Estimation of Apparent Parameters from Spectral Full-Waveform Induced Polarization Data

Induced Polarization (IP) is a geophysical method widely used in mining exploration to assess the presence of polarizable material, such as sulfides. To extract additional information from the data the Spectral Induced Polarization is commonly used, which utilizes the spectral content of the voltage wave to estimate the complex resistivity. However, in order to enhance the spectra resolution, particularly at high frequencies, the full current wave has to be considered. For this reason, in this work we employ the Full-Waveform IP, which requires the full recording of the current and voltage waves to compute the complex resistivity.

The Cole-Cole analytic equation is used to extract additional parameters from resistivity spectra, which can enhance the interpretation of the data. However, the estimation of Cole-Cole parameters constitutes a non-linear inverse problem, which can be affected by local minima. In this study, we first process the field data acquired in Northern Alsace (France), and then invert the resistivity spectra using both a local (Levenberg-Marquardt) and a global (Particle Swarm Optimization) inversion algorithm. Our results suggests that the Full-Wavevorm IP enables to obtain large bandwidth spectra with satisfying resolution, which in turns helps the estimation of apparent parameters at high frequencies.