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Wave-equation migration velocity analysis by inversion of differential image perturbations

Paul Sava and Biondo Biondi

paul@sep.stanford.edu, biondo@sep.stanford.edu

ABSTRACT

Wave-equation migration velocity analysis is based on the linear relation that can be established between a perturbation in the migrated image and the corresponding perturbation in the slowness function. Our method formulates an objective function in the image space, in contrast with other wave-equation tomography techniques which formulate objective functions in the data space. We iteratively update the slowness function to account for improvements in the focusing quality of the migrated image. Wave-equation migration velocity analysis (WEMVA) produces wrong results if it starts from an image perturbation which is not compliant with the assumed Born approximation. Other attempts to correct this problem lead to either unreliable or hard to implement solutions. We overcome the major limitation of the Born approximation by creating image perturbations consistent with this approximation. Our image perturbation operator is computed as a derivative of prestack Stolt residual migration, thus our method directly exploits the power of prestack residual migration in migration velocity analysis.



 
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Stanford Exploration Project
7/8/2003