Wave‐equation migration velocity analysis

Abstract

INTRODUCTION Seismic imaging is a two-step process: velocity estimation and migration. As the velocity function becomes more complex, the two steps become more and more dependent on each other. In complex depth imaging problems, velocity estimation and migration are applied iteratively in a loop. To assure that this iterative imaging process converges to a satisfactory model, it is crucial that the migration and the velocity estimation are consistent with each other. Kirchhoff migration often fails in complex areas, such as sub-salt, because the wavefield is severely distorted by lateral velocity variations and thus complex multipathing occurs. As the shortcomings of Kirchhoff migration have become apparent (O'Brien and Etgen, 1998), there has been a renewal of interest in wave-equation migration and the development of computationally efficient 3-D prestack depth migration methods based on the wave equation (Biondi and Palacharla , 1996; Biondi , 1997; Mosher et al. , 1997). H