Ali Gaaya¹, R. Ghenima¹, M. Saidi¹
(1) ETAP, Tunis, Tunisia

Abstract: Major and potential petroleum systems in Tunisia prospectivity and expectations

Around 480 wildcats have so far been drilled in Tunisia, resulting in 60 discoveries, 29 of which are producing fields at present. Three fields provide 77% of the national oil production. These fields (El Borma, Ashtart and SLK) are a clear illustration of three major and prolific petroleum systems:

1. The oldest proven petroleum system is formed by Silurian and Devonian black shales. Most prospective areas are located in the Ghadames basin (e.g.: El Borma giant field) and the Chotts area. The total proven hydrocarbons “in-place”, range between 3 and 3.5 Bb of oil and between 2 and 2.2 Tcf of gas.
2. The Cretaceous Petroleum System relies on two important source-rocks: the Albian-Vraconian shales (L.Fahdene Fm), and the Cenomano-Turonian platy limestones (Bahloul Fm). Most prospective areas are located within the Central Platform (e.g.: SLK field) and its extension offshore in the Pelagian basin(e.g.: Miskar gas field). This Petroleum System sourced 910 Mb-1060 Mb of oil, and 3.6 – 3.9 Tcf of gas.
3. The Ypresian represents the second overall producing Petroleum System in Tunisia. The source-rock is represented by limestones interbedded with blackshales (Bou Dabbous Fm). 10 discoveries have so far been made, the largest being the Ashtart oil field and the Hasdrubal gas field. Proven hydrocarbons in-place are estimated at 1.4 – 1.7 Bb oil and 1.4 – 1.6 Tcf gas.

Several other petroleum systems, either proven (Jurassic), but as yet of limited extension, or potential (e.g.: Ordovician, Permian, etc…) can make a significant addition to Tunisia’s oil and gas production.

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