454 



EXPLORATION GEOPHYSICS 



Self -potential surveys of sulphide ore bodies have also been described 

 by Kelly, % Mason § and others, ft 



Another example of the application of the spontaneous polarization 

 method to a geophysical study is provided in Figure 272, representing pro- 



FiG. 271. 



-Self-potential survey of Sain-Bel ore body. (After Schlumberger, Etude de la prospec- 

 tion Electrique du Sous-Sol.) 



files over one tunnel of an abandoned nickel prospect near Winesap, Chelan 

 County, Washington. The discussion and interpretation! was made by 

 Patty and Kelly in 1946. 



Surveys Over Anthracite Coal Deposits. — Anthracite coal quite 

 frequently shows the phenomenon of spontaneous polarization. It is found 

 that a positive instead of a negative center occurs over the upper part of the 

 anthracite beds. The potentials encountered are usually much smaller than 

 those found over sulphide ores. 



Corrosion Surveys. — The oxidation of pipe lines is an important commercial 

 problem which has been the object of numerous investigations. Xt The types of cor- 

 rosion that may afifect a buried metallic conductor may be enumerated as follows : §§ 



1. Soil corrosiveness. The conductor is attacked by the surrounding soil. 



2. Autogalvanic corrosion. If a metallic conductor connects two regions of the 



t S. F. Kelly, Engineering and Mining Journal, Vol. 114, Oct. 7 and Oct. 14, 1922. _ 

 § M. Mason, "Geophysical Exploration for Ores," A.I.M.E. Geophysical Prospecting, 1929, 

 p. 27. 



tt Broughton Edge and Laby, Geophysical Prospecting, pp. 81-84, 98-100. 

 t E. N. Patty and S. F. Kelly, "A Geological and Geophysical Study of the Chelan Nickel 

 Deposit," A.I.M.E. Tech. Pub. 1953. 



tt F. N. Speller, Corrosion Causes and Prevention (McGraw-Hill, 1935). 



O. P. Watts, "Electrochemical Theory of Corrosion," Trans. Electrochem. Soc, Vol. 64, pp. 

 125-153, 1933. 



T. G. Elliott, R. J. Sarjant, and W. Cullen, "Special Alloy Steels As Applied to Chemical 

 Engineering," J. Soc. Chem. Ind., Vol. 51, pp. 502-531, 1932. 



Scott Ewing, "Electrical Methods for Estimating the Corrosiveness of Soils," Amer. Gas 

 Assoc. Monthly, Vol. 14, pp. 356-360, 1932. 



W. G. Heltzel, "The Maintenance of Oil Pipe Lines," Proc. Amer. Petroleum Inst., Vol. 

 14, pp. 168-191, 1933. 



G. N. Scott, "Report of A.P.I. Research Associate to the Committee on Corrosion of Pipe 

 Lines," Proc. Amer. Petroleum Inst., Vol. 14, pp. 204-220, 1933. 



J. M. Pearson, "The Value of Soil-Survey Methods," Oil and Gas Journal, Nov. 18, 1938, 

 p. 100. 



§§ C. and M. Schlumberger and E. G. Leonardon, "Location and Study of Pipe Line Corrosion 

 by Surface Electrical Measurements," A.I.M.E. Geophysical Prospecting, Tech. Pub. 476 (1932). 



