LOTEM data processing for areas with high cultural noise levels

Strack, K. M.; Hanstein, T.; Eilenz, H.N.

doi:10.1016/0031-9201(89)90010-1

Cited by 43 publications

(31 citation statements)

References 4 publications

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“…The ®lters and stacking programs were designed according to Strack, Hanstein and Eilenz (1989), Buttkus (1991) and Strack (1992). The elimination of the noise must not change the phase and the amplitude of the base frequency and the ®rst harmonic of the signal.…”

Section: Data Processingmentioning

confidence: 99%

Electrical resistivity tomography to investigate geological structures of the earth's upper crust

Storz¹,

Jacobs²

2000

Geophysical Prospecting

164

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It is important to have detailed knowledge of the electrical properties of the earth's crust in order to recognize geological structures and to understand tectonic processes. In the area surrounding the German Continental Deep Drilling Project (KTB), we have used DC dipole–dipole soundings to investigate the electrical conductivity distribution down to a depth of several kilometres. We have adapted the electrical resistivity tomography (ERT) technique, a well‐established near‐surface method, to large‐scale experiments. Independent transmitting and receiving units were used to realize the concept of simultaneous multichannel registration of the scalar electrical potential at 44 dipoles. The measured data yielded apparent resistivities which were inverted to a 2D resistivity model ranging from the surface down to a depth of 4 km. Two highly conductive structures with steep inclination were detected. They are expected to be major fault zones embedded in a metamorphic body. The rather low resistivity (ρ < 10 Ωm) can be explained by the existence of graphitic minerals and/or electrolytic fluids.

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Section: Data Processingmentioning

confidence: 99%

Electrical resistivity tomography to investigate geological structures of the earth's upper crust

Storz¹,

Jacobs²

2000

Geophysical Prospecting

164

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“…The gate stacking refers to the stack of values of several measured decays at the same delay time. Strack et al (1989) have suggested deleting incoherent measurements by ordering data by amplitude before stacking. Secondly, the spectral peak at 50/60 Hz due to the power distribution grid is rejected thanks to the polarity changes of the transmitter wave and its base frequency (harmonic of 50/60 Hz).…”

Section: Skytem Datamentioning

confidence: 99%

Singular value decomposition as a denoising tool for airborne time domain electromagnetic data

Reninger

Martelet

Deparis

et al. 2011

Journal of Applied Geophysics

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International audienceAirborne Time Domain Electromagnetic (TDEM) surveys are increasingly carried out in anthropized areas as part of environmental studies. In such areas, noise arises mainly from either natural sources, such as spherics, or cultural sources, such as couplings with man-made installations. This results in various distortions on the measured decays, which make the EM noise spectrum complex and may lead to erroneous inversion and subsequent misinterpretations. Thresholding and stacking standard techniques, commonly used to filter TDEM data, are less efficient in such environment, requiring a time-consuming and subjective manual editing. The aim of this study was therefore to propose an alternative fast and efficient user-assisted filtering approach. This was achieved using the Singular Value Decomposition (SVD). The SVD method uses the principal component analysis to extract into components the dominant shapes from a series of raw input curves. EM decays can then be reconstructed with particular components only. To do so, we had to adapt and implement the SVD, firstly, to separate clearly and so identify easily the components containing the geological signal, and then to denoise properly TDEM data. The reconstructed decays were used to detect noisy gates on their corresponding measured decays. This denoising step allowed rejecting efficiently mainly spikes and oscillations. Then, we focused on couplings with man-made installations, which may result in artifacts on the inverted models. An analysis of the map of weights of the selected "noisy components" highlighted high correlations with man-made installations localized by the flight video. We had therefore a tool to cull most likely decays biased by capacitive coupling noises. Finally, rejection of decays affected by galvanic coupling noises was also possible locating them through the analysis of specific SVD components. This SVD procedure was applied on airborne TDEM data surveyed by SkyTEM Aps. over an anthropized area, on behalf of the French geological survey (BRGM), near Courtenay in Région Centre, France. The established denoising procedure provides accurate denoising tools and makes, at least, the manual cleaning less time consuming and less subjective

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“…Ruchkemann systematically compared different stacking methods [8] . Strack gave a detailed account of the tool chain for compensating for the distortion of the LOTEM signal caused by aperiodic and periodic noise [9][10] .…”

Section: V(t)=i(t)*g(t)+na (T)+np (T) mentioning

confidence: 99%

Estimation of the earth impulse of MTEM in very noisy environment

Zhang¹,

Di²,

Lei³

2016

Proceedings of the 7th International Conference on Environment and Engineering Geophysics &Amp; Summit Forum of Chinese Academy

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Abstract-we demonstrate how several tools, such as stacking, cross correlation, digital filtering, significantly attenuate the correlated and uncorrelated noise encountered during the estimation of the earth impulse response of multi-transient electromagnetic survey. This study focuses on processing of correlated cultural noise using digital recursive filtering. We also applied this to process the data observed from the MTEM singleline survey conducted over an underground hydrocarbon reservoir.

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LOTEM data processing for areas with high cultural noise levels

Cited by 43 publications

References 4 publications

Electrical resistivity tomography to investigate geological structures of the earth's upper crust

Electrical resistivity tomography to investigate geological structures of the earth's upper crust

Singular value decomposition as a denoising tool for airborne time domain electromagnetic data

Estimation of the earth impulse of MTEM in very noisy environment

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