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

Olsson, Per-Ivar; Dahlin, Torleif; Fiandaca, Gianluca; Auken, Esben

doi:10.1016/j.jappgeo.2015.08.009

Cited by 47 publications

(35 citation statements)

References 17 publications

(18 reference statements)

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“…Figure presents the inversion models of the three El‐logs, for all inversion parameters, together with the parameter uncertainty computed through equation , while Figure shows the fit of the DC data and of representative IP decays of the three inversions. The data standard deviations used in the inversion and for the computation of the parameter uncertainty were 1% on resistivity and 10% on each gate of the IP decays, plus a voltage noise floor

V_{n o i s e} = 0.1 normalm normalV

(see Olsson et al () for details on the computation of the total data uncertainty from

V_{n o i s e}

and the relative standard deviation). In Figure , it is seen that

σ_{max}^{''}

is a well‐resolved inversion parameter, with uncertainty comparable to the

σ_{b u l k}

uncertainty, while the frequency exponent

C

and, even more, the time constant

τ_{σ}

present significantly wider confidence intervals.…”

Section: Resultsmentioning

confidence: 99%

Permeability Estimation Directly From Logging‐While‐Drilling Induced Polarization Data

Fiandaca

Maurya

Balbarini

et al. 2018

Water Resources Research

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In this study, we present the prediction of permeability from time domain spectral induced polarization (IP) data, measured in boreholes on undisturbed formations using the El‐log logging‐while‐drilling technique. We collected El‐log data and hydraulic properties on unconsolidated Quaternary and Miocene deposits in boreholes at three locations at a field site in Denmark, characterized by different electrical water conductivity and chemistry. The high vertical resolution of the El‐log technique matches the lithological variability at the site, minimizing ambiguity in the interpretation originating from resolution issues. The permeability values were computed from IP data using a laboratory‐derived empirical relationship presented in a recent study for saturated unconsolidated sediments, without any further calibration. A very good correlation, within 1 order of magnitude, was found between the IP‐derived permeability estimates and those derived using grain size analyses and slug tests, with similar depth trends and permeability contrasts. Furthermore, the effect of water conductivity on the IP‐derived permeability estimations was found negligible in comparison to the permeability uncertainties estimated from the inversion and the laboratory‐derived empirical relationship.

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V_{n o i s e} = 0.1 normalm normalV

(see Olsson et al () for details on the computation of the total data uncertainty from

V_{n o i s e}

and the relative standard deviation). In Figure , it is seen that

σ_{max}^{''}

is a well‐resolved inversion parameter, with uncertainty comparable to the

σ_{b u l k}

uncertainty, while the frequency exponent

C

and, even more, the time constant

τ_{σ}

present significantly wider confidence intervals.…”

Section: Resultsmentioning

confidence: 99%

Permeability Estimation Directly From Logging‐While‐Drilling Induced Polarization Data

Fiandaca

Maurya

Balbarini

et al. 2018

Water Resources Research

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“…The measurement using the former approach is referred as 100% duty cycle measurement and the 236 latter as 50% duty cycle measurement (Olsson et al, 2015). The possibility of extracting the 237 spectral information contained in the TD signal depends considerably on the number of decades 238 acquired (Madsen et al, 2016;Madsen et al, 2017), and nowadays commercial instruments exist 239 that sample the full-waveform potential and current signals at high sampling rate (typically in the 240 kHz range) for the entire measurement time, allowing for advanced signal processing.…”

Section: Time-domain Spectral Induced Polarization 232mentioning

confidence: 99%

Subsurface imaging of water electrical conductivity, hydraulic permeability and lithology at contaminated sites by induced polarization

Maurya

Balbarini

Møller

et al. 2018

Geophysical Journal International

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“…With this approach, the charge and discharge effects were superimposed in the 100% duty cycle. Even though the current waveform in the present case was not modelled, as in Olsson et al (), we believe that the estimated integral chargeability can give a good approximation and that it can be sufficient for a qualitative evaluation of the results. The full waveforms of potential dipoles were recorded with a sampling rate of 3.75 kHz.…”

Section: Methodsmentioning

confidence: 74%

Data acquisition, processing and filtering for reliable 3D resistivity and time‐domain induced polarisation tomography in an urban area: field example of Vinsta, Stockholm

Rossi

Dahlin

Olsson

et al. 2018

Near Surface Geophysics

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There is an increasing demand for trustworthy engineering geological conceptual models in urban areas due to an increasing trend in the underground infrastructure construction. Good‐quality site investigations can reduce the risk of encountering unexpected geological conditions during construction. Geoelectrical measurements can be used as a tool for providing an overview of the site conditions and serve as a base for planning a geotechnical drilling program and for integration of the results. Geophysical surveys in urban environments may encounter problems due to strict logistical constraints and may be severely affected by electric and electromagnetic noise. Careful processing of the data is necessary to obtain a reliable estimation of the electrical properties of the ground, both electrical resistivity and chargeability. A large three‐dimensional dataset was acquired in the suburban area of Stockholm (Sweden), with the aim of investigating a weak zone in the crystalline bedrock, which had been pointed out by prior geological and geotechnical surveys. Full waveforms of potential dipoles were recorded and processed for removing harmonic noise and background drift. Moreover, a statistical algorithm for handling the quality of the full‐waveform shapes has been proposed. The goodness‐of‐fit test identifies full waveforms with noise that derives from direct current injections, caused by grounding spots of the adjacent metro line. The processed dataset is inverted for electrical resistivity and integral chargeability. The results image a large three‐dimensional volume of the underground. The inverted distribution of geophysical quantities marks out the presence of a wide zone of weak rock, which was not identified by geotechnical probing in the site investigation but documented during the construction phase. Such zones can potentially cause severe problems during the construction of underground infrastructure.

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

Cited by 47 publications

References 17 publications

Permeability Estimation Directly From Logging‐While‐Drilling Induced Polarization Data

Permeability Estimation Directly From Logging‐While‐Drilling Induced Polarization Data

Subsurface imaging of water electrical conductivity, hydraulic permeability and lithology at contaminated sites by induced polarization

Data acquisition, processing and filtering for reliable 3D resistivity and time‐domain induced polarisation tomography in an urban area: field example of Vinsta, Stockholm

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