石油与天然气地质 ›› 2019, Vol. 40 ›› Issue (3): 491-503.doi: 10.11743/ogg20190305

• 油气地质 • 上一篇    下一篇

“化学-沉积相”分析:一种研究细粒沉积岩的有效方法

刘可禹1,2, 刘畅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. 海洋国家实验室 海洋矿产资源评价与探测技术 功能实验室, 山东 青岛 266071;
    3. 中国地质调查局 油气资源调查中心, 北京 100083
  • 收稿日期:2018-12-19 修回日期:2019-03-06 出版日期:2019-06-28 发布日期:2019-04-26
  • 作者简介:刘可禹(1963-),男,博士、教授,含油气系统分析。E-mail:liukeyu@upc.edu.cn。
  • 基金资助:
    国家重点基础研究发展计划(973计划)项目(2014CB239004);国家科技重大专项(2017ZX05009-001);国家基金委"油气成藏机理"创新群体项目(41821002)。

“Chemo-sedimentary facies” analysis: An effective method to study fine-grained sedimentary rocks

Liu Keyu1,2, Liu Chang3   

  1. 1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China;
    2. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266071, China;
    3. Oil and Gas Survey, China Geological Survey, Beijing 100083, China
  • Received:2018-12-19 Revised:2019-03-06 Online:2019-06-28 Published:2019-04-26

摘要: 细粒沉积岩作为致密油气和页岩油气重要的勘探对象,具有粒度细、颜色均匀、非均质性强等特点,传统的岩心观察方法难以适用于细粒沉积岩的精细研究。通过获取细粒沉积岩手标本(岩心尺度)高分辨率(30 μm)的二维原位无机地球化学元素分布信息,结合图像分析,建立岩心尺度精细的“化学-沉积相”模型。在模型中,可以根据无机地球化学元素的平面分布清晰的识别细粒沉积岩的矿物成分和沉积构造。在此基础之上,能够提取不同部位的原位地球化学信息,针对细粒沉积岩沉积周期长厚度小的特点,实现在毫米-厘米级尺度上表征古环境、沉积物来源和成因,同时避免常规测试中粉碎均一化样品后所造成的信息干扰,为致密油气与页岩油气的勘探开发提供更加精细的沉积相模型和可靠的数据来源。

关键词: 2D-XRF扫描, 无机地球化学元素, 化学-沉积相, 细粒沉积岩, 沉积环境, 页岩油, 页岩气, 芦草沟组, 吉木萨尔凹陷

Abstract: Fine-grained sedimentary rocks,a key rock type bearing shale oil and gas,are characterized by fine grain size,colour uniformity and strong heterogeneity.Traditional sedimentological study based on visual observation and optical images alone becomes inadequate to precisely characterize such fine-grained rocks.Therefore,a "chemo-sedimentary facies" model for analyzing fine core-scale samples is established based on the high-resolution(down to 30 μm measurement intervals) 2D inorganic geochemical element mapping of rock slabs obtained by in-situ XRF scanning and optical images.Through the model,it is possible to unambiguously recognize the rock compositions and sedimentary fabrics.And then certain environment-sensitive elemental parameters(ratios) can be calculated in situ from individual chemo-sedimentary facies at millimeter-centimeter scales for the effective interpretation of depositional environment and provenance of fine-grained sediments,as well as their origin.Meanwhile,the method also avoids information interference in the conventional bulk compositional analyses whereby homogenized sample powders are often used.In conclusion,the method can help to establish more fine-scale sedimentary facies models and to provide reliable data for the exploration and development of tight and shale oil & gas.

Key words: 2D-XRF scanning, nonorganic geochemical element, chemo-sedimentary facies, fine-grained sedimentary rock, depositional environment, shale oil, shale gas, Lucaogou Formation, Jimusaer sag

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