Three-Component Analysis of Induced Polarization and Superparamagnetic Effects in Grounded-Wire Source TDEM Surveys

Abstract

The induced polarization (IP) and superparamagnetic (SPM) multieffect fields are generated due to complex physical characteristics and parameter information of polymetallic particles in grounded-wire source time-domain electromagnetic (TDEM) detection. Recent studies show that the accurate observation of IP characteristics and elimination of SPM interference can improve TDEM interpretation accuracy effectively. However, it is difficult to realize the accurate recognition and effective observation of the multieffect responses in the large range of nonuniform grounded-wire source signals. Therefore, in this study, the 3-D modeling of IP and SPM effects in grounded-wire source TDEM is realized by introducing the fractional Cole-Cole conductivity and susceptibility models and establishing the double-curl electric field convolution matrices. The response characteristics of IP and SPM effects are analyzed, and a three-component observational method of multieffect is proposed. The effectiveness of the proposed method is verified by carrying out observation experiments of IP and SPM equivalent circuits. The results show that observing the magnetic field component parallel to the grounded-wire source can obtain IP and SPM response characteristics earlier, and observing the vertical component can reduce the interference of SPM effect while obtaining more obvious IP responses. Through the comprehensive analysis of three-component responses, the IP and SPM characteristics can be better determined. This study has a guiding role in receiving the information of multieffect responses and improving the accuracy of polymetallic ore detection.