Wavefield‐continuation angle‐domain common‐image gathers for migration velocity analysis

Biondi, Biondo; Tisserant, Thomas; Symes, William W.

doi:10.1190/1.1817750

Cited by 13 publications

(5 citation statements)

References 16 publications

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“…obtained previously by Biondi et al (2003). In the absence of cross-line structural dips ðk m y ¼ 0Þ; it is equivalent to the 2-D Eq.…”

Section: Common-azimuth Approximationmentioning

confidence: 92%

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Theory of 3-D angle gathers in wave-equation seismic imaging

Fomel

2011

J Petrol Explor Prod Technol

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I present two methods for constructing angle gathers in 3-D seismic imaging by downward extrapolation. Angles in angle gathers refer to the scattering angle at the reflector and provide a natural access to analyzing migration velocity and amplitudes. In the first method, angle gathers are extracted at each downward-continuation step by mapping transformations in constant-depth frequency slices. In the second method, one extracts angle gathers after applying the imaging condition by transforming local offset gathers in the depth domain. The second approach generalizes previously published algorithms for angle-gather construction in 2-D and commonazimuth imaging.

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“…obtained previously by Biondi et al (2003). In the absence of cross-line structural dips ðk m y ¼ 0Þ; it is equivalent to the 2-D Eq.…”

Section: Common-azimuth Approximationmentioning

confidence: 92%

“…Additionally, I extend the second, post-migration approach to a complete 3-D wide-azimuth situation. Under the common-azimuth approximation, this formulation reduces to the result of Biondi et al (2003) and, in the absence of cross-line structure, it is equivalent to the Radon construction of Sava and Fomel (2003).…”

Section: Introductionmentioning

confidence: 97%

Theory of 3-D angle gathers in wave-equation seismic imaging

Fomel

2011

J Petrol Explor Prod Technol

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“…Both transformations in equations 1 and 2 are slant stacks in the space/time domain, or radial trace transforms in the Fourier domain. Three-dimensional extensions of these transformations are presented by Biondi et al (2003).…”

Section: Angle Transformmentioning

confidence: 99%

Multiple attenuation in the image space

Sava

Guitton

2005

GEOPHYSICS

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Multiples can be suppressed in the angle-domain image space after migration. For a given velocity model, primaries and multiples have different angle-domain moveout and, therefore, can be separated using techniques similar to the ones employed in the data space prior to migration. We use Radon transforms in the image space to discriminate between primaries and multiples and employ accurate functions describing angledomain moveouts. Since every individual angle-domain common-image gather incorporates complex 3D propagation effects, our method has the advantage of working with 3D data and complicated geology. Therefore, our method offers an alternative to the more expensive surface-related multiple-elimination (SRME) approach operating in the data space.Radon transforms are cheap but not necessarily ideal for separating primaries and multiples, particularly at small angles where the moveout discrepancy between the two kinds of events are not large. Better techniques involving signal/noise separation using prediction-error filters can be employed as well, although such approaches fall outside the scope of this paper. We demonstrate, using synthetic and real data examples, the power of our method in discriminating between primaries and multiples after migration by wavefield extrapolation, followed by transformation to the angle domain.

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“…We now derive and discuss the analytical relationships between reflection angles and offset dips after imaging. We start with the simpler 2D case (Sava and Fomel 2003), and then address the general 3D case (Biondi, Tisserant and Symes 2003). The application of the imaging condition transforms a wavefield propagating in time into an image cube that is a function of depth.…”

Section: A N G L E -D O M a I N C O M M O N -I M A G E G At H E R S Amentioning

confidence: 99%

3D angle‐domain common‐image gathers for migration velocity analysis

Biondi

Tisserant

2004

Geophysical Prospecting

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We analyze the kinematic properties of offset-domain Common Image Gathers (CIGs) and Angle-Domain CIGs (ADCIGs) computed by wavefield-continuation migration. Our results are valid regardless of whether the CIGs were obtained by using the correct migration velocity. They thus can be used as a theoretical basis for developing Migration Velocity Analysis (MVA) methods that exploit the velocity information contained in ADCIGs.We demonstrate that in an ADCIG cube the image point lies on the normal to the apparent reflector dip, passing through the point where the source ray intersects the receiver ray. Starting from this geometric result, we derive an analytical expression for the expected movements of the image points in ADCIGs as functions of the traveltime perturbation caused by velocity errors. By applying this analytical result and assuming stationary raypaths, we then derive two expressions for the Residual Moveout (RMO) function in ADCIGs. We verify our theoretical results and test the accuracy of the proposed RMO functions by analyzing the migration results of a synthetic data set with a wide range of reflector dips.Our kinematic analysis leads also to the development of a new method for computing ADCIGs when significant geological dips cause strong artifacts in the ADCIGs computed by conventional methods. The proposed method is based on the computation of offsetdomain CIGs along the vertical-offset axis (VOCIGs) and on the "optimal" combination of these new CIGs with conventional CIGs. We demonstrate the need for and the advantages of the proposed method on a real data set acquired in the North Sea.

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Wavefield‐continuation angle‐domain common‐image gathers for migration velocity analysis

Cited by 13 publications

References 16 publications

Theory of 3-D angle gathers in wave-equation seismic imaging

Theory of 3-D angle gathers in wave-equation seismic imaging

Multiple attenuation in the image space

3D angle‐domain common‐image gathers for migration velocity analysis

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