双相各向异性介质弹性波场有限差分正演模拟

从双相各向异性介质模型出发，以Boit理论为基础，推导了斜方晶系各向异性介质-阶弹性波动方程，引入固、流体密度比和孔隙几何参数，将Biot方程系数简化为测量简单、物理意义明确的物理量，采用交错网格技术建立了各向异性孔隙介质波动方程的高精度差分格式，并首次对这类差分格式的频散特性和稳定性作了详细分析讨论，解决了计算稳定性和边界反射问题，与解析解的对比以及理论模型的数值模拟都表明，该方法不仅大大降低了计算量，提高了正演速度，并且具有良好的稳定性和精确性。

ELASTIC WAVE FIELD SIMULATION WITH FINITE DIFFERENCE METHOD IN TWO-PHASE ANISOTROPIC MEDIUM

Based on the two-phase anisotropic medium model and Biot theory, the elastic wave equation is derived for orthorhombic anisotropic medium. The solid-fluid density ratio and the pore scale parameter are introduced to simplify the coefficients in Biot equation. These coefficients are easy to estimated and have definite physical meaning. Staggered grid and Higdon's absorbing boundary condition are adopted in finite difference scheme of first-order elastic wave equation in anisotropic porous medium. Detailed analyses of numerical dispersion and stability for the finite difference method scheme are given in this paper for the first time. The method proposed solves the problems of stability and boundary reflections. Comparison with the analytical solution and the numerical computation of theoretical models show that the proposed approach has pretty well stability and accuracy. The computation costs are also greatly decreased.