南海IODP U1501站始新统—渐新统有机地球化学特征及烃源条件分析  

Organic geochemical characteristics and hydrocarbon source conditions analysis of Eocene-Oligocene at IODP Site U1501 in the South China Sea

作　　者：刘传联[1] 陈莹 龚瑞雪 孙瑞 马瑞罡 张功成 LIU Chuanlian;CHEN Ying;GONG Ruixue;SUN Rui;MA Ruigang;ZHANG Gongcheng(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China;CNOOC Research Institute Co.,Ltd.,Beijing 100028,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]中海油研究总院有限责任公司,北京100028

出　　处：《中国海上油气》2020年第5期19-25,共7页China Offshore Oil and Gas

基　　金：“十三五”国家科技重大专项“南海深水区古海洋学与优质烃源岩关系研究(编号:2016ZX05026007-003)”;国家自然科学基金项目“南海始新世-渐新世钙质超微化石生物地层学与古海洋环境演变(编号:41876046);用南海沉积物中长链烯酮重建中新世大气二氧化碳浓度变化(编号:41930536)”部分研究成果。

摘　　要：以南海综合大洋钻探(IODP)368航次U1501站始新世—渐新世沉积物样品为研究材料,通过有机地球化学特征分析,并结合古生物学分析结果,探讨了其作为海相烃源岩的潜力。研究发现:U1501站始新统—渐新统样品有机质丰度总体偏低,多数样品有机碳含量小于0.5%,个别样品有机碳含量介于0.5%和1.0%之间;干酪根类型以Ⅱ型为主,有少量Ⅰ型;干酪根显微组分以腐泥组和镜质组为主,腐泥组含量普遍高于60%;正构烷烃分布以C21以下为主,C25以上含量低;Pr/Ph值均小于0.4;甾烷系列化合物以C27为主,C29含量低,但可见明显4-甲基C30甾烷(或甲藻甾烷);五环三萜烷中藿烷系列化合物比较发育,伽马蜡烷和奥利烷含量低。从有机地球化学和古生物学综合分析结果看,U1501站始新统—渐新统样品有机质来源主要为海洋水生生物和藻类,陆源高等植物的贡献相对较少,由此推测南海北部深水区始新统—渐新统具有海源海相烃源岩发育的可能性。Taking the Eocene-Oligocene sediment samples from Integrated Ocean Drilling Program(IODP)Site U1501 during the 368th voyage of ocean drilling in the South China Sea as the research material,through analyzing the organic geochemical characteristics,and combined with the results of paleontological analysis,we have discussed their potential as marine source rocks.The study found that the organic matter abundance of Eocene-Oligocene samples at Site U1501 is generally low,most samples have an organic carbon content of less than 0.5%,and individual samples have an organic carbon content of 0.5%~1.0%.The kerogen types are type II dominant,followed by a small amount of type I.The kerogen microscopic components are mainly sapropelite and vitrinite,and the content of sapropelite is generally higher than 60%.The distribution of normal alkanes in samples is mainly<C21,and the content of>C25 is low;the Pr/Ph values are all less than 0.4;sterane series compounds are dominated by C27,the C29 content is low,but 4-A grade C30 sterane(or dinostane)can be observed obviously;the pentacyclic triterpenes hopane series compounds are well developed,and the contents of gammacerane and oriente are low.The comprehensive analysis of organic geochemistry and paleontology suggests that the sources of organic matters in the Eocene-Oligocene samples from IODP Site U1501 are mainly marine aquatic organisms and algae,and the contribution of terrestrial higher plants is relatively limited.Therefore,it is inferred that the Eocene-Oligocene strata in the deep water area of the northern South China Sea show a potential of"sea sourced marine source rocks".

关 键 词：海源海相烃源岩 有机地球化学特征 始新统—渐新统 IODP U1501站 南海 

分 类 号：TE122.1[石油与天然气工程—油气勘探]