The study of petroleum reservoirs includes both characterization and evaluation of the potential interval, in order to touch all the parameters related to the reservoir (geology, petrophysics, logging, formation testing), for this study 4 wells (SF-1, SF- 2, SF-3, SF-4) were selected in Birkin basin, the aim of this study is to show the high petrophysical quality of TAGI reservoir, Lower Triassic sandstone in Birkin basin, Sif-Fatima using the results of laboratory petrophysical analysis. The results of log interpretation for the four study wells led us to say that the Lower Triassic sandstone claystone has the characteristics of a good reservoir with average porosity and permeability respectively in the order of: 18.15%, 540.10 md Keywords TAGI Berkin reservoirs; Sif-Fatima; petrophysical analysis. Porosity, permeability.