石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (4): 937-945.doi: 10.11743/ogg20230411

• 油气地质 • 上一篇    下一篇

莺歌海盆地中新统海相烃源岩形成环境及控制因素

裴健翔1(), 郭潇潇1, 薛海涛2, 吴杨瑜1, 李珊珊1, 李文浩2()   

  1. 1.中海石油(中国)有限公司海南分公司,海南 海口 570312
    2.中国石油大学(华东) 地球科学与技术学院,山东 青岛 266580
  • 收稿日期:2023-01-27 修回日期:2023-05-31 出版日期:2023-08-01 发布日期:2023-08-09
  • 通讯作者: 李文浩 E-mail:peijx001@163.com;liwh@upc.edu.cn
  • 第一作者简介:裴健翔,(1970—),男,教授级高级工程师,南海油气勘探。E?mail: peijx001@163.com
  • 基金项目:
    海南省院士创新平台科研项目,中海油科技项目(KJZH-2021-0003-00)

Environment and controlling factors of the Miocene marine source rocks in the Yinggehai Basin

Jianxiang PEI1(), Xiaoxiao GUO1, Haitao XUE2, Yangyu WU1, Shanshan LI1, Wenhao LI2()   

  1. 1.Hainan Branch,CNOOC,Haikou,Hainan 570312,China
    2.School of Geosciences,China University of Petroleum (East China),Qingdao,Shandong 266580,China
  • Received:2023-01-27 Revised:2023-05-31 Online:2023-08-01 Published:2023-08-09
  • Contact: Wenhao LI E-mail:peijx001@163.com;liwh@upc.edu.cn

摘要:

莺歌海盆地中钻遇中新统海相烃源岩的探井主要分布在盆地边缘及斜坡带,中新统海相优质烃源岩的形成条件与分布规律尚不明确。从生物和环境地球化学的角度,系统剖析了莺歌海盆地中新统海相烃源岩形成时期古海洋生产力、陆源有机质输入与氧化还原环境,揭示了烃源岩发育的主控因素,并预测了优质烃源岩分布。研究区中新统海相烃源岩中P/Ti值揭示古海洋生产力整体偏低,其中乐东区有增大的趋势。由于莺歌海盆地周围发育多条河流,陆源有机质供给充足,其中被子植物来源的奥利烷在中新统海相烃源岩(尤其是三亚组烃源岩)中普遍存在;莺北区、莺东斜坡、东方区和乐东区中新统海相烃源岩中Ni/Co值揭示烃源岩主要发育在偏氧化的沉积水体中,乐东区沉积环境有变好的趋势。烃源岩总有机碳含量(TOC)与P/Ti和Ni/Co相关性揭示古生产力和氧化还原环境仅对乐东区L30-1井区烃源岩发育具有一定控制作用;TOC值与奥利烷指数(奥利烷/C30藿烷)具有明显的正相关性,表明陆源有机质输入对中新统海相烃源岩发育具有明显的控制作用。受海南岛和红河双物源影响的莺北区H29-1井区陆源有机质供给充足,为中新统高有机质丰度海相陆源型烃源岩发育的有利场所;D29-2井区和L30-1井区附近古海洋生产力和保存条件较好,可发育内源型优质烃源岩。

关键词: 氧化还原环境, 古海洋生产力, 陆源有机质输入, 中新统海相烃源岩, 莺歌海盆地

Abstract:

Wells encountering the Miocene marine source rocks in the Yinggehai Basin are mostly confined to the edge and slope areas, leaving the overall forming environment and distribution of these high-quality source rocks in the basin a puzzle to be cracked. This paper, from the perspective of biogeochemistry and environmental geochemistry, reveals the main controlling factors of the formation and distribution of the source rocks through a systematical analysis of paleo-productivity, terrestrial organic matter input and redox conditions of the rocks in the basin. The P/Ti values of the source rocks indicate relatively low paleo-productivity, with only that of the Ledong area showing an increasing trend. The supply of terrestrial organic matter is relatively sufficient because of several rivers around the basin. Oleanane derived from angiosperms is widely occurring in the source rocks, especially those in the Sanya Formation. The Ni/Co ratios of the rocks from the Yingbei, Yingdong Slope, Dongfang and Ledong areas indicate an oxic environment with the redox conditions in the Ledong area better than the rest. The relationship between TOC values and P/Ti and Ni/Co ratios shows that the paleo-productivity and redox conditions only control the formation of the source rocks from L30-1 wellblock in the Ledong area. TOC values of the source rocks have a positive correlation with the oleanane index (oleanane/C30 hopane), showing that terrestrial organic matter input has a significant control effect on the development of marine source rocks. The H29-1 wellblock of the Yingbei area, provided with sufficient supply of terrestrial organic matter from both Hainan Island and the Red River, serves as a perfect location for enrichment of high orgnic marine source rocks. While the D29-2 and L30-1 wellblocks with fine paleo-productivity and redox conditions are relatively good for the formation of endogenous high-quality source rocks.

Key words: redox condition, paleo-productivity, terrestrial organic matter input, Miocene marine source rock, Yinggehai Basin

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