石油与天然气地质 ›› 2020, Vol. 41 ›› Issue (4): 811-823, 890.doi: 10.11743/ogg20200414

• 油气地质 • 上一篇    下一篇

渤海湾盆地沧东凹陷孔店组二段细粒沉积岩形成机理与环境演化

邓远1(), 陈世悦1, 蒲秀刚2, 鄢继华1, 陈佳3   

  1. 1. 中国石油大学(华东) 地球科学与技术学院, 山东 青岛 266580
    2. 中国石油 大港油田分公司, 天津 300280
    3. 中国石油大学(北京)克拉玛依校区, 新疆 克拉玛依 834000
  • 收稿日期:2018-11-19 出版日期:2020-08-01 发布日期:2020-08-11
  • 作者简介:邓远(1990-),男,博士研究生,非常规油气地质。E-mail:dengyuan_upc@163.com
  • 基金资助:
    国家自然科学基金项目(41572087)

Formation mechanism and environmental evolution of fine-grained sedimentary rocks from the second member of Kongdian Formation in the Cangdong Sag, Bohai Bay Basin

Yuan Deng1(), Shiyue Chen1, Xiugang Pu2, Jihua Yan1, Jia Chen3   

  1. 1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China
    2. Dagang Oilfield Company, PetroChina, Tianjin 300280, China
    3. China University of Petroleum(Beijing), Karamay, Xinjiang 834000, China
  • Received:2018-11-19 Online:2020-08-01 Published:2020-08-11

摘要:

非常规油气的兴起引发了细粒沉积岩研究的热潮,然而对湖相细粒沉积岩形成机理与环境演化的研究尚处于探索阶段。基于岩心、薄片、全岩X射线衍射、AMICS矿物分析和地球化学等资料,以岩石类型和沉积构造为依据,将渤海湾盆地沧东凹陷孔(孔店组)二段细粒沉积岩划分为层状细粒长英沉积岩相、块状细粒混积岩相、纹层状细粒混积岩相、纹层状白云岩相和块状白云岩相等5种岩相类型,详细分析每种岩相的沉积环境和形成机理。不同岩相按照一定次序叠置构成4类典型岩相组合,在气候干湿度、水体性质和物源供给强度等方面差异显著,分别对应强陆源输入沉积模式、季节性气候沉积模式、半干旱季节性气候沉积模式和持续干旱沉积模式。通过岩相组合划分和地球化学特征分析,孔二段沉积时期沧东凹陷沉积环境自下而上可划分为Ek2(4)~Ek2(3)季节性气候阶段、Ek2(2)潮湿气候阶段与Ek2(1)干旱-潮湿转换阶段。研究成果可以为沧东凹陷页岩油的勘探和开发提供理论依据。

关键词: 细粒沉积岩, 岩相, 形成机理, 沉积环境, 沧东凹陷, 渤海湾盆地

Abstract:

The development of unconventional oil and gas has triggered an upsurge of research in fine-grained sedimentary rocks.However, more research on the formation mechanism and depositional environment of lacustrine fine-grained sedimentary rocks is still needed.Through detailed description of core, thin section identification, X-ray diffraction analysis, automated mineral identification and characterization system (AMICS) and geochemical analysis, this paper establishes a classification scheme for lithofacies based on rock types and sedimentary structures.Fine-grained sedimentary rocks in the second member of the Kongdian Formation in the Cangdong Sag of Bohai Bay Basin was divided into five lithofacies: the laminated felsic fine-grained sedimentary rocks, massive mixed fine-grained sedimentary rocks, laminated mixed fine-grained sedimentary rocks, laminated dolomite and massive dolomite.The depositional environment and formation mechanism of each lithofacies type were analyzed.Four types of lithofacies assemblages were identified based on the superimposition patterns of different lithofacies.These assemblages vary in climate conditions, water body characteristics and terrigenous clastic input; and correspond to four depositional modes characterized respectively by intensive terrigenous sediment input, seasonal climate influence, semiarid seasonal influence, and prolonged arid.Analyses of the classification and geochemical indexes of the lithofacies assemblages show that the depositional environment in the second member of the Kongdian Formation can be divided into three stages from bottom to top: the seasonal climate stage from Ek2(4) to Ek2(3), the humid climate stage for Ek2(2) and the arid-humid transitory stage for Ek2(1).

Key words: fine-grained sedimentary rock, lithofacies, formation mechanism, depositional environment, Cangdong Sag, Bohai Bay Basin

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