基于横波分裂的转换波各向异性分析技术及应用

CONVERTED WAVE ANISOTROPIC ANALYSIS TECHNIQUE AND ITS APPLICATION BASED ON S WAVE SPLITTING

当横波不平行也不垂直穿过裂缝时,会发生横波分裂现象。这里基于横波分裂理论,采用二维分量旋转方法进行转换波分裂分析。为了得到地层裂缝信息,提高宽方位转换波径向分量成像质量,利用宽方位转换波的径向和横向分量资料,完成了多层裂缝介质的各向异性分析。在此基础上,还完成了转换波方位各向异性校正研究。首先,利用分量旋转方法求出第一裂缝介质层的各向异性方向、快慢横波时延等参数;然后,将快、慢横波时延应用于慢波数据进行慢波时延补偿;最后,根据第一层的方位角将快波和补偿后的慢波旋转回原来的径向和横向分量方向。这样,就完成了第一裂缝层的各向异性分析,同时还得到第一层的裂缝方向、裂缝密度、补偿后的径向分量等数据。依此类推,进行以下裂缝层的各向异性分析。该转换波各向异性分析技术已应用于川西XC气田的宽方位三维三分量地震数据处理,不但得到了裂缝参数,而且还消除了宽方位转换波的方位各向异性影响,提高了转换波径向分量的成像质量。

When S-wave is not parallel nor perpendicular through the fracture,S-wave splitting phenomenon occurs.In this paper,2-D component rotation method is applied to analyze converted wave splitting based on S-wave splitting theory.To obtain fracture information and improve radial component imaging quality,the anisotropic analysis of the multi-layer fracture media has been completed by wide-azimuth converted radial and transverse component data.Based on the previous result,it is realized that converted wave azimuth anisotropy correction.Firstly,the anisotropic direction and time delay between fast and slow wave have been found out on the first fracture layer by component rotation method.Secondly,the time delay is used to compensate slow wave time delay.Lastly,the fast wave and compensated slow wave are rotated back the original radical and transverse direction according to the first layer azimuth.So,the first layer anisotropic analysis has been completed.At the same time,the data of the fracture direction,fracture density and compensated radial component have been obtained.And so on,the below multi-layer fracture will be analyzed by above technique.The converted wave anisotropic analysis technique has been successfully applied to wide-azimuth 3D3C data in XC gas field in western Sichuan,and the fracture parameters have also been obtained.The azimuth anisotropy effects have been eliminated on wide-azimuth converted wave,and radial component imaging quality have improved greatly.