塔里木盆地下古生界碳酸盐岩层序界面类型划分及其意义

Classifications of sequence boundaries in the Lower Paleozoic carbonates in Tarim Basin and their significances

塔里木盆地海相碳酸盐岩储层是增储上产的重要领域。然而按照经典模式划分的碳酸盐岩层序,在生产中与目标优选及开发方式结合并不紧密,进而影响了实际生产。因此,根据不同的层序界面成因(即构造、暴露剥蚀、成岩强度等),结合塔里木盆地碳酸盐岩野外露头、地震剖面、测井曲线和岩心资料等综合因素,把海相碳酸盐岩层序界面划分为5种类型:即Ⅰ型(晚期强烈隆起喀斯特型)、Ⅱ型(早期强制海退剥蚀微喀斯特型)、Ⅲ型(早期溶蚀-弱剥蚀台地边缘型)、Ⅳ型(准同生间歇暴露浅水礁滩型)和Ⅴ型(同生无暴露碳酸盐岩台地型)。虽然不同界面类型的成因和储层特征迥异,但是依据地震、测井、钻井、岩心等现场资料很容易划分。这套层序划分可操作性强,在有利区带选择、油气高效富集区优选、开发井井型选择等方面均有很现实的生产指导意义。

Marine carbonate reservoirs in Tarim Basin are regarded as an important domain for reserve growth and production addition.However,the previous sequence stratigraphic division of the Lower Paleozoic carbonates is not suitable for target selection and development strategy optimization,influencing production.According to the genesis（such as tectonic,exposure and erosion,diagenetic intensity） of the sequence boundaries, and combining with data such as outcrop observations,seismic profiles,logging curves and core analysis of the marine carbonates in Tarim Basin,we recognized five types of marine carbonate sequence boundaries,including TypeⅠ（karst-type boundary from late strong uplifting）,TypeⅡ（micro-karst type boundary from early forced regression and erosion）,TypeⅢ（platform-margin type boundary from early dissolution and weak erosion）, TypeⅣ（shallow reef-bank type boundary from penecontemporaneous intermittent exposure）,and TypeⅤ（contemporary underwater carbonate platform type boundary ）.Although the genesis and reservoir characteristics of these sequence boundaries are quite different,they can be easily distinguished according seismic,logging, drilling and core data.This division scheme is pracitical and can be used to guide selection of favorable plays, identification of sweet spots and selection of development well types.