鄂尔多斯盆地陇东地区长7段致密砂岩微孔隙特征

发布时间：2018-07-13 21:44

【摘要】：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。
[Abstract]:Compact oil is a hot spot in the field of unconventional oil and gas. The Chang 7 member of Ordos Basin has been found to be rich in dense oil reserves and is one of the most important tight oil regions in China. Previous studies have shown that nano-level pore throats are of great significance for unconventional oil and gas reservoirs. By means of nitrogen adsorption, microscopic observation, pore permeability analysis, X-ray diffraction analysis and particle size analysis, the characteristics of micropores in tight sandstone of Chang 7 are studied, the distribution of micropores, the parameters of pore structure and the proportion of micropores in total pores are calculated. The effects of micropore types, mineral composition, granularity and sorting on the development of micropores were also discussed. The results show that the micropore structure of Chang 7 compact sandstone is complex, and the micropore is mainly composed of "ink bottle" pore and parallel wall slit capillary pore, mainly composed of clay intergranular pore and interlaminar fracture, and mica interlaminar lamellar pore. Dissolution micropores and intergranular micropores exist. The distribution of micropore volume is between (2.40 ~ 13.04) 脳 10 ~ (-3) cm~3/g, accounting for about 1 / 4 of the total pore volume. The micropore distribution can be divided into two types: bimodal type and single-peak type. In addition, the correlation analysis between micropore volume and mineral composition, particle size and separation shows that the micropore volume is positively correlated with clay mineral content, and negatively correlated with carbonate mineral content, while the micropore volume is correlated with quartz feldspar content. The median particle size and standard deviation have no obvious correlation. Therefore, it can be concluded that the clay and carbonate minerals of Chang 7 tight sandstone have some influence on the development of micropores.
【作者单位】：中国石油大学(北京)地球科学学院;油气资源与探测国家重点实验室;中国石油长庆油田分公司;
【基金】：国家重点基础研究发展计划(“973”计划)(编号:2014CB239003) 国家自然科学基金项目“致密砂岩微米—纳米系统石油充注的有效性及成藏效应”(编号:41472114)联合资助
【分类号】：P618.13

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