Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

Clay minerals show a distinct induced-polarization (IP) phenomenon, which is one of the most important factors for predicting groundwater flow and contaminant transport. This paper presents a step-by-step process to estimate Cole-Cole parameters from multi-frequency induced-polarization data measured on the surface of three-dimensional earth. First, the inversion of low-frequency resistivity survey data is made to identify the dc resistivity of a volume having IP effects. The other parameters, such as chargeability, time constant, and frequency dependency, are sought for the polarizable volume. Next, using multi-frequency IP data, frequency dependency can be obtained as high or low asymptotes of the slope of log phase vs. log frequency. Further, for low chargeability, intrinsic time constant is approximated by apparent one, which is derived from the relation ωτa = 1 at an angular frequency ω, where the imaginary component of spectral IP data has an extreme value. Finally, to obtain intrinsic m a two-step linearized procedure has been derived. For a body of given τ and c, forward modeling with a progression of m values yields a plot of observed vs. intrinsic imaginary components for a frequency. Since this plot is essentially linear, to extract the intrinsic imaginary component is quite simple with an observed value. Using the plot of intrinsic imaginary component vs. m, intrinsic m is determined. We present a synthetic example to illustrate that the Cole-Cole parameters can be recovered from multi-frequency IP data. A 3-D prism model was selected to represent clay-bearing zone, and this estimation procedure can be applied to an IP data for monitoring a contaminated zone in remediation process.