珠江口盆地开平凹陷南部区域中深层原油地球化学特征及成因  

Geochemical Characteristics and Genesis of Middle and Deep Oil in Southern Region of Kaiping Sag, Pearl River Mouth Basin

作　　者：高阳东 龙祖烈 陈聪 姜大朋 马宁 Gao Yangdong;Long Zulie;Chen Cong;Jiang Dapeng;Ma Ning(Exploration and Development Department,CNOOC China Limited,Beijing 100010,China;CNOOC China Limited,Shenzhen Branch,Shenzhen 518054,Guangdong,China;CNOOC Deepwater Development Limited,Shenzhen 518054,Guangdong,China)

机构地区：[1]中海石油(中国)有限公司勘探开发部,北京100010 [2]中海石油(中国)有限公司深圳分公司,广东深圳518054 [3]中海石油深海开发有限公司,广东深圳518054

出　　处：《吉林大学学报（地球科学版）》2024年第6期1883-1895,共13页Journal of Jilin University：Earth Science Edition

基　　金：中国海洋石油有限公司“十四五”重大科技项目(KJGG2021-0100)。

摘　　要：为了分析珠江口盆地开平凹陷原油地球化学特征,明确该区域的油气来源与分布规律,本研究基于开平凹陷南部区域中深层原油及烃源岩的地球化学实验分析测试资料,开展了地球化学特征、原油成因与来源,以及烃源岩评价及分子地球化学特征分析。结果表明:开平凹陷南部区域原油为高含蜡量、轻—中质原油。开平凹陷南部K18-1和K11-4含油气构造原油的地球化学特征较为类似,均具有C_(21)TT或C_(23)TT优势,较低的奥利烷含量,以及C_(27)、C_(29)规则甾烷优势,并有4-甲基C_(30)甾烷的分布,表明该区域原油具有藻类水生生物和陆源高等植物贡献,但K18-1和K11-4含油气构造的原油生烃母质不甚相同。K18-1含油气构造的原油较为特殊,与K11-4和其他区域原油均具有一定差异,奥利烷含量较低,C_(21)TT/C_(19+20)TT指数较高,为较为典型的湖相原油;K11-4含油气构造的原油则与开平凹陷等其他区域的原油相类似,奥利烷含量较高,C_(21)TT/C_(19+20)TT较低,为偏河流-三角洲相原油。开平凹陷南部区域不同层段烃源岩的地球化学特征差异较大,文昌组下段为Ⅰ—Ⅱ_(2)型有机质湖相烃源岩,文昌组上段—恩平组为Ⅱ_(1)—Ⅲ型三角洲煤系烃源岩,前者的有机质丰度及生烃潜力均优于后者。基于上述研究,结合油-源生物标志化合物参数对比及烃源岩的生烃潜力评价,综合认为开平凹陷南部区域原油主要来源于各自含油气构造下伏的文昌组下段烃源岩。开平凹陷南部区域具有较为优质的烃源条件,勘探前景较好。To analyze the geochemical characteristics of crude oil in the Kaiping sag of the Pearl River Mouth basin and to ascertain the hydrocarbon sources for more scientific and rational exploration and development strategies,this study conducted an analysis of geochemical features,crude oil genesis,and sourcing based on geochemical experimental analysis and testing data of crude oil and source rocks from the middle-deep layers in the southern region of the Kaiping sag.The results indicate that the crude oil in the southern Kaiping sag is characterized by high wax content and light-to-medium density.The crude oil from the K181 and K114 hydrocarbon-bearing structures in the southern Kaiping sag exhibits similar geochemical features,including a dominance of C_(21) TT or C_(23) TT,low oleanane content,a preference for C_(27) and C_(29) regular steranes,and the presence of 4 methyl C_(30) sterane,suggesting a contribution from both algal aquatic organisms and terrestrial higher plants.However,there are still certain differences in organic matter input and depositional environments between the hydrocarbon-generating precursors of the crude oil from the two hydrocarbon-bearing structures.The crude oil from the K181 hydrocarbon-bearing structure is relatively unique,differing from that of K114 and other regions.It has low oleanane content and a high C_(21) TT/C_(19+20) TT index,indicating it is a typical lacustrine crude oil.In contrast,the crude oil from the K114 hydrocarbon-bearing structure is similar to that from other regions in the Kaiping sag,with relatively high oleanane content and a lower C_(21) TT/C_(19+20) TT index,suggesting it is more fluvial-deltaic in nature.An evaluation of source rocks and an analysis of molecular geochemical characteristics indicate that there are significant differences in the geochemical features of source rocks from different intervals in the southern Kaiping sag.The lower member of the Wenchang Formation consists of TypeⅠⅡ_(2) organic matter lacustrine source rocks,while the upper me

关 键 词：开平凹陷 地球化学 油源对比 原油成因 烃源岩 珠江口盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]