Microscopic pore structure characteristics of Shanxi Formation coal reservoir in Daning-Jixian Block

ZHU Gengen; XIE Zhitao; WANG Tao; HU Haiyan; WANG Daxing

doi:10.13347/j.cnki.mkaq.20222299

Abstract：Accurate description of micro and nano pores in coal reservoir plays an important role in evaluating the reservoir and gas production capacity of coalbed methane,we used 6 continuous samples of high rank coal in Daning-Jixian area on the eastern mar-gin of Ordos Basin as the research object,and combined with high pressure mercury injection,low temperature N2 adsorption and low pressure CO2 adsorption experiments to characterize the pore structure characteristics.The aim of this study is to have an in-depth understanding of the full-size pore size distribution and explore the influencing factors of coal reservoir pore structure.The res-ults show that the pore volume and specific surface area of coal sample in the study area have obvious differences with the pore size distribution,and the contribution rate of coal sample micropores to pore volume and specific surface area is significant,especially the diameter less than 1.5 nm micropore provides storage space for most of the adsorptive gas.The contribution of mesoporous and mac-roporous to pore volume and surface area is relatively small,which is not conducive to coalbed methane seepage.The vitrinite con-tent of coal samples in the study area is positively correlated with pore volume and specific surface area,which contributes signific-antly to pore development.The relationship between inertinite content and pore volume and surface area is not obvious.With the in-crease of Mad,more adsorption pores are developed in coal samples,and pore volume and specific surface area are negatively correl-ated with Ad,indicating that the increase of Ad will lead to the decrease of pore volume and specific surface area.