A practical approach to OBC summation and geophone calibration in areas of shallow water and hard seafloor.

Beresford, Greg; Janex, Gaël

doi:10.1190/sbgf2005-292

Cited by 2 publications

(2 citation statements)

References 6 publications

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“…Amundsen and Reitan (1995) and Soubaras (1996), published a method to process the acoustic components, the hydrophone and vertical geophone. Later Beresford and Janex (1996), Schalkwijk, Wapenaar and Verschuur (2003), Muijs, Robertsson and Holliger (2007), Wang and Grion (2008), Edme and Singh (2009), and Hugonnet et al (2011), approached the theme of the ocean bottom seismic data processing. Hugonnet et al (2011), summarized the aspects of the hydrophone and geophone processing, based on Soubaras (1996), and called it as PZ summation (pressure with vertical particle velocity), generalizing it to the three-dimensional notation, under the least square sense.…”

Section: Introductionmentioning

confidence: 99%

Robust unidimensional PZ Summation

2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

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PZ summation is a mandatory step in ocean bottom sensor multi-component PP seismic processing flow, to attenuate receiver ghost and peg leg multiples from upgoing wavefield. It consists of an adaptive sum between the hydrophone and geophone components to adapt the vertical component to pressure in a least square sense. However, in spurious situations (nongaussian noised conditions), a robust method IRLS (Interactive Re-weighted Least Square) may be a better choice to run linear convolutional adapting filter. That proposal was applied on receiver gathers of the OBC data from Jubarte area, Brazil, using near receiver stack sections to quality control. Similar quality was obtained when short adaptive windows were used, but better quality was attained when applied on a selected near receiver stack section, as compared to Wiener-Levinson PZ summation results. The proposed method became a robust option to run PZ summation and perform the unidimensional upgoing and downgoing field decomposition, processing the first order receiver ghost and peg leg multiples.

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Section: Introductionmentioning

confidence: 99%

Robust unidimensional PZ Summation

2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

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“…There are three types of surface waves that are of keen interest to explorationists: Love waves (see Figure 1a) recorded by horizontal geophones with horizontal-particle motion perpendicular to the propagation direction, Rayleigh waves (see Figure 1b) (Haney and Douma, 2012) recorded by vertical-and horizontal-component geophones, and guided waves (Zhao et al, 1994;Aki and Richards, 2002;Beresford and Janex, 2005;Gaiser and Vasconcelos, 2008;Boiero et al, 2013) that propagate along the water-sediment interface in a borehole (denoted as Stoneley waves in Figure 1c) or the seafloor (Scholte waves). Amplitudes of Rayleigh and Love waves generally decrease with depth, so that the motion induced by their passage is limited to the shallow subsurface.…”

Section: Introductionmentioning

confidence: 99%

Opportunities and pitfalls in surface-wave interpretation

Schuster

Lü

et al. 2017

Interpretation

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CitationSchuster GT, Li J, Lu K, Metwally A, AlTheyab A, et al. (2017) Opportunities and pitfalls in surface-wave interpretation. AbstractMany explorationists think of surface waves as the most damaging noise in land seismic data. Thus, much effort is spent in designing geophone arrays and filtering methods that attenuate these noisy events. It is now becoming apparent that surface waves can be a valuable ally in characterizing the near-surface geology. This review aims to find out how the interpreter can exploit some of the many opportunities available in surface waves recorded in land seismic data. For example, the dispersion curves associated with surface waves can be inverted to give the S-wave velocity tomogram, the common-offset gathers can reveal the presence of near-surface faults or velocity anomalies, and back-scattered surface waves can be migrated to detect the location of near-surface faults. However, the main limitation of surface waves is that they are typically sensitive to S-wave velocity variations no deeper than approximately half to one-third the dominant wavelength. For many exploration surveys, this limits the depth of investigation to be no deeper than approximately 0.5-1.0 km. IntroductionTucker and Yorston (1973) wrote a book titled Pitfalls in Seismic Interpretation that aimed to reveal how processed seismic reflection sections could lead to misinterpretation of the subsurface geology. They summarize the content of their book in their preface: "The geometry or shape of the reflecting surface is equally tricky. It can turn synclines into anticlines, reverse the throw of faults, superimpose one structure on another by sideswipe, and create a diffraction-anticline. Our latest and perhaps most serious pitfall is computer-derived. The recording and playback can distort both the structure and stratigraphy. Here real structures can be suppressed, false bedding created, faults smeared, and all of the geology lost. Only through constant rapport between the geologist, the interpreter, and the processing engineer will these recording and playback errors be avoided."In the spirit of Tucker and Yorston (1973), this paper presents a review on interpreting surface waves in recorded data, not as noise but as signal. It will demonstrate how surface waves can be used to estimate the locations of near-surface S-wave velocity anomalies and their extent in depth. Similar to reflection migration, we show how surface waves can be migrated to estimate the locations of near-surface velocity anomalies. The examples in this paper also reveal some pitfalls leading to misinterpretation of surface waves, and their avoidance by using an integrative interpretation of P-wave velocity tomograms, surface-wave migration images, and S-wave velocity tomograms.

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A practical approach to OBC summation and geophone calibration in areas of shallow water and hard seafloor.

Cited by 2 publications

References 6 publications

Robust unidimensional PZ Summation

Robust unidimensional PZ Summation

Opportunities and pitfalls in surface-wave interpretation

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