aquifers with hydrodynamic gradients intervening between the pool and the 

 surface. An aquifer above a pool would have to be saturated by the rising gases 

 before they would be released for further upward migration. Waters contained 

 in the shales or siltstones could similarly absorb rising gases. If the water 

 should be flowing laterally in the formations between the pool and surface, and 

 it were not gas saturated under the existing conditions of heat and pressure, 

 then all gas entering the formation would be taken into solution and carried to 

 a new position, perhaps considerably removed from the area of the pool. The 

 fact that subsurface conditions generally are unknown to the prospector make 

 interpretation of geochemical anomalies extremely difficult. For a particular 

 exploration method to be acceptable, it must yield accurate information under 

 most conditions. When the performance record of a technique or procedure 

 is poor, it becomes uneconomical to use and is discarded. This seems to have 

 been the fate of the early geochemical prospecting methods. 



HISTORY In the early 1930's, geochemical prospecting 



methods were first tried in an effort to reduce 

 exploration costs, and by 1940 this form of prospecting reached a peak. From this 

 date on, interest waned, and a search of the current literature reveals only an 

 occasional paper published by commercial laboratories. In the past few years, 

 however, research programs directed at the geochemistry of petroleum have been 

 undertaken by some major oil companies. 



A distinction should perhaps be drawn between geochemistry and geo- 

 chemical prospecting. Geochemistry is a study of the basic chemistry of 

 pertroleum and its derivatives, i.e., trace-metal associations, genesis, etc. — 

 problems which may lead indirectly to the discovery of petroleum. Geo- 

 chemical prospecting is the applied side of geochemistry — that which may be 

 used in the direct discovery of petroleum. Information uncovered as a result 

 of pure geochemical research may be expected to provide significant leads 

 upon which future geochemical prospecting methods may be based. 



Among the problems being investigated is a study of the composition 

 and behavior of the organic components in rocks; such data might enable 

 geologists to determine the source rocks of petroleum. A study of the forma- 

 tion of rocks may throw light upon the environments under which ancient oil- 

 source rocks formed. Nickel and vanadium porphyrin compounds occur as 

 trace metals in crude oils, and are being investigated from the viewpoint of 

 learning the manner of petroleum migration as well as accumulation. While much 

 of this research is long range, current information may assist the field geologist 

 iu his recommendations on favorable areas in which to prospect. 



The Russians have had a coordinated research program in geochemical 

 exploration since the 1930's, but because of the language barrier, it has been 



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