鄂尔多斯盆地长7段页岩油优质储层特征分析

以YJ1井为研究对象, 采用扫描电子显微镜和高压压汞技术, 对鄂尔多斯盆地长7段页岩油储集空间进行定性和定量表征; 通过核磁共振技术研究储层可动流体, 详细地探讨影响储层质量差异的主控因素。结果表明, 鄂尔多斯盆地长7段页岩油优质储层的岩性主要为细粒?极细粒岩屑砂岩, 沉积微相主要为砂质碎屑流沉积; 储集空间包括原生粒间孔隙和次生溶蚀孔隙, 粒间孔占比多于溶蚀孔。根据孔隙结构特征, 将储层划分为3类, 其中Ⅰ类储层为研究区内最优质储层。研究区储层流体的可动性主要受孔隙结构的影响, 可动流体主要分布在大孔隙内, 有效的孔隙体积是流体可动性的制约因素。研究区内砂质碎屑流成因的砂体是形成优质储层的必要条件, 岩石中骨架颗粒与胶结物的比例是导致储层物性变化的原因, 当骨架颗粒增加而胶结物含量降低时, 易形成优质储层。

Analysis of Pore Properties of Favorable Shale Oil Reservoir of Chang-7 in Ordos Basin

Taking well YJ1 as the research object, the pore variety of shale oil reservoir of Chang-7 member in Ordos Basin is characterized qualitatively and quantitatively by using scanning electron microscope and high pressure mercury injection technology. The movable fluid in reservoir is researched by using nuclear magnetic resonance technology, and the main controlling factors affecting the difference of reservoir quality are discussed in detail. The results show that the lithology of high-quality shale oil reservoir in Chang-7 member of Ordos Basin is mainly fine-grained?very fine-grained lithic sandstone, and the sedimentary facies are mainly sandy clastic flow deposition. The reservoir pore types include primary intergranular pores and secondary dissolution pores, and the proportion of intergranular pores is more than that of dissolution pores. According to the type of pore variety, the reservoir can be divided into three types, among which the type I reservoir is the most high-quality reservoir in the study area, with good porosity and permeability. The mobility of reservoir fluid in the study area is mainly affected by the properties of pore variety, the mobile fluid is mainly stored in the macropores, and the effective pore volume is the factor restricting the mobility of fluid. The sand body caused by sandy clastic flow in the study area is a necessary condition for the formation of high-quality reservoir. The proportion of skeleton particles and cement in the rock is the key for the change of reservoir properties. When the skeleton particles increase and the cement content decreases, it is easy to form high-quality reservoir.