The authors discussed the behavior of the resistivity spectra by means of the Cole-Cole dispersion model. They also discussed the corrections with which the petrophysical resistivity spectrum can be reduced into an apparent resistivity spectrum caused by a polarizable body embedded in an unpolarizable environment. The application of the Cole-Cole dispersion model is a marked step forward in spectral IP analysis. However, closer attention must be paid to the assumptions and approaches on which the authors base the relations between the petrophysical and apparent spectra.
The authors based their relations between the true and apparent spectra on the use of the dilution factor B2. In accordance with the definition by Seigel (1959), they assumed that B2 is a real constant (independent of frequency) over the whole frequency range under consideration. First consider the justification for the assumption of the existence of a constant factor B2 in the light of an example calculated for phase spectra. Similar considerations could also be made with the aid of amplitude spectra.