The Research On Two-dimensional Finite-difference Seismic Wave Field Numerical Simulation

Numerical simulation of seismic wave is one of the important research topics of exploration seismology, it is also an important means of volatility, in the oil and gas exploration and development it plays an important role. Numerical simulation of seismic wave field methods commonly used pseudo-spectral method, finite difference method, finite element method. Finite difference method has advantages in it's calculation speed and small memory, the method has broad applicability in the near field and the complexity of the border, and it can accurately simulate wave propagation in various media and the formation of complex structures in the spread of laws, the method is the most widely used numerical method in exploration seismology.In this paper, the theoretical basis for the wave theory, the use of Taylor series expansion of the wave equation finite-difference equations and discrete expressions are derived in detail, for the traditional second-order accuracy finite difference method simulation of the problem of low precision, derived from time-domain second-order spatial accuracy of fourth-order finite-difference equations. Paper also comprehensively analyzed the impact of the initial conditions, the source, the algorithm stability and numerical dispersion factors in the numerical simulation of the finite difference method.Finite difference numerical simulation is limited in a region, when the wave propagation to the border, the border will result in reflection, which is not expect to arise. Through a large number of research literature research, the paper summarized and compared some common boundary conditions, then analyzed the transparent selection of boundary conditions and absorbing conditions in detail. On this basis, deduced and received discrete expression of the two boundary conditions. Numerical simulation in the verification process shows that these two kinds of boundary conditions on the border have a good reflection of the absorption.Through the establishment of uniform model, layered model and anticline syncline model various theoretical models, based on the FORTRAN programming language, paper achieved the numerical simulation of finite difference algorithm. To simulate different geological theoretical models, from the comparative analysis of the simulation results we can see that ,the choice of model parameters and the relationship between the parameters have a significant impact on the simulation results. Finite difference algorithm has certain advantages in both the simulation accuracy and the efficiency of simulation.Through integrated research, thesis that the wave equation finite-difference algorithm is simple, computationally efficient, simulation of the characteristics of high accuracy, it has a great meaning of theoretical research and broad application prospects.