Under The Kelvin Viscoelastic Medium Rayleigh Wave Forward Modeling And Analysis Of The Wave Field,

Rayleigh wave exploration is a new type of engineering geophysical exploration methods. Because of the strong energy of Rayleigh wave,high signal to noise ratio and high efficiency, it get more and more attention in recent years. The traditional theory of Rayleigh wave is generally assumed subsurface is elastic solid medium. Although to a certain extent, it is similar to the situation of subsurface reaction, it would be very difficult to describe the complex physics phenomena of the seismic waves transmission in the real stratum because of the viscoelastic and multiphase. At the moment, Rayleigh wave forward is still under the conditions of elastic numerical simulation. Forward is the basis of inversion, so it is necessary to make the Rayleigh wave forward under viscoelastic medium.The paper give a systemic introduction to the constructor method, time-varying characteristics and wave equation of Kelvin viscoelastic medium. Introducing the difference equation of temporal two orders and space ten orders precision starting from wave equation of two-dimension Kelvin viscoelastic wave, discussing boundary condition and initial condition of difference equation.In this paper, Kelvin viscoelastic theory and composition viscoelastic theory applied to Rayleigh wave forward modeling by 2D staggered-grid finite different scheme based on first order velocity-stress viscoelastic wave equation. Studying the characteristics of Rayleigh waves under Kelvin viscoelastic model and composition viscoelastic model Separately. Including the half-space homogeneous medium model and the horizontally layered model. Analyzing attenuation feature of Rayleigh wave under different quality factor and porosity. The forward results show that there is energy attenuation and spectrum absorption in Rayleigh wave propagation. The thesis deepen the understanding of Rayleigh wave propagation in real medium.