Curvatures and inhomogeneities: An improved common-reflection-surface approach

Schwarz, Benjamin; Vanelle, C.; Gajewski, Dirk; Kashtan, Boris

doi:10.1190/geo2013-0196.1

Cited by 56 publications

(31 citation statements)

References 24 publications

(52 reference statements)

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“…The use of zero-offset attributes obtained from a global optimization scheme with improved conflicting dip handling (Walda and Gajewski, 2015) has increased the quality of our results. Also, the application of non-hyperbolic operators such as i-CRS (Schwarz et al, 2014b) may lead to further improvement. Future work also includes the extension of the decomposition principle to 3D.…”

Section: Discussionmentioning

confidence: 98%

Enhancement of prestack diffraction data and attributes using a traveltime decomposition approach

2016

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Diffractions not only carry important information about small-scale subsurface structures, they also possess unique properties, which make them a powerful tool for seismic processing and imaging. Since a point diffractor scatters an incoming wave to all directions, a diffraction event implies better illumination than a reflection, because the rays travel through larger parts of the subsurface. Furthermore, unlike the reflection case, in which the emergence location of the reflected wave depends on the source position, in the case of non-Snell scattering, up-going and down-going raypaths are decoupled. Based on this decoupling, we introduce a diffraction traveltime decomposition principle, which establishes a direct connection between zero-offset and finite-offset diffraction wavefield attributes. By making use of this approach, we are able to enhance diffractions and obtain high-quality diffraction wavefield attributes at arbitrary offsets in the prestack domain solely based on zero-offset processing without any further optimization of attributes. We show the accuracy of the method by fitting diffraction traveltimes, and on simple waveform data. Application to complex synthetic data shows the ability of the proposed approach to enhance diffractions and provide high-quality wavefield attributes even in sparsely illuminated regions such as subsalt areas. The promising results reveal a high potential for improved prestack data enhancement and further applications such as efficient diffraction-based finite-offset tomography.K e y w o r d s :

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Section: Discussionmentioning

confidence: 98%

Enhancement of prestack diffraction data and attributes using a traveltime decomposition approach

2016

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“…Processing the data with the i‐CRS operator (e.g., Schwarz et al . ) might improve the determination of wavefield attributes since it better fits diffractions. High‐quality attributes will result in more reliable time migration velocities, improved NIP wave tomography, and better pre‐stack data enhancement opportunities.…”

Section: Discussionmentioning

confidence: 99%

Application of the 3D common‐reflection‐surface stack workflow in a crystalline rock environment

Ahmed

Schwarz

Gajewski

2015

Geophysical Prospecting

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A B S T R A C TSeismic data from crystalline or hardrock environments usually exhibit a poor signalto-noise ratio due to low impedance contrasts in the subsurface. Moreover, instead of continuous reflections, we observe a lot of steeply dipping events resembling parts of diffractions. The conventional seismic processing (common midpoint stack and dip moveout) is not ideally suited for imaging such type of data. Commonreflection-surface stack processing considers more traces during the stack than common midpoint processing, and the resulting image displays a better signal-to-noise ratio. In the last decade, the common-reflection-surface stack method was established as a powerful tool to provide improved images, especially for low-fold or noisecontaminated data. The common-reflection-surface stack and all attributes linked to it are obtained using a coherence-based automatic data-driven optimization procedure. In this work we applied the common-reflection-surface stack workflow to 3D crystalline rock seismic data, which were acquired near Schneeberg, Germany, for geothermal exploration. The common-reflection-surface stack itself provided an image of good signal-to-noise ratio. However, for data from environments with low acoustic impedance and poor velocity information, coherence, which is automatically obtained in the optimization procedure, provides an alternative way to image the subsurface. Despite the reduced resolution, for these data, the coherence image provided the best results for an initial analysis. Utilized as a weight, the coherence attribute can be used to further improve the quality of the stack. By combining the benefits of a decreased noise level with the high-resolution and high-interference properties of waveforms, we argue that these results may provide the best images in an entirely data-driven processing workflow for the Schneeberg data.

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“…Following the works of de Bazelaire (1988) and Höcht et al (1999), Schwarz et al (2014aSchwarz et al ( , 2015 found that all higher-order CRS-type stacking operators, including multifocusing (Gelchinsky et al, 1999), can be formulated in terms of the CRS attributes in two different ways, one accounting for overburden heterogeneity by the application of a constant slowness shift, the other, in correspondence with de Bazelaires shifted hyperbola, by a constant shift of the reference time. According to Höcht et al (1999) and Schwarz et al (2014b), both mechanisms can be related to the CRS attributes via Eqs (2) and…”

Section: Crs-based Passive Localizationmentioning

confidence: 99%

“…Alongside the co-existing multifocusing approach and the estimation of local event slopes (Fomel, 2007), several higher-order CRS formulations have been introduced in recent years (Landa et al, 2010;Fomel and Kazinnik, 2013;Schwarz et al, 2014b). By extending the work of de Bazelaire (1988) and Höcht et al (1999), Schwarz et al (2014aSchwarz et al ( , 2015 demonstrated that all these higher-order expressions, including the commonly used hyperbolic CRS operator, can either be formulated for the optical projection or an effective analog of the true kinematics of the wave propagation.…”

Section: Introductionmentioning

confidence: 98%

Passive seismic source localization via common-reflection-surface attributes

2016

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The common-reflection-surface (CRS) stack can be viewed as a physically justified extension of the classical common-midpoint (CMP) stack, utilizing redundant information not only in a single, but in several neighboring CMP gathers. The zero-offset CRS moveout is parameterized in terms of kinematic attributes, which utilize reciprocity and raypath symmetries to describe the two-way process of the actual wave propagation in active seismic experiments by the propagation of auxiliary one-way wavefronts. For the diffraction case, only the attributes of a single one-way wavefront, originating from the diffractor are sufficient to explain the traveltime differences observed at the surface. While paraxial ray theory gives rise to a second-order approximation of the CRS traveltime, many higher-order approximations were subsequently introduced either by squaring the second-order expression or by employing principles of optics and geometry. It was recently discovered that all of these higher-order operators can be formulated either for the optical projection or in an auxiliary medium of a constant effective velocity. Utilizing this duality and the one-way nature of the CRS parameters, we present a simple data-driven stacking scheme that allows for the estimation of the a priori unknown excitation time of a passive seismic source. In addition, we demonstrate with a simple data example that the output of the suggested workflow can directly be used for subsequent focusing-based normal-incidence-point (NIP) tomography, leading to a reliable localization in depth.K e y w o r d s :

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Curvatures and inhomogeneities: An improved common-reflection-surface approach

Cited by 56 publications

References 24 publications

Enhancement of prestack diffraction data and attributes using a traveltime decomposition approach

Enhancement of prestack diffraction data and attributes using a traveltime decomposition approach

Application of the 3D common‐reflection‐surface stack workflow in a crystalline rock environment

Passive seismic source localization via common-reflection-surface attributes

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