层状各向异性介质中普通电阻率测井的快速正演模拟与应用

Fast forward modeling of ordinary resistivity log in layered anisotropic medium and its application

本文应用混合法给出了水平层状各向异性介质中普通电阻率测井的快速正演算法。理论模型的计算结果证明，各向异性介质中电阻率测井的响应主要受横向电阻率影响，且响应的振幅完全由横向电阻率的大小确定。文中还研究了薄互层的响应与各向异性介质响应的等价性问题。对于砂、泥岩薄互储层，当组成薄互层的各个单层的厚度明显小于电极系的纵向分辨率时，薄互层的响应与等效的各向异性介质的响应基本上是一致的，很难从其电阻率的响应中了解到实际地层电阻率的真实变化情况。

Fast forward algorithm for ordmary resistivity log in horizontally-layered anisotropic medium is obtained by using hybrid method. Theoretical model result indicates that the response of reslstivity log in anisotropic medium is influenced mainly by lateral resistivity, and that the amplitude of response is determined only by lateral reslstivity. Authors also discuss equivalence between resistivity log response at thin interbed series and that in anisotropic medium. If the thickness of single mterbed in sand-shale interbeded reservoir is less than the vertical resolution of reslstivlty log system, the resistivity log response of thin interbed series is roughly consistent with that in equivalent anisotropic medium, so that resistivity variations of formations can hardly be found from the resistivity log responses.