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The state-of-the-art in migration methodology is
represented by migration using downward continuation
(24).
Such methods are accurate, robust, and capable of handling
models with large and sharp velocity variations.
These methods naturally handle multipathing
occurring in complex geology.
However, migration by downward continuation limits
angular accuracy since it is designed for energy
propagating mainly in the vertical direction.
A first goal of this thesis is to eliminate the dip limitation
of wave-equation migration. The solution proposed
involves wavefield extrapolation in general Riemannian
coordinates which follow the general direction of wave
propagation in the physical space. In this case,
extrapolation is done forward relative to the direction
of wave propagation, and not in the arbitrary downward
direction as in conventional migration.

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Stanford Exploration Project

11/4/2004