粘弹性介质地震波传播特征及反射特征研究

CHARACTERISTICS OF SEISMIC WAVE PROPAGATION AND REFLECTION IN VISCOELASTIC MEDIUM

理想弹性介质并不能解决许多复杂的实际问题。在实际介质中,地震波的传播过程存在吸收作用,使地震波能量发生了损耗、频带变窄、相位延迟、频率降低,尤其是高频部份。这种特性可以用传播矢量和衰减矢量来表示,衰减矢量越大,介质的吸收越强。这里通过引入广义平面波、纵横波品质因子以及衰减角,利用应力应变关系和连续性条件,推导了粘弹性介质精确的Zoeppritz方程,并通过求解精确的Zoeppritz方程,分析了粘弹性介质中传播矢量、衰减矢量、纵波反射系数、转换波反射系数与频率、衰减角、入射角、品质因子、速度等物理量之间的关系,详细地了解了粘弹性介质中地震波传播特征及反射特征,为粘弹性介质中储层预测问题的研究提供了理论基础。

Many complex practical problems can′t be solved if we assume the medium is ideal elastic medium.In the practice medium,absorption exists during the propagation of seismic waves,which makes the seismic wave energy lost、narrow band、phase delay、the frequency reduce,especially the high-frequency part.This behavior can be expressed by the propagation vector and the attenuation vector,and with the increasing of the attenuation vector,the absorption of the medium is stronger.In this paper,by introducing the generalized plane wave,vertical and horizontal wave quality factor and decay angle,using the relationship of stress-strain and continuity condition,derive the precise Zoeppritz equation in viscous medium.And by solving the exact equation of Zoeppritz,analyze the relationship between the propagation vector、the attenuation vector、reflection coefficients、transmission coefficients and frequency、attenuation angle、angle of incidence、velocity,detailed understand the characteristics of seismic wave propagation in the viscous medium,which provides a theoretical basis for the prediction of reservoir study in viscous medium.