Subsurface Logging Methods 



463 



as an electric log itself. It is obvious, therefore, that if a drilling-time log 

 of a well corresponds in pattern to an electric-potential log of that well 

 after the hole has been drilled, the drilling-time log made during the 

 drilling could be used for the purposes served by the electric log. This 

 has proved true particularly in the Gulf Coast area where long-range or 



Figure 217. Curves plotted from same data as those of figure 216. Solid line rep- 

 resents a plotted five-foot interval. Dotted line reflects an average plot. 



