154 C. A. HEILAND 
important information for the interpretation of resistivity measure- 
ments made at the surface. Secondly, the systematic “electrical cor- 
ing’”’ makes it possible to correlate wells by their “resistivity log’’ in 
much the same manner as it is possible by the sample log, and gives 
Resistwities in ohms mim ~ Logarithmic scale 
c ‘oo ANG KK 
aes — — NS CA MEE= 
mR a 
a =i oo \ \ 

W 7 \ iss —ym 
Nu MSS 
NX 
AWN 
Sooo 
sao WNT WR 

CLSSALT WATER SAND ——*C 
». Way | Sy 
distance befween wells : 3/4 mila 
gepths in feet 
Fic. 36.—Electrical correlations between two wells, Oklahoma City, 1929. (Waters 
No. 3 and Mackey No. 1.) 
not only a possibility for structural correlations, but at times enables 
one to recognize beds which may otherwise be overlooked. 
Figure 36 represents two resistivity logs obtained with the Schlum- 
berger method of electrical coring in two wells 34 mile apart near 
Oklahoma City. In this figure, the resistivities are plotted in log- 
arithmic scale. It is seen that the two curves are very similar in almost 
484 
