双相各向同性介质弹性波高精度波场分离数值模拟方法

HIGH-PRECISION WAVE FIELD SEPARATION NUMERICAL SIMULATION OF ELASTIC WAVE IN TWO-PHASE ISOTROPIC MEDIA

为了便于研究双相介质固流相混合弹性波场中纵横波波场的传播规律,提出了基于交错网格的Biot双相各向同性介质弹性波动方程高精度波场分离正演数值模拟方法。采用高阶交错网格有限差分法来构建一阶双曲型双相各向同性介质弹性波动方程正演算子实现波场正演,并在每一步递推过程中,分别计算出固相和流相分量相应的散度场(纯纵波场)和旋度场(纯横波场)。以均匀介质和层状介质模型为例进行波场分离数值模拟试验,计算结果表明,该方法能够从固流相的任一分量混合弹性波场中准确地分离出纯纵波波场和纯横波波场,具有计算精度和效率高的特点,同时指出快慢纵波相互伴生因而无法实现分离。

In order to study the propagation of the compress wave and shear wave in the hybrid wave field of the two-phase medium,the author puts forward high-precision wave field separation numerical simulation scheme on the isotropic Biot two-phase medium elastic wave equation based on the staggered-grid characteristic,and uses high-order staggered-grid finite-difference method to construct the wave field simulation operator with the first-order hyperbolic two-phase isotropic elastic wave equation,and calculates the divergence field（pure compress wave field） and curl field（pure shear wave field） in the solid phase and the fluid phase,respectively at each numerical recursive step.The paper takes isotropic medium model with two layers as example to do the numerical experiments,the results show that the method can correctly separate the pure compress wave and pure shear wave field from each component of the hybrid elastic wave field with perfect numerical precision and efficiency,at the same time,the paper also points out that the fast compress wave and slow compress wave are coupled and associated,therefore,they can＇t be separated.