各向异性介质中的AVO

AVO IN ANISOTROPIC MEDIA

分析了横向各向同性和方位各向异性介质的本构关系，由此讨论弹性波在两种各向异性介质中的传播特点，提出可表征这两种介质各向异性程度的广义参数．以此为基础讨论了两种各向异性介质中存在水平界面时的反射系数近似式，将Dely等人推导的横向各向同性介质中的反射系数公式推广到方位各向异性介质的主轴方向上．根据算例讨论修正的Banik和Thomsen的近似式，着重分析两种各向异性介质中的AVO关系及其对实际勘探的影响和指导意义．

The general constitutive relationship of transverse isotropy and azimuthal anisotropy,is discussed in this paper. After analyzing the characteristics of elastic waves propagating in these two kids of enisotropic media we deduce generalized expressions of anisotropy parameters which describe the anisotropy degree both in transversely isotropic media and azimuthal anisotropic media. When there is an interface in two anisotropic media the reflection coefficients are discussed respechtiely.The formula derived by Dely et. al. is extended to be used in the symmetric plane in azimuthal anisotropic media. Finally, comparing the exact reflection coefficients formula with Baulk's and Thomsen's approximations for typical shale and gas-sand models and carbonate rock models, we discuss the AVO in the two kinds of anisotropic media and its influence in actual exploration, especially for fraCtured reservoir.