层状介质时移时差属性分析

The attributes analysis of time difference and time-lapse in layered medium

1. 中国石化胜利石油管理局物探公司,山东东营 257100;2. 中国科学院地质与地球物理研究所,北京 100029

Geophysical Exploration and Development Corporation of Shengli Petroleum Administrative Bureau, SINOPEC.Dongying 257100, China

针对我国油藏特征主要是薄层和薄互层,而且大多采用水驱开采,叠后时移时差属性较弱,难以识别。为 此,就影响层状介质中叠前时移时差属性的各种因素进行了系统分析。设计了一个双层水平层状模型,探讨了 叠前时移时差随炮检距的变化规律以及地层结构(储层厚度,储层速度,储层埋深,上覆地层速度等)对叠前时差 的影响。结果表明,当储层埋深较浅,且上覆地层速度低于储层速度时,只要储层厚度以及速度的变化足够大, 利用叠前大炮检距时移时差来揭示储层动态变化是可能的;对于埋深很大、上覆地层速度接近或高于储层速度 的情形,叠前时移时差往往很小,实用性较差。

As an important attribute, post-stack time difference has been successfully used in monitoring the thermal front sweep range in heavy oil recovery, but only few study and application on prestack time difference. Each factors effecting on prestack time difference attribute is systemically analyzed by model computation in layered medium. Results show that as long as reservoir keeps a more shallow depth and a lower overburden velocity,and its thickness and variation of velocity are large enough. It is possible to study reservoir performance variation using prestack large offset time difference. For time-lapse seismic monitoring in the reservoir with a deeper depth or which velocity is near or e-ven lower than overburden velocity, prestack time differ ence attribute is very weak and difficult.