Focusing in Prestack Isochrone Migration Using Instantaneous Slowness Information

Tillmanns, Mark; Gebrande, H.

doi:10.1007/978-3-0348-8670-3_11

Cited by 4 publications

(5 citation statements)

References 18 publications

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“…It has furthermore been recognized that it is important to take into account local curvature of isochrons~within a Fresnel zone! while carrying out map-migration style imaging~see Tillmanns and Gebrande, 1999;Luth et al, 2005!. One can obtain the isochron curvature from the geometrical spreading associated with M s O isochron rays.…”

Section: Discussionmentioning

confidence: 99%

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Extended isochron rays in prestack depth (map) migration

Duchkov

Hoop

2010

GEOPHYSICS

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Many processes in seismic data analysis and seismic imaging can be identified with solution operators of evolution equations. These include data downward continuation and velocity continuation. We have addressed the question of whether isochrons defined by imaging operators can be identified with wavefronts of solutions to an evolution equation. Rays associated with this equation then would provide a natural way of implementing prestack map migration. Assuming absence of caustics, we have developed constructive proof of the existence of a Hamiltonian describing propagation of isochrons in the context of common-offset depth migration. In the presence of caustics, one should recast to a sinking-survey migration framework. By manipulating the double-square-root operator, we obtain an evolution equation that describes sinking-survey migration as a propagation in two-way time with surface data being a source function. This formulation can be viewed as an extension of the exploding reflector concept from zero-offset to sinking-survey migration. The corresponding Hamiltonian describes propagation of extended isochrons (fronts with constant two-way time) connected by extended isochron rays. The term extended reflects the fact that two-way time propagation now takes place in high-dimensional space with the following coordinates: subsurface midpoint, subsurface offset, and depth. Extended isochron rays can be used in a natural manner for implementing sinking-survey migration in a map-migration fashion.

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Section: Discussionmentioning

confidence: 99%

“…It also provides a local curvature of an isochron~front! that can be used while implementing a map-migration style imaging as proposed in Tillmanns andGebrande~1999! andLuth et al~2005!. In the case of a constant velocity v, we get an explicit formula for the Hamiltonian:…”

Section: Appendix a Hamiltonian For Common-offset Isochron Raysmentioning

confidence: 99%

Extended isochron rays in prestack depth (map) migration

Duchkov

Hoop

2010

GEOPHYSICS

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“…Because the beam-based migration methods mentioned above are all based on the input data in local τ − p domain, the ray parameters of the specular reflection have been calculated beforehand (Takahashi, 1995;Tillmanns and Gebrande, 1999). On the other hand, only picking a few dominant ray parameters for imaging can be benefit for implementation efficiency.…”

Section: Introductionmentioning

confidence: 99%

The characteristic wave decomposition and imaging in VTI media

Liu

Wang

Bao

2015

Journal of Applied Geophysics

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“…sured in a shot or receiver gather with the slowness of emanating or incoming waves in the model. The use of slowness information in a prestack depth migration is implicit in other techniques such as plane-wave migration (e.g., Temme, 1984;Akbar et al, 1996), but the SWDS gives the user the opportunity to evaluate separately the traveltime and slowness imaging conditions (Tillmanns and Gebrande, 1999). By tuning the window lengths, a local slant stack can be designed to produce a robust measure of instantaneous slowness in the data (Milkereit, 1987a).…”

Section: Introductionmentioning

confidence: 99%

“…Direct wavefront tracking methods (Vidale, 1990;Moser, 1991;Qin, et al, 1992) are more efficient for calculating traveltimes, but they do not provide the slowness of the incoming or downgoing wavefields. Tillmanns and Gebrande (1999) approach the problem by applying straight-ray migrations (Simon et al, 1996), which allows them to rapidly estimate isochrones and take-off angles in the subsurface. The validity of the straightray approximation depends on the amount of velocity heterogeneity in the model, but the effects on the sharpness of a reflection image are potentially severe, particularly if the shallow subsurface is complicated (Peddy et al, 1986).…”

Section: Introductionmentioning

confidence: 99%

Slowness‐weighted diffraction stack for migrating wide‐angle seismic data in laterally varying media

Avendonk

2004

GEOPHYSICS

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Wide-angle prestack depth migration is an important tool for studying the nature of reflecting boundaries in the earth's crust. The slowness-weighted diffraction stack (SWDS) method has been used to incorporate both two-way traveltime constraints and slowness information in the migration. For this purpose, traveltimes and apparent slownesses of reflected arrivals must be calculated in the image space. Earlier applications of SWDS required a 1D or gently varying seismic velocity structure to obtain these quantities by ray tracing in the image space. I show that the apparent slownesses can also be derived directly from one-way traveltime maps using Fermat's principle. The SDWS is applied to an existing onshore-offshore wide-angle data set, and the example shows that the method can be used to image detailed reflectivity structure at great depths.

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Focusing in Prestack Isochrone Migration Using Instantaneous Slowness Information

Cited by 4 publications

References 18 publications

Extended isochron rays in prestack depth (map) migration

Extended isochron rays in prestack depth (map) migration

The characteristic wave decomposition and imaging in VTI media

Slowness‐weighted diffraction stack for migrating wide‐angle seismic data in laterally varying media

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