SUMMARY Magnetic susceptibility logs can be made as 



easily as an electric log. The logging speed is 

 limited only by the limitations of hoists and recorders. Logs can be obtained in 

 conventional oil- or water-base muds as well as in open hole. Logs have con- 

 siderable character and exhibit good reproducibility. Magnetic susceptibility is 

 an independent rock property and is controlled primarily by the iron content 

 in the rock. Natural magnetic properties are easily correlated, and magnetic 

 horizons have been correlated over considerable distances where other logging 

 methods gave poor correlation. The use of magnetic tracers in drilling fluids has 

 made possible the evaluation of filter cake build-up and has permitted permeable 

 zones as well as zones of lost circulation to be detected. The magnetic suscepti- 

 bility log in conjunction with the total field log has given control information 

 for interpretation of surface magnetometer surveys. 



BIBLIOGRAPHY 



Broding, R. A., and others, 1952, Magnetic well logging: Geophysics, v. 17, no. 1, p. 1-26. 

 Hicks, W. G., Location of permeable zones by magnetic tracers: Magnolia Petroleum Co. 



Field Research Lab., Rept. 54.2 FEO. 

 Patent No. 2,535,666. 



436 



