Pgs Geophysical As

Pgs Americas, Inc.

Junru Jiao

Ruben D Martinez

Sverre Brandsberg-Dahl

John Frier Willis

Yeashung Sonny Lin

Chaoguang Zhou

David Richard Lowrey

Daniel Solano

A programmable computer is used to perform the following. 3D seismic data sets, corresponding to each azimuth in seismic data obtained from a multi-azimuth marine seismic survey, are migrated in grids oriented with the corresponding azimuth. Acquisition geometry is stored for each trace in the seismic data sets for each azimuth. Residual analysis, based on the corresponding azimuth, is performed on each of the migrated data sets, generating residuals and reflectors for each azimuth. The residuals and reflectors generated for each azimuth are rotated and merged on a master grid. Reflection tomographic inversion is applied iteratively to the rotated and merged residuals and reflectors to update a velocity model using the acquisition geometry as based on the master grid. The earth's subsurface is imaged using the updated velocity model.

Method for building velocity models for imaging in multi-azimuth marine seismic surveys

A method for estimating seismic velocities in vertically transversely isotropic media includes generating an initial estimate of vertical interval velocity and interval normal moveout velocity with respect to depth from seismic data. An initial estimate is generated of a first anisotropy parameter with respect to depth. The first anisotropy parameter is related to the interval normal moveout velocity and the interval vertical velocity. An initial estimate is generated with respect to depth of a second anisotropy parameter. The second anisotropy parameter is related to the first anisotropy parameter and an interval anelliptic parameter. A first tomographic inversion is performed with respect to the interval normal moveout velocity and the second anisotropy parameter at a constant value of the first anisotropy parameter until travel time differentials reach minimum values. Layer depths are adjusted with the initial estimate of vertical interval velocity. Using values of the second anisotropy parameter determined in the first tomographic inversion, a second tomographic inversion is performed of interval normal moveout velocity and the first anisotropy parameter with respect to depth. The adjusted layer depths, interval normal moveout velocities and interval vertical velocities are again adjusted and interval anelliptic parameters are calculated from the second tomographic inversion.

Method for three dimensional seismic travel time tomography in transversely isotropic media

A method for interpreting seismic data below a salt layer includes depth migrating the seismic data to a bottom of the salt layer. The migrating including generating an initial model of velocities below the salt layer. The initial model is scaled by a plurality of scale factors at at least one image position. At least one of the plurality of scale factors for which a depth migrated image below the salt layer is optimum is selected as the scale factor.

Method for sub-salt migration velocity analysis

A method is disclosed for processing seismic data. The method includes prestack depth migrating the seismic data to generate common image gathers using an initial velocity-depth model. Horizons in the migrated seismic data are selected. Residual migration velocity analysis in the depth-offset domain is performed with respect to each selected horizon, and the velocity-depth model is updated based on the residual migration velocity analysis.

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Katy, TX, United States of America

Junru Jiao