Fractal Analysis on Heterogeneity of Pore–Fractures in Middle–High Rank Coals with NMR

Because of the complex nature of coal reservoirs, no determined method can clearly assess their pore–fracture structure. This paper combines a fractal method with the transverse relaxation time (T 2) of nuclear magnetic resonance (NMR) to study pore–fractures in a coal reservoir. Based on 10 coal samples with vitrinite reflectance (R o,m) in the range 1.32–2.43%, the pore size/volume distribution from mercury intrusion porosity (MIP) and NMR was compared, revealing that a strong correspondence exists, and that the correspondence for pore diameter of >100 nm is better than that for pore diameter of