Nonlinear Complex Resistivity
complex resistivity (NLCR) is a geophysical method of stimulating materials
with an electrical current sine wave of variable frequency and measuring
the voltage response. The ratio of the amplitudes of the voltage
to the current normalized by the geometry of the electrodes is the magnitude
of the resistivity. The shift in time between the stimulus current
and response voltage is a phase shift. Deconvolved response by stimulus
and summed root mean square harmonics are the total harmonic distortion.
Deviation of the real and imaginary parts of the complex resistivity transfer
function versus frequency from the Hilbert transform expectation are Hilbert
Distortions. Both distortions are measures of nonlinearity.
complex resistivity measurements as a function of frequency from 0.001
Hz to 1,000 Hz are useful in a variety of applications where remote measurements
of active chemical processes are important. As all chemical reactions
involve electron charge movement, NLCR can measure or observe nearly all
chemical processes (some are too fast or too slow). NLCR is used
in the laboratory, in boreholes, between boreholes or between holes and
the surface, from the surface and inside tunnels. It requires contact
with the ground to inject a current and has not been successfully employed
from airborne platforms. It has applications to the study of corroding
metals, ore exploration and delineation, clay-organic reactions for petroleum
exploration, environmental characterization and monitoring, ground water,
archaeology, and agriculture.
<more to come>
Copyright 1999 by Gary R. Olhoeft.
All Rights Reserved.