GEOLOGIC AND ECONOMIC BACKGROUND 37 



determined principally by the nature of the geophysical technique employed, 

 terrain conditions, local land ownership, etc. 



It is obvious from these factors that specific cost is a characteristic of 

 individual surveys and that only an approximate general tabulation of 

 relative costs can be made. Table 3 is such a tabulation, listing the methods 

 in the order of increasing cost. 



TABLE 3 

 APPROXIMATE COST OF GEOPHYSICAL PROSPECTING 



Method Cost per moiitJi^^'' Cost per moiith^^''' 



1940 1949 



Magnetic $ 500- 700 $ 1,000- 2,50O<^> 



Aerial magnetic $ 6- 12 per profile mile"" 



Gravitational : 



Gravimeter 3,000- 5,000 3,500- 6,000'"' 



Torsion balance 3,500- 4,500 2,000- 6,000 



Marine gravity work 10,000-20,000'" 



Electrics.! ' 



Self potential 1,000- 1,500 



Resistivity 3,000- 5,000 4,000- 5,000 



Equipotential 2,500- 3,000 



Geochemical 3,000- 6,000 4,500- 6,000 



Seismic 



Reflection 6,000-11,000 7,000-20,000'^' 



Refraction 6,000-15,000 9,500-22,000 



Shallow refraction 2,500- 4.000 



Marine seismic work 20,000-75,000 



Slim-hole drilling .25-1.75/ft. .50-3.00/ft. 



'*' Data from the first edition of Exploration Geophysics, compiled in 1939-1940. 

 "'' Compiled from figures submitted by : 



J. A. Sharpe, Frost Geophysical Corporation, Tulsa, Oklahoma. 



E. J. Handley, Century Geophysical Corporation, Tulsa, Oklahoma. 



William B. Heroy, Geotechnical Corporation, Dallas, Texas. 



Raymond L. Sargent, geophysicist, Houston, Texas. 



Leo Horvitz, Horvitz Research Laboratories, Houston, Texas. 



E. V. McColIum, geophysicist, Tulsa, Oklahoma. 



John Bible, Tidelands Exploration Company, Houston, Texas. 



Henry Salvatori, Western Geophysical Company, Los Angeles, California. 



H. Klaus, Klaus Exploration Company, Lubbock, Texas. 



L. L. Nettleton, Gravity Meter Exploration Company, Houston, Texas. 



John H. Wilson, Independent Exploration Company, Fort Worth, Texas. _ 



Raymond A. Peterson, United Geophysical Company, Pasadena, California. 



Dart Wantland, Bureau of Reclamation, Dept. of the Interior. 

 ""' Higher figure for marshy or difficult terrain. 

 "" Excluding cost of photography or radio location. 

 «" If helicopters are used, add $13,000-$18,000. 

 '" Lower figure for inland waters. 

 '^' Higher figures include all "extras." 



Rosairef has presented an interesting summary of the various factors 

 which are important in formulating and applying geophysical exploration 

 programs. The economics of geophysical exploration is but one phase of 

 the larger sphere of petroleum exploration economics, albeit an increasingly 



t E E. Rosaire, "On the Strategy and Tactics of Exploration for Petroleum," Jour. Soc. Pet. 

 Geoph., Vol. VI, No. 1, July, 1935; Geophysics. Vol. Ill, No. 1, Jan., 1938. 



