横向各向同性介质纵波方位各向异性物理模型研究  

Compressional wave (P-wave) azimuthal anisotropy physical model studies in transversally isotropic medium

作　　者：齐宇[1,2] 魏建新[1,3,2] 狄帮让[1,3,2] 刘震[1,2] 

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)资源与信息学院,北京102249 [3]CNPC物探重点实验室,北京102249

出　　处：《石油地球物理勘探》2009年第6期671-674,689,共5页Oil Geophysical Prospecting

基　　金：国家"973"计划项目(2006CB202306)资助

摘　　要：Ruger公式表明:在各向异性介质中,当各向异性参数、纵波阻抗、横波速度、介质密度已知的情况下,反射系数是方位角和入射角的二元函数;若采用固定炮检距观测方式,只改变测线与裂缝方向之间的夹角,则反射系数可化简为方位角的一元函数,根据Ruger公式便可得到不同炮检距下的反射系数值。本文基于Ruger公式,运用物理模型模拟方法,在水中以50,100,150mm的炮检距观测了HTI介质的地震响应,了解了反射波振幅、反射旅行时随裂缝方位角变化的规律。研究表明:在不同炮检距情况下,裂缝层顶、底界面的反射纵波振幅均出现方位AVO响应,即当方位角为0°时,纵波反射振幅最大,当方位角为90°时,纵波反射振幅最小;裂缝对纵波旅行时也产生影响,即反射时间随方位角增大而增大。物理模拟实验结果与理论计算结果相近,从而为裂缝识别和预测提供了借鉴。Ruger formula demonstrates that in isotropic media if the isotropic parameters,P-wave impedance,share wave velocity and medium density are known,then the reflection coefficient is the dualistic function of the reflection coefficient and incidence angle. However if the fixed offset was adopted for the observation,only changing the included angle between seismic line and azimuth,then the reflection coefficient can be simplified to simple function of the azimuth,so from Ruger formula the reflection coefficients can be derived for different offsets. Based on Ruger formula and by using physical modeling method,the seismic response for HTI media in the water were observed in 50mm,100mm and 150mm offset respectively. The changing rule of reflection wave amplitude and reflection wave travel time with azimuth was understood. The studies demonstrates that when offsets change,the reflection P-wave amplitude on the top and bottom of the fracture layer shows azimuth AVO response,when azimuth is 0 degree,the reflection P-wave amplitude is maximum,when azimuth is 90 degree the reflection P-wave amplitude is minimum,the P-wave travel time is also affected by fracture,that is,reflection time increases with the azimuth increase,the results from physical modeling experiment are close to the results from the theoretical calculation,it is believed that the studies provides reference for fracture recognition and prediction.

关 键 词：各向异性 反射系数 方位角HTI介质 正演模拟 预测裂隙 

分 类 号：P618.13[天文地球—矿床学] P631.44[天文地球—地质学]