致密油是当今非常规油气领域的研究热点。鄂尔多斯盆地长7段已发现致密油储量丰富,是中国最主要的致密油区之一。前人研究表明,纳米级孔喉对于非常规油气储层具有重要意义。采用氮气吸附、镜下观察、孔渗分析、X-射线衍射分析及粒度分析等实验手段研究长7段致密砂岩微孔隙特征,计算微孔分布、孔隙结构参数、微孔在总孔隙中的比例,并讨论了微孔隙类型以及矿物成分、粒度、分选对微孔发育的影响。研究表明,长7致密砂岩微孔隙结构复杂,微孔主要由“墨水瓶”型孔和平行壁狭缝型毛细孔组成,主要以黏土晶间孔及层间缝、云母层间片状孔、溶蚀微孔及杂基粒间微孔的形式存在。微孔体积分布在(2.40~13.04)×10~(-3)cm~3/g之间,约占总孔隙体积的1/4左右,微孔分布可分为2类:双峰型和单峰型。此外,对微孔体积与矿物成分、粒度及分选进行相关性分析,发现微孔体积与黏土矿物含量呈正相关关系,与碳酸盐矿物含量呈负相关关系;而微孔体积与石英+长石含量、中值粒径、标准偏差没有明显的相关性。因此,可认为长7段致密砂岩的黏土和碳酸盐矿物对其微孔的发育有一定的影响。 Tight oil is a hot spot in the field of unconventional oil and gas. The Ordos Basin, Chang 7 Member, has found abundant tight oil reserves and is one of the most important tight oil zones in China. Previous studies show that nano-pore throat is of great significance for unconventional oil and gas reservoirs. Micropore characteristics of sandstone in Chang 7 sandstone were studied by means of nitrogen adsorption, microscopic observation, pore-permeability analysis, X-ray diffraction analysis and particle size analysis. The micropore distribution, pore structure parameters and the proportion of micropores in the total pore were calculated The effects of microporosity and mineral composition, particle size and sorting on micropore development were also discussed. The results show that the pore structure of Chang 7 tight sandstone is complex. The micropores mainly consist of “ink bottle ” type pores and parallel-wall slit type capillary pores. The pores are mainly composed of intercrystalline pores and interlaminar seams, Holes, dissolved micropores and miscellaneous intergranular micropores exist. The pore volume distribution is between (2.40 ~ 13.04) × 10 ~ (-3) cm ~ 3 / g, accounting for about 1/4 of the total pore volume. The pore distribution can be divided into two types: bimodal type and mono Peak type. In addition, correlation analysis between micropore volume, mineral composition, particle size and sorting showed that there was a positive correlation between micropore volume and clay mineral content and a negative correlation with carbonate mineral content. However, micropore volume was inversely related to quartz + Stone content, median diameter, standard deviation no significant correlation. Therefore, it can be considered that the clay and carbonate minerals in the Chang 7 tight sandstone have a certain impact on the micropore development.