陆相富碳酸盐页岩纹层组合对页岩油富集的控制作用——以渤海湾盆地济阳坳陷古近系沙河街组页岩为例

Controlling effects of lamina assemblages on shale oil enrichment for lacustrine carbonate-rich shales： A case study of shales in the Paleogene Shahejie Formation， Jiyang Depression， Bohai Bay Basin

李军亮 王民 秦峰 王勇 魏晓亮 孟伟 沈安超 宋兆京 余昌琦 李俊乾 刘嘉祺

Junliang LI Min WANG Feng QIN Yong WANG Xiaoliang WEI Wei MENG Anchao SHEN Zhaojing SONG Changqi YU Junqian LI Jiaqi LIU

陆相页岩油勘探已取得突破，但页岩油富集高产的主控地质因素尚不清晰，制约着页岩油的高效开发。精细刻画不同纹层特征可揭示页岩油富集主控因素。本文以济阳坳陷古近系沙河街组富碳酸盐页岩为研究对象，通过薄片鉴定和场发射扫描电镜观察，剖析了典型纹层储集空间和含油性的特征，揭示了页岩纹层组合对页岩油富集的控制作用。研究发现，济阳坳陷沙河街组四段上亚段富碳酸盐页岩的纹层可划分为纤维状方解石纹层、泥晶方解石纹层、粉晶方解石纹层、富黏土矿物纹层和混合矿物纹层5种类型，主要发育“泥晶方解石纹层+富黏土矿物纹层+混合矿物纹层”和“纤维状方解石纹层+粉晶方解石纹层+富黏土矿物纹层+混合矿物纹层”2种纹层组合模式；富黏土矿物纹层和混合矿物纹层有机质含量高，是页岩油富集的物质基础；粉晶方解石纹层储集空间发育，是页岩油储集的优势纹层；富黏土矿物纹层与粉晶方解石纹层或泥晶方解石纹层叠置分布，可构成页岩油富集的最佳纹层配置，该类纹层组合的富碳酸盐页岩是页岩油勘探开发的重要目标。

Breakthroughs have been achieved in the exploration of lacustrine shale oil. However， the dominant geological factors controlling the enrichment and high yield of shale oil remain unclear， restricting its efficient exploitation. The fine characterization of various laminae can reveal the major factors controlling shale oil enrichment. This study focuses on the carbonate-rich shales of the Paleogene Shahejie Formation in the Jiyang Depression. Using thin section observations and field emission scanning electron microscopy （FE-SEM）， we analyze the reservoir spaces and oil-bearing properties of typical laminae and reveal the controlling effects of the lamina assemblages of shales on oil enrichment. The results indicate that carbonate-rich shales in the upper sub-member of the 4th member of the Shahejie Formation （E） within the Jiyang Depression contain five lamina types： fibrous calcite laminae， micritic calcite laminae， very fine crystalline calcite laminae， clay-mineral-rich laminae， and mixed laminae. Major lamina assemblages include the combination of micritic calcite laminae， clay-mineral-rich laminae， and mixed laminae， and the combination of fibrous calcite laminae， very fine crystalline calcite laminae， clay-mineral-rich laminae， and mixed laminae. The clay-mineral-rich and mixed laminae， among others， exhibit high organic matter content， serving as the material basis for shale oil enrichment. Meanwhile， the very fine crystalline calcite laminae， with well-developed reservoir spaces， act as preferential storage media for shale oil. Additionally， the superposition of clay-mineral-rich laminae with very fine crystalline or micritic calcite laminae forms the optimal lamina configuration for shale oil enrichment. Therefore， the carbonate-rich shales with the clay-mineral-rich laminae and very fine crystalline or micritic calcite laminae assemblage serve as an important target for shale oil exploration and exploitation.

10.11743/ogg20250205