Definition of New Play Concepts in the Algerian Offshore

Kheidri, L.H., S. Ziou, N. Abdelouahab, Sonatrach, Boumerdes, Algeria

The Algerian offshore belongs to the southern margin of Algero-Provençal and Alboran Basins. The structural framework of Algerian offshore is explained as resulting from the aftermath of two consecutive phases : 1. Middle–late Miocene rifting: During this phase a dramatic extension was initiated. Depending on their geological position, during this period, the Algero-Provençal basin behave as back arc basin and the alboran basin as transtansion­al one. 2. Post-Messinian compressional evolution. During the late Miocene until now all the Algerian Western offshore is affected by a compressional/contractional regime. The subsi­dence history at these times has been considered either thermal or flexural.

In the Western Algerian offshore just one exploration well (HBB-1) was carried out, the definition of the petroleum system remains uncertain. The difference in the structural style may have a direct impact on the type of plays. Thus we can have several petroleum systems depending on (02) two previously defined basins.

   1. The Algero-Provençal basin : This basin may show two types of plays. The first Type is situated in the front of the inner zones of the chain, is associated with ramp anticlines which develop during the thrust phases southward .. The second Type, is associated to the tilted block systems which develop in the back of the inner zones . This particularly concerns Oligo-Miocene to Quaternary formations.

   2. The South Alboran basin (Habibas):The occidental part is rather characterized byplays associated to the transtensional basin system which develops in the Habibas area. Onshore