The gas-bearing basin of ahent-timimoun (algeria): structural evolution and geochemical evaluation

摘要

The sector of study,as large as 120,000Km~2,is located int he Algerian Central Sahara at 800 Kms S-S/W of Algiers and 400Kms SW of hte huge gas field of Hassi R' mel (Rserves estimated at about 80 TCF).It englobs,in fact.two depressions: the Ahnet's at south,and hte Timimoun's at the North.Aside of the Hassi R'mel field,the Ahnet-Timimoun Basin contains the most important reserves of gas discovered to date in Algeria.The main gas reservoirs are known to be exclusively sandstoned and belong ot the ordovician and the Tournaisian.the present study is a contribution to the assesment of gas reserves important ones porobable,to be explored in the limits of the Ahnet-Timimoun basin.the aim is to study the gas generation and conservation conditions in the prenamed reservoirs.We connducted a paleostructural reconstitution and a geochemcial evaluation of soruce rock of the Silurian,the middle and upper Devonian,through the entyire Basin.All this allowed us to apprehend the age of the formation ofhte different structures and also to estimate the timings of generation,expulsion and settlement of gas accumulation in reservoirs.At the end,a volumetric estimation is made.