PETROLEUM SYSTEM ANALYSIS OF THE KIRKKAVAK FORMATION IN THE HAYMANA BASIN, CENTRAL ANATOLIA, TURKEY

The Haymana Basin, one of the Central Anatolian Basins of Turkey, developed from Late Cretaceous to Middle Eocene during the closure of the northern branch of the Neo-Tethys Ocean. The basin is located to the south of Ankara and has been explored for its oil and gas potential since the 1950s. The most important units with hydrocarbon potentials in the basin are the Maastrichtian Haymana and the Paleocene Kirkkavak formations. For many years, the Haymana Formation was considered the main potential source rock even though it has low total organic carbon values (TOC %); in general less than 0.5%. There is also one wildcat well drilled in 1976. The well targeted the Haymana Formation but it did not produce any oil or gas.

During this study, we have measured a complete section and collected systematic samples of the Kirkkavak Formation in the northern part of the basin. The section contains oil seeps in many locations. We have conducted geochemical analysis on the samples to determine total organic carbon (TOC %), oxygen (OI) and hydrogen index (HI), Tmax, production index (PI), and generating source potential (S2). Several exhibit good TOC, Tmax, and HI values: 1.96% TOC, 437^oC Tmax, and 511 mg HC/g Corg HI. The results suggest that certain stratigraphic intervals of the Paleocene Kirkkavak Formation has very good source rock potential with kerogen type II, which produce mostly oil and little gas. However, there are several stratigraphic intervals of the formation that should be considered as immature zone based on the Tmax and PI values.