石油与天然气地质 ›› 2025, Vol. 46 ›› Issue (4): 1349-1366.doi: 10.11743/ogg20250421

• 油气地质 • 上一篇    下一篇

东海陆架盆地西湖凹陷宝武地区平湖组石英溶蚀作用及机制

刘开逍1,2(), 王俊辉1,2(), 阴国锋3, 陈锦霖1,2, 武洋1,2, 李勇霖1,2, 代正明1,2, 姚文娇1,2, 姜在兴4, 徐杰5   

  1. 1.中国石油大学(北京) 油气资源与工程全国重点实验室,北京 102249
    2.中国石油大学(北京) 地球科学学院,北京 102249
    3.中国石油化工股份有限公司 上海海洋油气分公司,上海 200120
    4.中国地质大学(北京) 能源学院,北京 100083
    5.中国地质大学(北京) 海洋学院,北京 100083
  • 收稿日期:2024-12-24 修回日期:2025-03-31 出版日期:2025-08-30 发布日期:2025-09-06
  • 通讯作者: 王俊辉 E-mail:2023210043@student.cup.edu.cn;wangjunhui@cup.edu.cn
  • 第一作者简介:刘开逍(2001—),男,博士研究生,岩石学与储层地质学。E-mail: 2023210043@student.cup.edu.cn
  • 基金项目:
    中国石油大学(北京)科研基金项目(2462020BJRC002);中国石油大学(北京)科研基金项目(2462022YXZZ010)

Quartz dissolution and its mechanisms in the Pinghu Formation, Baowu area, Xihu Sag, East China Sea Shelf Basin

Kaixiao LIU1,2(), Junhui WANG1,2(), Guofeng YIN3, Jinlin CHEN1,2, Yang WU1,2, Yonglin LI1,2, Zhengming DAI1,2, Wenjiao YAO1,2, Zaixing JIANG4, Jie XU5   

  1. 1.State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum (Beijing),Beijing 102249,China
    2.College of Geosciences,China University of Petroleum (Beijing),Beijing 102249,China
    3.Shanghai Offshore Oil & Gas Company,SINOPEC,Shanghai 200120,China
    4.School of Energy Resources,China University of Geosciences (Beijing),Beijing 100083,China
    5.School of Ocean Sciences,China University of Geosciences (Beijing),Beijing 100083,China
  • Received:2024-12-24 Revised:2025-03-31 Online:2025-08-30 Published:2025-09-06
  • Contact: Junhui WANG E-mail:2023210043@student.cup.edu.cn;wangjunhui@cup.edu.cn

摘要:

为了明确西湖凹陷平湖斜坡带宝武地区平湖组石英溶蚀的成岩环境、特征、机制及其对储层的影响,综合利用岩石薄片、扫描电镜、烃源岩地球化学参数、X射线衍射和重矿物等分析测试资料,研究了相关的成岩环境及其演化规律。研究表明:①研究区存在酸性和碱性两种石英溶蚀作用,其溶蚀机理存在显著差异。酸性环境下石英在碱金属离子作用下与有机酸络合形成络合物导致溶蚀,碱性环境下石英直接与OH-离子反应生成HSiO3-离子而发生溶蚀。成岩环境演化影响石英的溶蚀,根据溶蚀边界特征可将其划分为交代型溶蚀和增孔型溶蚀两种类型。②高岭石交代型溶蚀是碱金属离子作用下有机酸溶蚀的结果。伊利石、绿泥石和碳酸盐矿物交代型溶蚀是碱性溶蚀的结果。增孔型溶蚀在酸性和碱性环境中均可发生。石英溶蚀程度呈现明显的环境分异性,溶蚀强度从碱性环境—酸性环境—酸-碱过渡环境—弱酸性环境依次减弱。石英溶蚀程度与晶体扭曲面的数量、温度和碱金属离子含量呈正相关关系。③石英增孔型溶蚀的演化序列为扭曲面溶蚀—平坦面(雨痕状)溶蚀—平坦面(蜂窝状)溶蚀—石英颗粒部分缺失;交代型溶蚀的演化序列为高岭石交代溶蚀—碳酸盐矿物交代溶蚀—伊利石交代溶蚀—绿泥石交代溶蚀。粒缘溶蚀、次生加大边溶蚀和自生石英溶蚀改善孔隙结构,增加渗透率。黏土矿物交代溶蚀石英颗粒形成粒间及晶间溶孔对形成储层孔隙贡献较大。

关键词: 溶蚀机制, 成岩环境, 石英溶蚀, 平湖组, 西湖凹陷, 东海陆架盆地

Abstract:

This study aims to determine the diagenetic environments, characteristics, and mechanisms of quartz dissolution in the Pinghu Formation within the Baowu area, Pinghu slope zone, Xihu Sag, East China Sea Shelf Basin (ECSSB)and to assess the impact of quartz dissolution on reservoirs. By integrating data from rock thin-section observation, scanning electron microscopy (SEM), X-ray diffraction analysis, and heavy mineral analysis, along with the geochemical parameters of source rocks, we explore the quartz dissolution-related diagenetic environments and their evolutionary patterns. The research results indicate the occurrence of acidic and alkaline quartz dissolution with significantly different mechanisms in the study area. In the acidic digenetic environment, quartz dissolves through complexation with organic acids in the presence of alkali metal ions, while in the alkaline digenetic environment, quartz reacts directly with OH- to form HSiO3-. The evolution of diagenetic environments affects quartz dissolution, which can be classified into two types based on the characteristics of dissolution boundaries: metasomatic and porosity-enhancing types. The metasomatic dissolution by kaolinite occurs through organic acid dissolution in the presence of alkali metal ions, whereas the metasomatic dissolution by illite, chlorite, and carbonate minerals is driven by alkaline dissolution. The porosity-enhancing dissolution occurs in both acidic and alkaline environments. The degree of quartz dissolution varies significantly with the diagenetic environment, decreasing in the order of alkaline, acidic, acidic-alkaline transitional, and weakly acidic environments. Furthermore, this degree is positively correlated with the number of kinking crystal planes, temperature, and alkali metal ion content. The porosity-enhancing quartz dissolution includes kinking plane dissolution, flat plane dissolution (raindrop imprint-like), and flat plane dissolution (honeycomb-like), leading to the partial missing of quartz grains. The metasomatic quartz dissolution involves kaolinite, carbonate minerals, illite, and chlorite. Additionally, grain-edge dissolution, secondary overgrowth rim dissolution, and authigenic quartz dissolution improve pore structures and increase reservoir permeability. Notably, the metasomatic dissolution of quartz grains by clay minerals leads to the formation of intergranular and intercrystalline dissolution pores, significantly increasing the reservoir porosity.

Key words: dissolution mechanism, diagenetic environment, quartz dissolution, Pinghu Formation, Xihu Sag, East China Sea Shelf Basin (ECSSB)

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