Geological Characterization of Lower Devonian Reservoirs in Reggane Basin, Algeria

In the Reggane basin, the most promising petroleum system is represented by the Lower Devonian, Cambro-Ordovician, and Carboniferous reservoirs. Most of the traps are linked to structures with very complex geometry, generally leaning on reverse faults, under superficial detachment levels. The generation of hydrocarbons took place, in the Paleozoic during the burial period (Upper Devonian-Carboniferous) and probably during the overheating of the Jurassic. The basin architecture is the outcome of a superposition of several tectonic phases from the Caledonian to the Hercynian tectonic events. The main reservoirs are in the North-East part of the basin, namely the Lower Devonian, Ordovician, and Carboniferous. The Gedinnian and the Siegenian are the main reservoirs of the Lower Devonian sequence, with the Emsian as a secondary reservoir. The Carboniferous and Ordovician reservoirs became targets after the discovery of dry gas in the Kahlouche and Anzeglouf areas. The main gas fields in the Reggane basin are Hassi-M’dakane, Feidjet-El-Had, Kahal-Tabalbala, Djebel-Hirane, Kahlouche, Tiouliline, Reggane, Azrafil, and Anzeglouf. The current geometry of the Reggane basin is marked by two major structural axes, resulting from a complex tectonic history. Reggane basin is elongated NW – SE, relatively asymmetric. The southern flank of the basin is characterized by a hallow dip plunging towards the North and affected by rare reverse faults. On the other hand, the northern flank is affected by many faults and folds. These faults arrangement of the various faults that have affected this basin can be broken down into two main sets: NW - SE set: this direction is very important; it all appears along the northern edge of the basin and presents a comparable direction to the Ougarta ridge. A set of submeridian directions: concentrated in the SE part of the basin (eastern periclinal closure constituting the transition zone between the Reggane basin and the Azzel Matti slab). This fault sets form an extension of the major submeridian accidents in the Hoggar shield. Two other directions of less represented the E-W faults forming an accident relay along the edge of the basin with the Ougarta ridge and the NE - SW faults. This study will help to define the quality and extension of the Lower Devonian sandstone reservoirs in the northern part of the Reggane basin, the construction of favorable zone maps for exploration with risk-weighted reservoir spaces, identification, and evaluation of "Tight Gas Reservoir", and trap analysis and petroleum potential the Reggane basin.