引用本文: 汪涛涛, 纪文明, 李耀华, 公繁浩. 2025. 松辽盆地齐家—古龙凹陷青山口组一段页岩岩相类型及孔隙发育特征. 地质科学, 60(1): 62-77. doi: 10.12017/dzkx.2025.005 . CSTR: 32087.14.dzkx.2025.005 Citation: Wang Taotao, Ji Wenming, Li Yaohua, Gong Fanhao. 2025. Petrographic types and pore development characteristics of shales in the first member of Qingshankou Formation, Qijia-Gulong Sag, Songliao Basin. Chinese Journal of Geology , 60(1): 62-77. doi: 10.12017/dzkx.2025.005 . CSTR: 32087.14.dzkx.2025.005

松辽盆地齐家—古龙凹陷青山口组一段陆相纯页岩型页岩油取得高产突破，但对其不同岩相孔隙发育特征及其影响因素缺乏系统认识。在岩相划分的基础上，通过场发射扫描电镜、高压压汞和低温N ₂ 吸附等实验，对比不同岩相页岩孔隙类型和孔隙结构特征，探讨泥页岩孔隙发育特征的主控因素。结果表明：依据“矿物组成—沉积构造—有机质丰度”3级标准，青一段页岩主要发育块状黏土质/混合质/云质泥岩、纹层状黏土质/富有机质黏土质（TOC＞3%）/长英质/介壳页岩等7种岩相类型。孔隙类型主要发育粒间孔、黏土矿物集合体内孔、溶蚀孔、生物体腔孔及层理缝。不同岩相页岩孔隙发育特征差异显著，以富有机质纹层状黏土质/长英质页岩和部分介壳页岩为优势岩相。富有机质纹层状黏土质页岩中有机质演化伴生有机酸溶蚀作用强烈，以溶蚀孔的大介孔为主。纹层状长英质页岩中长英质矿物含量增加，以介孔、宏孔为主，有利于粒间孔的保存和溶蚀孔的发育。部分纹层状介壳页岩发育大量介壳体腔孔和粒间孔。青一段泥页岩孔隙发育主控因素为岩相类型，其次受长英质含量、碳酸盐胶结作用及TOC含量综合影响。

齐家—古龙凹陷 白垩系青山口组 Abstract:

High-yield breakthroughs have been achieved in the land-phase pure shale-type shale oil in the first member Qingshankou Formation(shortened as the Qing 1 member)of the Qijia-Gulong Sag in the Songliao Basin. However, a comprehensive understanding of the pore development characteristics across different lithofacies and their influencing factors remains lacking. This study utilized a petrographic framework, supplemented by analytical techniques such as field emission scanning electron microscopy (FESEM), high-pressure mercury intrusion, and low-temperature N ₂ adsorption experiments to compare the pore structures and types in shales of differing petrographic phases, and to explore the controlling factors of the pore development characteristics of mud shales. The results show that according to the three-level standard of"mineral composition, sedimentary structure and organic matter abundance", and the shale in the Qing 1 member mainly develops seven types of lithofacies. These include massive clayey/mixed/cloudy mudstone, laminated clayey/organic matter-rich clayey (TOC > 3%)/ felsic/shell shale. The pore types mainly develop intergranular pores and pore structures. The pore types mainly develop intergranular pores, pores within clay mineral aggregates, dissolution pores, biomass cavity pores and inter-laminar crack. The pore development characteristics of different lithological shales differ significantly, with laminated organic-rich clayey/felsic shales and some shell shale as the dominant lithological phases. Organic-rich laminated clayey shale has strong organic acid dissolution associated with organic matter evolution, and large mesoporous pores dominate the dissolution pore. The felsic mineral content increases in the laminated felsic shale, which is dominated by mesopores and macropores, which is favorable for the preservation of intergranular pores and the development of dissolution pores. Some of the laminated shell shales have residual shell chambers and intergranular pores. The main controlling factor of pore development in the mud shale in the Qing 1 member is the petrographic type, followed by the combined influence of long quartz mineral content, carbonate cementation and TOC content.

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Regional geological background and comprehensive histogram of Qijia-Gulong Sag in Songliao Basin

Figure 2.

Core photos of Qing 1 member in the Qijia-Gulong Sag of Songliao Basin

Figure 3.

The partitioning diagram of three-terminal meta-lithofacies (a) and the relationship between clay mineral content and lithology, organic matter abundance and sedimentary structure (b) of shale of Qing 1 member in Qijia-Gulong Sag, Songliao Basin

Figure 4.

Optical photomicrographs of the Qing 1 member in the Qijia-Gulong Sag of Songliao Basin

Figure 5.

Scanning electron microscopy (SEM) of the shale of the first member of the Cretaceous Qingshankou Formation in Qijia-Gulong Sag, Songliao Basin

Figure 6.

Combined pore size characterization of shale in the Qing 1 member, Qijia-Gulong Sag, Songliao Basin

Figure 7.

Scatter diagram of the relationship between shale mineral composition and TOC and porosity, pore volume and specific surface area in the Qing1 member of Qijia-Gulong Sag