南襄盆地泌阳和南阳凹陷古近系核桃园组页岩地质特征与勘探建议

Geological characteristics and exploration suggestions for shale in Paleogene Hetaoyuan Formation of Biyang and Nanyang sags, Nanxiang Basin

王勇 李艳然 朱颜 张育衡 牛明伟 熊健 李恒权 王琦

WANG Yong LI Yanran ZHU Yan ZHANG Yuheng NIU Mingwei XIONG Jian LI Hengquan WANG Qi

中国石化 河南油田分公司，河南 南阳 473132 中国石化 河南油田分公司 勘探开发研究院，河南 南阳 473132

Henan Oilfield Company, SINOPEC, Nanyang, Henan 473132, China Exploration and Development Research Institute, Henan Oilfield Company, SINOPEC, Nanyang, Henan 473132, China

南襄盆地泌阳凹陷和南阳凹陷古近系核桃园组页岩层与已突破的东部断陷盆地的页岩层系存在明显的地质差异。目前对该区页岩油地质特征形成机制认识不清，制约了其勘探开发进程。通过岩心、X衍射、薄片、扫描电镜和激光共聚焦等分析手段，系统研究了南襄盆地不同凹陷核桃园组页岩地质特征的差异，并提出下一步勘探建议。南襄盆地核桃园组页岩以纹层状混合质页岩为主，其中泌阳凹陷以纹层状云灰质—长英质混积页岩为主，发育基质型页岩油；南阳凹陷以纹层状长英质—黏土质混合页岩为主，砂岩夹层发育，主要为夹层型页岩油。泌阳凹陷页岩具有常压、中—低演化程度、中—高丰度特征，表现为储集性能中等—好、含油性好、可压性好以及可动性中等；南阳凹陷页岩具有常压、中等演化程度、中—低丰度的特点，储集性能中等、含油性中等—好、可压性及可动性中等。对比研究表明，边界断层及古水深控制不同凹陷湖盆类型；湖盆类型与古沉积环境的协同作用影响了页岩的岩相类型；有机质组分和成烃生物类型控制了页岩丰度。南阳凹陷淡水湖盆中—低丰度夹层型页岩油、泌阳凹陷咸化湖盆常压基质型页岩油均具备良好的成藏条件。针对泌阳凹陷页岩层含油性好、甜点相对集中的特点，建议加强低成本工程工艺攻关，探索夹层型页岩油直斜井效益开发模式；针对南阳凹陷页岩层纵向跨度大、断层复杂的特点，建议采用大斜度井实现纵向多层大规模压裂改造。

The shale layers in the Paleogene Hetaoyuan Formation of the Biyang and Nanyang sags in the Nanxiang Basin show significant geological differences from the shale strata in the eastern rift basins where breakthroughs have been achieved. The limited understanding of the formation mechanism of shale oil and its geological characteristics in this area constrains its exploration and development. Through core analysis, X-ray diffraction (XRD), thin-section observation, scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM), the geological differences of the shale in the Hetaoyuan Formation across various sags in the Nanxiang Basin were systematically studied, and suggestions for future exploration were proposed. The Hetaoyuan Formation in the Nanxiang Basin mainly develops laminated mixed shale. Particularly, the Biyang Sag mainly develops laminated dolomitic and felsic mixed shale and is abundant in matrix-type shale oil. The Nanyang Sag mainly develops laminated felsic and argillaceous mixed shale with well-developed sandstone interlayers, primarily containing sandwich-type shale oil. The shale in the Biyang Sag exhibits normal pressure, medium to low evolution degree, and medium to high organic matter abundance, with medium to good reservoir property, good oil-bearing capacity, good compressibility, and medium mobility. The shale in the Nanyang Sag exhibits normal pressure, medium evolution degree, and medium to low organic matter abundance, with medium reservoir property, medium to good oil-bearing capacity, and medium compressibility and mobility. Comparative analysis revealed that boundary faults and paleo-water depth controlled the types of lake basins in different sags. Lake basin types and the paleo-depositional environment collectively affected shale lithofacies types. The organic matter components and hydrocarbon-generating organism types controlled the abundance of organic matter in shale. The sandwich-type shale oil with medium to low organic matter abundance in the freshwater lake basin of the Nanyang Sag and the matrix-type shale oil under normal pressure in the salt lake basin of the Biyang Sag possess favorable reservoir-forming conditions. For the shale layers in the Biyang Sag, which have good oil-bearing properties and relatively concentrated sweet spots, it is recommended to strengthen research on low-cost engineering technologies and explore efficient development models for sandwich-type shale oil through vertical and deviated wells. For the shale layers in the Nanyang Sag, which feature large vertical spans and complex faults, highly deviated wells are recommended for large-scale, multi-layer vertical fracturing.

中国石化科技部项目 P23035;中国石化科技部项目 P24207

https://doi.org/10.11781/sysydz2025040705