Practical reflection tomography and maximum entropy imaging

Whiting, Peter

doi:10.1190/1.1888799

Cited by 4 publications

(1 citation statement)

References 15 publications

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“…Reflection tomography is understood as a nonlinear inverse problem, the associated objective function often having several local minima (e.g. Whiting 1991). Non-definition of the forward modelling operator simply increases the chance of being trapped in some local minimum.…”

Section: The Associated Inverse Problemsmentioning

confidence: 99%

Smooth velocity models in reflection tomography for imaging complex geological structures

Lailly¹,

Sinoquet²

1996

Geophysical Journal International

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S U M M A R YSeismic imaging of geological structures with severe lateral velocity variations requires pre-stack depth migration of the seismic data. Such processing requires itself an accurate determination of the distribution of the propagation velocities. Reflection tomography turns out to be quite attractive for this purpose. Furthermore, migration velocity analysis can complete this technique whenever complexity of wave propagation makes the picking of reflection traveltimes very cumbersome, if not impossible. Two different subsurface representations can be used to perform these methods: the blocky model representation and the smooth model representation. In reflection tomography, using blocky models with finite velocity jumps can create shadow zones and the possible non-definition of the forward problem. Smooth models, on the other hand, are created such that they do not have such shadow zones but require specific techniques to integrate a priori geological information. Also, use of blocky models for migration brings, in general, artificial dicontinuities to migrated seismic events, thus making almost impossible the interpretation of these events which is the basis of migration velocity analysis. Should we use smooth models, such an interpretation becomes possible. Thus, in spite of some inherent limitations, smooth models are well adapted to run reflection tomography coupled with migration velocity analysis for the imaging of complex geological structures.

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Section: The Associated Inverse Problemsmentioning

confidence: 99%

Smooth velocity models in reflection tomography for imaging complex geological structures

Lailly¹,

Sinoquet²

1996

Geophysical Journal International

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Applications of Pre-Stack Depth Migration

Whiting

Smith

1992

Exploration Geophysics

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Migration artifacts and velocity analysis

Xu¹,

Huang²

2007

SEG Technical Program Expanded Abstracts 2007

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An advantage of Kirchhoff depth migration is that it can perform common offset migration, which outputs commonoffset image gathers (COIGs). These are typically used as input to a tomography program for velocity model building. For large surveys, the COIGs can be generated from relatively small common offset datasets which substantially reduces computational requirements in both memory and I/O. However, common offset migration generally encounters a migration ambiguity problem. As a result, the COIG displays strong artifacts when the imaging ambiguity is present. Therefore, it causes problems in velocity analysis because automatic event pickers may not be able to distinguish the artifacts from true events. When artifacts are picked, conventional tomography fails for velocity estimation. In this paper, we propose a tomography algorithm which effectively uses both the reflected events and artifacts in COIGs. It provides the correct velocity update even when artifacts have been picked. A GOM case shows promising results.

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Practical reflection tomography and maximum entropy imaging

Cited by 4 publications

References 15 publications

Smooth velocity models in reflection tomography for imaging complex geological structures

Smooth velocity models in reflection tomography for imaging complex geological structures

Applications of Pre-Stack Depth Migration

Migration artifacts and velocity analysis

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