Primary Evaluation of Coal Bed Methane Generation and Storage from Klariz Formation (Shemshak Group) Coal Seams in Galandrud Area, Central Alborz

With increasing the world population, domestic economies, and living standards, the demand for traditional fossil fuels has been increased worldwide, especially for the natural gas. Therefore, with the waning of conventional hydrocarbon reservoir, the exploration and production of unconventional reservoirs including gas from coal is increasingly becoming economical. Due to the vast existence of coal deposits in Upper Triassic-Middle Jurassic deposits (Shemshak Group) in Iran, which extends from the north to the centre and the east of the country, the study and evaluation of these unconventional gas reservoirs become necessary. In order to evaluate the initial volume of the produced and absorbed gas in coal reservoirs, Galandrud area in the Central Alborz was a subject of this study. To accomplish this, detailed analyses including pyrolysis, proximate, and organic petrography on the coal samples were carried out. Based on the experimental results and by using empirical formulas, the volumes of the produced and absorbed gas in the coal layers were calculated. Organic petrography showed that the coal was humic compound (kerogen type III) and vitrinite maceral was the dominant constituent which represented catagenesis degree of thermal maturation (Ro=0.6 to 0.8%) suggesting high volatile bituminous capable of producing methane hydrocarbon. The calculation based on empirical formulas showed that the amount of the produced gas per ton of coal was 5.22 cubic meters and the absorbed volume was about 0.89 cubic meters per ton of coal on average. According to the total storage volume of coal in Galandrud area, the amount of the produced methane is about 319 million cubic meters and gas in place in the coal seams in this area reaches more than 52 million cubic meters.