双相介质的AVO资料中蕴含的流体信息的定量分析

振幅随偏移距变化(AV0)弹性参数的反演是储层预测的一个重要方法.利用正演技术分析双相介质的地震资料中含有的流体信息,有助于提高AVO弹性参数反演的可靠性.本文应用Russell推出的计算纵波反射系数的AVO线性近似公式,对双相介质的纵波资料中所含有的流体信息进行定量分析,研究从AV0资料的反演中可以确定哪些弹性参数或它们的组合关系.文中考虑的弹性参数有流体因子、剪切模量和密度三者的相对扰动量.在时间城内对反射系数的正演计算公式进行线性化,得到灵敏度矩阵,并用奇异值分解(SVD)计算其特征值和特征向量采分析弹性参数的反演.由计算结果可知,在入射角较小时由AV0资料反演只能得到流体因子和密度两者的相对扰动量;若想同时获得三个参数的相对扰动量,就必须增大入射角.

Quantitative analysis of fluid information contained in seismic AVO data in porous media

The inversion of AVO elastic parameters is an important way to reservoir prediction. Analyzing the fluid information contained in porous medium seismic data by forward technique can help improve the reliability of AVO elastic parameter inversion. With Russell approximate formula for reflection coefficient estimation, we analyse quantitatively the fluid information contained in the P-wave data of porous media and analyse which elastic parameters or their combination can be determined. Elastic parameters involved in the paper are the relative perturbation of the fluid factor, shear modulus and density. In the time domain, the forward estimation formula of reflection coefficient is linearized to obtain the sensitivity matrix, whose eigenvalue and eigenvector can be calculated by SVD. Eigenvalue and eigenvector can be used to analyse inversion of elastic parameters. The results show that we can obtain perturbations of two elastic parameters for small incident angles. If we want to obtain three perturbations, the incident angel should be increased.