The Petroleum Generation Potential of Greece

Nickos Rigakis, Konstantinos A. Nicolaou, Nikolaos Roussos, and Fedon Marnelis
Hellenic Petroleum SA, Maroussi, Greece

Greek geological provinces are separated into Eastern post-orogenic basins with Tertiary clastic sediments and Western thrust fold belts with Mesozoic carbonates.
Most explored Eastern basins are W. Thrace, Prinos, Thermaikos and Grevena. Hydrocarbon source rocks have been identified within Miocene and Upper Eocene clastics, rich in TOC and organic matter with high quantities of terrigenous input. The expected hydrocarbons are both oil and gas.
In Western Greece have been identified four source horizons in the Mesozoic sequence of Ionian zone. The best source is the Posidonia beds, Lower Toarcian age rich in organic matter of marine origin. Very good source horizons have been identified within the Triassic sediments, while shales of Albian-Cenomanian age are potential sources in eastern Ionian. Minor potential source is the Upper Posidonia beds. In Preapulian (Paxi) zone the main source horizon is the Upper Jurassic shales. All these sources are capable to produce oil. Possible hydrocarbon sources have been found in the post-orogenic sediments, capable for gas generation.
Oil window is located quite deep in the central parts of Western Greece basins, while in Eastern Greece is found in shallower depths, due to higher geothermal gradient. Lower maturity in W. Greece favors oil generation and preservation in deep areas, under Triassic evaporites.
Oil presence in many wells drilled in Greece, along with the hydrocarbon discoveries and the abundant oil seeps, indicates that oil generation and migration has taken place in all the above sedimentary basins.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece