--> Abstract: Geology and Coal Resources of Zonguldak Basin (Northwest Turkey) as a Potential Source for Coal Bed Methane, by M. N. Yalcin; #91004 (1991)

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Geology and Coal Resources of Zonguldak Basin (Northwest Turkey) as a Potential Source for Coal Bed Methane

YALCIN, M. NAMIK, Tubitak, Marmara Research Center, Gebze, Turkey

The Carboniferous clastic sequence of Zonguldak basin contains several coal seams that have been mined since 1848 by underground methods. Coal seams are located in a Namurian to Westfalian D progradational delta and fluid plain sequence that is approximately 3500 m thick. These units are affected by Hercynian orogenic movements. Related tectonism and uplift led to a widespread erosion. Consequently, younger units, mainly Cretaceous shallow-marine carbonates, rest unconformably on different sections of the Carboniferous strata.

There exist up to 8 coal seams in Namurian, 20 to 26 in Westfalian A, and up to 8 coal seams in Westfalian B, C, and D. The average combined thickness values are 8 m, 34 m, and 7 m, respectively. However, due to the lateral changes in seam thickness and due to the erosion, both the number and combined thickness of coal seams may change remarkably. Majority of the coals in the exploitation area are of highly volatile C to A bituminous rank. Vitrinite reflectance values range from 0.6 to 1.2% [R(0) mean]. However, to the north below the Black Sea and east below the cover beds coaly units are buried deeper. Consequently, both rank and maturity are expected to increase. Methane content of some coal seams is determined by desorption data which indicate a methane content of 5 to 16 m per to of coal.

In addition to classical methods, data from some deep wells have been used to determine the thermal history by the method of basin modeling. Amount of gas generated in coals is then computed with the help of a kinetic approach. Furthermore, timing of gas generation has also been determined, which enabled consideration of migrational and diffusional gas losses.

Data from coal geology, geochemistry, and modeling are combined to evaluate the coal bed methane potential of the basin in an integrated and quantitative manner.

 

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)