Seismic Amplitude Inversion for Interface Geometry of Multi-layered Structures

Wang, Yanghua; Pratt, R. G.

doi:10.1007/pl00001052

Cited by 18 publications

(10 citation statements)

References 13 publications

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“…Once the right-hand side quantities are estimated, equation 14 becomes a tridiagonal system, which can be solved efficiently regardless of how many segments are set along the raypath (Wang and Houseman, 1994;Wang and Pratt, 2000). This is obviously a great advantage over the previous scheme which involves calculation of the Jacobian matrix and its inverse.…”

Section: Ray Tracing Based On Minimum Variationmentioning

confidence: 99%

Seismic ray tracing in anisotropic media: A modified Newton algorithm for solving highly nonlinear systems

Wang

2014

GEOPHYSICS

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Seismic ray tracing with a path-bending method leads to a nonlinear system that has much stronger nonlinearity in anisotropic media than the counterpart in isotropic media. Any path perturbation causes changes to directional velocities, which depend not only upon the spatial position but also upon the local propagation direction in anisotropic media. To combat the high nonlinearity of the problem, the Newton-type iterative algorithm is modified by enforcing Fermat's minimum-time principle as a constraint for the solution update, instead of conventional error minimization in the nonlinear system. As the algebraic problem is incorporated with the physical principle, it is able to stabilize the solution for such a highly nonlinear problem as ray tracing in realistically complicated anisotropic media. With this modified algorithm, two ray-tracing schemes are presented. The first scheme involves newly derived raypath equations, which are approximate for anisotropic media but the minimum-time constraint will ensure that the solution steadily converges to the true solution. The second scheme is based on the minimal variation principle. It is more efficient than the first one as it solves a tridiagonal system and does not need to compute the Jacobian and its inverse in each iteration. Even in this second scheme, Fermat's minimum-time constraint is employed for the solution update, so as to guarantee a robust convergence of the iterative solution in anisotropic media.

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Section: Ray Tracing Based On Minimum Variationmentioning

confidence: 99%

Seismic ray tracing in anisotropic media: A modified Newton algorithm for solving highly nonlinear systems

Wang

2014

GEOPHYSICS

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“…When we extract the amplitudes from the gathers, travel times are also obtained concomitantly. Demigration on re¯ection amplitudes (and travel times) is followed, as described in WANG et al (2000). The result is then considered as diraction-free, raw amplitudes (and travel times) for the input to inversion.…”

Section: Amplitudes Extracted From Prestack Gathersmentioning

confidence: 99%

Decomposition of Structural Amplitude Effect and AVO Attributes: Application to a Gas-water Contact

Wang

Worthington²,

Pratt

2002

Pure and Applied Geophysics

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Ð The structural amplitude eect, associated with focusing and defocusing due to the re¯ector curvature, importantly contributes to re¯ection seismic amplitudes. This paper develops a conciliatory approach for estimating the structural amplitude eect and the attributes of amplitude variation versus oset (AVO). The AVO attributes are extracted from raw amplitudes, in which the structural eect is taken into account explicitly based on a structural model reconstructed from travel-time inversion. One of the goals is to conduct the AVO analysis not just locally (per CDP) but also horizontally to see the global variation along the re¯ection. The lateral variations of AVO attributes are decomposed by the Chebyshev expansion. The method is demonstrated with an example of weak shallow gas-water contact appearing on a 2-D seismic pro®le of a site survey in the North Sea.

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“…where A is the projection matrix composed of the basis vectors, H is the Hessian matrix, D =diag{μ j } is the damping matrix given in terms of damping factors μ j with units of ( model parameter ) − 2 and g ^ is the gradient vector. The basis vector a ( j ) , a column of the projection matrix A , is built up in this paper using the gradient vector g ^ ( j ) , corresponding to the j th parameter group (Wang & Pratt 2000). Readers may refer to Kennett et al (1988), Sambridge (1990), Williamson (1990) and Oldenburg et al (1993) for variant designing procedures of the basis vectors a ( j ) .…”

Section: Inversion Proceduresmentioning

confidence: 99%

“…where A 0 is the amplitude at the source point, C Q is the inelastic attenuation factor, C is the product of all the relevant reflection and transmission coefficients, and L is the geometrical spreading function (Wang & Pratt 2000). The inelastic attenuation is given by…”

Section: Inversion Proceduresmentioning

confidence: 99%

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Seismic amplitude inversion for interface geometry: practical approach for application

Wang¹,

White²,

Pratt³

2000

Geophys. J. Int.

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Summary This paper presents a practical approach for the application of real seismic amplitude data in the context of reflection seismic tomography. The estimation of recorded seismic amplitudes from reflection seismic gathers is performed with the aid of pre‐stack time migration, which enhances continuity and reflection strength and reduces reflection point dispersal and diffraction effects. Moreover, contraction of the Fresnel zone by migration brings the amplitudes closer to the ray amplitudes assumed in the inversion. De‐migration of the amplitudes follows, so that we recover a set of ‘true’ observations for input to inversion. To make the amplitude inversion robust, the effect of noise in the amplitude data is mitigated by applying iteratively a locally reweighted regression, which can efficiently reject amplitude outliers. This approach is applied to a reflection seismic profile from the North Sea to constrain the geometry of a stack of interfaces by using both the amplitude inversion and a joint inversion with traveltime data. The application example represents a valuable contribution to the discussion of how the combined effort of imaging and inversion of seismic data should be organized when we are dealing with field data.

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Seismic Amplitude Inversion for Interface Geometry of Multi-layered Structures

Cited by 18 publications

References 13 publications

Seismic ray tracing in anisotropic media: A modified Newton algorithm for solving highly nonlinear systems

Seismic ray tracing in anisotropic media: A modified Newton algorithm for solving highly nonlinear systems

Decomposition of Structural Amplitude Effect and AVO Attributes: Application to a Gas-water Contact

Seismic amplitude inversion for interface geometry: practical approach for application

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