Variable‐depth streamer acquisition: Broadband data for imaging and inversion

Soubaras, Robert; Lafet, Y.

doi:10.1190/1.3627683

Cited by 15 publications

(6 citation statements)

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“…The vertical component of the particle motion velocity measurement has a notch pattern different from that of the pressure measurement and hence can be used to fill the notches in the pressure measurements. Another solution uses a variable-depth streamer to take advantage of different notch patterns along the streamer, i.e., data at higher source-to-receiver offset have a different notch pattern than data at shorter offsets, such that loss of signal at certain notches can be compensated for at some later stage in processing, e.g., after imaging (Soubaras and Lafet 2013). It would however be attractive to deghost the variable-depth streamer data earlier in the data processing sequence.…”

Section: Introductionmentioning

confidence: 99%

Noise transfer in variable‐depth streamer deghosting

Ferber

Manen

2016

Geophysical Prospecting

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Single‐component towed‐streamer marine data acquisition records the pressure variations of the upgoing compressional waves followed by the polarity‐reversed pressure variations of downgoing waves, creating sea‐surface ghost events in the data. The sea‐surface ghost for constant‐depth towed‐streamer marine data acquisition is usually characterised by a ghost operator acting on the upgoing waves, which can be formulated as a filtering process in the frequency–wavenumber domain. The deghosting operation, usually via the application of the inverse Wiener filter related to the ghost operator, acts on the signal as well as the noise. The noise power transfer into the deghosted data is proportional to the power spectrum of the inverse Wiener filter and is amplifying the noise strongly at the notch wavenumbers and frequencies of the ghost operator. For variable‐depth streamer acquisition, the sea‐surface ghost cannot be described any longer as a wavenumber–frequency operator but as a linear relationship between the wavenumber–frequency representation of the upgoing waves at the sea surface and the data in the space–frequency domain. In this article, we investigate how the application of the inverse process acts on noise. It turns out that the noise magnification is less severe with variable‐depth streamer data, as opposed to constant depth, and is inversely proportional to the local slant of the streamer. We support this statement via application of the deghosting process to real and numerical random noise. We also propose a more general concept of a wavenumber–frequency ghost power transfer function, applicable for variable‐depth streamer acquisition, and demonstrate that the inverse of the proposed variable‐depth ghost power transfer function can be used to approximately quantify the action of the variable‐depth streamer deghosting process on noise.

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Section: Introductionmentioning

confidence: 99%

Noise transfer in variable‐depth streamer deghosting

Ferber

Manen

2016

Geophysical Prospecting

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“…Examples are acquisition techniques combined with some form of special processing, such as over-under (Hill et al,. 2006), slanted (Soubaras et al, 2013), dual sensors based on hydrophone P and velocity Vz configurations (Tenghamn et al, 2007), or even a conventional flat-tow hydrophone-only acquisition combined with advanced processing techniques to mitigate the ghost effect on the receiver side. All these techniques can help overcome the ghost effect, to various extents, and can provide improved temporal bandwidth at both ends of the frequency spectrum.…”

Section: Introductionmentioning

confidence: 99%

Case Study of Broadband Multimeasurement Streamer and Multilevel Source Seismic Data from the North Sea

Zarkhidze¹,

Abbas²,

Dhelie³

et al. 2015

Proceedings

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We present a case study of the Edvard Grieg field in the North Sea covering a seismic survey acquired using a multimeasurement towed streamer system to provide a high-quality broadband image, with improved seismic interpretation at target and a high resolution representation of shallow subsurface. Analysis of the individual measurements demonstrates the high fidelity pressure (P) component, with a good signal-to-noise separation on both the vertical (Pz) and the crossline horizontal (Py) pressure gradient measurements. The three components are used for the purpose of wavefield reconstruction by joint deghosting and crossline reconstruction. Images and spectra of the wavefield reconstruction results are presented, including comparison with deghosting using only pressure and vertical particle velocity (Vz). A high-resolution processing sequence through prestack time migration is described, covering the advantages and challenges of processing very densely sampled shot gathers at 6.25 x 6.25m surface grid. The data was migrated with a small isometric subsurface bin, and high-resolution images of the reservoir zone and the shallow surface demonstrate the advantage of the multimeasurement approach and provide data suitable for shallow geohazard analysis.

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“…The idea was first introduced by Ray (1982). More recently, Soubaras (2010) and Soubaras and Lafet (2011) presented an extension to this idea, where the actual de-ghosting was performed as part of the migration/imaging algorithm.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study on multi‐level source design

Shen

Elboth

Tian

et al. 2014

Geophysical Prospecting

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A B S T R A C TThis paper studies aspects that influence the de-ghosting performance of marine multi-level sources based on a modified Johnson model. The normalized squared error between actual signature and its corresponding ghost-free signature is introduced to evaluate the multi-level source design. The results show that optimum depth combinations and volume combinations exist in the design. However, there is also some flexibility in the volume combination which makes it possible to optimize with respect to residual bubble oscillation. By considering both operational aspects and performance, we propose that three or four levels in a multi-level source are reasonable. Compared to a horizontal source, a multi-level source can be designed to reduce the notch effect, strengthen the down-going energy and improve the energy transmission directivity. Studies of the influence of depth and firing time deviations indicate that a multi-level source is more stable than a normal horizontal source in an operational environment.

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Variable‐depth streamer acquisition: Broadband data for imaging and inversion

Cited by 15 publications

References 1 publication

Noise transfer in variable‐depth streamer deghosting

Noise transfer in variable‐depth streamer deghosting

Case Study of Broadband Multimeasurement Streamer and Multilevel Source Seismic Data from the North Sea

Theoretical study on multi‐level source design

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