Research Of The Effect Of Internal Complex Velocity Interfaces On The Simulation Of Finite Difference Seismic Wave

Finite difference is an import tool in numerical simulation of seismic wave,because of its easy implementation,high efficiency and low-memory requirement.Finite difference has been widely used in seismology and geophysics prospect.With the development of earth sciences,computational model becomes larger and more complex so we need higher performance seismic forward algorithm.Using the higher order staggered mesh scheme can effectively suppress the dispersion error in the case of coarse mesh,and then reduce the computational memory requirements and save computing resource.However,the larger grid step size would cause the finite difference meshes to increase the representation error of the complex internal interface.In the actual seismic model,there are a large number of welded interface.Due to the limitations of the discrete media,it is difficult to accurately simulate the boundary conditions in staggered grid finite difference.The problem is more serious due to the use of a larger space step compared to the lower order schemes in high order finite difference schemes.In this paper,different methods of dealing with welded interface are discussed by using high order staggered grid finite difference scheme.The numerical characteristics of interface errors are analyzed,which provides the basis for the selection of seismic wave numerical simulation.In the first part,this paper introduces the basic information of finite difference modelling algorithm,and summarizes the research progress of high order staggered grid finite difference and methods to handle welded interface errors.The second part mainly introduces the basic realization of finite difference forward modeling in elastic wave equation,including mesh layout,high order scheme,seicmic source and absorbing boundary.The third analyzes the interface numerical error of the finite difference,and introduces the four ways to handle media interface:direct method,grid average,volume integration averaged method and effective orthorhombic averaged medium method.In the fourth part,the paper respectively shows the solution of the different media handling methods and characteristics of interface errors in different grid parameters by numerical experiments.In the last part,some suggestions about the grid set of finite difference is been given.