层状介质AVO叠前反演

本文基于贝叶斯理论的框架,联合应用似然函数及先验随机约束信息进行AVO地震参数反演,所获取的反演参数是后验概率分布函数(PPDF)的最可能解。在反演中,假定噪声及模型参数是高斯分布的,采用岩石物理的研究方法及结果建立模型参数协方差矩阵以约束反演。反演采用非线性迭代的方法,不依赖初始模型的选择,反演的速度较快,适合于叠前AVO反演。在忽略了地震数据的带限特性所引起的动校正拉伸及调谐效应的影响后,对合成记录及实际资料进行AVO反演,得到了P波阻抗反射系数、S波阻抗反射系数及密度反射系数,进而计算其他岩性参数,为识别孔隙流体性质提供了新的手段。

Prestack AVO inversion of layered medium

Based on the framework of Bayes theory, the paper combines application of likelihood function and prior stochastic constrain information to carry out the inversion of AVO seismic parameter, and acquired inversed parameter is probable solution of posterior probability distribution function (PPDF). During inversion, assuming that the noise and model parameters are Gaussian distribution, using petrophysical study approaches and results to create model parameter covariance matrix in order to constrain inversion,the inversion adapts non-linear iteration algorithm that do not rely on the selection of initial model; the speed of inversion is fast, which is suitable for prestack AVO inversion. After neglecting the influence of NMO stretching and tuning effect caused by band-limited character of seismic data, the AVO inversion is carried out for synthetic records and real data, which obtained the reflection attributes of P-wave impedance, S-wave impedance and density.Furthermore the other lithologic parameters can be further computed, which provides new tool for identification of pore-fluid nature.