BORE-HOLE INVESTIGATIONS 



1109 



Fig. 693. 

 (Courtesy of Lane-Wells Company.) 



which represent formation contacts. An understanding of the causes of these sloping 

 transitions is helpful in their interpretation. The primary cause of this type of repre- 

 sentation is the length of the measuring device. The nature of the instruments requires 

 a measuring device approximately three feet in length for the gamma-ray curve and 

 one foot for the neutron curve. This means that the complete zone of contact may 

 cover as much as five feet for the former and three feet for the latter. It is obvious 



Fig. 694. 

 (Courtesy of Lane-Wells Company.) 



