The main geothermal reservoirs in the south Algeria and their interest for local economic development

The study area is one of the important geothermal provinces in south Algeria. It is characterized by a hot arid climate with intense dryness and very high evaporation rates. The Albian geothermal system is exploited by the wells mainly for domestic and agricultural purposes. The sandstone Continental Intercalary (CI) formation constitutes the reservoir for the Albian aquifer, covering an area of 600,000 km(2). This reservoir is covered by calcareous formations which yield the chemical characteristics of highly mineralized Na-Cl type representing the deep thermal waters and Ca-SO4 type determined the presence of evaporate lithology. For a better understanding of geothermal reservoir characteristic, a multidisciplinary approach was adopted, including hydrogeochemistry and geothermometry. More than fifty samples collected from wells recently in 2017 with a temperature average between 38 and 60 degrees C and conductivities range from 2010 to 3460 mu S/cm. Geochemical analysis of those thermal waters exhibits a certain degree of salinity with sodium-chloride type waters domination. The maximal geothermal reservoir temperature estimated using geothermometry is about 120 degrees C.