Preliminary hydrocarbon source rock assessment of the Paleozoic and Mesozoic formations of the Western Black Sea region of Turkey

Source rock maturity and potential of Paleozoic and Mesozoic formations in the Eregli, Zonguldak, Bartin, Ulus, and Eflani subregions of the western B lack Sea region (WBSR) have been investigated by rock-eval pyrolysis, refle cted-light microscopy, and palynofacies analyses. The %Ro values of dispers ed organic matter of the Paleozoic formations primarily range from 0.72 to I.8%, but values as high as 2.6% occur locally in the Silurian Findikli For mation in the Eregli subregion. The %Ro values of Namurian-Westphalian coal seams in the K20/H well drilled in the Zonguldak subregion range from 0.87 to 1.52%, with increasing depth consistent with sedimentary depth of buria l. Most Cretaceous age samples have reflectance values ranging from 0.44 to 1.6%Ro that indicates they are marginally mature to mature with respect to the oil window. Rock-eval pyrolysis demonstrates that the Paleozoic format ions have limited oil-generation potential (HI values < 200 mg HC/g C-org) but good gas potential (TOC values rip to 3%). Cretaceous formations have b etter petroleum source rock characteristics but they too are primarily gas prone. Variations in the source rock maturity probably reflect variable bur ial histories in different localities of the WBSR.