Characterization of Noise Modes in Multicomponent (4C) Towed-streamer

Teigen, Øyvind; Özdemir, Kemal; Kjellesvig, B. A.; Goujon, Nicolas; Pabon, Jahir

doi:10.3997/2214-4609.20148847

Cited by 8 publications

(4 citation statements)

References 5 publications

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“…) and to regularize the in‐line sampling to 3.125 m. Noise attenuation is particularly important for the accelerometer signals as these are subject to both transverse and torsional modes along the cable (Teigen et al . ). After noise attenuation, there is usable bandwidth on the accelerometers to about 3 Hz (Özdemir et al .…”

Section: Methodsmentioning

confidence: 97%

Fidelity and repeatability of wave fields reconstructed from multicomponent streamer data

Eggenberger

Christie

Vassallo

et al. 2014

Geophysical Prospecting

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A B S T R A C TWave field reconstruction -the estimation of a three-dimensional (3D) wave field representing upgoing, downgoing or the combined total pressure at an arbitrary point within a marine streamer array -is enabled by simultaneous measurements of the crossline and vertical components of particle acceleration in addition to pressure in a multicomponent marine streamer. We examine a repeated sail line of North Sea data acquired by a prototype multicomponent towed-streamer array for both wave field reconstruction fidelity (or accuracy) and reconstruction repeatability. Data from six cables, finely sampled in-line but spaced at 75 m crossline, are reconstructed and placed on a rectangular data grid uniformly spaced at 6.25 m in-line and crossline. Benchmarks are generated using recorded pressure data and compared with wave fields reconstructed from pressure alone, and from combinations of pressure, crossline acceleration and vertical acceleration. We find that reconstruction using pressure and both crossline and vertical acceleration has excellent fidelity, recapturing highly aliased diffractions that are lost by interpolation of pressure-only data. We model wave field reconstruction error as a linear function of distance from the nearest physical sensor and find, for this data set with some mismatched shot positions, that the reconstructed wave field error sensitivity to sensor mispositioning is one-third that of the recorded wave field sensitivity. Multicomponent reconstruction is also more repeatable, outperforming single-component reconstruction in which wave field mismatch correlates with geometry mismatch. We find that adequate repeatability may mask poor reconstruction fidelity and that aliased reconstructions will repeat if the survey geometry repeats. Although the multicomponent 3D data have only 500 m in-line aperture, limiting the attenuation of non-repeating multiples, the level of repeatability achieved is extremely encouraging compared to full-aperture, pressureonly, time-lapse data sets at an equivalent stage of processing.

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Section: Methodsmentioning

confidence: 97%

Fidelity and repeatability of wave fields reconstructed from multicomponent streamer data

Eggenberger

Christie

Vassallo

et al. 2014

Geophysical Prospecting

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“…A particularly acute issue related to dual-sensor streamers is the effect of mechanical vibrations that are induced as the streamer is towed through the water. Teigen et al (2012) present a summary of the mechanisms that generate these mechanical vibrations. The noise will be recorded by both pressure and particle motion sensors, but because the amplitude of the particle motion associated with mechanical vibrations is significantly larger than the associated pressure change when measured relative to the seismic signal, the particle motion data are most sensitive to this source of noise.…”

Section: Noise Considerationsmentioning

confidence: 99%

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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“…Dense spatial sampling: Vibration modes in a towed streamer were described by Teigen et al (2012). The main mode is the transverse vibration mode, with relatively high amplitude and low propagation velocity.…”

Section: Marine Sensor Requirementsmentioning

confidence: 99%