石油与天然气地质 ›› 2025, Vol. 46 ›› Issue (5): 1536-1553.doi: 10.11743/ogg20250510

• 油气地质 • 上一篇    

鄂尔多斯盆地三叠系延长组长73油层亚组页岩岩相及页岩油差异赋存与微观运聚特征

张一帆1(), 葸克来1,2, 操应长1,2, 张博3, 王秀娟4, 尤源4, 马文忠4, 王雨轩1, 孙琦慧1   

  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.中国石油大学（华东） 深层油气重点实验室，山东 青岛 266580
    3.中国石油 长庆油田勘探事业部，陕西 西安 710018
    4.中国石油 长庆油田公司，陕西 西安 710018
  • 收稿日期:2025-04-11 修回日期:2025-09-06 出版日期:2025-10-30 发布日期:2025-10-29
  • 第一作者简介:张一帆（1997—），女，博士研究生，页岩油气。E-mail： 870436231@qq.com。
  • 基金项目:
    国家自然科学基金青年科学基金项目(42402155)

Shale lithofacies， differential shale oil occurrence and its microscropic migration and accumulation features in the 3rd sub-group of the 7th oil group of the Triassic Yanchang Formation， Ordos Basin

Yifan ZHANG1(), Kelai XI1,2, Yingchang CAO1,2, Bo ZHANG3, Xiujuan WANG4, Yuan YOU4, Wenzhong MA4, Yuxuan WANG1, Qihui SUN1   

  1. 1.School of Geoscience，China University of Petroleum （East China），Qingdao，Shandong 266580，China
    2.State Key Laboratory of Deep Oil and Gas，China University of Petroleum （East China），Qingdao，Shandong 266580，China
    3.Exploration Division of PetroChina Changqing Oilfield Company，Xi’an，Shaanxi 710018，China
    4.Changqing Oilfield Company，PetroChina，Xi’an，Shaanxi 710018，China
  • Received:2025-04-11 Revised:2025-09-06 Online:2025-10-30 Published:2025-10-29

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摘要：

页岩纹层类型、储集空间类型及页岩油赋存状态是影响页岩油微观运聚的主要因素。以鄂尔多斯盆地三叠系延长组长73油层亚组页岩为研究对象，综合应用薄片及电镜观察、地化参数、矿物参数自动定量分析（AMICS）、氮气吸附、高压压汞、二维核磁共振、激光共聚焦等定性和定量的分析手段，对页岩纹层和页岩微观孔隙进行划分，明确页岩油赋存状态及分布特征，进而讨论页岩油的微观运聚过程。研究结果表明：①长73油层亚组页岩主要发育4种纹层类型（富有机质纹层、富凝灰质纹层、粉砂级长英质纹层和黏土纹层）和3种纹层组合（“富有机质+粉砂级长英质”纹层组合、“富有机质+富凝灰质”纹层组合和块状泥岩）；②不同纹层孔隙类型和含量差异显著，粉砂级长英质纹层面孔率平均值为6.59%，长石溶孔发育，富凝灰质纹层面孔率平均值为3.50%，主要发育晶间孔，部分发育微裂缝；③结合纹层有机质特征和孔-缝配置细划长73油层亚组页岩岩相，分别为“富有机质+富凝灰质”页岩岩相（Ⅰ型与Ⅱ型）和“富有机质+粉砂级长英质”页岩岩相（Ⅲ型），Ⅰ型与Ⅱ型主要区别于裂缝发育程度；④Ⅰ型中页岩油可动性强，含油性一般，页岩油运聚发生于厚层Ⅰ型内部；Ⅱ型和Ⅲ型可动性一般，Ⅲ型含油性好，在垂向接触时有利于页岩油由Ⅱ型向Ⅲ型运移。本研究通过划分页岩纹层类型，精细刻画不同纹层的储集空间，阐明了页岩油差异赋存规律，明确了页岩油在页岩岩相间的运聚特征，为揭示页岩油微运聚机理奠定基础。

关键词: 储集空间, 赋存特征, 微观运聚特征, 纹层类型, 页岩油, 延长组, 鄂尔多斯盆地

Abstract:

The shale lamina type， reservoir space type， and shale oil occurrence state represent major factors influencing the microscopic migration and accumulation of shale oil. This study focuses on shales in the 3rd sub-group of the 7th oil group of the Triassic Yanchang Formation （also referred to as the Chang 73 oil sub-group） in the Ordos Basin. By integrating a series of qualitative and quantitative analysis methods， including thin section observation， scanning electron microscopy （SEM）， geochemical analysis， advanced mineral identification and classification system （AMICS）， nitrogen （N2） adsorption experiments， high-pressure mercury intrusion （HPMI）， two-dimensional nuclear magnetic resonance （NMR）， and confocal laser scanning microscopy （CLSM）， we categorize the laminae and micropores in the shales and determine the occurrence states and distribution characteristics of shale oil. Accordingly， the microscopic migration and accumulation process of shale oil is discussed. The results indicate that shales in the Chang 73 oil sub-group primarily contain four lamina types （organic-rich， tuff-rich， silt-sized felsic， and clay laminae） and three lamina assemblages （organic-rich + silt-sized felsic lamina assemblage， organic-rich + tuff-rich lamina assemblage， and massive mudstones）. These lamina types show significantly different pore types and contents. Specifically， the silt-sized felsic laminae exhibit an average areal porosity of 6.59%， with well-developed feldspar dissolution pores. The tuff-rich laminae have an average areal porosity of 3.50%， which are dominated by intercrystalline pores， with some containing microfractures. Based on the organic matter characteristics and pore-fracture configuration of the laminae， the shale lithofacies of the Chang 73 oil sub-group are further subdivided into the “organic-rich + tuff-rich” combination （types Ⅰ and Ⅱ） and “organic-rich + silt-sized felsic” combination （type Ⅲ）， with types Ⅰ and Ⅱ differing primarily in fracture density. Type Ⅰ shales feature high oil mobility but moderate oil-bearing properties， with shale oil migration and accumulation occurring within thickly layered shales. In contrast， both types Ⅱ and Ⅲ shales exhibit moderate oil mobility， while type Ⅲ shales present excellent oil-bearing properties. This creates favorable conditions for the shale oil migration from type Ⅱ to type Ⅲ shales in cases when both types occur in vertical contact. Through lamina classification and the fine-scale characterization of reservoir spaces across different lamina types， this study elucidates differential shale oil occurrence patterns and characterizes shale oil migration among various shale lithofacies， providing a foundation for understanding the mechanisms behind the microscopic migration and accumulation of shale oil.

Key words: reservoir space, occurrence characteristics, microscropic migration and accumulation characteristics, lamina type, shale oil, Yanchang Formation, Ordos Basin

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