Abstract:

The two-point ray-tracing is an effective method to solve complex geological structure reflection wave ray-tracing.In this paper，a new two-point ray-tracing method is proposed，it is based on the first-break wave ray-tracing tomography algorithm，and grid division is used to discrete model，through the forward procession of two-step ray-tracing method，the grid cells minimum travel-time from source point and receive point is calculated respectively，and each cell sum of the twice travel-times is taken as the minimum travel-time，again along the layer interface，the nearest minimum travel-time cell is researched.Then the Particle Swarm Optimization (PSO) algorithm is used to search the minimum travel-time point in this cell，as the reflex point，through the backward procession，the ray path is traced from this point to source point and receive point respectively with the Linear Travel-time Interpolation (LTI) algorithm.Finally the two-point ray-tracing path is obtained.

Key words: linear travel-time interpolation algorithm, grid division, two-point ray-tracing, preliminary wave, seismic survey