Seismic Wavefield Modeling And Its Application

This research paper includes three parts:(1) seismic ray tracing algorithm; (2) seismic wave field modeling; (3) joint travel time tomography with multiple travel time information.Respect to the seismic ray tracing, we first put forward a multistage modified shortest path ray tracing (referred to multistage MSPM), and develop corresponding algorithm to track multiple (reflected, transmitted, and converted) arrivals in complex layered media. The multistage MSPM algorithm is compared against one popular finite difference Eikonal solver (namely the multistage fast marching method, referred to the multistage FMM), as a result, the multistage MSPM is adventurous over the multistage FMM in terms of solution accuracy and CPU time. In order to trace multi-value seismic ray paths in complex structure, we develop another ray tracing method, called the extremum value algorithm based on the multistage MSPM, which is suitable for the multi-value ray path tracing in the complex velocity structure. In the seismic exploration a fast and accurate ray tracing algorithm is needed so that an interface element method is proposed based on the multistage MSPM algorithm, which has a big advance in CPU time.Respect to the seismic wave field modeling, we use finite difference method to realize first-order wave equation simulation and separation, staggered grid pseudo-spectral method for first-order wave equation simulation and separation. Based on the above principle, we realize the second-order wave equation modeling and its separation by using normal grid pseudo-spectral method. The showing results are favorable and satisfactory in terms of solution accuracy and frequency scatter remove.Respect to joint travel time tomography, we successful combines the multistage MSPM algorithm with the subspace inversion solver to form a method for joint travel time tomography with multiple travel time information. The numerical results show its good performance.