20 E. ik. ROSATRE 
Prospect Prospect Evaluation Final Evaluation by Drill 
Development and Culling Prior to Exploitation 
A B C€ DD, VE. eae N 
B Co Dy ek N 
iS Dg oe N 
D 1 Dae iS N 
E F-- N 
F N 
N (Active wildcat drilling) 
The justification for successive prospect evaluation is that the 
experience gained thereby will be valuable in the later phase of pros- 
pect discovery by the same method. Thus, if, in a given area, the ap- 
propriate exploration methods are: 
Library methods 
Surface methods 
Torsion balance 
Reflection seismograph 
Drill 
there may be a strong temptation to skip either or both the surface 
methods and the torsion balance in prospect evaluation, particularly 
if experience shows that not all prospects shown by the reflection 
seismograph are indicated by one or both of these methods. However, 
even if there existed only incomplete correspondence between these 
methods (i.e., that the torsion balance, say, did not indicate anom- 
alies at all reflection seismograph structures), the method of lower 
resolving power should be used in sequence for prospect evaluation, 
not only because of its lower operating cost, but also because the ex- 
perience and data secured in the course of prospect evaluation by 
this method of lower resolving power would be useful in the later 
stage of prospect development by that same method. 
These conclusions suggest that an exploration department should 
be completely integrated, consisting of the use of geological and geo- 
physical methods under the supervision of one head. Also, pro- 
ficiency in the effective use of one method of exploration should not 
be considered a valid reason for neglecting the use of other methods, 
for the result may be either an inherently greater hazard in exploita- 
tion, or an inherently greater cost in discovery. Thus, if an explora- 
tion department in the Gulf Coast relied wholly upon geological 
264 
