Origin of oils and source rocks characterization of the Turija-Sever oil field (SE Pannonian Basin, Serbia)

Abstract

Oils from recently drilled wells in the Turija-Sever oil field were investigated in order to understand their genetic relationships, and to define the depositional environment, thermal maturity and geologic age of the corresponding source rocks, which are still unknown. Oils from the Turija-Sever oil field are generally similar and probably belong to the same genetic type. They originate from source rocks deposited in reducing to dysoxic redox conditions, with organic matter (OM) originating from mixed marine/terrestrial sources. Slight differences among oils are reflected through certain lower contribution of algal OM to oils from the northern part of the field and/or its faster degradation under dysoxic conditions. Oils were generated from source rocks in an early stage of oil window, corresponding to vitrinite reflectance between 0.60 and 0.65 %. Source rocks are of Tertiary age. Estimated source rocks depth interval and temperature interval of oil generation correspond to 2300 m – 2500 m and 124 °C – 138 °C, respectively.