下扬子地区大隆组页岩孔隙发育特征及主控因素

为了研究下扬子地区二叠系大隆组页岩孔隙结构特征，联合扫描电镜、高压压汞、N₂/CO₂气体吸附实验手段对页岩储层孔隙结构进行了研究。结果表明，研究区二叠系大隆组页岩孔隙类型以有机质孔、粒间孔、粒内孔、溶蚀孔和微裂缝为主；孔隙结构为多峰态-多尺度孔隙并存，微孔-介孔-宏孔都有发育，各个尺度的孔隙对孔容都有所贡献，其中以0.75～1.5 nm的微孔、10～35 nm的介孔及大于100 nm的宏孔为主。通过拟合孔体积、比表面积与埋深、有机碳(TOC)、成熟度(R_O)以及矿物含量的相关性发现，微孔表面积与埋深、TOC呈正相关；微介孔体积和表面积均与R_O呈负相关；宏孔体积与埋深、TOC、黏土矿物含量呈负相关，与R_O呈较正相关；宏孔表面积与埋深成正比，与R_O成反比。研究结果说明下扬子地区大隆组页岩孔隙发育主要受控于埋深、TOC、R_O、黏土矿物含量等因素。

The development characteristics and main control factors of shale pores in the Dalong Formation of Lower Yangtze region

In order to study the pore structure characteristics of the Permian Dalong Formation shale in the Lower Yangtze area, the pore structure of the shale reservoir was studied by means of scanning electron microscopy, high-pressure mercury injection and N₂/CO₂ gas adsorption experiments. The results show that the pore types of the Permian Dalong Formation shale in the study area are mainly organic pores, intergranular pores, intragranular pores, dissolution pores and microfractures. The pore structure is multi-modal and multi-scale, and micropores, mesoporous and macropores are developed. The pores of all sizes contributed to the pore volume, and the micropores of 0.75~1.5 nm, mesoporous pores of 10~35 nm and macropores larger than 100 nm were the main ones. By fitting the correlation between pore volume, specific surface area and buried depth, TOC, maturity(R_O) and mineral content, it was found that the surface area of micropore was positively correlated with burial depth and TOC.The volume and surface area of micro-mesoporous pore were negatively correlated with R_O. Macropore volume is negatively correlated with burial depth, TOC, and Clay mineral content, while it is positively correlated with R_O. Macropore surface area is proportional to buried depth and inversely proportional to R_O. The research results show that the development of shale pore in the Dalong Formation of the Lower Yangtze area is mainly controlled by factors such as burial depth, TOC, R_O and clay mineral content.