纵波速度频散属性反演方法研究

Inversion method for the velecity dispersion-dependent attribute of P-wave

(中国石油大学(华东)地球资源与信息学院,山东青岛266555)

Zhang Shixin,College of Geo-Resources and Information,China University of Petroleum (East China),Qingdao 266555,China

利用与频率有关的地震属性进行储层特征描述一直是地球物理学家研究的热点,由于含烃类储层会造成地震波的衰减和速度频散,因此,反映速度频散的属性在一定程度上可以指示含烃类储层。基于弥散介质界面反射系数随频率变化的假设,通过研究纵波法向入射时反射振幅随频率的变化规律,推导了包含表征纵波速度频散程度属性的反射系数近似公式,构建了反演方程,通过小波域分频和贝叶斯三参数反演分别得到分频地震数据和密度相对变化量,最终反演得到频散属性数据体。模型实验和实际资料的应用结果表明，纵波速度频散属性对含气储层具有较好的指示效果。

The application of frequency-dependent seismic attributes for reservoir characterization is always the research focus of geophysicists.It is noticed that the anomalously high attenuation and velocity dispersion is associated with hydrocarbon reservoirs and the attribute about velocity dispersion can be used to indicate the hydrocarbon reservoir.Based on the assumption that reflection coefficient on interface between dispersion medium varies with frequency,the normal reflection coefficient approximate formula including P-velocity dispersion-dependent attribute is proposed,and the dispersion dependent attribute can be estimated from the inversion.By utilizing Bayesian three-parameter AVO inversion and wavelet decomposition,we can respectively obtain frequency-division seismic data and relative variation of density.Finally,P-wave velocity dispersion-dependent attribute can be estimated.The modeling and actual application results show that the P-velocity dispersion-dependent attribute is a good indicator for gas reservoir.