PETROLEUM. 



57 



development presages a time, soon to arrive if not already here, when 

 the present rate of production can no longer be sustained in its full 

 vigor. Just so soon as the aggregate output is compounded of senile 

 and youthful fields, with the latter no longer in the ascendency, the 

 resource as a whole will pass inevitably into a period of slowing and 

 more costly production, even though the resource is yet but half 

 exhausted.^ The period of economic stress, then, waits merely on this 

 concatenation of circumstances, by no means upon a marked physical 

 exhaustion of the resource. 



WHAT PETROLEUM EXHAUSTION MEANS. 



It appears from the foregoing section that the petroleum re- 

 source is not only strictly limited in size but also in ability to sustain 



MILLIONS OP BARRELS 



SOO 1000 1500 2000 2500 3000 



, I 



'APPALACHIAN 



i- 



lima-indiana 

 illinois 



kansas-oklahoma 

 north texas 

 northvtkt louisiana k3 

 gulf coast 

 colorado 

 wyoming-moktana 

 california 



Fig. 9. — Chart showing the approximate degree of exhaustion of the principal 

 petroleum fields op the united states. the " unused portions " can be greatly 

 increased by reconstructed methods of production. data from u. s, geological 

 Survey. 



the present rate of increase in production. We may examine, then, 

 what would be involved in a curtailment of activities dependent upon 

 petroleum, since this necessity lies in prospect, in order to be better 

 prepared to weigh the gravity of the issue. 



As already noted, crude petroleum^ is converted into four main 

 products — gasoline, kerosene, fuel oil, and lubricating oils — and a 

 group of substances less consequential at present which may be 

 termed by-products. The social importance of these five classes of 

 products may be examined in turn, although some of the points have 



* An oil field in Its youth is vigorous ; then. In particular, gushers pour forth their 

 exuberance. Later, in maturity and with increasing age, the production is maintained 

 with growing difficulty ; many more wells must be drilled ; the oil responds less willingly 

 to stronger pumping. Eventually the production declines long before the field is near 

 exhaustion. The gasoline content of the oil also decreases, as a rule, with the aging of 

 the field or pool. 



* Apart from the one-fifth, more or less, used in the crude condition, which falls 

 largely into the class of fuel oil. 



