nlcr

Nonlinear Complex Resistivity

Nonlinear 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.
Nonlinear 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,
infrastructure characterization, archaeology, and agriculture.