济阳坳陷泥页岩沉积微相及储层微观结构研究

Mud shale oil and gas is one of the main unconventional oil and gas resource types , and it will be an important supplement of conventional energy source because of the huge resource potential. A lot of horizons of shale oil and gas developed， their distribution is wide and are at high maturity in the Jiyang depression in the Paleogene，which is the prospecting exploration area of mud shale oil and gas . Mud shale reservoir has the characteristics of compact structure, small particle size, complex rock composition,low porosity,and strong reservoir heterogeneity ; and impacted by tectonic and climate changes, mud shales formed under different sedimentary microfacies conditions have big differences in the mineral composition ， petrofabric , lithology combination (shale, sandstone, limestone), vertical sequence, and diagenesis,they directly affect the mud shale oil and gas enrichment process. This project will take the Paleogene mud shale development sections of the Jiyang depression as research object, through accurate identification of mineral composition and fabric types, summarize mud shale facies type and vertical evolution mode；discusses and their relationship with skeleton sedimentary facies ,analysis the dynamic process of the different types of shale sedimentary microfacies, and shale reservoir microstructure characteristics, determine the effect of sedimentary microfacies property responsible for shale reservoir heterogeneity. Obectlively evaluate the pore types and sizes of the contribution of petroleum accumulation,grasp the vertical development and plane distribution characteristics of the organic-rich shale, in order to provide a support to optimize goals of the shale exploration and exploitation.

泥页岩油气是非常规油气资源的主要类型之一，并以其巨大的油气资源潜力成为常规能源的重要补充。济阳坳陷古近系泥页岩发育层位多、分布范围广、成熟度较高，是泥页岩油气勘探的重要前景领域。泥页岩储层整体表现为结构致密、粒度细小、孔隙度低、储层非均质性强。受构造位置和气候变化等影响，不同沉积微相属性及微相组合条件下的泥页岩在矿物成分、岩石组构、岩性组合、垂向序列、成岩作用等方面具有很大的差异，直接影响了泥页岩储层的微观结构特征及油气富集过程。本项目以济阳坳陷古近系泥页岩发育段为研究对象，通过精确鉴定泥页岩矿物组成及岩石组构类型，总结泥页岩岩相类型及垂向演化模式，探讨不同岩相泥页岩的沉积微相属性划分及与骨架沉积相之间的配置关系，深入分析泥页岩不同沉积微相属性下的成因及沉积动力学过程。详细解剖泥页岩储层微观结构特征，客观评价泥页岩孔隙类型及尺寸对油气储集的贡献，明确沉积微相属性对泥页岩储层非均质性的控制作用，掌握富含有机质泥页岩的垂向发育情况和平面展布情况，优选济阳坳陷古近系泥页油气勘探有利目标区。

济阳坳陷泥页岩整体表现为结构致密、粒度细小、孔隙度低、储层非均质性强。不同沉积微相属性及微相组合条件下的泥页岩在矿物成分、岩石组构、岩性组合、垂向序列、成岩作用等方面具有很大的差异，直接影响了泥页岩储层的微观结构特征及油气富集过程。分析泥页岩基本沉积特征，划分岩相及微相类型， 分析泥页岩沉积微相平面和垂向分布特征，全息表征不同岩相类型的储层微观结构特征，探讨微相对储层微观结构的控制作用。项目的主要认识包括：（1）富有机质纹层状灰岩、 富有机质页状灰岩、中有机质纹层状混合细粒岩、富有机质页状黏土岩和贫有机质块状混合细粒岩是最为发育的 5 种岩相类型。(2)在骨架沉积相控制下，以泥页岩岩石类型及岩相特征为基础，综合控制泥页岩发育的水动力条件、古湖盆底形及事件沉积等因素，对半深湖-深湖泥页岩进行沉积微相划分。（3）平阔半深湖微相、水下隆起半深湖微相、深洼微相、浊积周缘微相、近岸水下扇前缘微相等是东营凹陷西部沙三下亚段泥页岩主要的微相类型。（4）黏土矿物絮凝成因孔、黏土矿物收缩缝、方解石重结晶晶间孔、白云石化晶间孔、有机质边缘收缩缝、碳酸盐岩溶蚀孔、生烃超压缝、层间微缝等是重要的储集空间类型。（5）不同岩石类型内孔、缝发育状况差异较大；微米级孔隙分选较差，开放孔较小，孔隙连通性中等；纳米级孔隙形态复杂，多为圆柱形孔、平行板状孔。（6）沉积微相控制了孔隙架构矿物的组成、组构及平面分布，气候控制下的湖泊咸化程度影响了细粒物质的垂向叠置混合方式，进而控制了储集空间的类型及其组合。（7）综合油气生成潜力、油气可流动性、油气储集性能、可压裂性等因素，预测富有机质纹层状灰岩、富有机质灰质纹层状细粒混合沉积岩为有利岩相类型。（8）平阔半深湖微相发育的泥页岩储层有机质含量较高，脆性矿物以方解石为主，孔隙和裂缝类型多样，孔隙连通性中等且孔隙的开放性较好，可视为页岩油勘探开发有利相带区。