Mirror imaging of OBS data

Grion, S.; Exley, Russell; Manin, Michel; Miao, Xiaogui; Pica, A.; Wang, Yi; Granger, Pierre‐Yves; Ronen, Shuki

doi:10.3997/1365-2397.2007028

Cited by 73 publications

(31 citation statements)

References 15 publications

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“…Having pressure information just above the seabed has been turned to an advantage for the separation of up-and downgoing (receiver-side ghost) waves using techniques such as "PZ summation" (Barr and Sanders, 1989;Soubaras, 1996;Schalkwijk et al, 1999); imaging using these separate components of the seismic data allows the reconstruction of the frequency band affected by the ghost notch effect (Godfrey et al, 1998;Grion et al, 2007;Dash et al, 2009). However, these additional data are often not used while performing migration, particularly during wavefield extrapolation: Receiver-side wavefields are generally obtained by backpropagation of particle velocity components at the receiver locations (Chang andMcMechan, 1986, 1994;Sun and McMechan, 1986;Yan and Sava, 2008).…”

Section: Ravasi and Curtismentioning

confidence: 99%

“…Several authors have used the receiver ghost for migration of ocean-bottom data (Godfrey et al, 1998;Ronen et al, 2005;Grion et al, 2007;Dash et al, 2009). Muijs et al (2007) make an early attempt to image using primary and free-surface multiples together: the final image contains crosstalk artifacts however; they are caused by interference of up-and downgoing waves not associated with the same subsurface reflector.…”

Section: Introductionmentioning

confidence: 99%

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Elastic imaging with exact wavefield extrapolation for application to ocean-bottom 4C seismic data

Ravasi

Curtis

2013

GEOPHYSICS

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A central component of imaging methods is receiver-side wavefield backpropagation or extrapolation in which the wavefield from a physical source scattered at any point in the subsurface is estimated from data recorded by receivers located near or at the Earth's surface. Elastic reverse-time migration usually accomplishes wavefield extrapolation by simultaneous reversed-time 'injection' of the particle displacements (or velocities) recorded at each receiver location into a wavefield modeling code. Here, we formulate an exact integral expression based on reciprocity theory that uses a combination of velocity-stress recordings and quadrupole-dipole backpropagating sources, rather than the commonly used approximate formula involving only particle velocity data and dipole backpropagating sources. The latter approximation results in two types of nonphysical waves in the scattered wavefield estimate: First, each arrival contained in the data is injected upward and downward rather than unidirectionally as in the true time-reversed experiment; second, all injected energy emits compressional and shear propagating modes in the model simulation (e.g., if a recorded P-wave is injected, both P and S propagating waves result). These artifacts vanish if the exact wavefield extrapolation integral is used. Finally, we show that such a formula is suitable for extrapolation of ocean-bottom 4C data: Due to the fluid-solid boundary conditions at the seabed, the data recorded in standard surveys are sufficient to perform backpropagation using the exact equations. Synthetic examples provide numerical evidence of the importance of correcting such errors.

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Section: Ravasi and Curtismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Elastic imaging with exact wavefield extrapolation for application to ocean-bottom 4C seismic data

Ravasi

Curtis

2013

GEOPHYSICS

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“…Note that an image of the downgoing field denoted as p þ can also be constructed by means of mirror imaging (Grion et al, 2007) by, for example, injection of the ghost data as if it were recorded not on the seabed but at a sea surface twice as high:…”

Section: A Review Of Vector-acoustic Migrationmentioning

confidence: 99%

Vector-acoustic reverse time migration of Volve ocean-bottom cable data set without up/down decomposed wavefields

et al. 2015

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Methods for wavefield injection are commonly used to extrapolate seismic data in reverse time migration (RTM). Injecting a single component of the acoustic field, for example, pressure, leads to ambiguity in the direction of propagation. Each recorded wavefront is propagated both upward and downward, and spurious (or ghost) reflectors are created alongside real reflectors in the subsurface image. Thus, wavefield separation based on the combination of pressure and particle velocity data is generally performed prior to imaging to extract only the upgoing field from multicomponent seabed or towed marine seismic recordings. By instead combining vector-acoustic (VA) data with monopoleand dipole-type propagators in the extrapolation of shot or receiver gathers, we show that wavefield separation (or deghosting) can instead be performed "on-the-fly" at limited additional cost. This strategy was successfully applied to a line of a North Sea ocean-bottom cable data set, acquired over the Volve field. We then evaluate additional advantages over standard RTM with decomposed fields such as improved handling of the directivity information contained in the acquired VA data for clearer shallow sections and better focused space-lag common image gathers, and imaging of the downgoing component without the need for additional finite-difference modeling via mirror migration. Finally, we prove the robustness of our method with respect to sparse and irregular receiver sampling.

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“…In fact, the ocean surface acts as a mirror to reflect the energy from the subsurface, so the receiver ghosts can be used for mirror imaging to enhance the illumination. Only the first-order down-going multiples are used in the mirror imaging method in VSP data (Zhang et al, 2005) and OBS data (Grion et al, 2007;Grion, 2012).…”

Section: Introductionmentioning

confidence: 99%

Reverse time migration of multiples for OBS data

Zhang

2014

SEG Technical Program Expanded Abstracts 2014

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Mirror imaging of OBS data

Cited by 73 publications

References 15 publications

Elastic imaging with exact wavefield extrapolation for application to ocean-bottom 4C seismic data

Elastic imaging with exact wavefield extrapolation for application to ocean-bottom 4C seismic data

Vector-acoustic reverse time migration of Volve ocean-bottom cable data set without up/down decomposed wavefields

Reverse time migration of multiples for OBS data

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