沧东凹陷孔二段页岩有机质富集特征研究  

Investigation of enrichment characteristics of organic matter in shale of the 2nd member of Kongdian formation in Cangdong sag

作　　者：方正 蒲秀刚[3] 陈世悦[1,2] 鄢继华[1,2] 韩文中[3] 时战楠 张伟[3] 陈星燃 董庆民 FANG Zheng;PU Xiugang;CHEN Shiyue;YAN Jihua;HAN Wenzhong;SHI Zhannan;ZHANG Wei;CHEN Xingran;DONG Qingmin(Key Laboratory of Deep Oil and Gas,China University of Petroleum,Qingdao,Shandong 266580,China;School of Geosciences,China University of Petroleum,Qingdao,Shandong 266580,China;Research Institute of Exploration and Development,PetroChina Dagang Oilfield Company,Tianjing 300280,China)

机构地区：[1]中国石油大学(华东)深层油气重点实验室,山东青岛266580 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]中国石油大港油田公司勘探开发研究院,天津300280

出　　处：《中国矿业大学学报》2021年第2期304-317,共14页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(41572087)。

摘　　要：为深化对渤海湾盆地沧东凹陷孔店组二段(孔二段)典型湖相富有机质页岩有机质非均质性的认识,本文利用岩石学、元素地球化学、有机地球化学及测井曲线等资料,基于实测总有机碳(TOC)、测井曲线模型(ΔlgR)、母质来源及微观赋存状态总结有机质富集特征,并结合沉积环境演化探讨有机质富集控制因素,认为有机质具有以陆源高等植物为主的混源特征反映孔二段沉积时期陆源输入对有机质富集特征发挥了重要作用,一方面向湖泊输送大量陆源有机质,另一方面提供营养物质促进湖泊表层初级生产力.研究结果表明:Ek_(2)^(2)和Ek_(2)^(3)富有机质页岩中有机质呈"中碳—高碳(TOC为0.7%~4.0%)与高碳—富碳(TOC为2.0%~7.0%)"的韵律型富集,Ek_(2)^(1)下部呈先增后减型富集;在湖侵期,水深增加(Rb/K值为0.002~0.004)形成的良好保存条件是有机质富集的重要前提条件,气候干湿旋回(干湿指数C值为0.15~0.53)形成了受控于陆源输入的韵律型富集特征;在高位期,气候、水深、盐度的变化(干湿指数C值由0.1~0.2变为0.2~0.3、Rb/K值由0.002~0.003变为0.002~0.004、Sr/Ba值由1.0~2.0变为0.5~1.0)导致有机质由陆源输入、初级生产力、保存条件共同作用转变为受控于陆源输入,形成先增后减型富集特征.To deepen the understanding of organic matter heterogeneity of the typical lacustrine organic-rich shale in the 2nd member of Kongdian formation in Cangdong sag,Bohai Bay Basin,the enrichment characteristics of organic matter in Ek2 were summarized in this paper based on TOCcontents measured in lab,logging model(ΔlgR),biological sources,and microscopic occurrence state.The data of petrology,elemental geochemistry,organic geochemistry,and well logs were analyzed.And the controlling factors were discussed in the study of sedimentary environment evolution.It is considered that the organic matter biological sources which are mixed sources dominated by terrigenous higher plants showed that terrestrial input plays an important role in the accumulation of organic matter during the sedimentary period of Ek_(2).On the one hand,more terrestrial organic matter is transported into the lake,and on the other hand,nutrients are provided to promote the lake paleoproductivity.Results showed that the enrichment characteristics of organic matter in Ek_(2)^(2) and Ek_(2)^(3) are a rhythmic type of mediumhigh carbon(TOC0.7%—4.0%)and high-rich carbon(TOC2.0%—7.0%).In the lower part of Ek_(2)^(1) there is a type of increasing first and then decreasing.In the lacustrine transgression period,the good preservation condition formed by water depth increasing(Rb/K 0.002—0.004)is an important precondition of organic matter enrichment,and the dry-wet climate cycles(dry-wet index Cvalue 0.15—0.53)form a rhythmic type of organic matter enrichment controlled by the terrestrial input.In the highstand period,the changes in climate,water depth,and salinity(dry-wet index Cvalue 0.1—0.2 to 0.2—0.3,Rb/K 0.002—0.003to0.002—0.004,Sr/Ba 1.0—2.0to 0.5—1.0)result in the transformation of the controlling factors from factors working together(including terrestrial input,paleoproductivity,and preservation condition)to controlling by terrestrial input.

关 键 词：沧东凹陷 孔店组二段 有机质富集 有机质母质来源 陆源输入 

分 类 号：TE122[石油与天然气工程—油气勘探]