impossible to follow this program closely. A textbook, (Kartsev, et al., 1954) , 

 embodying much of this work is published in Russian for the college student. 

 It is believed to be the only one available on this subject. Periodically, at 

 national meetings, Russians in the field of geochemical exploration re-evaluate 

 methods and plan future programs. At the Conference of Geochemical Prospect- 

 ing for Petroleum and Gas held in Moscow, March 1955, the Russian geo- 

 chemists (Kalinin, et al., 1955) noted their extremely unfavorable position 

 with respect to the development of theoretical principles and with respect to 

 the geochemical methods. 



The geochemical methods that are briefly described in this paper are based 

 upon the detection of some effect created by migrating gases of petroliferous 

 origin. 



SOIL-GAS METHOD In 1929, Laubmeyer (1933) conducted the 



first successful series of soil-gas studies. 

 Known oil districts were investigated to determine whether gas leakages were 

 higher than in adjoining non-petroliferous areas. To collect samples, he augered 

 a hole from 3 to 6 feet deep and then sealed it for 24 to 48 hours. The gas 

 filling the hole was removed for immediate analysis. Using portable analytical 

 equipment, Laubmeyer brought the gas samples into contact with a heated 

 platinum filament and burned it with air oxygen. The resulting heat of com- 

 bustion increased the resistance of the platinum wire, the amount of which 

 then was measured by means of a sensitive galvanometer. This method, de- 

 signed to detect methane down to 1 part in 10 10 parts of air, yielded results 

 that showed hydrocarbons occurred in greater quantities over fields of known 

 oil production than over barren areas. Laubmeyer 's reliance on the detection 

 of very low values of methane was found to be unwise, since such non-petrolifer- 

 ous sources of methane as lignites and coals also gave confusing anomalies. 



The Russians became interested in soil-gas methods, and in 1932 Sokolov 

 published the results of his investigations. Using a similar system of bore holes, 

 he first reduced the hole pressure and then collected the gas sample by displac- 

 ing water from a specially designed container. Methane and heavier hydro- 

 carbons were separated by reducing the temperature to that of liquid oxygen 

 (-183C). The lighter fraction, methane, remained gaseous while the heavier 

 hydrocarbons condensed. A high ratio of light to heavy fraction was interpreted 

 as being over a gas reservoir; a low ratio was indicative of being over an oil 

 pool. This method of gas analysis characteristically showing high methane 

 values to fall directly over the oil reservoir, confirmed Laubmeyer's findings. 

 This type of anomaly is shown in Figure 28-1. 



A disadvantage of this technique is the difficulty in obtaining usable samples 

 from areas where ground water is near the surface or from hard rock, compact 

 clays, and sand hills. 



623 



