Acta Petrologica et Mineralogica

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.

Lower Yangtze region; Dalong Formation; pore structure; developmental characteristics; main control factor