关键词: 甲烷, 等温吸附, 解吸率, 细观, 裂隙

Abstract: Under the urgent requirement of improving the quality and efficiency of emerging energy industry, it is of great significance to actively promote the development of coalbed methane industry to alleviate the current domestic energy situation. The adsorption and desorption characteristics of coal reservoir constrained by formation stress are directly related to the layout of gas drainage operation. Based on this, this paper carried out an experimental study on the adsorption and desorption characteristics of methane under stress-constrained coal, and also carried out CT scanning test and analysis on the internal structure characteristics of coal after desorption of methane. The results show that: The relationship between the adsorption capacity of methane and pore pressure is almost linear, which accords with Langmuir model. It is considered that 80 ℃ is the reasonable temperature point for coal to desorb methane. After gas desorption, more pores will be formed and more secondary fractures will be developed. The porosity of different layers ranges from 6.32% to 9.38%, with an average porosity of 7.4%. In different types of pores, the proportion of pores and fractures with pore diameter less than 30 μ m is as high as 76.36%. Generally speaking, the pore fracture structure with small pore size is the main channel for methane desorption, diffusion and migration.