Spectral Induced Polarization Laboratory Measurements Combining Two and Four-Electrode Measurement Configurations

Summary Spectral Induced Polarization (SIP) is a geophysical technique which measures the frequency dependent electrical properties of geologic materials which can, in turn, be linked to underlying petrophysical parameters. Four-electrode SIP measurements exhibit errors above 100 Hz related to parasitic capacitive coupling (PCC) inside of the instrumentation and to the impedance of the potential electrodes. These errors can easily mask the true sample response. Existing techniques to correct SIP data infected with these errors can be complex and prone to operational error. Here we present a simple procedure that utilizes joint two- and four-electrode measurements using the same sample holder to validate high frequency SIP data. We tested the practicality of this approach by performing a series of two electrode SIP measurements on a known NaCl solution using conventional coiled current electrodes composed of different metals. We compared this procedure with both theoretical values and against a four-electrode correction procedure (referred to as the Wang correction), which utilizes four impedance measurements to directly calculate high frequency phase errors in instruments with differential amplifiers. We found that two electrode measurements conducted with coiled Ag-AgCl electrodes performed well for resistive samples and for highly polarizable samples above 100 Hz, and for conductive samples above 1 kHz. The use of joint two- and four-electrode measurements on the same sample holder is simpler than existing correction techniques and presents a straightforward alternative to the validation of high-frequency four-electrode data.