Applying finite-difference method to ray tracing

Lin Zhang

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ABSTRACT

For a given slowness model, the traveltime field can be calculated, on a regular grid, with finite-difference methods. The contour lines of this field define the trajectories of wavefronts. From the orthogonal relations between wavefronts and rays, one can calculate another field whose contour lines define the trajectories of rays. Two-point ray tracing can then be accomplished by finding the contour line of a given value. The method is limited to rays traveling in one direction and associated with first arrivals. The algorithm can efficiently trace rays to destinations on a regular grid, and thus can be applied to tomographic inversion and time-to-depth conversion of migrated images