Abstract：The raylet method based on reciprocity of traveltime field is potentially capable of dealing with multi-paths.However this method cannot readily obtain the extremum of the total traveltime field which is the sum of a field from the source and a field from the receiver as the ray path.So we calculate transverse or longitudinal first-order derivative of the total traveltime field,and pick up its zero points to constitute the ray path by means of the inverse interpolation.Furthermore,besides a first-arrival ray,other later-arrival rays can be also obtained with a multi-stage algorithm.We test influence characteristics of grid size and the length of derivative operator on our computation accuracy in a homogeneous media and a media with a constant gradient in depth compared with exact analytical results.Then we indicate applicability of our method in a desired laterally velocity-varied media in contrast to the conventional kinematic ray tracing.Finally our tests in both a low-velocity multi-path model and Marmousi model prove that our proposed method achieves satisfactory computational efficiency and accuracy.
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