鄂尔多斯盆地延长组页岩孔隙结构特征及其控制因素

以鄂尔多斯盆地延长组长 7 油层组富含有机质灰黑色页岩为例，利用低压氮气吸附测试方法，分析 了页岩的孔隙形态、比表面积及孔容，并研究了页岩孔隙结构特征影响因素。 研究表明：鄂尔多斯盆地 延长组长 7 油层组页岩孔隙形态复杂，主要发育狭缝形和墨水瓶状孔；页岩的矿物组成以石英和黏土矿 物为主，前者体积分数为 17.10%～72.33%，与 TOC 含量呈明显的负相关性，后者体积分数为 12.37%～ 61.55%；页岩的 BET 比表面积为 0.380～3.030 m2/g，BJH 总孔体积为 0.696～6.575 mm3/g，且中孔孔隙提 供了主要的孔容并贡献了主要的比表面积；页岩的孔容和比表面积主要受 TOC、黏土矿物及石英等含量 的影响，同时也受碳酸盐矿物及长石含量的影响，其与 TOC、黏土矿物及长石等的含量呈正相关性，而与 石英及碳酸盐矿物的含量呈负相关性；TOC 和黏土矿物是延长组页岩微孔孔容和中孔孔容的主要贡献 者，而石英是延长组页岩大孔孔容的主要贡献者。

Characteristics and controlling factors of shale pore structure of Yanchang Formation in Ordos Basin

The pore structure characteristics and influence factors of Chang 7 member of shale of the Upper Triassic Yanchang Formation in Ordos Basin were analyzed by low-pressure N2 adsorption/desorption analysis. The result shows that the shale pore structure of Chang 7 member in Ordos Basin is complicated, and pores are mainly consist of parallel-plate pores with four sides open and ink bottle-shaped. The mineral compositions of the shale are mainly quartz and clays, the former content is between 17.1% and 72.33%, and the latter content is between 12.37% and 61.55%. The BJH pore volume of the shale is concentrated in the range of 0.696-6.575 mm3/g, and the BET specific surface area is between 0.380 m2/g and 3.030 m2/g. The contents of TOC, clays and quartz have significant effects on the pore volume and pore specific surface area, whereas the carbonate and feldspar have a little influence. The pore volume and pore specific surface area are positively correlated with the contents of TOC, clays and feldspar, and negatively correlated with the contents of quartz and carbonate. The TOC and clays have significant control on microporeand mesopore volumes, whereas the quartz has positive effect on macropore volumes.