TWO-POINT RAY TRACING BASED SEISMIC TRAVEL TIME TOMOGRAPHY INVERSION METHOD

摘要

A two-point ray tracing based seismic travel time tomography inversion method, comprising the steps of: acquiring seismic data (S1); establishing an initial one-dimensional continuous layered model in which the speed in a layer can continuously change (S2); representing a ray parameter p by a variable q, representing a hypocentral distance X as a function X=f(q) of the variable q, solving the X=f(q) by using the Newton iteration method (S3); calculating the direct wave travel time and the reflected wave travel time according to the ray parameter p (S4); comparing the theoretical arrival time and the actual data arrival time (S5); and adjusting the model speed parameter by means of the optimization algorithm until the difference between the theoretical arrival time and the actual arrival time meets a given error criterion (S6). According to the present invention, by establishing the one-dimensional continuous layered model in which stratum speed can continuously change, the number of division layers is greatly reduced, such that the actual stratum speed structure is described more accurately, improving the inversion calculation efficiency; and the ray parameter p is solved by using the variable q, which ensures fast and stable convergence even in the case of large incident angles.