板桥-北大港地区部分原油地球化学特征及成因分析  

The Geochemical Characteristics and Its Genesis of Some of the Oils from Banqiao-Beidagang Area

作　　者：孙超[1] 侯读杰[1] 张小涛[1] 马宁[1] 

机构地区：[1]中国地质大学(北京)能源学院,北京100083

出　　处：《石油天然气学报》2012年第11期26-30,167,共5页Journal of Oil and Gas Technology

基　　金：国家自然科学基金项目(40972097)

摘　　要：对板桥-北大港地区选取的原油样品做了相关试验分析,并对试验数据进行了对比研究。原油的全油碳同位素值集中在3个区间上,对应的生烃母质来源和沉积环境存在明显的差异。全油碳同位素值分布于-28.8‰～-27.8‰的第1类原油,以低熟油为主,Pr/Ph值小于1、高含量的β-胡萝卜烷和伽马蜡烷,反映了咸水、还原-强还原的沉积环境特征,规则甾烷相对含量ααα-20R-C29甾烷>ααα-20R-C27甾烷>ααα-20R-C28甾烷,结合碳同位素值认为该类原油生源是以水生生物、藻类为主。第2类原油样品全油碳同位素值分布于-27.2‰～-26.5‰,部分样品遭受生物降解,生源以水生生物为主且有少量的陆源高等植物输入,为淡水、弱还原-弱氧化的沉积环境。碳同位素值介于-25.5‰～-24.8‰之间的第3类原油全油碳同位素值异常偏重,规则甾烷相对含量ααα-20R-C27甾烷>ααα-20R-C29甾烷>ααα-20R-C28甾烷,Pr/Ph值大于1.55,认为该类原油有机质来源以浮游生物为主,沉积环境特征为淡水、弱氧化-氧化。Through comparative analyses of the experimental data of selected oils from Banqiao-Beidagang Area,the crude oil samples were divided into three classes.Class Ⅰ was featured by low maturity with relatively low Ts/(Ts+Tm),ααα20S/20(S+R)-C29 & ββ(αα+ββ)-C29 values,the lowest full oil carbon isotopic values was ranged from-28.8‰ to-27.8‰,with low contents of C29 Ts and C30 diahopane,high contents of β-carrotanes and high gammacerane indices,Pr/Ph<1,and the relative content of regular sterane was C29>C27>C28,which indicated organic matter of source rock was originated from lower aquatic organism and algae and deposited in the high salinity and strong reducing environment.Class Ⅱ was characterized by medium values of carbon isotope ranging from-27.2‰ to-26.5‰,with relatively higher content of 18α(H)-oleanane,relatively lower contents of β-carotane and gammacerane,and the relative content of regular sterane was C27>C29>C28,which deposited in weak oxido-reduction and fresh water environment,besides,some Class 2 crude oil samples have undergone biodegradation.Class Ⅲ was stamped by the highest values of carbon isotope which have a range of-25.5‰ to-24.8‰,Pr/Ph>1.55,and the relative content of regular sterane is C27>C29>C28.It shows that plankton is dominant in organic-matter,which is deposited in weak oxido-reduction and fresh water environment.

关 键 词：板桥-北大港地区 地球化学 生物标志物 生物降解 

分 类 号：P618.13[天文地球—矿床学]