Influence of coalification on pore structure evolution in middle-ranked coals

The influence of coalification on coal structure evolution in middle ranked coals is significant for physical assessment coalbed methane (CBM) reservoirs, which provides insights the intrinsic connection between jump and pore heterogeneity. A total 26 middle-ranked were samples covering Liupanshui Coalfield Guizhou Province, Anhe Henan Huaibei Anhui Sanjiang Basin Heilongjiang Ordos Shaanxi Province Qinshui Shanxi Province. Based a series experiments including vitrinite reflectance, maceral identification, nitrogen adsorption fractal method, inner link property parameters reservoirs rank was revealed. results show that dominated by inertinite two types pores are divided according to adsorption/desorption curves along with size distribution. specific surface area positively correlated volume, micropore volume negatively averaged transitional volume. low average sizes have relatively high per unit nm. With increase rank, fluctuating points correspond 1.16%–1.19%, 1.41%–1.43% 1.86%–1.91% R o, max , respectively. boundary corresponding second can be more specifically defined as 1.16%–1.19% from established nominal range 1.1%–1.3%. dimension D NA1 NA2 increasing area. Furthermore, has negative correlation size, indicating smaller diameter lower content complex structure.