四川盆地及周缘上奥陶统五峰组-下志留统龙马溪组关键界面基本特征  

Basic characteristics of key interfaces in Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in Sichuan Basin and its periphery,SW China

作　　者：王玉满[1] 王红岩[1] 邱振[1] 沈均均[2] 张琴[1] 张磊夫 王灿辉 李新景[1] WANG Yuman;WANG Hongyan;QIU Zhen;SHEN Junjun;ZHANG Qin;ZHANG Leifu;WANG Canhui;LI Xinjing(Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China;Yangtze University,Wuhan 430100,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]长江大学,武汉430100

出　　处：《石油勘探与开发》2022年第1期32-44,共13页Petroleum Exploration and Development

基　　金：中国石油科技项目“海相页岩气勘探开发技术研究”(2021DJ1904);中国石油勘探与生产分公司海相页岩气选区课题(kt2018-01-06)。

摘　　要：以典型剖面详测和重点资料点解剖为基础,结合观音桥段介壳层典型特征分析,以特定斑脱岩层为重点,系统研究四川盆地及周缘上奥陶统五峰组—下志留统龙马溪组内部关键界面基本特征及其与富有机质页岩沉积关系。研究区五峰组—龙马溪组发育特征笔石带、观音桥段介壳层、斑脱岩密集段、结核体等4种具有界面属性的标志层,可成为笔石页岩内地层划分与对比的关键界面:观音桥段介壳层是五峰组—龙马溪组内部最标准的关键界面,也可作为判断重点地区富有机质页岩沉积规模的重要标志;发育两种类型8个斑脱岩密集段,主要赋存于7个笔石带,与观音桥段介壳层在厚度、自然伽马响应等方面具有相似的界面特征,属构造界面(即事件性沉积),并具有全域、大区域和局部3种分布规模,可相应成为三级、四—五级层序界面,对富有机质页岩沉积具有差异控制作用;特征笔石带的首现层位即为等时界面,与富有机质页岩沉积并无直接关系;结核体仅在局部区域产出,且在纵向和横向分布的稳定性较差,与富有机质页岩沉积关系并不明显。Based on anatomy of key areas and data points and analysis of typical features of shell layer in Guanyinqiao Member,basic characteristics of key interfaces,mainly bentonite layers,in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in the Sichuan Basin and its surrounding areas and the relationship between these key interfaces with the deposition of organic-rich shale have been examined systematically.The Wufeng Formation-Longmaxi Formation has four types of marker beds with interface attributes,namely,the characteristic graptolite belt,Guanyinqiao Member shell layer,section with dense bentonite layers,and concretion section,which can be taken as key interfaces for stratigraphic division and correlation of the graptolite shale.The shell layer in Guanyinqiao Member is the most standard key interface in Wufeng Formation-Longmaxi Formation,and can also be regarded as an important indicator for judging the depositional scale of organic-rich shale in key areas.There are 8 dense bentonite sections of two types mainly occurring in 7 graptolite belts in these formations.They have similar interface characteristics with the shell layer in Guanyinqiao Member in thickness and natural gamma response,and belong to tectonic interfaces(i.e.,event deposits).They have three kinds of distribution scales:whole region,large part of the region,and local part,and can be the third,fourth and fifth order sequence interfaces,and have a differential control effect on organic-rich shale deposits.The horizon the characteristic graptolite belt occurs first is the isochronous interface,which is not directly related to the deposition of organic-rich shale.Concretions only appear in local areas,and show poor stability in vertical and horizontal directions,and have no obvious relationship with the deposition of the organic-rich shale.

关 键 词：四川盆地 上奥陶统五峰组 下志留统龙马溪组 观音桥段 笔石带 介壳层 斑脱岩 结核体 富有机质页岩 

分 类 号：TE122[石油与天然气工程—油气勘探]