Multiple attenuation in the image space

Sava, Paul; Guitton, Antoine

doi:10.1190/1.1852789

Cited by 42 publications

(11 citation statements)

References 22 publications

(20 reference statements)

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“…Therefore, preprocessing of the initial image, such as multiple suppression, is suggested before applying the generalized Born wavefield modeling. Multiple-prediction and suppression techniques in the image domain (Sava and Guitton, 2005;Artman et al, 2007) can be useful to Another interesting feature of the method is that, for a typical subsalt application, the migration operator used for imaging the synthesized Born data set can be much better behaved (or less singular) than the one used for imaging the original data set. This is because the former avoids propagating wavefields through the salt body, so that the complexities in the salt geometry have little influence on the operator itself.…”

Section: Discussionmentioning

confidence: 99%

Imaging and velocity analysis by target-oriented wavefield inversion

Tang

2011

GEOPHYSICS

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This thesis develops a novel target-oriented inversion framework that uses wavefields as carriers of information to image both low-and high-wavenumber components of the earth model in complex geological settings, such as subsalt regions. The lowwavenumber component of the earth model is often known as background velocity, whereas the high-wavenumber component of the earth model is often known as reflectivity. I address the problem of reflectivity imaging with target-oriented wavefield least-squares migration, and the problem of velocity estimation with target-oriented wavefield tomography.Reflectivity images of the subsurface are commonly produced by prestack depth migration. When the overburden is complex and the reflectors are unevenly or insufficiently illuminated, the migration operator alone is inadequate to provide an optimal image.I tackle the problem of distorted illumination in reflectivity imaging by wavefield least-squares migration. I formulate least-squares migration in the image domain and solve it in a target-oriented fashion. In the image-domain formulation, explicit computation of the Hessian operator (the resolution function that measures the illumination deficiency of the imaging system) is the most important and challenging step. I develop a novel method based on phase encoding to efficiently and accurately compute the target-oriented Hessian operator. By design, the phase-encoded Hessian converges to the exact Hessian either deterministically (for plane-wave phase encoding) or statistically (for random phase encoding), while having the important advantages that no Green's functions need to be stored during computation and that v the number of wavefield propagations is also drastically reduced. The target-oriented Hessian operator is then used to recover the reflectivity by iterative inverse filtering. I regularize the inversion with dip constraints, which naturally incorporate interpreted geological information into the inversion.Accurate imaging of the reflectivity also requires an accurate background velocity model. High-quality velocity model-building in complex geology requires wavefieldbased velocity analysis to properly model band-limited wave phenomena. However, the high cost and lack of flexibility of target-oriented model-building prevent this method from being widely used in practice.I overcome the cost and flexibility issues of wavefield-based migration velocity analysis by developing target-oriented wavefield tomography. Target-oriented wavefield tomography is achieved by synthesizing a new data set specifically for velocity analysis. The new data set is generated based on an initial unfocused target image and by a novel application of generalized Born wavefield modeling, which correctly preserves velocity kinematics by modeling both zero and non-zero subsurface-offset-

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Section: Discussionmentioning

confidence: 99%

Imaging and velocity analysis by target-oriented wavefield inversion

Tang

2011

GEOPHYSICS

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“…Therefore, preprocessing of the initial image, such as multiple suppression, are suggested before applying generalized Born wavefield modeling. Multiple-prediction and suppression techniques in the image domain (Sava and Guitton, 2005;Artman et al, 2007) can be useful to identify and remove multiples in the initial image and gathers.…”

Section: Target-oriented Wavefield Tomography Wb201mentioning

confidence: 99%

Target-oriented wavefield tomography using synthesized Born data

Tang

Biondi

2011

GEOPHYSICS

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We present a new strategy for efficient wave-equation migration-velocity analysis in complex geological settings. The proposed strategy has two main steps: simulating a new data set using an initial unfocused image and performing wavefield-based tomography using this data set. We demonstrated that the new data set can be synthesized by using generalized Born wavefield modeling for a specific target region where velocities are inaccurate. We also showed that the new data set can be much smaller than the original one because of the target-oriented modeling strategy, but it contains necessary velocity information for successful velocity analysis. These interesting features make this new data set suitable for target-oriented, fast and interactive velocity model-building. We demonstrate the performance of our method on both a synthetic data set and a field data set acquired from the Gulf of Mexico, where we update the subsalt velocity in a target-oriented fashion and obtain a subsalt image with improved continuities, signal-to-noise ratio and flattened angle-domain common-image gathers.

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“…For example, in the angle domain, only the primaries are flat as suggested by Reference [15]. Therefore, they proposed to transform the migrated data in that domain.…”

Section: Introductionmentioning

confidence: 99%

Wave Equation Datuming Applied to Seismic Data in Shallow Water Environment and Post-Critical Water Bottom Reflection

2017

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Abstract:Coastal areas are generally characterized by human manufacturing; thus, seismic data analysis is necessary to characterize the properties of the subsoil, the main purpose of which is to clarify risk situations. In the case of very shallow water environments, seismic multiple attenuation becomes a challenge when the reflection of the seafloor is post-critical, so it is not recorded because of the acquisition parameters. We propose an approach to attenuate the multiples by using wave equation datuming that does not require the detection of seafloor reflection and avoids the seafloor reflection prediction and related approximations in the post-critical conditions. Moreover, this approach allows for the enhancement of higher frequencies, and, consequently, an increase in resolution, demonstrating that it is a powerful tool to attenuate multiples and reverberations, especially where other approaches are found to be inefficient. An example of the application of seismic data acquired in the continental shelf of South Chile is reported.

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Multiple attenuation in the image space

Cited by 42 publications

References 22 publications

Imaging and velocity analysis by target-oriented wavefield inversion

Imaging and velocity analysis by target-oriented wavefield inversion

Target-oriented wavefield tomography using synthesized Born data

Wave Equation Datuming Applied to Seismic Data in Shallow Water Environment and Post-Critical Water Bottom Reflection

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