摘要
应用大量的原油和岩石样品地球化学分析资料,结合孢粉-藻类资料,分析了北部湾盆地涠西南凹陷和乌石凹陷流沙港组二段湖相烃源岩质量与4-甲基C_(30)甾烷丰度的关系。结果表明:优质湖相烃源岩对应高丰度的4-甲基C_(30)甾烷,其4-甲基C_(30)甾烷指数大于1.5;好湖相烃源岩对应中等丰度的4-甲基C_(30)甾烷,其4-甲基C_(30)甾烷指数为0.5～1.5;一般湖相烃源岩则对应低含量的4-甲基C_(30)甾烷,其4-甲基C_(30)甾烷指数小于0.5。高丰度的4-甲基C_(30)甾烷与富藻层、高无定形有机质层和优质烃源岩有明显的正相关性,充分证明了4-甲基C_(30)甾烷丰度与烃源岩质量有密切关系,即高丰度的4-甲基C_(30)甾烷预示着高生产力的优质烃源岩。依据原油中4-甲基C_(30)甾烷指数的分布,推测北部湾盆地优质烃源岩主要集中分布在涠西南凹陷和乌石凹陷东洼的东北区,而海中凹陷、迈陈凹陷和福山凹陷可能均不发育大规模的优质烃源岩。
The relationship between the quality of lacustrine source rock in Second Member of Liushagang Formation of Weixinan and Wushi sags in Beibuwan basin and the abundance of 4-methyl-steranes has been studied based on plenty of geochemical data of oils and source rock samples combined with sporopollen-algae data.The result shows that high-quality lacustrine source rock is of high abundance of 4-methyl-C 30 sterane with 4-methyl-C 30 sterane index greater than 1.5;good lacustrine source rock is of medium abundance of 4-methyl-C 30 sterane with 4-methyl-C 30 sterane index between 0.5~1.5;fair lacustrine source rock is of low abundance of 4-methyl-C 30 sterane with 4-methyl-C 30 sterane index lower than 0.5.Obvious positive correlation between high abundance 4-methyl-steranes and algae assemblage formation,high amorphous organic matter layer and high-quality source rock demonstrates a close relationship between high abundance of 4-methyl-steranes and source rock quality,i.e.,high abundance of 4-methyl-C 30 sterane is an indication of high quality source rocks of high productivity.From the distribution of 4-methyl-C 30 sterane index in crude oil,it can be inferred that high quality source rocks are mainly distributed in Weixinan sag and north-eastern area of east subsag of Wushi sag;while in Haizhong sag,Maichen sag and Fushan sag,high quality source rock are rarely developed.
作者
傅宁
FU Ning(CNOOC Research Institute Co.,Ltd.,Beijing,100028,China)
出处
《中国海上油气》
CAS
CSCD
北大核心
2018年第5期11-20,共10页
China Offshore Oil and Gas
基金
"十三五"国家科技重大专项"中国近海潜在富烃凹陷比较性研究与有利勘探方向预测(编号:2016ZX05024-002)"部分研究成果
关键词
4-甲基C30甾烷
烃源岩质量
相关性
流沙港组二段
北部湾盆地
4-methyl-C30 sterane
source rock quality
relevance
Second Member of Liushagang Formation
Beibuwan basin
作者简介
傅宁,男,教授级高级工程师,长期从事石油地球化学综合研究。地址:北京市朝阳区太阳宫南街6号院海油大厦A座(邮编:100028)。E-mail:funing@cnooc.com.cn。
