石油与天然气地质 ›› 2025, Vol. 46 ›› Issue (6): 1960-1979.doi: 10.11743/ogg20250614

• 油气地质 • 上一篇    下一篇

渤海湾盆地东营凹陷沙四上亚段-沙三下亚段页岩裂缝发育特征及成因机制

刘惠民1,2(), 李军亮1,3, 刘鑫金1,3(), 于福生4, 闫嘉杰4, 王勇1,3, 任嘉4, 冯海风4, 魏晓亮3, 杨晨4   

  1. 1.页岩油气富集机理与高效开发全国重点实验室，山东 东营 257015
    2.中国石化 胜利油田分公司，山东 东营 257000
    3.中国 石化 胜利油田分公司 勘探开发研究院，山东 东营 257015
    4.中国石油大学（北京） 地球科学学院，北京 102249
  • 收稿日期:2025-09-29 修回日期:2025-11-03 出版日期:2025-12-30 发布日期:2025-12-25
  • 通讯作者: 刘鑫金 E-mail:liuhuimin717.slyt@sinopec.com;liuxinjin.slyt@sinopec.com
  • 第一作者简介:刘惠民（1969—），男，博士、教授级高级工程师，常规油气与页岩油勘探。E-mail：liuhuimin717.slyt@sinopec.com。
  • 基金项目:
    国家科技重大专项(2024ZD1400100);国家自然科学基金项目(U24B6002);中国石油化工集团有限公司项目(P23084);中国石油化工集团有限公司项目(P24027)

Characteristics and genetic mechanism of natural fractures in shales from the upper sub-member of the Sha 4 Member to the lower sub-member of the Sha 3 Member in the Dongying Sag， Bohai Bay Basin

Huimin LIU1,2(), Junliang LI1,3, Xinjin LIU1,3(), Fusheng YU4, Jiajie YAN4, Yong WANG1,3, Jia REN4, Haifeng FENG4, Xiaoliang WEI3, Chen YANG4   

  1. 1.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development，Dongying，Shandong 257015，China
    2.Shengli Oilfield Company，SINOPEC，Dongying，Shandong 257000，China
    3.Exploration and Development Research Institute，Shengli Oilfield Company，SINOPEC，Dongying，Shandong 257015，China
    4.College of Geosciences，China University of Petroleum （Beijing），Beijing 102249，China
  • Received:2025-09-29 Revised:2025-11-03 Online:2025-12-30 Published:2025-12-25
  • Contact: Xinjin LIU E-mail:liuhuimin717.slyt@sinopec.com;liuxinjin.slyt@sinopec.com

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摘要：

天然裂缝是页岩油藏重要的储集空间和主要渗流通道，控制了页岩油气的运移、富集和单井产能。渤海湾盆地东营凹陷（沙河街组）沙四上亚段-沙三下亚段泥页岩目前仍存在对泥页岩裂缝类型和发育规律认识不清的问题。通过岩心观察、成像测井解释、卷积神经网络预测和岩石物理实验综合研究，分析了该区页岩裂缝发育特征、发育期次、主控因素及成因机制。研究结果表明：①东营凹陷沙四上亚段-沙三下亚段页岩天然裂缝可分为构造裂缝、成岩裂缝和异常高压裂缝3种类型；构造裂缝是该区的主要裂缝类型，细分为低角度张-剪复合裂缝、中-高角度剪裂缝、中-高角度“Y”型剪裂缝、高角度扭-张裂缝、高角度混合裂缝和近直立张裂缝等6种亚类。②不同类型裂缝呈NEE向、近WE向和NWW向展布，与断裂密切共生；经历了6个构造演化阶段。③页岩天然裂缝发育程度受构造、页岩有机碳含量和页岩脆性指数共同控制。裂缝发育程度与到断层距离呈负相关，与有机碳含量和脆性指数呈正相关。④裂缝发育受构造应力状态控制。沙四上亚段-沙三下亚段及沙二段—东营组在断陷阶段伸展应力状态下形成中-高角度剪裂缝和张-剪混合裂缝。东营组在沉积末期挤压应力状态下形成低角度张-剪复合裂缝。馆陶组-明化镇组在拗-断作用下形成近直立的张裂缝和异常高压裂缝。⑤直剪实验证明页岩层理倾角、层理厚度及层面结合强度对裂缝的发育样式具有影响。

关键词: 成因机制, 主控因素, 裂缝发育特征, 页岩油储层, 东营凹陷, 渤海湾盆地

Abstract:

Natural fractures act as both important reservoir spaces and primary seepage pathways in shale oil reservoirs， governing the migration， enrichment， and single-well productivity of shale oil and gas. However， the types and developmental patterns of natural fractures are yet to be clarified for the shales from the upper sub-member of the 4th member of the Shahejie Formation （Es4U） to the lower sub-member of the 3rd member of the formation （Es3L） in the Dongying Sag. In this study， we analyze the developmental characteristics， evolutionary stages， major controlling factors， and genetic mechanisms of natural fractures in the shales by integrating core observations， formation micro-imaging （FMI） log interpretation， convolutional neural network （CNN）-based prediction， and petrophysical experiments. The results indicate that natural fractures in the shales can be classified into three types： structural fractures， diagenetic fractures， and anomalously high pressure-induced fractures. Among these， structural fractures predominate in the sag and can be further divided into six sub-types： low-angle tensile-shear composite fractures， medium- to high-angle shear fractures， medium- to high-angle Y-shaped shear fractures， high-angle transtensional fractures， high-angle hybrid fractures， and nearly vertical tensile fractures. These various types of fractures extend in the NEE， nearly EW， and NWW directions and closely coexist with faults. These fractures have experienced six tectonic evolutionary stages， and their development is jointly controlled by structural influence， total organic carbon （TOC） content， and the brittleness index of the shales. Specifically， the fracture density shows a negative correlation with the distance from faults， whereas it exhibits positive correlations with both the TOC content and brittleness index of the shales. Additionally， the fracture development is controlled by tectonic stress regimes. Under extensional stress during the rifting stage from the Es4U to Es3L and from the Sha 2 Member （Es2） to the Dongying Formation， medium- to high-angle shear fractures and tensile-shear composite fractures are formed. In contrast， the compressive stress during the late depositional stage of the Dongying Formation led to the formation of low-angle tensile-shear composite fractures， while the depression-rifting process during the deposition of the Guantao-Minghuazhen formations caused the development of both nearly vertical tensile fractures and anomalously high pressure-induced fractures. Results from direct shear tests demonstrate that for the same type of fractures， their development patterns are affected by the dip angle and thickness of shale beddings， as well as the bond strength along bedding planes.

Key words: genetic mechanism, primary controlling factor, fracture characteristics, shale oil reservoir, Dongying Sag, Bohai Bay Basin

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