页岩储层岩石物理模型及地震AVO响应模拟

Rock physics model and simulation of seismic AVO responses for a shale reservoir

通过模拟并分析各向异性页岩岩石物理模型,研究页岩中干酪根含量变化对页岩弹性各向异性的影响,其结果为应用AVO方法定量解释页岩储层厚度和干酪根含量提供依据。岩石物理模型预测了页岩速度和各向异性参数随干酪根含量的变化规律。应用传播矩阵方法计算薄层页岩的AVO响应,得到反射系数关于页岩层厚度、入射波频率、干酪根含量和入射角的函数。数值模拟结果表明:在干酪根含量不变且在同一入射角下的反射系数在频率域呈周期变化,该周期与薄层厚度成反比;对同一频率入射波和相同入射角,反射系数幅值随干酪根含量增加而变大。

The influence of kerogen content to the elastic anisotropy of shale rocks has been studied through the simulation and analysis of physical model of anisotropic shale rocks. The results offer the reference for quantita- tive interpretation of shale reservoir thickness and kerogen content by using AVO method. The rock physics model predicts the change law of shale velocity and anisotropic parameters with kerogen content. Then, using the propaga- tion matrix method to calculate the AVO response of thin shale rocks, the authors get the reflection coefficient that is a function of the shale layer thickness, the frequency of incident wave, the kerogen content and the incident an- gle. Numerical simulation results show that the reflection coefficient in the kerogen content remains constant and in the same incident angle is periodic changes in the frequency domain, and the period is inversely proportional to the thin bed thickness. For the same frequency and the same incident wave angle of incidence, the reflection coefficient amplitude increased with the kerogen content increased.