双相多孔介质中体波传播特性影响参数研究

Parametric studies of propagation characteristics of bulk waves in two-phase porous media

基于修正的Biot理论,通过数值计算分别研究了3种体波(P1、P2、S波)的波速和衰减与固体颗粒压缩性、频率、孔隙率、流体黏滞系数、动力渗透系数等参数之间的关系。分析结果表明:(1)P1、P2波的波速和衰减与固体颗粒压缩性之间近似呈线性变化关系,而S波则几乎保持不变,并通过定量比较发现,能否忽略固体颗粒压缩性的影响取决于固体骨架体变模量(bK)与固体颗粒体变模量(sK)的比值;(2)孔隙率对P1、S波波速的影响较为显著,并且预测当孔隙率接近于1.0时,P1、P2波之间发生相互转换;(3)3种体波的波速和衰减均随流体黏滞系数和动力渗透系数而变化,且在这两个参数下的变化规律基本相反;(4)3种体波的波速和衰减均随频率的增大而增大,其中,频率对P2波的影响较大。

Based on the modified Biot theory, the effects of grain compressibility, frequency, porosity, fluid viscosity and dynamic permeability on the velocity and attenuation of the three bulk waves （P1, P2, S） in infinite two-phase porous media are studied by numerical calculation, respectively. Numerical results show that： （1） the velocity and attenuation of compressional waves （Pb P2） are variable and approximately linear with grain compressibility, while those of shear wave （S） almost keep constant, and by quantitative comparison, it is found that whether the effect of grain compressibility can be neglected or not depends on the ratio between skeleton bulk modulus Kb and grain bulk modulus Ks. （2） The porosity affects the velocity of Pl and S obviously; and it can be predicted that mutual conversion between P1 and P2 when the porosity almost reaches 1.0. （3） Both the fluid viscosity and the dynamic permeability have effects on the velocity and attenuation of P1, P2 and S, but for each of the waves, the variation trends with those two parameters are almost opposite. （4） The velocity and attenuation of the three bulk waves increase with frequency; and among them P2 is affected by frequency most.