The petroleum system of the Oudna field (offshore of northeastern Tunisia) in the geodynamic context of Sicilian-Tunisian Strait

  The Oudna field part of the offshore northeastern Tunisia, straddles between two structural domains, the Tunisian Atlas to the north and the Pelagian Sea to the south. The study of this field has confirmed adequate petroleum system in Fahdene Formations (Albian-Cenomanian) and Birsa (Serravallian) resulting from the combination of several sedimentary, tectonic and thermal factors. To do this, we have identified on the different seismic profiles the horizons corresponding to the top of the tertiary formations. As a result, the isochron and isopach maps of these horizons that have shown the existence of three network faults represented by two main directions of NW-SE and NE-SW and a minor EW direction. The distribution of hydrocarbon indications in boreholes is controlled by NW-SE faults (pervious) and NE-SW faults (sealing). These lineaments are the result of the Alpine tectonics (Atlasic in Tunisia) which played a very important role in the structuring of the Gulf of Hammamet. During the Tortonian phase (NW-SE maximum horizontal stress), the region was characterized by reverse kinematic NE-SW faults and normal NW-SE faults contributed to structuring a hydrocarbon traps, associated with NE-SW trending faults. In Plio-Quaternary, the NW-SE grabens (as continental rift Pantellaria part of the Sicily Channel) were formed and associated with an alkaline volcanism. These grabens are the result from the migration of the subducting plate (slab) from west to east, at the Tyrrhenian Sea.