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In this study, a series of laboratory experiments were performed to firstly analyze the characteristics of the pore structure in low-rank coal (R_o < 0.70%), and then relationships between fractal dimensions and coal rank, coal composition and pore structure, and their impacts on methane adsorbability and seepage ability were studied too. The desorption isotherms of low-rank coal mainly belongs to Type B, which are primarily caused by ink-bottle-shaped and narrow-slit pores that are good for coalbed methane (CBM) enrichment, but bad for seepage. The seepage pores are dominated by primary plant macropores (>1000 nm), with a poor development of mesopores (100–1000 nm). The fractal features of adsorbed pores and seepage pores were defined and calculated using fractal dimensions D₂ (2.563–2.926) and D₄ (2.683–3.263), respectively. D₂ has a positive correlation with moisture content, while D₄ has a …