Contribution of Mineral Impurities to Coalbed Methane Accumulation and Retention

Abstract

The implemented research shows that coalbed gas content in face area is proportional to pyrite content of coal, calculated with respect to iron and sulfur contents determined on X-ray fluorescent spectrometer. These results confirm the hypothesis on methane formation in coal during recovery of carbon oxides in the presence of iron-bearing minerals, in particular, pyrite, and water, and explain different contents of methane in the same rank coals. The obtained inverse proportion between the coalbed gas content in the face area and the sorption surface of coal allows supposing that methane accumulations concentrate mainly in the "solid solution" and in the closed porosity, i.e. in the coal structure. For this reason, it is more difficult and longer to recover such methane from coal than methane accumulated in open pores and fractures, which quickly leaves coal in face area.