Seismic velocity estimation and time to depth conversion of time‐migrated images

Cameron, Maria K.; Fomel, Sergey; Sethian, James A.

doi:10.1190/1.2370164

Cited by 10 publications

(7 citation statements)

References 14 publications

(12 reference statements)

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“…Equation 14 is equal to the one given in Cameron et al ͑2006, 2007͒. We note that although v dix M is directly available as input, the factor F depends on quantities belonging to dynamic ray tracing along the image ray. This means our image-ray construction must contemplate a simultaneous solution of the kinematic and dynamic ray-tracing systems.…”

Section: Relating Time-and Depth-domain Velocity Functionsmentioning

confidence: 99%

“…Derivations for velocity spreading along the image ray in the 2D and multiazimuth 3D situations were given in Cameron et al ͑2006, 2007͒. In this appendix, we derive equation 13 for the velocity spreading factor F pertaining to the single-azimuth 3D case. Our starting point is equation A-13, relating the azimuth-dependent migration velocity…”

Section: Appendix a 3d Kirchhoff Prestack Time Migrationmentioning

confidence: 99%

“…From the very definition of time migration, the most consistent depth conversion would be along image rays in such a way that the depth velocities needed for the image-ray tracing would be obtained directly from the given time-migration velocity field. A method that does exactly that was presented recently by Cameron et al ͑2006, 2007͒. Besides time-migrated data, the method requires in its 3D version that the time-migrated velocity field is available for at least three directions along the measurement surface. This requirement might impose some limitations to the applications of the method in practice.…”

Section: Introductionmentioning

confidence: 99%

“…Our objective is to present theory and numerical examples for a 3D image-ray tracing and velocity-estimation algorithm in which it is sufficient to know the time-migration velocity field in a single direction only. Our approach is similar to that of Cameron et al ͑2006, 2007͒, but the range of practical applications is extended. A discussion on the actual differences between the two approaches is provided in Appendix B.…”

Section: Introductionmentioning

confidence: 99%

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Image-ray tracing for joint 3D seismic velocity estimation and time-to-depth conversion

Iversen

Tygel

2008

GEOPHYSICS

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Seismic time migration is known for its ability to generate well-focused and interpretable images, based on a velocity field specified in the time domain. A fundamental requirement of this time-migration velocity field is that lateral variations are small. In the case of 3D time migration for symmetric elementary waves (e.g., primary PP reflections/diffractions, for which the incident and departing elementary waves at the reflection/diffraction point are pressure [P] waves), the time-migration velocity is a function depending on four variables: three coordinates specifying a trace point location in the time-migration domain and one angle, the so-called migration azimuth. Based on a time-migration velocity field available for a single azimuth, we have developed a method providing an image-ray transformation between the time-migration domain and the depth domain. The transformation is obtained by a process in which image rays and isotropic depth-domain velocity parameters for their propagation are esti-mated simultaneously. The depth-domain velocity field and image-ray transformation generated by the process have useful applications. The estimated velocity field can be used, for example, as an initial macrovelocity model for depth migration and tomographic inversion. The image-ray transformation provides a basis for time-to-depth conversion of a complete time-migrated seismic data set or horizons interpreted in the time-migration domain. This time-to-depth conversion can be performed without the need of an a priori known velocity model in the depth domain. Our approach has similarities as well as differences compared with a recently published method based on knowledge of time-migration velocity fields for at least three migration azimuths. We show that it is sufficient, as a minimum, to give as input a time-migration velocity field for one azimuth only. A practical consequence of this simplified input is that the image-ray transformation and its corresponding depth-domain velocity field can be generated more easily.

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Section: Relating Time-and Depth-domain Velocity Functionsmentioning

confidence: 99%

Section: Appendix a 3d Kirchhoff Prestack Time Migrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Image-ray tracing for joint 3D seismic velocity estimation and time-to-depth conversion

Iversen

Tygel

2008

GEOPHYSICS

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“…The velocity model is refined and updated though a number of PSDM iterations using tomographic updates [3]. The depth model reflects how the separation of the subsurface is transformed into formations and indicates which part of the subsurface reflects the respective formation [4]. Conventional velocity analysis methods generally assume flat-layered geology and mild lateral velocity variations.…”

Section: Possible Velocity Errors In Velocity Model Buildingmentioning

confidence: 99%

Error Recognition in Velocity Model Building for Prestak Kirchoff Depth Miration Using Rmo Analysis

Grigorova¹

2015

Proceedings

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The main purpose in seismic investigations is the correct illustration of geology in the study area. In seismic processing even small variations can have a significant impact, hiding the real signature or introducing artifacts. Velocity errors can be critical for accurate seismic representations of the modeled geology and ignoring them can damage the structural interpretation of the study area. As far as the velocity model is representative of the subsurface, Kirchoff pre-stack depth migration (PSDM) is a reasonable representation of the modeled geology. Keywords: Velocity model, RMO, seismic tomography, velocity errors, PSDM. INTRODUCTIONBuilding a depth-velocity model is an important step in the PSDM workflow. Migration needs an accurate velocity model to fully focus reflections and correctly position reflectors in space. Pre-Stack Depth Migration requires an accurate interval velocity model to achieve optimum results. The process requires utilisation of RMS velocities from the seismic data. The determination of an accurate migration velocity in time domain is a crucial step in seismic imaging. In case migration velocity is unappropriated then significant changes in geology can occur in the depth migrated data. The effect of velocity on depth migration is significant since the velocity errors leads to improper positioning and poor focusing migrated reflection events. Here is described relationship between inaccurate input velocities and depth positional errors on the depth migrated section. It is demonstrated that even small velocity errors are problematic, especially with pre-stack depth migration.

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A new insight into the structural architecture of Sharyoof field, Say’un–Masilah basin, Yemen

Abdullah

Al‐Areeq

Elmahdy³

et al. 2021

Arab J Geosci

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Seismic velocity estimation and time to depth conversion of time‐migrated images

Cited by 10 publications

References 14 publications

Image-ray tracing for joint 3D seismic velocity estimation and time-to-depth conversion

Image-ray tracing for joint 3D seismic velocity estimation and time-to-depth conversion

Error Recognition in Velocity Model Building for Prestak Kirchoff Depth Miration Using Rmo Analysis

A new insight into the structural architecture of Sharyoof field, Say’un–Masilah basin, Yemen

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