石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (1): 31-43.doi: 10.11743/ogg20240103

• 油气地质 • 上一篇    下一篇

琼东南盆地陆源海相烃源岩有机质富集机理

侯读杰1,2(), 吴克强3, 尤丽3, 张自鸣1,2, 李雅君1,2, 熊小峰3, 徐敏1,2, 严夏泽1,2, 陈威合1,2, 程熊1,2   

  1. 1.中国地质大学(北京) 能源学院,北京 100083
    2.海相储层演化与油气富集机理教育部重点实验,北京 100083
    3.中海石油(中国)有限公司 海南分公司,海南 海口 570312
  • 收稿日期:2023-03-09 修回日期:2023-10-27 出版日期:2024-02-01 发布日期:2024-02-29
  • 第一作者简介:侯读杰(1964—),男,教授、博士研究生导师,油气地球化学及成藏研究。 E-mail: hdj@ cugb.edu.cn
  • 基金项目:
    国家自然科学基金项目(41472108)

Organic matter enrichment mechanisms of terrigenous marine source rocks in the Qiongdongnan Basin

Dujie HOU1,2(), Keqiang WU3, Li YOU3, Ziming ZHANG1,2, Yajun LI1,2, Xiaofeng XIONG3, Min XU1,2, Xiazhe YAN1,2, Weihe CHEN1,2, Xiong CHENG1,2   

  1. 1.School of Energy Resources,China University of Geosciences (Beijing),Beijing 100083,China
    2.Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Abundance Mechanism,Ministry of Education,Beijing 100083,China
    3.Hainan Branch of CNOOC (China) Limited,Haikou,Hainan 570312,China
  • Received:2023-03-09 Revised:2023-10-27 Online:2024-02-01 Published:2024-02-29

摘要:

琼东南盆地渐新统陆源海相烃源岩是深水区的一套重要烃源岩。从盆地构造格局、古气候、沉积相和三角洲规模4个方面对琼东南盆地渐新统陆源海相烃源岩的形成机理进行了分析。结果表明:盆地构造格局整体上控制了烃源岩的发育类型,断陷期的崖城组陆源有机质主要以近岸堆积形式形成煤系烃源岩;而陵水组(E3l)陆源有机质则以河流-三角洲搬运形式形成陆源海相烃源岩。崖城组三段(崖三段,E3y3)和三亚组二段(三二段,N1s2)沉积期陆源高等植物最繁盛;崖二段(E3y2)-崖一段(E3y1)和陵水组二段(陵二段,E3l2)-陵一段(E3l1)沉积期次之,陆源高等植物供给充足。沉积相带控制陆源有机质的差异,同时卸载的不同形成了明显差异的陆源海相烃源岩。陆源海相烃源岩有利的发育区域为三角洲前缘-内浅海以及海底扇。大规模的三角洲可以输送更高生物通量的陆源有机质,提高了烃源岩有机质丰度,从而形成海域最为重要的一类有特色的气源岩。

关键词: 构造格局, 沉积相, 三角洲规模, 有机质丰度, 陆源海相烃源岩, 琼东南盆地

Abstract:

The Oligocene terrigenous marine source rocks in the Qiongdongnan Basin serve as a significant suite of source rocks in deep-water areas. We analyze their formation mechanisms from the aspects of the basin’s tectonic framework, paleoclimate, sedimentary facies, and delta scale. The results indicate that the tectonic framework of the basin generally determines the source rock types. Specifically, the terrigenous organic matter of the Yacheng Formation, deposited during the rifting stage, predominantly accumulates offshore and forms coal-measure source rocks. In contrast, the terrigenous organic matter from the Lingshui Formation (E3l) forms terrigenous marine source rocks via fluvial-deltaic transport. The 3rd member of the Yacheng Formation (E3y3) and the 2nd member of the Sanya Formation (N1s2) witnessed the most luxuriant terrigenous higher plants, followed by the 1st to 2nd members of both the Yacheng and Lingshui formations (E3y1 to E3y2, and E3l1 to E3l2). These contributed significantly to an abundant supply of terrigenous higher plants. Variations in sedimentary facies zones determine the differences in terrigenous organic matter, whose differential deposition leads to the formation of significantly varying terrigenous marine source rocks. Favorable areas for the terrigenous marine source rocks include delta fronts to inner neritic zones, along with submarine fans. Large-scale deltas facilitate the transport of terrigenous organic matter with higher biotic fluxes, thus improving the organic matter abundance of source rocks. As a result, significant and characteristic gas source rocks are formed in the sea area.

Key words: tectonic framework, sedimentary facies, delta scale, organic matter abundance, terrigenous marine source rock, Qiongdongnan Basin

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