Application of a Modified Low-Field NMR Method on Methane Adsorption of Medium-Rank Coals

Methane adsorption capacity is an important parameter for coalbed methane (CBM) exploitation and development. Traditional examination methods are mostly time-consuming could not detect the dynamic processes of adsorption. In this study, a modified low-field nuclear magnetic resonance (NMR) method that compensates these shortcomings was used to quantitatively examine seven medium-rank coals. Based on typical T 2 amplitudes obtained from NMR measurement, volume adsorbed calculated. The results indicate Langmuir samples in range 18.9–31.85 m3/t which increases as coal rank increases. pore size 1-10 nm main contributor gas samples. Comparing isotherms volumetric method, absolute deviations between two less than 1.03 while relative fall within 4.76%. decrease vitrinite reflectance ( id="M2"> R o ) 1.08% 1.80%. These show credible measure precision may be influenced by rank.