3D Stereotomographic Inversion on Real Data Set

Chalard, E.; Podvin, Pascal; Bégat, Soazig Le; Berthet, Philippe; David, B.

doi:10.3997/2214-4609-pdb.5.b008

Cited by 2 publications

(7 citation statements)

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“…The introduction of an L 1 ‐cost function should also be tested for improving the robustness of the inversion. The extension to 3D (Chalard et al . 2002) will benefit from this work, leading to a fast and robust tool.…”

Section: Resultsmentioning

confidence: 99%

“…We simply have to add the lateral dimension for all the types of data and model parameters. For practical application of the method, the important result was to discover that in 3D stereotomography the velocity macromodel can be constrained from a single lateral slope at the surface (at either the shot or receiver point), leading to much easier stereotomographic picking on 3D multistreamer marine acquisitions (Chalard et al . 2000, 2002).…”

Section: Stereotomographymentioning

confidence: 99%

“…The efficiency of stereotomography has been demonstrated over several years (Le Bégat, Podvin and Lambaré 2000; Alerini 2002; Alerini et al . 2002, 2003a; Chalard et al . 2002; Nguyen et al .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Stereotomography: a semi‐automatic approach for velocity macromodel estimation

Lambaré¹,

Alerini²,

Baina³

et al. 2004

Geophysical Prospecting

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A B S T R A C TMost methods for velocity macromodel estimation require considerable operator input, mainly concerning the regularization and the picking of events in the data set or in the migrated images. For both these aspects, slope tomography methods offer interesting solutions. They consider locally coherent events characterized by their slopes in the data cube. Picking is then much easier and consequently denser than in standard traveltime tomography. Stereotomography is the latest slope tomography method. In recent years it has been improved significantly, both from an algorithmic point of view and in terms of practical use. Robust and fast procedures are now available for 2D stereotomographic picking and optimization.Concerning the picking, we propose simple criteria for the selection of relevant data among the automatically picked events. This enables an accurate smooth velocity macromodel to be estimated quite rapidly and with very limited operator intervention. We demonstrate the method using a 2D line extracted from the Oseberg NH8906 data set. I N T R O D U C T I O NPrestack depth migration remains the best way of imaging the subsurface, in particular in areas of complex geology. This process is, however, very sensitive to the velocity macromodel and therefore great care must be taken at this very important step (Fagin 1998). Since standard approaches based on Dix's formula are not acceptable in complex media, two main types of method remain available: migration-based velocity analysis (MVA) and traveltime tomography. Tomography is particularly interesting in the case of 3D applications for which MVA is expensive, although traveltime picking in 3D tomography is a difficult and time-consuming process, requiring significant expertise.In order to facilitate the picking, a slope tomography method, known as stereotomography, was proposed for es-

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Section: Resultsmentioning

confidence: 99%

Section: Stereotomographymentioning

confidence: 99%

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Stereotomography: a semi‐automatic approach for velocity macromodel estimation

Lambaré¹,

Alerini²,

Baina³

et al. 2004

Geophysical Prospecting

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“…Depending on the ray coverage and parametrization of the velocity model, the memory required to store the velocity model part 8N obs N m b will be greatly reduced by only storing relevant (nonzero) elements (particularly when using basis functions with a local support for describing the velocity model). This can be compared to classical stereotomography and the extension to 3-D by Chalard et al (2002), for which…”

Section: Discussionmentioning

confidence: 99%

“…Stereotomography was first developed for 2‐D isotropic media with picking of PP events in the time domain (Billette & Lambaré 1998). Later extensions of the method include 3‐D PP streamer data (Chalard et al 2002), 2‐D isotropic PP / PS events (Alerini et al 2007) and 2‐D first‐arrival VSP data (Gosselet et al 2003, 2005). Although picking is easier in stereotomography than in classical tomography, it remains the bottleneck of the approach.…”

Section: Introductionmentioning

confidence: 99%

PP/PSanisotropic stereotomography

Nag

Alerini

Ursin

2010

Geophysical Journal International

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S U M M A R YStereotomography is a slope tomographic method which gives good results for background velocity model estimation in 2-D isotropic media. We develop here the extension of the method to 3-D general anisotropic media for PP and PS events. We do not take into account the issue of shear wave degeneracy. As in isotropic media, the sensitivity matrix of the inversion can be computed by paraxial ray tracing. We introduce a 'constant Z stereotomography' approach, which can reduce the size of the sensitivity matrix. Based on ray perturbation theory, we give all the derivatives of stereotomography data parameters with respect to model parameters in a 3-D general anisotropic medium. These general formulas for the derivatives can also be used in other applications that rely on anisotropic ray perturbation theory. In particular, we obtain derivatives of the phase velocity with respect to position, phase angle and elastic medium parameters, all for general anisotropic media. The derivatives are expressed using the Voigt notation for the elastic medium parameters. We include a Jacobian that allows to change the model parametrization from Voigt to Thomsen parameters. Explicit expressions for the derivatives of the data are given for the case of 2-D tilted transversely isotropic (TTI) media.We validate the method by single-parameter estimation of each Thomsen parameter field of a 2-D TTI synthetic model, where data are modelled by ray tracing. For each Thomsen parameter, the estimated velocity field fits well with the true velocity field.

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3D Stereotomographic Inversion on Real Data Set

Cited by 2 publications

References 0 publications

Stereotomography: a semi‐automatic approach for velocity macromodel estimation

Stereotomography: a semi‐automatic approach for velocity macromodel estimation

PP/PSanisotropic stereotomography

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