An Investigation of the Coal Seam Gas Content and Compositon in Soma Coal Basin, Turkey

The Miocene Soma Basin in Turkey is estimated to contain at least one billion tons of lignite and about half of this reserve is present at depths greater than 600 m. In the Soma Basin, Turkish Coal Enterprises (TKI) has conducted open cut coal mining and underground coal mining activities for several decades in the Northern and Central part of the basin. It is known from the mining operations that the Soma coal basin has considerably gassy coal seams, but until now there isn’t any sufficient scientific and technical research about gas content and composition of coal seams in the basin. Recently, coal exploration activities have been extended to the Southern part of the basin by means of exploratory drilling. In this context, 49 coal core samples were collected and were analysed in terms of gas content and composition. The gas content measurements indicate that as much as 4.2 m3/t coal is present in the coal recovered from 1010.50 to 1010.90 m below the surface. The composition of the gas is dominantly methane with more than 80 %. Considering the chemical composition of the gas and gas indices, the source of the coal gas is biogenic probably generated by bacteria that are introduced to the coal seam by fresh water following mainly the normal faults bordering the graben structure. The possibility of coalbed methane potential of the basin is also investigated with regard to preliminary gas content data