致密砂岩储层黏土矿物晶间孔隙特征及其对物性影响的研究——以鄂尔多斯盆地延长组长6油层组为例

针对致密砂岩储层黏土矿物晶间孔隙定量表征不足的问题, 以扫描电子显微镜图像和EDS能谱分析资料为基础, 研究鄂尔多斯盆地延长组长6油层组黏土矿物及晶间孔隙的发育特征, 将晶间孔参数定量化, 对不同类型黏土矿物晶间孔进行定性与定量结合表征。在此基础上, 根据矿物含量计算不同类型黏土矿物对储层孔隙度的贡献, 探究其对致密砂岩储层物性参数的影响机制。结果表明, 不同黏土矿物的发育特征及晶间孔特征有较大的差异; 黏土矿物的孔喉和面孔率大小趋势为伊蒙混层>绿泥石>伊利石, 类圆状孔隙和孔隙缩小型喉道发育较广泛; 黏土矿物发育特征和孔隙结构是储层物性及剩余油分布的主要影响因素。

Characteristics of Nano-pores of Clay Minerals in Tight Reservoirs and Their Effects on Reservoir Properties: A Case Study of Yanchang-6 Oil Formation in Ordos Basin

In view of the lack of quantitative characterization of intercrystalline pores of clay minerals in tight sandstone reservoirs, the development characteristics of clay minerals and intercrystalline pore in Yanchang-6 oil formation in Ordos Basin were studied based on scanning electron microscope image and energy spectrum analysis. The intercrystalline pore parameters were quantified, and the intercrystalline pores of different types of clay minerals were characterized qualitatively and quantitatively. On this basis, the contribution of different types of clay minerals to reservoir porosity was calculated according to the mineral content, and the mechanism of its influence on the physical properties of tight reservoirs was explored. The results showed that there were significant differences in the development characteristics of different clay minerals and the characteristics of intercrystalline pores. The size trend of pore throat and facial rate of clay minerals was illite/smectite formation > chlorite > illite. Clay mineral development characteristics and pore structure were the main influencing factors of reservoir physical properties and residual oil distribution.