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Title: Method for imaging with low frequency electromagnetic fields

A method for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The traveltimes corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter .alpha. for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography.
Authors:
 [1] ;  [2]
  1. (Lafayette, CA)
  2. (Berkeley, CA)
Publication Date:
OSTI Identifier:
869650
Report Number(s):
US 5373443
DOE Contract Number:
AC03-76SF00098
Resource Type:
Patent
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
Country of Publication:
United States
Language:
English
Subject:
method; imaging; frequency; electromagnetic; fields; method; imaging; frequency; electromagnetic; fields; interpreting; electromagnetic; data; ray; tomography; determine; earth; conductivity; accuracy; resolution; imaging; method; steps; placing; transmitters; various; positions; plurality; transmitter; holes; placing; plurality; receivers; plurality; receiver; holes; transmitters; generate; electromagnetic; signals; diffuse; medium; earth; receivers; measured; diffusion; field; data; transformed; wavefield; data; traveltimes; corresponding; wavefield; data; obtained; charting; wavefield; data; regularization; parameter; alpha; transform; desired; property; medium; conductivity; derived; velocity; constructed; wavefield; data; ray; tomography; electromagnetic signals; electromagnetic fields; electromagnetic fields; electromagnetic field; electromagnetic field; magnetic field; magnetic field; magnetic fields; magnetic fields; electromagnetic signal; various positions; imaging method; frequency electromagnetic; frequency electromagnetic; transmitters generate; field data; field data; field data; field data; field data /702/324/