Transient electromagnetic responses during the transmitter on-time

2010 ◽  
Author(s):  
Gregory M. Schultz ◽  
Jonathan S. Miller ◽  
Lin-Ping Song ◽  
Leonard Pasion
Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 426-430 ◽  
Author(s):  
Hesham M. El‐Kaliouby ◽  
Essam A. Eldiwany

The transient voltage response of a central loop electromagnetic system above a buried polarizable parallelepiped target (such as pyrites, sulfides, clays, etc.) is studied. The voltage response, which includes a positive part and a negative part (related to the polarization properties), is studied by varying the body characteristics, including the Cole‐Cole parameters, body dimensions, depth, and thickness. By varying the loop radius and by using profiling, the lateral body dimensions can be identified, particularly using the negative response for polarizable bodies. There is a clear difference in the dependencies of the positive and negative voltage responses on the body characteristics, which means that the negative voltage is not just redundant data, but we may use it, together with the positive response, to have better understanding for the body dimensions and polarization parameters effects.


Geophysics ◽  
1990 ◽  
Vol 55 (8) ◽  
pp. 1098-1100 ◽  
Author(s):  
G. W. Hohmann ◽  
G. A. Newman

Abnormal decay curves that are depressed or change sign often are observed in coincident‐loop and central‐loop transient electromagnetic (TEM) measurements, particularly in areas of conductive overburden. With the publication of papers by Smith and West (1989a, b) and Flis et al. (1989), the phenomenon, which is due to induced polarization (IP) in near‐surface, weakly polarizable material such as clay, is well understood.


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