Numerical modeling of PP- and PS-wave azimuthal anisotropy in HTI media  

HTI介质中PP与PS波方位各向异性数值模拟与分析(英文)

作　　者：钱忠平[1] 张少华[1] 赵波[1] 雷娜[1] 李向阳 

机构地区：[1]中油集团公司地球物理勘探局,河北涿州072751 [2]British Geological Survey,Edinburgh,EH9 3LA,UK.

出　　处：《Applied Geophysics》2012年第4期429-439,495,496,共13页应用地球物理（英文版）

摘　　要：This study focuses on the factors that may affect the feasibility of performing elliptical anisotropy analysis on azimuthal PP and PS-wave data in HTI media, with the aim of using the modeling results as guidance in real seismic data application. Our results reveal that there is an offset limitation for both PP- and PS-waves in elliptical anisotropy fitting, and that PS-waves show a wider applicable offset range and larger observable azimuthal anisotropy than PP-waves. The major axis of the elliptical fit to the amplitudes of the R-component is perpendicular to the fracture strike, which is opposite to that in PP-wave analysis. The azimuthal interval travel time of PS-waves shows a nearly elliptical distribution and the major axis of the fit ellipse is perpendicular to the fracture strike, which is same as that in PP-wave analysis. For data within the applicable offset range, the anisotropic magnitude obtained from amplitude and travel time attributes of PP- and PS-waves exhibits a dependence on fracture density, and the major to minor axis ratio of the fit ellipse may be used to infer the relative distribution of fracture densities.通过数值模拟研究了HTI介质中利用宽方位多分量地震数据进行各向异性分析时会影响结果的几种因素,模拟了PP与PS波的方位各向异性响应,分析了利用PP与PS波随方位变化的地震属性进行裂缝检测的可行性。结果显示:针对HTI介质的椭圆方位各向异性分析对地震数据的炮检距分布范围有限制,并且PS波数据适合于椭圆方位各向异性分析的炮检距范围要明显大于PP波数据,其显示出的方位各向异性特征也比PP波更加明显。PS波方位振幅拟合的椭圆长轴方向垂直于裂缝方向,而PP波方位振幅拟合的椭圆长轴平行于裂缝方向。与PP波类似,PS波R分量的层间旅行时也具有椭圆方位各向异性特征,其长轴方向垂直于裂缝方向。PS波R分量与PP波的方位振幅属性与层间旅行时属性均显示了与裂缝密度的相关性,当数据的炮检距范围合适时,拟合椭圆的长短轴之比可以用于刻画裂缝的相对密度。

关 键 词：HTL media numerical modeling fracture characterization azimuthal anisotropy 

分 类 号：P631.4[天文地球—地质矿产勘探]