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Measuring time-domain spectral induced polarization in the on-time: decreasing acquisition time and increasing signal-to-noise ratio

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Author

Summary, in English

Combined resistivity and time-domain direct current induced polarization (DCIP) measurements are traditionally carried out with a 50\% duty cycle current waveform, taking the resistivity measurements during the on-time and the IP measurements during the off-time. One drawback with this method is that only half of the acquisition time is available for resistivity and IP measurements, respectively. In this paper, this limitation is solved by using a current injection with 100\% duty cycle and also taking the IP measurements in the on-time. With numerical modelling of current waveforms with 50\% and 100\% duty cycles we show that the waveforms have comparable sensitivity for the spectral Cole–Cole parameters and that signal level is increased up to a factor of 2 if the 100\% duty cycle waveform is used. The inversion of field data acquired with both waveforms confirms the modelling results and shows that it is possible to retrieve similar inversion models with either of the waveforms when inverting for the spectral Cole–Cole parameters with the waveform of the injected current included in the forward computations. Consequently, our results show that on-time measurements of IP can reduce the acquisition time by up to 50\% and increase the signal-to-noise ratio by up to 100\% almost without information loss. Our findings can contribute and have a large impact for DCIP surveys in general and especially for surveys where time and reliable data quality are important factors. Specifically, the findings are of value for DCIP surveys conducted in urban areas where anthropogenic noise is an issue and the heterogeneous subsurface demands time-consuming 3D acquisitions.

Publishing year

2015

Language

English

Pages

316-321

Publication/Series

Journal of Applied Geophysics

Volume

123

Document type

Journal article

Publisher

Elsevier

Topic

  • Geotechnical Engineering

Keywords

  • Cole–Cole
  • Duty cycle
  • Induced polarization
  • SNR
  • Signal-to-noise ratio
  • Spectral
  • Waveform

Status

Published

Project

  • Geoelectrical Imaging for Site Investigation for Urban Underground Infrastructure

ISBN/ISSN/Other

  • ISSN: 0926-9851