Finite Difference Numerical Simulation Of Elastic Wave Field In 3D Complex Media

Seismic exploration has been widely used in energy mineral resources and engineering exploration. But most of them are 2D seismic exploration and 2D numerical simulation of seismic wave field. In recent years, there is a great development trend of 3D and 4D seismic exploration, and in this paper, we mainly focused on the 3D numerical simulation of seismic wave field. The actual medium underground is anisotropic and viscous. The simulation of seismic wave field propagating in 3D anisotropic and viscoelastic medium is one of the important topics in seismic exploration. 3D seismic wave field simulation can be used to validate the theoretical algorithm, to identify characteristics of the wave field, and to design field observation system.In this paper, we use the rotated staggered grid to simulate the 3D one- order velocitystress wave equation, and redistributed velocity, stress components and media parameters on different grid nodes, comparing with the traditional staggered grid. The Stress components, elastic modulus and the velocity component, the density are respectively distributed on the nodes of the grid and the middle of the grid. In order to get the Spatial derivative of the velocity and stress, we need to calculate four derivative values in the diagonal direction, and then wo can get the derivative of the horizontal direction and the vertical direction. When using the rotated staggered grid to simulating seismic wave propagation in viscoelastic media and anisotropic media, we don’t have to average the elastic modulus, So we can overcome the unstable results in the traditional staggered grid, and the numerical accuracy of the wave field has been improved.In this paper, we discussed the numerical simulation of seismic wave field in elastic anisotropy medium, and used the Kelvin media to simulate the viscoelastic medium, and analyzed the difference of wave field between the viscoelastic medium and the elastic media. In order to solve the artificial boundary conditions of the numerical simulation, We Used CE absorbing boundary and non- splitting PML absorbing boundary to attenuate the wave field near the border of model, and contrasted the effect of the two boundary conditions in same situations. If we don’t have an appropriate grid spacing and sampling interval when numerical calculation, the results will be numerical dispersion. In order to ensure that the numerical calculation more stable, we introduced FCT Flux correction technology to suppress the numerical dispersion in numerical simulation effectively. With FCT technology, we can appropriate increasing the grid spacing and sampling interval or decreasing spatial difference order on the same scale model in the wave field simulation.In order to simulate the surface waves, we combine the free boundary condition and CE/NPML absorbing boundary conditions, and described particle motion in the surface wave propagation, taking the advantage of 3D numerical simulation. There is the great significance to aware seismic wave field propagation in actual media using 3D wave field numerical simulation. To optimize the design of the Program, We used the distributed Shared memory mechanism by using the MPI + OpenMP parallel library, as the result, the efficiency of the program and the utilization of hardware have been improved greatly.