石油学报 ›› 2024, Vol. 45 ›› Issue (5): 804-816.DOI: 10.7623/syxb202405004

• 地质勘探 • 上一篇    下一篇

沧东凹陷深湖亚相纹层状页岩成因及页岩油可动性影响因素

解德录1, 赵贤正2, 金凤鸣1, 蒲秀刚1, 韩文中1, 时战楠1, 张伟1, 董雄英1   

  1. 1. 中国石油大港油田公司 天津 300280;
    2. 中国石油天然气集团有限公司咨询中心 北京 100724
  • 收稿日期:2023-12-29 修回日期:2024-04-10 发布日期:2024-06-03
  • 通讯作者: 赵贤正,男,1962年10月生,2005年获中国石油大学(北京)博士学位,现为中国石油天然气集团有限公司咨询中心教授级高级工程师、李四光地质科学奖及孙越崎能源大奖获得者,主要从事油气勘探与开发研究和管理工作。Email:xzzhao@petrochina.com.cn
  • 作者简介:解德录,男,1990年6月生,2021年获南京大学博士学位,现为中国石油大港油田公司博士后,主要从事非常规油气地质及甜点预测工作。Email:dlxie@smail.nju.edu.cn
  • 基金资助:
    国家重点研发计划项目"战略性资源开发区风险评估应用示范"(2022YFF0801204)、中国石油天然气股份有限公司科技重大专项"陆相页岩油规模增储上产与勘探开发技术研究"(2023ZZ15)和中国博士后基金项目(2022M710567)资助。

Genesis of deep lacustrine subfacies laminated shale and influence factors on shale oil mobility in Cangdong sag, Bohai Bay Basin

Xie Delu1, Zhao Xianzheng2, Jin Fengming1, Pu Xiugang1, Han Wenzhong1, Shi Zhannan1, Zhang Wei1, Dong Xiongying1   

  1. 1. PetroChina Dagang Oilfield Company, Tianjin 300280, China;
    2. CNPC Advisory Center, Beijing 100724, China
  • Received:2023-12-29 Revised:2024-04-10 Published:2024-06-03

摘要: 纹层是深湖亚相页岩的重要沉积结构,对页岩油的可动性具有重要影响。以渤海湾盆地沧东凹陷孔店组二段(孔二段)为例,综合X射线衍射、岩石热解、X射线荧光光谱、全自动矿物分析、场发射扫描电镜和氮气吸附等测试技术,从微米—纳米尺度探讨了纹层状页岩中页岩油的特征和成因,并深入分析了页岩油可动性的控制因素。研究结果表明:孔二段页岩主要有5类纹层,即长英质纹层、灰云质纹层、黏土质纹层、方沸石质纹层和混合质纹层,其中,前3类纹层的平均厚度分别约为250 μm、125 μm和65 μm。这些纹层主要构成了3类纹层状页岩:纹层状长英质页岩、纹层状灰云质页岩和纹层状混合质页岩。根据细粒沉积的有机相分类,纹层状长英质页岩形成于强外源输入的淡水沉积环境,而纹层状灰云质页岩形成于高含硫的碳酸盐/蒸发岩等相对咸水沉积环境,这反映二者在高效生烃机理上存在差异。进一步研究表明,有机-无机地质因素共同影响纹层状页岩中页岩油的可动性。有利于页岩油流动的因素包括:页岩具有适中的总有机碳含量(1 % ~4 %)和最高热解峰温(435~450 ℃),发育产气型干酪根而非产油型干酪根,具有更高的碳酸盐含量而非长英质含量、大孔径和更低的孔隙比表面积。研究成果有望为深化陆相页岩油"甜点"评价、指导页岩油勘探开发提供理论指导。

关键词: 纹层, 深湖亚相, 页岩油, 沧东凹陷, 渤海湾盆地

Abstract: The laminae, the fundamental sedimentary structure of deep-lacustrine subfacies shales, have an important influence on the mobility of shale oil. This paper is a case study of the Member 2 of Kongdian Formation in Cangdong sag of Bohai Bay Basin. Comprehensively using the testing techniques such as X-ray diffraction, Rock-eval, X-ray fluorescence spectra, advanced mineral identification and characterization system, high resolution field emission scanning electron microscopy, and N2 adsorption, the paper explores the features and genesis of laminated shale oil at the micro- and nano-scale, and deeply analyzes the controlling factors of shale oil mobility. The results show that there are mainly five types of laminae in the study area, i.e., felsic laminae, calcareous-dolomitic laminae, clayey laminae, analcime laminae, and mixed laminae. The average thickness of felsic, lime-dolomitic and clayey laminae is approximately 250 μm, 125 μm, and 65 μm, respectively. These laminae mainly develop three types of laminated shales, i.e., laminated felsic shale, laminated calcareous-dolomitic shale, and laminated mixed shales. The classification of organic facies based on fine-grained sedimentation indicates that laminated felsic shale originate from freshwater depositional environment with strong external input, whereas laminated calcareous-dolomitic shale are formed in saline water depositional environment of sulfur-rich carbonate and evaporite. This reveals the differences in efficient hydrocarbon generation mechanisms between laminated felsic and calcareous-dolomitic shales. The further research suggests that the mobility of shale oil is jointly affected by both organic and inorganic geological factors. The conditions favorable for the mobility of shale oil is as below. (1) Shale has the moderate total organic carbon contents in the range from 1 % to 4 %, with the maximum pyrolysis temperatures in the range from 435 ℃ to 450 ℃. (2) Gas-producing kerogen is developed in shale, rather than oil-producing kerogen. (3) Shale possesses higher carbonate content compared to felsic content, large pore diameter, and low pore specific surface area. This study is expected to improve the evaluation of "sweet spots" in continental shale oil and guide shale oil exploration and development.

Key words: laminae, deep lacustrine subfacies, shale oil, Cangdong sag, Bohai Bay Basin

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