Importance of Time of Hydrocarbon Expulsion and Erosion on the Petroleum System in Gemrik Field, Southeast Turkey

Abstract

Gemrik Province is located in a structurally complex area on the north of Bozova Fault, southeast Turkey. Several source rock intervals have been identified in the study area which are clayed limestone of the Karabogaz, Karababa-A, and Derdere Sferli. These source rocks are responsible for sourcing the Karababa-C reservoir rock. The source rocks are composed of Type II kerogen with the initial TOC ranging from 0.95 – 2.25 %. The HI values of these intervals are between 440–550. These values indicate that the Cretaceous Karabogaz, Karababa-A and Derdere Sferli source rocks have enough potential for hydrocarbon generation and they are mostly in oil window, but the hyrocarbon expulsion time and the preservation of trapped hydrocarbon are the other critical issues for the petroleum system. The hydrocarbon generation in Gemrik started in Middle Eocene time (42 Ma ago) and the expulsion occured between Oligocene to Upper Miocene time (30 Ma-15 ma ago). The area was exposed to the multiple erosions during Tertiary, as it was tectonically active. Especially, the region was uplifted during Middle to Upper Miocene time causing the removal of the Oligocene, Eocene and Paleocene sediments in the area. As a result of that the temperature decreased, the maturity remained stable and finally hydrocarbon generation and migration ended. Also, the uplift resulted in occurence of the fractures on the seal rock resulting in the loss of the already trapped hydrocarbon. Gemrik Field is a good example to show the risks of oil and gas exploration in the areas where there is no hydrocarbon generation or expulsion for a long time period.

AAPG Datapages/Search and Discovery Article #90194 © 2014 International Conference & Exhibition, Istanbul, Turkey, September 14-17, 2014