Print this pageHistory of the Eocene Oil and Gas Fields in Tunisia: A Progressive Analogic Approach
Hela Ben Jemia1, Fethia Mejri1, and P. F. Burollet2
1 ETAP, Tunis, Tunisia
2 CIFEG, N/A, France
The authors attempt to describe the Eocene discoveries in Tunisia where hydrocarbons are hosted in Nummulites-bearing limestone widely distributed in the Palaeogene Tethyan realm.
The key play lies in the identification of facies change boundary from porous nummulites accumulation margin to deeper marine limestone (source rock) regarding concepts obtained by analogy with Libyan, Canadian and Tunisian fields. Early in the fifties, drilling activities performed on the Sfax Basin showed a hydrocarbon potential in Eocene carbonates.
The comparison of play concept with the Libyan Sirte Basin, suggested the development of high-energy carbonates above antecedent paleotopographic high and supported regional limit between the porous zones and the deep marine deposits.
An analogy with reservoir-prone reef margin was made between Eocene play and Devonian reservoirs of Western Canada (Swan Hills bank complex, Leduc reefs or Triassic Baldonnel skeletal dolomite), fed by surrounding black series.
The seismic surveys conducted in early seventies on Sfax basin provided information both on tectonic history and on structural habitat of Eocene series. The art of exploration was choosing prospects with sufficient reservoir thickness in close proximity to source rock. The new play concept was challenged at the Sfax basin with two discoveries (SIT and ASH) used as models for further intensive exploration. Similarities are recognized with the Mid-Eocene nummulites-banks producing oil and gas (Kerkennah islands). Following possible analogies with stratigraphic traps of pinch-out type as some Mississipian fields of Western Canada or the Silurian of Western Libya Tigi field, there was a research on the southern pinch-out of the Lower Eocene reservoirs.
New concept exploration pivoting around fractured reservoir was bloomed with the SLK discoveries (Upper Cretaceous chalky carbonates).
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005