Anisotropic true‐amplitude migration

Tong, Fei; Dellinger, Joe; Murphy, Gary E.; Hensley, Jeffrey L.; Gray, Samuel H.

doi:10.1190/1.1820246

Cited by 9 publications

(4 citation statements)

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“…To date, very few anisotropic model data sets have been publicly released. One anisotropic model, which is meant to investigate the behavior of seismic waves around a thrusted shale layer (as encountered frequently in the Canadian Foothills), has appeared both as a physical model data set (Leslie and Lawton, 1998) and a F-D synthetic data set (Fei et al, 1998). Figure 4 shows images of the synthetic data set migrated using isotropic and anisotropic migration algorithms.…”

Section: The Role Of Seismic Modelingmentioning

confidence: 99%

Seismic migration problems and solutions

Gray¹,

et al. 2001

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Historically, seismic migration has been the practice (science, technology, and craft) of collapsing diffraction events on unmigrated records to points, thereby moving (“migrating”) reflection events to their proper locations, creating a true image of structures within the earth. Over the years, the scope of migration has broadened. What began as a structural imaging tool is evolving into a tool for velocity estimation and attribute analysis, making detailed use of the amplitude and phase information in the migrated image. With its expanded scope, migration has moved from the final step of the seismic acquisition and processing flow to a more central one, with links to both the processes preceding and following it. In this paper, we describe the mechanics of migration (the algorithms) as well as some of the problems related to it, such as algorithmic accuracy and efficiency, and velocity estimation. We also describe its relationship with other processes, such as seismic modeling. Our approach is tutorial; we avoid presenting the finest details of either the migration algorithms themselves or the problems to which migration is applied. Rather, we focus on presenting the problems themselves, in the hope that most geophysicists will be able to gain an appreciation of where this imaging method fits in the larger problem of searching for hydrocarbons.

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Section: The Role Of Seismic Modelingmentioning

confidence: 99%

Seismic migration problems and solutions

Gray¹,

et al. 2001

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“…In this paper, we modify the space‐time domain CFP analysis of Kabir (1997) to estimate anisotropic parameters for weak transverse isotropy media, and we use the Canadian Foothills model as an example. This model draws inspiration from the geology encountered in the Canadian foothills, where exploration targets often lie below a thrusted shale layer (Leslie and Lawton 1998; Fei et al . 1998).…”

Section: Introductionmentioning

confidence: 99%

“…Based on this model, seismic data used in this paper were generated by finite differences (Fei et al . 1998).…”

Section: Introductionmentioning

confidence: 99%

Depth migration anisotropy analysis in the time domain

Kumar¹,

Sen²,

Ferguson³

2007

Geophysical Prospecting

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A B S T R A C TIn areas of complex geology such as the Canadian Foothills, the effects of anisotropy are apparent in seismic data and estimation of anisotropic parameters for use in seismic imaging is not a trivial task. Here we explore the applicability of commonfocus point (CFP)-based velocity analysis to estimate anisotropic parameters for the variably tilted shale thrust sheet in the Canadian Foothills model. To avoid the inherent velocity-depth ambiguity, we assume that the elastic properties of thrust-sheet with respect to transverse isotropy symmetry axis are homogeneous, the reflector below the thrust-sheet is flat, and that the anisotropy is weak. In our CFP approach to velocity analysis, for a poorly imaged reflection point, a traveltime residual is obtained as the time difference between the focusing operator for an assumed subsurface velocity model and the corresponding CFP response obtained from the reflection data. We assume that this residual is due to unknown values for anisotropy, and we perform an iterative linear inversion to obtain new model parameters that minimize the residuals. Migration of the data using parameters obtained from our inversion results in a correctly positioned and better focused reflector below the thrust sheet. For traveltime computation we use a brute force mapping scheme that takes into account weakly tilted transverse isotropy media. For inversion, the problem is set up as a generalized Newton's equation where traveltime error (differential time shift) is linearly dependent on the parameter updates. The iterative updates of parameters are obtained by a least-squares solution of Newton's equations. The significance of this work lies in its applicability to areas where transverse isotropy layers are heterogeneous laterally, and where transverse isotropy layers are overlain by complex structures that preclude a moveout curve fitting.

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“…Current anisotropic depth migration algorithms also correct for velocity changing with direction in the dipping clastic overburden-particularly in the case where the clastic overburden and the target reflectors have different dips. Several papers over the past seven years illustrate the improvements in imaging when we stop ignoring anisotropy and begin to correct for it (Ball, 1995;Vestrum and Muenzer, 1997;Vestrum, et al, 1998;Ferguson and Margrave, 1998;Schmid et al, 1998;Dai et al, 1998;Fei et al, 1998;Vestrum et al, 1999, Kirtland Grech et al, 2001etc. ).…”

Section: Introductionmentioning

confidence: 99%

2D and 3D anisotropic depth migration case histories

Vestrum

2002

SEG Technical Program Expanded Abstracts 2002

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Anisotropic depth migration (ADM) has become more commonplace over the past four years. The data-processing examples detailed here illustrate the robustness of the method in a variety of structured settings in the Alberta Foothills. The public-domain structural line, the Husky/Talisman dataset, illustrates subtle improvements in imaging with a dramatic improvement in accuracy of horizon depths when ADM is applied to these data. A 3D survey in a difficult imaging area, Nordegg/Chungo, shows significant healing of broken basement reflectors when we correct for anisotropy in the complex-dipping clastic overburden. Finally, in the Blackstone area where we observe intense folding in the near surface, comparisons between poststack time migration, prestack time migration, prestack depth migration, and prestack anisotropic depth migration in the Blackstone area show the similar stepchange improvements as we imrove the technology of our algorithm.

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Anisotropic true‐amplitude migration

Cited by 9 publications

References 0 publications

Seismic migration problems and solutions

Seismic migration problems and solutions

Depth migration anisotropy analysis in the time domain

2D and 3D anisotropic depth migration case histories

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