Stereotomography of seismic data acquired on undulant topography

Jin, Changkun; Zhang, Jianzhong

doi:10.1190/geo2017-0411.1

Cited by 9 publications

(4 citation statements)

References 35 publications

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“…Alternatively, the reciprocity principle can be used to estimate the slope at a given OBS position using the records of the other OBSs triggered by the shots located at the vertex of the targeted instrument (Alerini 2006;Alerini et al 2009). It should also be noted that in the case of rugged topographies often encountered in onshore case studies, slopes are corrected according to the undulant surface locally by performing an analysis using the horizontal and vertical component of the slowness vectors (Jin & Zhang 2018).…”

Section: Discussionmentioning

confidence: 99%

Mitigating the ill-posedness of first-arrival traveltime tomography using slopes: application to the eastern Nankai Trough (Japan) OBS data set

Sambolian

Górszczyk

Operto

et al. 2021

Geophysical Journal International

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Summary First-arrival traveltime tomography is one of the most used velocity model building techniques especially in sparse wide-angle acquisitions for deep crustal seismic imaging cases. Relying on the inversion of a picked attribute, the absolute traveltimes, the approach is ill-posed in terms of non-uniqueness of the solution. The latter is remedied by proper regularization or the introduction of prior information. Indeed, since traveltime kernels are vulnerable to the velocity-depth ambiguity, the inversion is stabilized by the introduction of complementary data like reflections and explicit reflectors in the velocity models. Here, we propose to supplement first-arrival traveltimes by their slopes, in other words the horizontal component of the slowness vectors at the sources and/or receivers. Slopes are a crucial attribute in state of the art scattering-based or reflection-based tomographic methods like slope tomography or wavefront tomography where the differential information is needed in order to locate the scattering events position or to parametrize the wavefront. The optional but valuable injection of slopes as an objective measure in first-arrival traveltime tomography stabilizes the problem by constraining the emergence angle or in turn implicitly the turning point depth of the rays. We explain why slopes have a tremendous added value in such a tomographic problem and highlight its remedial effect in cases where the medium is unevenly illuminated. We also show that the contribution of slopes become even more significant when the acquisition is sparse as it is generally the case with ocean-bottom seismometer surveys. The inferred models from such an extended time-attributes tomography will be used as initial guesses in a full-waveform inversion workflow context. The proposed strategy is benchmarked in 2D media against a dip section of the SEG/EAGE overthrust model and then followed by a revisit of ocean bottom seismometers data from the eastern-Nankai subduction margin as a real deep crustal case study.

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Section: Discussionmentioning

confidence: 99%

Mitigating the ill-posedness of first-arrival traveltime tomography using slopes: application to the eastern Nankai Trough (Japan) OBS data set

Sambolian

Górszczyk

Operto

et al. 2021

Geophysical Journal International

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“…To obtain a more precise velocity model and reduce the impact of human factors, this article proposes a joint tomographic inversion which can simultaneously use the traveltime and its gradient data of the reflected and refracted waves to invert the underground velocity model without determining the corresponding relationship between the seismic events and the reflection interfaces beforehand (Billette and Lambar, 1998). Moreover, the traveltime gradient can reflect the direction of ray propagation at the shot point and receiver point to solve the multipath problem of reflected rays, strengthen the constraint on the model space, and improve the inversion effect (Jin and Zhang, 2018). However, this requires picking the gradients in common-source gathers and in common-receiver ones, respectively.…”

Section: Introductionmentioning

confidence: 99%

Crustal velocity structure in the South Yellow Sea revealed by the joint tomographic inversion of reflected and refracted seismic waves

Fanghui

et al. 2023

Front. Earth Sci.

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The crustal velocity structure in the South Yellow Sea (SYS) Basin is crucial for understanding the basin’s geological structure and evolution. OBS (ocean-bottom station) data from the OBS2013 line have been used to determine the crustal velocity structure in the SYS. The velocity model of the upper crust in the northern SYS was determined using first-arrival traveltime tomography. The model showed a higher resolution shallow crustal velocity structure but a lower resolution middle-lower crustal velocity structure. The crustal velocity structure, together with the Moho discontinuity in the SYS Basin, was also constructed using a human–computer interactive traveltime simulation, and the result was highly dependent on the prior knowledge of the operator. In this study, we reconstructed a crustal velocity model in the SYS Basin using a joint tomographic inversion of the traveltime and its gradient data of the reflected and refracted waves picked from the OBS data. The resolution of the inverted velocity structure from shallow-to-deep crust was improved. The results revealed that the massive high-velocity body below the Haiyang Sag of the Jiaolai Basin extends to the Qianliyan Uplift in the SYS; the low-velocity Cretaceous strata directly cover the pre-Sinitic metamorphic rock basement of the Sulu orogenic belt; and the thick Meso-Paleozoic marine strata are retained beneath the Meso–Cenozoic continental strata in the northern depression. The Moho depth in the SYS Basin ranges from 28 to 32 km.

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“…The inverse problem is implemented by building explicitly the sensitivity matrix and the resulting sparse tomographic system is solved with a linear conjugate-gradient method during each iteration of the velocity model update, this update being either performed in a linear or nonlinear way. Since the original formulation (Billette 1998), different variants emerged; for example, 3-D extension (Chalard et al 2000), post-stack formulation (Lavaud et al 2004), application in borehole settings (Gosselet et al 2005), adaptation for anisotropic media (Nag et al 2006;Barbosa et al 2008), accounting for converted primary waves (Alerini et al 2007) or wide-aperture data (Prieux et al 2013), triangulated model parametrization (Yang et al 2018), handling complex topography (Jin & Zhang 2018). All of the aforementioned variants follow the same framework of the classical formulation using ray tracing as a forward solver and explicitly building the sensitivity matrix for the inversion.…”

Section: Introductionmentioning

confidence: 99%

Parsimonious slope tomography based on eikonal solvers and the adjoint-state method

Sambolian

Operto

Ribodetti

et al. 2019

Geophysical Journal International

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Velocity macromodel building is an essential step of the seismic imaging workflow. Indeed, obtaining acceptable results through migration or full waveform inversion is highly dependent on the kinematic accuracy of the background/initial velocity model. Two decades ago, stereotomography was proposed as an alternative to reflection traveltime tomography, the first relying on semi-automatic picking of locally coherent events associated with small reflection or diffraction segments tied to scatterers in depth by a pair of rays, while the latter on interpretive picking of laterally continuous reflections. The flexibility of stereotomography paved the way for many developments that have shown the efficiency of the method whilst emphasizing on the complementary information carried out by traveltimes and slopes of locally coherent events. A recent formulation recast stereotomography under a matrix-free formulation based on eikonal solvers and the adjoint-state method. In the latter, like in the previous works, the scatterer positions and the velocity field are updated jointly to tackle the ill-famed velocityposition coupling in reflection tomography. Following on from this adjoint-state formulation, we propose a new parsimonious formulation of slope tomography that offers the chance to restrain the problem to minimizing the residuals of a single data class being a slope, in search of a sole parameter class being the subsurface velocity field. This parsimonious formulation results from a variable projection, which is implemented by enforcing a consistency between the scatterer coordinates and the velocity macromodel through migration of kinematic attributes. We explain why the resulting reduced-parametrization inversion is more suitable for tomographic problems than the most common joint inversion strategy. We benchmark our method against the complex Marmousi model along with a validation through time domain full waveform inversion and then present the results of a field data case study.

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Stereotomography of seismic data acquired on undulant topography

Cited by 9 publications

References 35 publications

Mitigating the ill-posedness of first-arrival traveltime tomography using slopes: application to the eastern Nankai Trough (Japan) OBS data set

Mitigating the ill-posedness of first-arrival traveltime tomography using slopes: application to the eastern Nankai Trough (Japan) OBS data set

Crustal velocity structure in the South Yellow Sea revealed by the joint tomographic inversion of reflected and refracted seismic waves

Parsimonious slope tomography based on eikonal solvers and the adjoint-state method

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