Deharmonics, a Method for Harmonic Noise Removal on Vibroseis Data

Martin, F.; Muñoz, Pedro

doi:10.3997/2214-4609.201400619

Cited by 2 publications

(3 citation statements)

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“…Now steps I-IV will be described in detail. Here, our steps I-III basically correspond to steps 3-5 in Martin and Munoz (2010).…”

Section: The Decontamination Methodsmentioning

confidence: 99%

“…With modern vibroseis surveys, including the well established 'slip-sweep' technique, usually much more effort is put into carefully controlling the actual source signal that is transmitted into the ground (e.g., by measurements of acceleration at the baseplate and reaction mass), so that the harmonics are not a major problem. Martin and Munoz (2010) already showed how their (rather similarly operating) approach attenuates harmonic contaminations that originate from strong first-breaks and that are folded back into previous records during slip-sweep acquisition. The decontamination approach, introduced here, is mainly applicable to older, deep seismic sounding surveys when these kinds of noise are recognized during processing and an improved reprocessing is planned.…”

Section: O N C L U S I O N Smentioning

confidence: 95%

“…In a special issue of Geophysical Prospecting on vibroseis acquisition and processing, several papers deal with the origin of harmonic noise and its removal, especially in combination with the slip-sweep method (Sallas 2010: Boucard andOllivrin 2010;Saragiotis, Scholtz and Bagaini 2010;Bagaini 2010;Krohn et al 2010). Martin and Munoz (2010) also described a very similar, subtractive method for the attenuation of harmonic energy in the case of slip-sweep surveys, where the harmonic components typically contaminate previous records by back-folded correlation noise. Polom (1997) and Okaya, Karageorgi and McEvilly (1992) presented methods to suppress several kinds of harmonic and non-harmonic noise effects in deep-seismic data by analysing single traces visually in the frequency-time (f-T) domain in order to determine appropriate operators to separate the noise from the signal portions.…”

Section: Introductionmentioning

confidence: 98%

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Effective elimination of subharmonic ghost events from vibroseis data

Stiller

Jaeckel

Weber

2012

Geophysical Prospecting

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Harmonic or subharmonic noise is often present in vibroseis data as reverberation‐like, laterally coherent bands occurring parallel to and before or after, the main events. Such periodic noise is typically generated during the standard correlation process when the actual source signal travelling through the subsurface is, for whatever reason, different from the desired source signal, i.e., the pilot‐sweep controlling the baseplate and used for correlation. A typical cause can be that harmonic or subharmonic frequency partials are generated in addition to the vibroseis sweep's desired fundamental frequencies. These harmonics produce strong ‘ghost events’ during correlation of the geophone trace with the pilot‐sweep, originating from additional correlations between the fundamental and harmonic frequencies. Especially subharmonic ‘ghosts’ will overlap with ‘good’ fundamental signals, since for typically used up‐sweeps they are folded to later traveltimes, where the signal/noise‐ratio is already lower, thus aggravating or preventing a reliable interpretation of possible later reflections. Here, a method is introduced to remove these unwanted noise trains (with only negligible impact on the fundamental signal) by transforming the seismogram traces into a so‐called ‘(sub)harmonic domain’. In this domain, the respective harmonic noise portions are focused and separated from the fundamental signals, enabling easier detection and appropriate suppression. After back‐transformation to the x‐T domain, the records are free from the corresponding harmonic contamination and can then be processed as usual. The method operates in a data‐driven fashion, i.e., the traces are not uniformly processed but are processed depending upon their actual (sub)harmonic content. The decontamination procedure can be applied universally, i.e., to uncorrelated/correlated and/or vertically unstacked/stacked data either in a manual, semiautomated or fully automated manner. The method works perfectly for synthetic vibroseis traces with or without harmonic/subharmonic portions. The application to real, crustal‐scale vibroseis records that were acquired in 2006 in the Dead Sea region, Israel and that were severely contaminated by subharmonic ground‐roll ghosts covering reflectivity from the basement to the Moho, shows the robustness and success of the presented method.

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“…Now steps I-IV will be described in detail. Here, our steps I-III basically correspond to steps 3-5 in Martin and Munoz (2010).…”

Section: The Decontamination Methodsmentioning

confidence: 99%

Section: O N C L U S I O N Smentioning

confidence: 95%