A Newly Re-Emerging Petroleum Area on the North Africa Plate Margin: The Sicily Channel

Fink, Paul; Zimmer, Wolfgang
ADX Energy, Vienna, Austria.

The multi - play hydrocarbon province between Sicily and Tunisia has recently experienced a significant increase in exploration activity. Tunisia has seen its first ever deep water offshore well (ADX, 2010) and large gas discoveries offshore Sicily. Several companies - including the majors - have covered the area with large dual sensor 2D and 3D seismic surveys.

The area is tectonically complex, but offers two outstanding exploration attractions, i.e. the possibility for very large structural traps and several - partly independent -oil and gas play types. On the other hand some of the geological reasons and perceptions why exploration activity during the past 25 years was minimal are still present. Examples from the large dual sensor 3D survey recently acquired by ADX in Italy and Tunisia will demonstrate how many risk factors can be reduced.

The area contains in a very general sense moving from SE to NW three different tectonic areas, each with different risk profiles of the several petroleum systems: A classical foreland belt with mainly normal and wrench faulting, an inverted foreland basin, several flexural belts with the inner zones being progressively more deformed and thrusted. In order to conduct successful and risk mitigated exploration in each of these areas, the major unconformities and related tectonic events need to be correctly identified on seismic. One key to success is the ability to map the Oligocene (Pyrenean) unconformity beneath which a proven Mesozoic oil and gas condensate system is developed, mainly in carbonate reservoirs. Seismic data acquired in the past failed to image this unconformity and the structures beneath, whereas the data acquired over the last two years shows excellent resolution. In addition to the definition of structuring and related erosional levels, the area and burial depth of related hydrocarbon charge areas can be defined and thereby quantify the CO2 risk created by overheated carbonates.

Post this unconformity, clastic sedimentation dominated as a consequence of the evolving Alpine orogeny. Several key unconformities exist and can now also be defined on seismic with high confidence, thus reducing risk and understanding the overprint on older - pre Pyrenean structures. Whilst the several play types do exist in almost all tectonic belts, their risk profile varies significantly from the foreland to the inner zone.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012