Field-scale comparison of frequency- and time-domain spectral induced polarization

Abstract

In this paper we present a comparison study of the time-domain (TD) and frequency-domain (FD) spectral induced polarization (IP) methods in terms of acquisition time, data quality and spectral information retrieved from inversion. We collected TDIP and FDIP surface measurements on three profiles with identical electrode setups at two different field sites with different lithology. In addition, TDIP data were collected in two boreholes using the El-Log drilling technique in which apparent formation resistivity and chargeability values are measured during drilling using electrodes integrated within the stem auger. The TD and FD data were processed and inverted with similar approaches. The IP voltage decays and complex impedance spectra were inspected quadrupole by quadrupole for outliers. In the inversion, the apparent resistivity values and the full IP decays (in TD) or the full complex impedance spectra (in FD) for all quadrupoles were inverted simultaneously in 2-D using a modified parametrization of the Cole-Cole model. Furthermore, inversions of synthetic models mimicking the field situations were performed. The comparisons reveal that TD and FD results are comparable not only qualitatively, but also quantitatively. Furthermore, the surface inversions are in agreement with the borehole results and lithology, within the resolution capability of the surface measurements. In particular, comparable spectral IP parameters were retrieved for both sites with both measurement approaches, with relaxation times between 10 −2 s and 1 s, suggesting a spectral coverage at least up to 100 Hz for both TD and FD measurements. However, for the employed data acquisition procedures and instrumentations, the TD measurements had an advantage in terms of acquisition speed and usable spectral acquisition range compared to the FD measurements. We conclude that the TD method, as the FD method, is a suitable tool to recover spectral IP information in the field, provided that the measurement procedures are planned accordingly and the subsurface IP response is in the spectral range covered by the measurements.

Influence of smectite and salinity on the imaginary and surface conductivity of volcanic rocks

“…In particular, different types of clay minerals (smectites, illite, chlorite, the electrical properties of earth materials. With frequencydomain IP or spectral analysis of time-domain IP, complex conductivity tomography of the sub-surface can be performed and provide, besides the classical real conductivity (or resistivity), the imaginary conductivity, chargeability or phase-angle (Auken et al 2014;Fiandaca, Madsen and Maurya 2018;Maurya et al 2018b;Lévy et al 2019c).…”

Tracking Magmatic Hydrogen Sulfur Circulations Using Electrical Impedance: Complex Electrical Properties of Core Samples at the Krafla Volcano, Iceland

“…Moreover, the bulk real conductivity at 1 Hz, σ 1Hz , is used to represent the real part of the conductivity (equation ). The value at 1 Hz is chosen as it is most relevant for field applications, but the bulk real conductivity is considered almost frequency independent (see, e.g., Maurya et al, ). where σ and Z ′ are the real part of the bulk electrical conductivity and impedance, respectively.…”

“…The peak frequency at which the MPA is reached, is, however, missing in this description. Since it is a more complicated and ambiguous parameter to calculate, both in field and in time domain IP studies, we do not analyze it quantitatively here (Fiandaca et al, ; Maurya et al, ).…”

“…Moreover, the bulk real conductivity at 1 Hz, 1Hz , is used to represent the real part of the conductivity (equation (3)). The value at 1 Hz is chosen as it is most relevant for field applications, but the bulk real conductivity is considered almost frequency independent (see, e.g., Maurya et al, 2018).…”

Electrical resistivity tomography and time-domain induced polarization field investigations of geothermal areas at Krafla, Iceland: comparison to borehole and laboratory frequency-domain electrical observations

“…IP can be either measured in frequency-domain (FDIP) or in time-domain (TDIP). In both cases, it is possible to obtain the average relaxation time, in addition to the amplitude of the polarization, usually represented by the chargeability or the phase angle (Flores Orozco et al 2012;Kemna et al 2012;Fiandaca et al 2018;Flores Orozco et al 2018;Maurya et al 2018). The relaxation time is the time taken by the charge carriers (ions, electrons or holes, responsible for polarization) to relax, that is to return to their initial position (Revil et al 2015;Misra et al 2016;Abdulsamad et al 2017;Bücker et al 2018).…”