What is it about?
The spikes that appear in electromagnetic well logs are called "polarization horns" because since the 1990's they are attributed to the effects of surface charge build-up at the interfaces between layers. Instead, by studying the mathematical expressions for the rate of change of the field components as the transmitter and receiver cross the interface, this paper shows that the horns are actually related to the discontinuous behavior of the current density field parallel to the interfaces.
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Why is it important?
This new interpretation changes the emphasis from surface charges, that are related to the component of the current density field normal to the interface, to the discontinuity of the current density field parallel to the interface. Recognizing that the causes of the horn effect are not related to a single aspect (surface charges) helps to build a more complete understanding of the phenomenon.
Perspectives
We hope that our work will help to advance the analysis of electromagnetic phenomena involved in well logs, and ultimately contribute to improving their interpretation.
Cícero Régis
Universidade Federal do Para
Read the Original
This page is a summary of: A new look at the causes of “polarization” horns in electromagnetic well logging, Geophysics, November 2020, Society of Exploration Geophysicists,
DOI: 10.1190/geo2020-0163.1.
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