四川盆地上三叠统须五段页岩微观孔隙结构及其控制因素
Characteristics and Controlling Factors of Micropore Structures of the 5th Shale Member of the Xujiahe Formation of Upper Triassic in Sichuan Basin

摘要： 为了深入研究四川盆地上三叠统须五段陆相页岩储层微观孔隙结构，运用氩离子抛光扫描电镜(SEM)、低温氮气吸脱附以及相关地球化学分析实验等技术对该地区页岩储层的微观孔隙结构进行了研究，并对控制其纳米孔隙发育的主要因素进行了探讨。结果表明：四川盆地须五段页岩微观孔隙可分为有机孔和无机孔(粒间孔、粒内孔、晶间孔、溶蚀孔)，微裂缝可分为构造微裂缝、有机质生排烃缝和成岩收缩缝等；孔隙结构类型以两端连通的圆柱孔、平行平面间的缝状孔和呈锥形的管孔为主；微观孔隙孔径分布区间大(1~80 nm)，峰值主要集中于2~8 nm之间；以中孔(2~50 nm)为主，所占比例为6021%(或以黏土矿物孔为主，所占比例为4462%)；页岩的有机质丰度和黏土矿物含量是控制纳米孔隙发育的主要因素。
Abstract: To deeply study the micropore characteristics of the 5th shale member of the Xujiahe Formation of Upper Triassic in Sichuan Basin, the microscopic pore structures of the shale reservoir were systematically studied by using Argoion polishing Scanning Electron Microscope(SEM), low temperature nitrogen adsorptiondesorption technology and related geochemical experiments. Meanwhile, the influences on the development of nanopore were discussed. The studies revealed that the micropores in shale can be classified into organic pores, inorganic pores (intergranular pores, intragranular, intercrystalline pores and dissolution pores) and the microcrack can be classified into structure microcrack, pressure crack form hydrocarbon generating and expelling, diagenetic constricted crack. Whats more, the pore structures can be mainly divided into three kinds, such as cylindrical pore with both ends open, Slit shaped holes between the parallel planes and taper pipe bore. The micropore diameters are largely ranged from 1 to 80 nm and the peak is distributed in 2 to 8 nm. The pore volume is mainly composed of mesopores (2 to 50 nm) with the proportion of 6021% (or mainly composed of the pores of clay mineral with the proportion of 4462%). In addition, organic richness and the content of clay minerals are believed to be the main controlling factors of nanopore development