Ray Tracing Forward Modeling With Seismic First Arrival Times

Ray tracing is a kind of fast, valid and approximate computation method on wave field, because the method is fast and effective in calculation, and the ray paths is very intuitionistic, it is widely applied to such seismic signal disposal realm as the forward modeling of wave field, migration imaging, tomogrphy, etc. This thesis introduces the linear traveltime interpolation method(LTI),analyses the error which is resulted from the linear hypothesis in the linear traveltime interpolation method, puts forward a nonlinear traveltime interpolation method based on the regularity of seismic wave propagation, proves that the nonlinear traveltime interpolation method is more accurative than the linear traveltime interpolation method in calculating the traveltime in the field near the source point with the numerical modeling calculation. On the basis of synthesizing the advantage both of the nonlinear traveltime interpolation method and the linear traveltime interpolation method, the author puts forward a method called nonlinear/linear traveltime interpolation, in the field near the source point, the traveltime is calculated using nonlinear traveltime interpolation, while LTI is used to calculate the traveltime far from the source. And proves that the nonlinear/linear traveltime interpolation method is more accurative than the single linear traveltime interpolation method through the numerical modeling calcultion with material model. With the development of the seismic exploration technology, increasingly complicated geological exploration target and the structural imaging have become a focus, this paper proposed a ray tracing in 3D about the seismic first arrival times with discrete bilinear traveltime interpolation, proved that the principle and the method is corrective and useful based on the numerical modeling calculating.