Influence of coal composition and maturity on methane storage capacity of coals of Raniganj Coalfield, India

Gas content of the samples lies between 3.08 and 14.96 cc/g, on daf basis and generally increases with depth. Langmuir volume (VL) for the coals varies between 17.4 and 29.8 cc/g (daf) and exhibits a moderately positive linear relationship with increase in depth (R2 = 0.58). Reflectance shows a strong linear positive relationship (R2 = 0.70) with Langmuir volume indicating the development of additional micropores with rank enhancement, thereby providing more surface area for adsorption. Gas content results are encouraging though the seams are considerably undersaturated. A very good correlation is observed for the combined effect of ash, moisture and carbon on volume adsorbed for the studied coals and can be used to predict adsorption capacity from compositional data.