川东北—鄂西地区下震旦统陡山沱组烃源岩特征及形成环境  

Source rock characteristics and depositional environment of Lower Sinian Doushantuo Formation in northeastern Sichuan and western Hubei

作　　者：张道亮 杨帅杰 王伟锋[1] 付小东 张建勇 李文正 ZHANG Daoliang;YANG Shuaijie;WANG Weifeng;FU Xiaodong;ZHANG Jianyong;LI Wenzheng(School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China;Hangzhou Research Institute of Geology,PetroChina,Hangzhou,Zhejiang 310023,China)

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [2]中国石油天然气股份有限公司杭州地质研究院,杭州310023

出　　处：《石油实验地质》2019年第6期821-830,共10页Petroleum Geology & Experiment

基　　金：国家科技重大专项(2017ZX05008005);中国石油天然气股份有限公司重大科技项目(2018A-0105)联合资助

摘　　要：陡山沱组暗色泥页岩是川东北—鄂西地区新元古界震旦系一套重要的烃源岩。对该地区符家沟、陈家湾、花鸡坡等一系列露头剖面进行观察取样,通过有机地球化学、成烃生物和主微量元素分析等技术手段,明确陡山沱组烃源岩特征和形成环境。陡山沱组烃源岩区域厚度为50~250 m,存在镇巴—城口和宜昌—五峰2个厚度中心;有机质丰度较高,平均可达2.04%;成烃生物类型多样,以浮游藻类为主,有机质类型好,主要为Ⅰ—Ⅱ1型;烃源岩现今热演化程度高,处于过成熟热演化生气阶段。利用元素地球化学指标对烃源岩形成环境进行判别,陡山沱组烃源岩整体形成于缺氧—贫氧环境,但在不同地区存在一定差异。川东北地区烃源岩形成于水体低能、低盐度、缺氧—贫氧的深水陆棚环境;鄂西地区烃源岩形成于水体能量较强、低盐度、缺氧的台内盆地环境。The dark shale of the Doushantuo Formation is an important source rock of the Neoproterozoic Sinian in northeastern Sichuan and western Hubei.A series of outcrop profiles in this area at Fujiagou,Chenjiawan and Huajipo were observed and sampled.The characteristics and depositional environment of source rocks of the Doushantuo Formation were identified by means of organic geochemical analysis,organic matter type and major-trace element analysis.The source rocks of the Doushantuo Formation are 50-250 m thick,with maximums of Zhenba-Chengkou and Yichang-Wufeng.The abundance of organic matter is relatively high,averaging 2%.The hydrocarbon generating organic matter is diverse,but mainly phytoplankton.Source rocks have good organic matter types,mainly type I-II1.Organic matter is in the stage of overmature thermal evolution and generates gas.In this study,the deposi tional environment of hydrocarbon source rocks was analyzed by using element geochemical indices which show that the source rocks of the Doushantuo Formation were formed in a suboxic to anoxic environment,but differences exist in different areas.Source rocks in the northeastern Sichuan were deposited in a deep water shelf environment with relatively stable energy,low salinity and suboxic to anoxic conditions.Source rocks in the western Hubei were formed in a platform inner sag environment with high energy,low salinity and anoxic conditions.

关 键 词：烃源岩分布 地球化学特征 形成环境 陡山沱组 下震旦统 川东北—鄂西地区 

分 类 号：TE122.1[石油与天然气工程—油气勘探]