Organic geochemical characteristics and hydrocarbon generation potential of the Artova and Zile Tertiary coals (Tokat)

The organic-petrographic and organic-geochemical characteristics and hydrocarbon-generation potential of coals of the Tokat Province, formed in a limnotelmatic depositional environment- namely, from Zile and Artova counties, in the western and southwestern parts of the province, respectively - were evaluated within the scope of this study. Two coals seams with a total thickness of about 17 m in the vicinity of Zile are being mined by open-pit method and are used in nearby population centers. Organic-geochemical evaluations were done using Rock-Eval pyrolysis and GC, GC-MS and C13-isotopic analyses such that the amounts and types, as well as the degree of coalification, of the organic matter were determined. On the basis of organic-petrographic, coal-quality and maturation characteristics, the highly variable Artova and Zile coals are classified as sub-bituminous. The results of Rock-Eval analysis indicate type II/III and type III kerogen. The organic components of the coals are predominantly huminite-group macerals and, to a lesser extent, are from the inertinite and liptinite groups. Furthermore, the coals have high ash and sulfur contents. On the basis of maceral contents, the depositional environment of these coals was either a forest swamp or lake. The organic-matter contents and types suggest potential for gas generation rather than for petroleum generation.