PETROLEUM RESOURCES—LEVORSEN 
©) oil or gas field 
6 Miles 
Figure 1.—Drilling density of an area in Oklahoma typical of many counties in the mid- 
continent region. 
is rather amazing. Figure 1 shows an 
area of around 320 square miles in 
Oklahoma which is typical of many 
counties. ‘The dry holes or salt-water 
wells—each representing a geologic 
column—average less than a mile 
apart. One might conclude from this, 
no wonder they find oil! When we 
think of the plains region of Canada 
with test wells 50 miles or more apart, 
the immensity of the drilling program 
necessary to locate all the oil fields 
becomes apparent. 
We then come back to the first part, 
which is the crux of the problem— 
t Dry hole — av. 2800'- 3800' 
is there enough oil which remains to 
be discovered? If there is not, then 
there is not much need of more drilling. 
But if there is oil—in terms of our 
national needs—remaining to be found 
then we should be on with the business 
of locating it. The presently known 
recoverable oil reserves of 21 billion 
barrels or more—about 12 times the 
annual consumption—is merely a 
working stock. Much of the oil we 
are using today was unknown 20 
years ago, and likewise the oil we will 
use 20 years hence is in a large part 
still undiscovered. The really impor- 
