2.5D modelling, inversion and angle migration in anisotropic elastic media

Foss, S. K.; Ursin, Bjørn

doi:10.1046/j.1365-2478.2004.00400.x

Cited by 5 publications

(6 citation statements)

References 33 publications

(67 reference statements)

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“…In this section, we illustrate the relative significance (magnitude) of the factors making up the amplitude in 2.5‐D imaging inversion according to . We use ocean bottom cable (OBC) data (a single cable) from the North Sea, the same data we used in another paper, in which we developed and carried out reflection tomography in 2.5‐D (Foss et al 2004). We apply the transform in both for PP and PSV reflection data and assume a transversely isotropic background medium with a vertical axis of symmetry.…”

Section: Examplementioning

confidence: 99%

“…It is not uncommon for ocean bottom cable (OBC) seismic data to be collected along a single line, and the question arises of how to make optimal use of these data. Also, 2.5-D scattering theory can be applied in reflection tomography or migration velocity analysis (Foss et al 2004). Such an application leads to fast, though approximate, algorithms that carry out the reflection tomography slicewise ( Fig.…”

Section: Introductionmentioning

confidence: 99%

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Linearized 2.5-dimensional parameter imaging inversion in anisotropic elastic media

Foss¹,

Hoop

Ursin³

2005

Geophysical Journal International

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S U M M A R YIn this paper we derive 2.5-D short-period seismic modelling and imaging-inversion formulae in the Born approximation for anisotropic elastic media. The 2.5-D approach encompasses 3-D wave scattering measured in a common-azimuth acquisition geometry subject to 2-D computations under appropriate assumptions. The lowest possible symmetry of the medium in this approach, in principle, is monoclinic, while the medium must be translationally invariant in the normal direction to the associated symmetry plane. In the presence of caustics, artefacts may be generated by the imaging-inversion procedures. We show that in the 2.5-D approach the analysis of artefacts in the 2-D symmetry plane implies the corresponding analysis in 3-D in the framework of the common-azimuth acquisition geometry. An interesting aspect of our results is the occurrence of out-of-plane geometrical spreading in the least-squares removal of the contrast source radiation patterns on the data. We finally introduce the 2.5-D generalized Radon transform that generates common-image-point gathers. The reconsideration of 2.5-D scattering theory is motivated by the increase in use of ocean-bottom acquisition technology. It is not uncommon for ocean bottom cable (OBC) seismic data to be collected along a single line, and the question arises of how to make optimal use of these data. We show the effect of the factors making up the amplitude in the 2.5-D generalized Radon transform on OBC field data from the North Sea.

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Section: Examplementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Linearized 2.5-dimensional parameter imaging inversion in anisotropic elastic media

Foss¹,

Hoop

Ursin³

2005

Geophysical Journal International

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“…A similar notation is used for the receiver, namely, p r ( y ) = ( p r 1 , p r 3 ) and p ( x r ). Observe that the out‐of‐plane slowness p 2 is zero in 2.5D (Bleistein 1986; Foss and Ursin 2004). In an isotropic medium, the P‐wave polarization vectors are the unit vectors of the slowness vectors, denoted by h ( x s ) = ( h 1 ( x s ), h 3 ( x s )) and h ( x r ) = ( h 1 ( x r ), h 3 ( x r )) for the polarization vectors at the source and receiver, respectively.…”

Section: Isotropic Pp Common‐image‐point Gathersmentioning

confidence: 99%

“…Here, we present the expressions for the creation of PP common‐image‐point gathers assuming an isotropic medium. A complete description of the 2.5D formulae for anisotropic media and other acquisition geometries can be found in the review by Foss and Ursin (2004). Formulae for the 3D case can be found in the review by Ursin (2004).…”

Section: Introductionmentioning

confidence: 99%

A practical approach to PP seismic angle tomography

Foss

Ursin

Sollid

2004

Geophysical Prospecting

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A B S T R A C TThe use of the differential semblance misfit function on common-image-point gathers in the angle domain lends itself to an automated tomographic approach through a gradient-based search in the model space. The velocity model is described by a layer-based model with linear velocity trends and a superimposed bicubic B-spline. The interfaces of the layer-based model are computed by map migration of the PP zero-offset traveltimes of key reflectors. The common-image-point gathers are produced by a restricted inverse generalized Radon transform or amplitude-versus-anglecompensated migration. We present a complete description of all 2.5D formulae for isotropic velocity analysis of PP reflections and the results for ocean-bottom seismic data.

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“…Many papers have been published which study and emphasize the importance of generating common-image-angle gathers directly at the subsurface points rather than the universally used surface-offset image gathers, especially in complex geological areas where the wavefield includes multipathing ͑e.g., ten Kroode et al, 1994;Nolan and Symes, 1996;Brandsberg-Dahl et al, 1999;Rousseau et al, 2000;Xu et al, 2001;Audebert et al, 2002;Koren et al, 2002;Rickett and Sava, 2002;Brandsberg-Dahl et al, 2003;Foss and Ursin, 2004;Sollid and Ursin, 2003;Soubaras, 2003;Bleistein et al, 2005aBleistein et al, , 2005bWu and Chen, 2006;Biondi, 2007a Manuscript received by the Editor 28 December 2009; revised manuscript received 13 July 2010; published online 4 January 2011. 1 Although the theory of angle-domain imaging is well established, its implementation, especially for large-scale 3D models or for highresolution reservoir imaging, remains extremely challenging.…”

Section: Introductionmentioning

confidence: 99%

Full-azimuth subsurface angle domain wavefield decomposition and imaging Part I: Directional and reflection image gathers

2011

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We present a new subsurface angle-domain seismic imaging system for generating and extracting high-resolution information about subsurface angle-dependent reflectivity. The system enables geophysicists to use all recorded seismic data in a continuous fashion directly in the subsurface local angle domain ͑LAD͒, resulting in two complementary, full-azimuth, common-imageangle gather systems: directional and reflection. The complete set of information from both types of angle gathers leads to accurate, high-resolution, reliable velocity model determination and reservoir characterization. The directional angle decomposition enables the implementation of specular and diffraction imaging in real 3D isotropic/anisotropic geological models, leading to simultaneous emphasis on continuous structural surfaces and discontinuous objects such as faults and small-scale fractures. Structural attributes at each subsurface point, e.g., dip, azimuth and continuity, can be derived directly from the directional angle gathers. The reflection-angle gathers display reflectivity as a function of the opening angle and opening azimuth. These gathers are most meaningful in the vicinity of actual local reflecting surfaces, where the reflection angles are measured with respect to the derived background specular direction. The reflection-angle gathers are used for automatic picking of full-azimuth angle-domain residual moveouts ͑RMO͒ which, together with the derived background orientations of the subsurface reflection horizons, provide a complete set of input data to isotropic/anisotropic tomography. The full-azimuth, angle-dependent amplitude variations are used for reliable and accurate amplitude versus angle and azimuth ͑AVAZ͒ analysis and reservoir characterization. The proposed system is most effective for imaging and analysis below complex structures, such as subsalt and subbasalt, high-velocity carbonate rocks, shallow low-velocity gas pockets, and others. In addition, it enables accurate azimuthal anisotropic imaging and analysis, providing optimal solutions for fracture detection and reservoir characterization.

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2.5D modelling, inversion and angle migration in anisotropic elastic media

Cited by 5 publications

References 33 publications

Linearized 2.5-dimensional parameter imaging inversion in anisotropic elastic media

Linearized 2.5-dimensional parameter imaging inversion in anisotropic elastic media

A practical approach to PP seismic angle tomography

Full-azimuth subsurface angle domain wavefield decomposition and imaging Part I: Directional and reflection image gathers

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