基于低温氮吸附实验的页岩油储层微观孔隙结构

Study on Micro Pore Structure Characteristics of Shale Oil Reservoirs Based on Low Temperature Nitrogen Adsorption Experiment

为研究页岩油储层微观孔隙结构特征,以松辽盆地青山口组页岩油储层样品为例,基于低温氮吸附并结合扫描电镜、TOC与X衍射等实验方法,开展页岩油储层微观孔隙结构特征及其影响因素研究。结果表明:研究储层段有机质富集且成熟度较好,利于油气成藏;以黏土矿物为主,平均体积分数42.6%;低温氮吸/脱附曲线属II+IV型复合曲线且产生H3型滞后环,表明孔结构复杂不规整,以狭缝平板孔、楔形孔为主;微小孔、中孔贡献了主要的孔比表面积与孔体积;基于FHH分形模型,孔隙具有显著的分形特征,分形维数在2.67~2.75,相关系数在0.92以上,表明孔隙空间较小、孔隙结构复杂、非均质性较强。TOC与黏土矿物有利于中孔与微小孔的发育,是影响页岩油储层微观孔隙结构的主要因素。

In order to study the micro pore structure characteristics of shale oil reservoir,taking the shale oil reservoir samples of Qingshankou Formation in Songliao Basin as an example,the characteristics and influencing factors of micro pore structure of the shale oil reservoir are studied based on low-temperature nitrogen adsorption and combined with SEM,TOC and X-ray diffraction.The experimental results show that the organic matter in the studied reservoir section is enriched and mature,which is conducive to hydrocarbon accumulation;It is mainly composed of clay minerals,with an average volume fraction of 42.6%;Its low-temperature nitrogen absorption/desorption curve belongs to type II+IV composite curve and produces H3 hysteresis ring,indicating that the pore structure is complex and irregular,mainly including slit flat hole and wedge-shaped hole;Micro pores and mesopores contribute the main pore specific surface area and pore volume;Based on FHH fractal model,pores have significant fractal characteristics,the fractal dimension is between 2.67~2.75 and the correlation coefficient is more than 0.92,indicating that the pore space is small,the pore structure is complex and the heterogeneity is strong.TOC and clay minerals are conducive to the development of mesopores and micro pores,which is the main factors affecting the micropore structure of shale oil reservoir.