摘要：In order to explore the pore microstructure characteristics of coal reservoirs in Dacheng area, Hebei Province, based on high pressure mercury intrusion experiments, the micropore pore volume, specific surface area and pore structure of coal reservoirs in the study area were studied. The results show that the mercury intrusion porosity of 8 samples in the study area is between 4.42% and 6.28%. The pore distribution characteristics show a bipolar distribution, that is, micro and small pores are dominant, with an average of about 77.29% of the total pore content; the larger pores are second, accounting for 16.42%; and the mesopores are the least, accounting for 6.29%. The proportion of macropores is 7.26~24.35%, the proportion of mesopores is 4.97~15.95%, the proportion of small holes is 22.45~33.67%, and the proportion of micropores is 36.16~56.60%. The proportion of micropores in the coal reservoirs in the study area is 88.22~91.00%, the small holes are 8.74—11.17%, the proportion of mesopores is 0.15~0.60%, and the proportion of macropores is 0.01~0.03%. The specific surface area ratio of micropores is an absolute advantage, up to about 90%. The pore volume median pore diameter of each coal seam in the study area is between 8 and 25 nm, with an average of 12.19 nm; the median diameter of the specific surface area is between 4 and 5 mm, with an average of 4.44 nm. From the value of the median pore diameter (pore volume or specific surface area) of mercury intrusion, its size is located in the small pore size section and close to the micropore section, indicating that the coal pores in the whole area are dominated by micro and small pores, and the adsorption capacity of coal reservoirs. Strong, but due to other pore size is not developed, the coalbed methane will have a seepage bottleneck during the development process.
