北部湾盆地流二段油页岩地球化学特征及成因  

Geochemical Characteristics and Genesis of Oil Shale in Beibuwan Basin

作　　者：李友川 李宏义 兰蕾 LI YouChuan;LI HongYi;LAN lei(CNOOC Research Institute Co.Ltd.,Beijing 100028,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028

出　　处：《沉积学报》2022年第3期616-625,共10页Acta Sedimentologica Sinica

基　　金：国家科技重大专项(2016ZX05026-004)。

摘　　要：北部湾盆地涠西南凹陷和乌石凹陷流二段普遍发育油页岩。有机地球化学分析表明,北部湾盆地流二段油页岩具有高的有机质丰度,油页岩的有机碳含量下限为3%,含油率介于3.5%~10%,达到中等和优质油页岩矿品级,同时属于优质烃源岩。全岩有机显微组分、干酪根镜检和热解等分析表明,北部湾盆地流二段油页岩藻类含量丰富,藻类是有机质的主要来源,有机质类型主要为腐殖—腐泥型,部分为腐泥型,以湖相腐殖—腐泥型油页岩为主,部分为湖相腐泥型油页岩。流二段油页岩中镍和钼等微量元素含量普遍较高,镍和钼的含量与有机碳含量之间存在很好的正相关关系,说明流二段油页岩形成时期北部湾盆地具有富营养湖泊特征。北部湾盆地流二段油页岩中还原硫含量高,普遍大于1%,流二段油页岩形成于还原的沉积环境,具有很好的有机质保存条件。高有机质生产力及湖侵体系域顶部和高位体系域底部的中深湖还原环境共同控制了北部湾盆地流二段油页岩的发育。Oil shale is widely developed in Member 2 of Liushagang Formation of the Weixinan Sag and Wushi Sag in the Beibuwan Basin.Organic geochemical analysis shows that oil shale in Member 2 contains an abundance of organic matter.The lower limit of TOC for oil shale is 3%,and the oil yield is between 3.5%and 10%,reaching the middle and high quality oil shale ore grade,and they are also an excellent source rock.Whole-rock organic maceral,kerogen microscopy and pyrolysis analysis show that this oil shale is rich in algae,which are the main source of organic matter.Most of the organic matter is humic-sapropel type,with some being sapropel type.The humic-sapropel and sapropel oil shale are both lacustrine.The contents of trace elements such as Ni and Mo in oil shale are generally high,with a positive correlation with the organic carbon content,all showing that the characteristics of a eutrophic lake during the formation of the oil shale.The geochemical indicators such as the reduced sulfur content show that it formed in a reducing sedimentary environment with good organic matter preservation conditions.The high organic matter productivity and the reducing environment of the middle and deep lakes at the top of TST and bottom of HST controlled the development of oil shale in Member 2 of Liushagang Formation in Beibuwan Basin.

关 键 词：北部湾盆地 流二段 油页岩 地球化学特征 成因 

分 类 号：P618.13[天文地球—矿床学]