228 AKNTUAL REPORT SMITHSONIAN INSTITTJTION, 1942 



essential to its growth, and if it sliould fail to find new supplies, it 

 would quickly relapse into a stifling routine operation and gradually 

 stagnate. 



The primary work of the petroleum geologist is in the field of oil 

 discovery. His work is, therefore, fundamental and of vital im- 

 portance, not only to the economy of the industry, but of the nation 

 as well, for oil has certainly become one of the necessities of well- 

 being for this age. He does many other kinds of work within the 

 industry, particularly in the scouting, leasing, and production depart- 

 ments, but failing of discovery, they would all be of little value, 

 for everything he does is subordinate to his function in the main- 

 tenance of supplies of crude oil. 



Probably as good a measure as any of the role of science in the 

 discovery process is to be found in the most recent of the annual 

 surveys made by Lahee ^ of the basis upon which wildcat well loca- 

 tions were made in 1940. During this year he finds that of the 3,038 

 wildcat wells drilled, 2,051, or approximately two-thirds, were drilled 

 because of geological and geophysical reasons, and of the remain- 

 ing one-third, most were drilled for various nontechnical reasons and 

 part for unknown reasons. Moreover, he finds that of the wells 

 drilled on technical advice, 15.6 percent were producers as against 

 only 4.2 percent successful in the case of wells drilled for non- 

 technical reasons. It was, therefore, nearly four times as advan- 

 tageous to use technical reasons for making wildcat locations as to 

 use nontechnical reasons. 



One of the curious situations in petroleum geology is that in spite 

 of our theories, and of all the workers who have given thought 

 to the problem, little is known of the origin of oil, how it migrates, 

 or how it accumulates. About all that is known is that it is now 

 found in traps of various kinds, and as a consequence, almost the 

 entire geological effort toward discovery consists in the search for 

 such traps. The most obvious trap is an up-fold or deformation of 

 the earth's strata which will keep the oil within the affected area. 

 In the idiom of the profession, these are called "structures" and a 

 pool which produces from such an anomaly is called a "structural 

 pool." 



Less obvious and much more difficult to find are those traps that 

 I'esult from a variation in the porosity or in the stratigraphy of the 

 reservoir rock. Pools producing from such situations are called 

 "stratigraphic" pools. Random drilling lias been particularly 

 adapted to the discovery of "stratigraphic" pools, for in them we 

 find no guiding surface or shallow indications. Most of the oil 

 fields of the great producing areas of Ohio, Pennsylvania, West 



'Lahee, F. H., Wildcat drilling In 1940. Bull. Amer. Assoc. Petrol. Geol., vol. '25, pp. 

 997-1003, June 1941, 



