Tendouf Province

Collaborating Authors

Tendouf Province

A Geochemical Potential Review of the Tindouf Basin, Algerian Sahara

Takherist, D. (Division Exploration, Sonatrach) | Malla, M.S. (Division Exploration, Sonatrach)

OnePetroJune, 2000

Abstract. The Tindouf basin which is forming at the present time a vast E-W striking depression is bound in the north by the Anti-Atlas belt, in the south by the Eglab shield, in the East by the Boubernous arch with an extension to the West, beyond the Algerian border. The Tindouf basin, spreading over some 100.000 sq km, is quite underexplored, since only 11 wells were drilled there. Some gas shows were encountered in the sandstones of EAN-1 (Ordovician), Htn-1 (lower Devonian) and NG-1 (Tournaisian - Strunian). The main reservoir horizons are: the sandstones and quartzites of Cambrian and Ordovician, the sandstones of lower Devonian (Emsian) and of Tournaisian- Strunian. All the horizons likely to form source-rocks were sampled and analysed. The northern flank of the basin shows a higher organic matter ratio with the following values: - The Ordovician, of about 2000 m thick, holds clay horizons (clays of Feijas and Ktaoua, 670m and 300m thick, respectively) are organic-matter rich with a T.O.C of 2% in HMA-1. - The Upper Silurian, generally represented by the Famennian and Strunian clays, is 1600m thick with T.O.C of up 2.32% in HMA-1. As to the south flank, the source-rocks become more detritic and poorer in organic matter. - The present geothermal gradient ranges from 35.7°C/km in the north (IGA-1) to 26.3°C/Km in the south. - All the horizons are overmature (dry gas and more) in the north flank However, the maturity is decreasing progressively towards the southern flank, since it is still in the oil-phase. The southern flank of the basin is a hydrocarbon prospective area where exploration activity will certainly lead to new traps highlight, related to structures and noses. INTRODUCTION To determine the source-rock levels, based on sampling and analysis of all the beds susceptible to The Tindouf Basin is an asymmetrical contain these rocks. pericratonic basin (Fig.1). Its southern flank has a To describe the state of maturity of the organic very low deep whereas the northern flank is steeply matter and its evolution through time. upright and strongly tectonised. The sedimentary To estimate the quality and amount of the series are some hundred meters thick in the south hydrocarbons generated. and reach over 8500 m in the centre of the basin. They consist essentially of Palaeozoic shaly deposits. A thickness of the Mesozoic sediments 2. GEOLOGICAL FRAMEWORK does not exceed 150 m. In general all the series 2.1. Geological Setting thicken from the south to the north. The Tindouf The Tindouf basin is located in the far southwest of basin is practically unexplored (Fig.2) and only 11 the Western Sahara. It is defined by the following wells were drilled in an area of about 100.000km

OnePetro

WPC

WPC-30115

16th World Petroleum Congress