Determination of reservoir rock type is one of the most important tasks for simulation, modelling and prediction of the hydrocarbon reservoir behavior. Hence, using methods that predict rock types as accurately as possible, is of great importance. In this study, some of the most useful methods were applied, including the Flow Zone Indicator method, the Winland R35 method and the Stratigraphic Modified Lorenz Plot. The methods were applied to the Whicher Range gas field in the Western Australia. The data set consisted of 377 core data from four different wells and included: depth, air permeability, reservoir permeability and porosity. The main goal of this thesis is to classify the hydraulic flow units in the reservoir and predict permeability. Five flow units were obtained using the Flow Zone Indicator method and the same number of flow units were obtained for the Winland R35 method. Stratigraphic Modified Lorenz Plot resulted in one to four flow units for each well. Both of the methods, Flow Zone Indicator and Winland R35, gave a good permeability prediction with an R2 value of 0.990 and 0.970, respectively. However, the Flow Zone Indicator had best correlation for permeability prediction.