沁水盆地中东部海陆过渡相页岩微观孔隙结构特征

为探究沁水盆地石炭二叠系海陆过渡相页岩微观孔隙结构特征,运用扫描电镜、低温氮吸附实验和高压压汞实验等手段,分析了海陆过渡相页岩储层的孔隙类型、形态、孔径分布等特征。结果表明:研究区海陆过渡相页岩纳米级孔隙广泛发育,孔隙类型以有机质孔为主,同时亦发育大量的矿物粒间孔和部分粒内孔;孔隙形态以平行板状居多,还包括一定量的狭缝型孔,以及少量墨水瓶型孔和一端封闭的孔隙;页岩孔径分布范围跨度较大,介孔(2~50 nm)是研究区页岩纳米级孔隙的主体,提供的比表面积和孔体积均达到60%以上,微孔对比表面积的贡献同样值得重视。有机质孔以微孔为主,其发育程度对页岩气的吸附存储有重要影响,TOC含量是BET比表面积和BJH孔体积的重要控制因素;黏土矿物提供了大量介孔,其含量对比表面积和孔体积同样具有控制作用。

Characteristics of micro-scale pore structures of marine-continental transitional shale from the mid-eastern area,Qinshui Basin

In order to study the pore characteristics of the Permo-Carboniferous shale,some experiments including scanning electron microscope,nitrogen sorption-desorption experiments and mercury intrusion method were conducted to analyze the characteristics of the pore types,pore morphology,and pore size distribution.The results show that the nano-scaled pores in marine-continental transitional shale developed widely.Organic pores were the main pore type,and many intergranular pores with some intragranular pores were also found in the shale.The pores were mainly slit-shaped and parallel-plate.The meso-pores with the 2-50 nm pore size distribution were the main body of the nano-scaled pores,and they made a major contribution to pore specific surface area and pore volume in a common content of over 60%.The micro-pores also provided a considerable value of the surface area.Organic pores were primarily the micro-pores,and the TOC content was an important controlling factor of BET surface area and BJH pore volume.The content of clay minerals with a large quantity of meso-pores also had an effect on the value of surface area and pore volume.