Kretase Yaşlı Sapça Formasyonunun Jeolojik Konumu ve Potansiyel Hidrokarbon İçeriğinin Değerlendirilmesi, Zonguldak-Türkiye

Abstract

The Sapça Formation, which was deposited during Early Cretaceous (Albian) age, is cropped out in south of the Zonguldak Province and this formation is supposed to be deposited during the global oceanic anoxic event (OAE1b). Therefore, this study aims to determine organic maturity and hydrocarbon source rock potential of the Sapça Formation using Rock-Eval pyrolysis, organic petrography and as well as mineralogical, micro- and mesoporosity analyses. Mineralogical analyses show that quartz, calcite, feldspar and clay minerals form the main minerals of the samples collected from the Sapça Formation. Organic petrography studies indicate that the macerals of vitrinite and inertinite have been identified in the samples, in which the macerals of inertinite are abundant. Random vitrinite reflectance in the samples cannot be measured due to vitrinite size is smaller than the measurement area. Total organic carbon content of the Sapça Formation is between %0.13 and %1.41 which indicates inadequate to adequate organic richness. S1 values are between 0.01 and 0.15. S2 values, except for three samples (T-32, T-33 and KRS-29) which can be classified as fair HC source potential, are generally below 2 mg HC/g rock that indicate the formation has poor HC source potential. Hydrogen index values show that the formation contains Type II/III mixed, Type III and Type IV kerogen. Production index values indicate the formation is immature to early mature. Tmax values are between 433°C and 445°C, indicating early oil window. Micro- and mesoporosity data of selected 12 samples of the Sapça Formation as well as Tasmaca Formation and Alacaağzı Formation show that TOC values of Sapça and Tasmaca Formations increase with decreasing micro- and mesoporosity and this could be a result of immature organic matter.