A Marine Broadband Case Study Offshore China

Bunting, Tim; Lim, Bee Jik; Lim, Chui Huah; Pei, S.; Yang, Shuang; Zhang, Z. B.; Xie, Yu Hong; Li, L.

doi:10.3997/2214-4609.201400633

Cited by 2 publications

(2 citation statements)

References 4 publications

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“…A common feature of all these methods is that they do not seek to mitigate the presence of ghosts, which are an inevitable product of marine acquisition, but rather they record information with different ghost characteristics such that, when all the data are combined, there is good S/N at a wider range of frequencies. One approach is based on recording data with multiple streamers at different constant depths (e.g., Sønneland, et al, 1986;Amundsen, 1993;Hill et al, 2006;Moldoveanu et al, 2007;Bunting et al, 2011). If the same wavefield is recorded by receivers at two different depths, the receiver-side ghost effects for each depth will be different.…”

Section: Introductionmentioning

confidence: 98%

Wavefield-separation methods for dual-sensor towed-streamer data

et al. 2013

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A dual-sensor towed streamer records the pressure and vertical component of particle motion associated with the incident wavefield that may be used to separate the wavefield into its upand downgoing parts. This procedure requires information about the water properties (wave-propagation velocity and density) and is robust in the presence of errors in the estimation of these quantities of the magnitude likely to be encountered. In practice, the particle motion data recorded by current towed marine streamers encounter very strong mechanical noise such that, for the lowest frequencies, the wavefield separation must be approximated by deconvolving the ghost function from the pressure data. This procedure requires information about the streamer depth and is robust to small depth errors over the frequency range for which it is required for dual-sensor streamer processing, but it is much more sensitive if applied over the bandwidth necessary to deghost pressure data acquired at a conventional streamer depth. The signal-to-noise ratio can be further enhanced by recombining the up-and downgoing pressure fields at the sea surface, which has the effect of applying a ghostlike filter to noise that is recorded by only one of the two sensors. In practical marine acquisition scenarios, spatial sampling is often insufficient to yield an accurate result, especially in the crossline direction. If each streamer is processed independently assuming that the wavefield propagation is purely inline, significant errors can be introduced. For arrivals with high emergent angles, errors may also be introduced even if the wavefield propagation actually is purely inline due to incorrect treatment of spatially aliased energy. However, these effects are almost entirely confined to very shallow events. They can be mitigated by using independently derived information about the crossline propagation angle and, for data comprising predominantly forward scattered energy, appropriate application of linear moveout.

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Section: Introductionmentioning

confidence: 98%

Wavefield-separation methods for dual-sensor towed-streamer data

et al. 2013

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“…The method was first introduced in the * E-mail: shlsmile@yeah.net mid-1980s by (Sønneland and Berg 1985;Sønneland et al 1986). An improved de-ghosting method was introduced by (Posthumus 1993), while more recent applications of this technique were described by (Moldoveanu 2006;Özdemir et al 2008;Bunting 2011). The over-under technique has only had limited commercial success due to the challenge of accurately controlling streamer positioning and its reduced 3-D efficiency compared to conventional towing.…”

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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A Marine Broadband Case Study Offshore China

Cited by 2 publications

References 4 publications

Wavefield-separation methods for dual-sensor towed-streamer data

Wavefield-separation methods for dual-sensor towed-streamer data

Theoretical study on multi‐level source design

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