Recent applications of turning-ray tomography

Zhu, Xiaowei; Valasek, Paul A.; Roy, Baishali; Shaw, Sylvie; Howell, Jack; Whitney, Steve; Whitmore, Norman Daniel; Anno, Phil D.

doi:10.1190/1.2957894

Cited by 40 publications

(11 citation statements)

References 25 publications

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“…Both ways have been successfully applied to other challenging environments (e.g., Zhu et al . , ; Cyz and Malinowski ). However, static corrections are based on the assumption that rays travel nearly vertically between the receivers at the surface and a chosen datum layer.…”

Section: Methods and Depth Imaging Strategymentioning

confidence: 98%

Seismic depth imaging of a geothermal system in Southern Tuscany

Riedel

Dutsch

Alexandrakis

et al. 2015

Geophysical Prospecting

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A B S T R A C TThis work represents a case study concerning the application of reflection seismic imaging methods in the context of geothermal exploration. Our goal is to obtain accurate structural images of a geothermal active area in southern Tuscany. These images will be required in subsequent studies as the input for geological model building and numerical simulation of the heat transport and fluid flow. The target region exhibits great geologic complexity, including strong velocity contrasts, lateral nearsurface inhomogeneities, fracture zones, and significant topography. Those features are typical for a volcanic hard-rock environment and pose significant challenges to conventional seismic imaging methodology. Therefore, we apply a sophisticated and robust depth imaging workflow to previously acquired surface seismic data. Within our workflow, we focus on estimating the seismic velocities of the predominant rock units and subsequently carry out Kirchhoff pre-stack depth migration and Fresnel volume migration to obtain high-resolution images of the subsurface. Our results demonstrate that the applied methodology provides a valueable tool for imaging in a complex environment such as a volcano-geothermal area. In detail, the resulting reflector images show the main horizons that delineate the Tuscan sedimentary rocks in the target region. The images from standard Kirchhoff migration can be significantly enhanced by utilizing Fresnel volume migration, which eliminates migration artefacts and provides a better result. Moreover, we obtain the migration velocities and depths for an important regional reflector, known as the K-horizon, which is of major interest for geothermal characterization.

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Section: Methods and Depth Imaging Strategymentioning

confidence: 98%

Seismic depth imaging of a geothermal system in Southern Tuscany

Riedel

Dutsch

Alexandrakis

et al. 2015

Geophysical Prospecting

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“…Initial velocity model can be derived from migration velocity analysis or traveltime tomography (Lambaré, 2008;Zhu et al, 2008;Zhou, 2006) or Laplace domain waveform inversion methods Cha, 2009, 2008). The acoustic wave equation is only an approximation to the wave physics in real 3-D world.…”

Section: Basic Workflow For Layer-stripping Fwimentioning

confidence: 99%

Layer-stripping full waveform inversion with damped seismic reflection data

Bian

2011

J. Earth Sci.

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Full waveform inversion (FWI) directly minimizes errors between synthetic and observed data. For the surface acquisition geometry, reflections generated from deep reflectors are sensitive to overburden structure, so it is reasonable to update the macro velocity model in a top-to-bottom manner. For models dominated by horizontally layered structures, combination of offset/time weighting and constant update depth control (CUDC) is sufficient for layer-stripping FWI. CUDC requires ray tracing to determine reflection traveltimes at a constant depth. As model complexity increases, the multi-path effects will have to be considered. We developed a new layer-stripping FWI method utilizing damped seismic reflection data, which does not need CUDC and ray tracing. Numerical examples show that effective update depth (EUD) can be controlled by damping constants even in complex regions and the inversion result is more accurate than conventional methods. KEY WORDS: full waveform inversion, velocity model building, layer-stripping strategy, damped wave equation, sensitivity analysis.

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“…Successes in such tomostatics correction have been reported by many authors ͑e.g., De Amorim et al, 1987;Zhu et al, 1992Zhu et al, , 2008Rajasekaran and McMechan, 1996;Taner et al, 1998;Chang et al, 2002;Li et al, 2009;Yordkayhun et al, 2009͒. Wide ray-angle coverage is a prerequisite of a successful first-arrival tomography. In other words, the method requires a large number of rays going through the model area evenly with different ray angles.…”

Section: Introductionmentioning

confidence: 99%

Tomographic velocity model building of the near surface with velocity-inversion interfaces: A test using the Yilmaz model

et al. 2010

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First-arrival traveltime tomography is a popular approach to building the near-surface velocity models for oil and gas exploration, mining, geoengineering, and environmental studies. However, the presence of velocity-inversion interfaces ͑VIIs͒, across which the overlying velocity is higher than the underlying velocity, might corrupt the tomographic solutions. This is because most first-arrival raypaths will not traverse along any VII, such as the top of a low-velocity zone. We have examined the impact of VIIs on first-arrival tomographic velocity model building of the near surface using a synthetic near-surface velocity model. This examination confirms the severe impact of VIIs on first-arrival tomography. When the source-to-receiver offset is greater than the lateral extent of the VIIs, good near-surface velocity models can still be established using a multiscale deformable-layer tomography ͑DLT͒, which uses a layer-based model parameterization and a multiscale scheme as regularization. Compared with the results from a commercial grid-based tomography, the DLT delivers much better near-surface statics solutions and less error in the images of deep reflectors.

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Recent applications of turning-ray tomography

Cited by 40 publications

References 25 publications

Seismic depth imaging of a geothermal system in Southern Tuscany

Seismic depth imaging of a geothermal system in Southern Tuscany

Layer-stripping full waveform inversion with damped seismic reflection data

Tomographic velocity model building of the near surface with velocity-inversion interfaces: A test using the Yilmaz model

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