Lower Devonian Combined Traps Ahnet Basin Western Sahara- Algeria

Ragmani Athmane.R¹, Boukhallat Saad.B¹, and Azni Lynda.A^2
1Sonatrach Exploration Algeria, Boumerdes Algeria, Algeria
²Sonatrach Exploration Algeria, Boumerdes Algeria, Algeria

The Ahnet basin located in the western part of the Saharan Platform, exhibits several features witnessing very important and complex structural history. Since exploration was focused on Ahnet basin, several gas accumulations were discovered in various reservoir formations of several ages, like the Ordovician, Lower Devonian and Tournaisian – Strunian. Geochemical analysis and modelling reveals that Silurian and Frasnian shales are widespread in the area and represent the main source rocks in the entire basin. Modelling of the thermal history shows that the complexity and the variability of hydrocarbon generation process and degree of filling of the traps. Lower Devonian reservoirs, Gedinnian top Siegenian and Emsian are major exploration and production targets in Ahnet basin. 03 of the 07 In Salah Gas fields are located in this area. During the Palaeozoic, there was no evidence of major tectonic activity has been. High frequency, in particular during Gedinnian, sea level changes and subsidence rates mainly controlled the depositional framework of the Palaeozoic sediments from the Cambrian to the end of Carboniferous.
Many of non conventional play types has been identified in Ahnet and Gourara basin wich is represent the extension to the north Tournaisian paleo valleys, Strunian turbidites, Emsian shorefaces and Gedinnian stratigraphics.
Numerous combined traps can be expected regarding the Lower Devonian facies variations related to the structural configuration of the Ahnet Basin.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece