Permeability, rock type and core facies are the most important parameters of the reservoirs. It has been attempted in this study that above parameters are predicted indirectly from electrical logs by using fuzzy logic and fuzzy possibility method. Then the obtained results are compared with the core data. For this purpose, core data and logs of two wells in Coastal Fars gas field are used. This soft computing concept of fuzzy logic has been around since the 1960’s, but has only recently been applied to reservoir characterization and in use modeling. This is mainly due to the dramatic improvement in the speed of computers. The results reveal a very good match between the measured core data analyses and the fuzzy logic determination of permeability, rock types and core facies.