川东南茅口组缝洞型储层地球物理响应特征及形成机制研究

Geophysical response and formation mechanism analysis of fractured-vuggy reservoir in Maokou formation in southeast Sichuan

为深入认识川东南茅口组缝洞型储层的地球物理响应特征并分析其形成机制,以钻井、测井资料为基础,采用离散合成记录与地质剖面对比、正演模拟的方法开展茅口组储层地震-地质特征分析,建立了四类缝洞型储层地球物理响应特征并分析了其地质形成机制,指出茅口组上部的波状反射和顶部空白反射反映缝洞体在茅口组上部或顶部发育,为较可靠的含气缝洞体响应;斜亮点可以反映缝洞体存在,但不能证实缝洞体是否被充填,在研究区勘探具有一定有风险;透镜状反射虽然理论上是较为有利的勘探目标,但目前未见钻井钻达,有待下步勘探证实.本次研究建立的四类缝洞体响应特征及地质模型对川东南地区缝洞储层的勘探具有重要的参考价值.

Ancient karst of the Maokou formation is ubiquitous in southeast Sichuan. The reservoir is mainly controlled by fracture development and karstifieation. In order to better understand geophysical response and formation mechanism of fractured-vuggy reservoir in Maokou formation, the paper based on drilling data and logging data, by way of discrete synthetic seismogram and forward modelling, studied geophysical-geological characteristic of Maokou formation, then established 4 typical geophysical response patterns and analyzed geological model for each pattern. It is pointed out that the undulated seismic reflection in the upper part and blank reflection at the top of Maokou formation indicating well developed fractures and vugs, and such reflections correspond to gas bearing fracture-rug structure~ inclined bright spot also indicated fracture-vug structure, while their fill up status is difficult to be testified, and exploration risk is potential; lenticular seismic reflections are favorable exploration targets in theory and still remain to be testified. Study results in this paper can provide good references for exploration of fractured-vuggy reservoir in the studied area.