Dariyan formation of Aptian age is major the oil reservoirs in the South Pars field. Occurrence of the world’s great unconformity at the end of Aptian, has caused the formation is strongly influenced by the meteoric diagenesis processes and development of dissolution pores. The goal of reservoir characterization is to study Reservoirs properties such as porosity, permeability and water saturation. The porosity-permeability relationships in the framework of hydraulic flow units can be used to characterize heterogeneous reservoir rocks. A flow unit is defined as correlatable and mapple zones latterally and vertically within a reservoir which control fluid flow and is significantly different from those of other rocks. Each flow unit is characterized by a flow zone indicator (FZI).