皖南地区古生界页岩孔隙特征及影响因素

为了评估下扬子皖南地区古生界页岩气储层性质，应用扫描电子显微镜、高压压汞法、N₂和CO₂气体吸附法，对皖南地区古生界页岩孔隙特征和孔隙结构进行研究，并探讨页岩孔隙发育的主要影响因素。结果表明，皖南地区古生界页岩孔隙度和渗透率低，页岩样品中常见粒间孔、凝絮孔、溶蚀孔、基质晶间孔和有机质孔，并且发育微米-纳米级孔隙。古生界页岩孔隙中50%以上为微孔和介孔；孔隙结构主要为圆柱孔、狭缝型孔和混合型孔，平均孔径范围为4.17~12.06 nm。页岩孔容和比表面积随着有机碳(TOC)含量的增大而增大；页岩孔隙度随着有机质成熟度(R_o)的增大而减小；页岩孔容随着黏土矿物含量的增加而增大，随着脆性矿物含量的增加而减小。

Pore Characteristics and the Controlling Factor of the Paleozoic Shale in the South Anhui

In order to assess the property of the Paleozoic shale gas reservoir in the south Anhui of Yangtze region, based on the scanning electron microscopy, high pressure mercury-injection, N₂ and CO₂ gas adsorption methods, the pore characteristics and structures of shale samples from the Paleozoic shales in the South Anhui were studied, and the controlling factors of pores development were discussed. The results show that the porosity and permeability of shale samples are low, and the microscopic pores mainly include inter-grain pores, floe pores, dissolution pores, matrix intergranular pores and organic pores, and the micro-nano scale pores are well developed in these shales. The main pore types in the Paleozoic shales are micropores and mesopores, which account for over 50%. The pore structure of shale is dominated by the parallel-plate pore, cylinder pore and mixed pore, and the average size is about 4.17-12.06 nm. The pore volume and specific surface area increase with the increasing of total organic carbon content (TOC). The porosity of shale reduces as the vitrinite reflectance (R_o) increases. The pore volume increases with the increasing of clay mineral content, but decreases with the increasing of brittle mineral content.