Structural Model of the Algerian Offshore: Impact on Style and Dimension of Traps

Nabil Saadallah* and Mohamed S. Tighilt, Sr.
Sonatrach, Algeria
*[email protected]

Algeria is structurally subdivided into two major tectonic provinces that are separated by the South Atlas Fault zone. In the south, the Sahara Platform is characterized by a thick sedimentary series with structures that formed during the Paleozoic Era. In the Northern Province, the Alpine domain is marked by Cenozoic mountain chains (Alpine orogenesis). The Sahara Platform holds most of the country’s hydrocarbon resources, and intensive exploration has resulted in a more certain estimate of its petroleum reserves and resources. The Northern Province, including the Algerian offshore, remains underexplored. Because it is a part of the Alpine domain, the geology of the Algerian offshore is extremely complex, The Algerian offshore covers a surface area of approximately 100,000 square km located in the southern part of the Mediterranean Sea. The stratigraphy and petroleum systems of this basin are very poorly known. Borehole penetrations include one well (HBB-1) and two core drills (ARZ-1 and ALG-1). In addition 9,000 km of 2-D seismic data were acquired. The interpretation of the seismic data revealed important aspects such as basin geometry and the thickness of the sedimentary cover. The interpretation led to the subdivision of the stratigraphic units in the eastern part of Algerian offshore. This presentation will show a more detailed geodynamic model with a new interpretation of each sedimentary sequence. It will discuss their deformation style, show balanced cross-sections and the calculated extensional rates. The proposed structural model suggests an architecture involving pull-part basins. The impact of this structural modeling on the petroleum system will be related to the prediction of trap dimensions in the sedimentary cover.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain