany making the run to be sure that all symbols used are understood, and some- 

 times special scales are furnished to aid in taking the information from the 

 curves. 



It will be assumed that the curves made by the three electrodes have been 

 correlated at a particular level and that the information from all curves has 

 been entered on the form. This basic information is underlined in Figure 25-10. 



543 



