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Pierre F. Burollet1, Fathia Mejri2, Hatem Ben Kilani2, Kamel Ben Boubaker2
(1) CIFEG, Forcalquier, France
(2) ETAP - Tunis

Abstract: Deep prospects in Tunisia

In Central and Eastern Tunisia, generally, the exploration wells were bottomed in various levels of the Cretaceous, rarely in Jurassic. Very few of them reached the Triassic, none the Pre-Triassic basement.

During the last 50 years several hypothesis were proposed on the role of the basement due to special projects such as gravimetric surveys and the European Geotraverse.

Recently, in NE Tunisia, ‘Utique I’ well went through thick Triassic carbonates with good porous horizons; they produced CO2 due to their vicinity of basement blind thrusts. Deep oil and gas shows have been reported from Malta in Jurassic and Triassic facies, resembling those of SE Sicily.

Important gas shows have been observed in Jurassic dolomitic limestones (ABK 1-2). Source beds are described along the NS Axis, both in Triassic and Jurassic series. So, below Eastern Tunisia, Lower Mesozoic objectives exist. They would be very deep (4 to 6 km) except on both sides of the NS Axis where they could be shallower.

On the other hand, Eocene and Late Cretaceous fractured carbonates are known in N Tunisia where they produce oil and gas (Belli, Zinnia, etc.). They may be interesting objectives below the Tellian and Numidian nappes, especially the Eocene Bou Dabbous Limestone, rich source bed, which may be observed with large thicknesses in the Nefza tectonic window. It has given important oil and gas shows in wells near Bizerte. It would be sealed by the thick Souar Shale and buried below the thick Numidian nappe.

South of Central Tunisia, around Gafsa and Tozeur, deep wells could reach Pre-Triassic series. Oil and gas are produced South of the Chotts in Triassic and Ordovician sandstones, from Ordovician or Silurian source beds.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana