石油与天然气地质 ›› 2022, Vol. 43 ›› Issue (3): 682-695.doi: 10.11743/ogg20220316

• 油气地质 • 上一篇    下一篇

银额盆地古生界过成熟烃源岩特征及其地球化学意义

陈治军1,2(), 张春明1(), 贺永红2, 文志刚1, 马芳侠2, 李渭3, 高怡文2, 陈义国2, 张慧元3, 魏东涛3   

  1. 1.长江大学 资源与环境学院,湖北 武汉 430100
    2.陕西延长石油(集团)有限责任公司研究院,陕西 西安 710075
    3.中国地质调查局 西安地质调查中心,陕西 西安 710054
  • 收稿日期:2021-04-19 修回日期:2022-03-08 出版日期:2022-06-01 发布日期:2022-05-06
  • 通讯作者: 张春明 E-mail:chenzhijun2203@aliyun.com;Zhangcm1991@163.com
  • 作者简介:陈治军(1980—),男,高级工程师、博士研究生,油气地球化学。E?mail: chenzhijun2203@aliyun.com
  • 基金资助:
    国家自然科学基金项目(41872144);延长石油集团科技攻关项目(ycsy2020jcyj-B-03)

Characteristics and geochemical indication of over-mature source rocks in the Paleozoic, Yingen-Ejinaqi Basin

Zhijun Chen1,2(), Chunming Zhang1(), Yonghong He2, Zhigang Wen1, Fangxia Ma2, Wei Li3, Yiwen Gao2, Yiguo Chen2, Huiyuan Zhang3, Dongtao Wei3   

  1. 1.College of Resources and Environment,Yangtze University,Wuhan,Hubei 430100,China
    2.Research Institute of Yanchang Petroleum (Group) Company Limited,Xi’an,Shaanxi 710075,China
    3.Xi’an Center of Geological Survey,China Geological Survey,Xi’an,Shaanxi 710054,China
  • Received:2021-04-19 Revised:2022-03-08 Online:2022-06-01 Published:2022-05-06
  • Contact: Chunming Zhang E-mail:chenzhijun2203@aliyun.com;Zhangcm1991@163.com

摘要:

银额盆地的部分钻井和野外露头发现了古生界过成熟烃源岩,对于分析盆地古生界油气成藏条件、探讨过成熟烃源岩地球化学问题等有重要的意义。对25个过成熟烃源岩样品开展测试分析,研究其地球化学特征,分析其原始生烃潜力。结果表明:①烃源岩总有机碳含量平均为1.31 %,有机质类型为Ⅱ1-Ⅱ2型,镜质体反射率Ro平均为4.20 %,为残余有机碳含量较低、混合型干酪根的过成熟烃源岩;②主要受控于热降解作用,过成熟烃源岩的生物标志化合物普遍呈现“正构烷烃具有双峰型、甾类化合物中孕甾烷(含升孕甾烷)具有异常高的相对含量、萜类化合物中三环萜烷的相对含量较高、芳烃化合物中低碳环数化合物占据优势”等特征;③提出了“有机碳构成”的概念,建立了基于岩石热解资料计算有机碳构成的方法,计算结果表明虽然本研究中过成熟烃源岩的有效碳仅占极小的一部分,但烃源岩原始总有机碳含量平均为2.07 %,且烃源岩具有持续时间长、产率较高的生烃特征,明确了银额盆地古生界过成熟烃源岩具有较高的生烃潜力。

关键词: 有机碳构成, 生物标志化合物, 地球化学特征, 过成熟烃源岩, 古生界, 银额盆地

Abstract:

The Paleozoic source rocks encountered by some wells and present on outcrops in Yingen-Ejinaqi Basin are believed to carry with them important geochemical information that will help understand the oil and gas accumulation conditions in the Paleozoic system of the basin. Geochemical characterization and hydrocarbon generation potential assessment of 25 such rock samples indicate over-mature (Ro=4.20 %) source rocks with low total organic carbon (TOC) content (1.31 %) and mixed kerogen types (typesⅡ1-Ⅱ2). They are mainly products of thermal degradation with biomarkers showing a bimodal N-alkanes, abnormally high relative abundance of pregnane (including L pregnane) in steroids, high relative abundance of tricyclic terpene in terpenoids, a predominance of low-carbon ring number compounds in aromatic compounds and other characteristics. A concept of “organic carbon composition” is presented and a method for calculating its value based on rock pyrolysis data is established. The results show that although the pyrolytically effective carbon only accounts for a fraction of organic carbon composition of the over-mature source rock, the original average TOC content of source rock is high at 2.07 %. In addition, the duration of hydrocarbon generation is long and its yield is high. Therefore, the Paleozoic over-mature source rocks in Yingen-Ejinaqi Basin are suggested to have a high original hydrocarbon generation potential.

Key words: organic carbon composition, biomarker compound, geochemical characteristics, over-mature hydrocarbon source rock, Paleozoic, Yingen-Ejinaqi Basin

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