Injection of CO 2 into a reservoir for enhanced oil recovery (EOR) results in complex uid phase behaviour that require accurate reservoir uid characterizations by equations of state (EOS) to capture the phase interactions in miscible CO 2 oods. Amal is a giant Libyan eld classied as low shrinkage type of oil and characterized by relatively law solution gas-oil ratio (GOR) of 400 scf/STB and oil gravity of 35 ºAPI. The eld has been producing since1960's under active bottom water drive that maintained the current reservoir pressure at levels higher than the bubble point pressure. The main objective of this paper is to establish an EOS model able to characterize Amal phase behaviour accurately in immiscible and miscible conditions. A model that statically validated against the conventional PVT data and dynamically validated to match the slim-tube experiments. Three parameters PengRobinson (PR) and Soave-Redlich-Kwong (SRK) equations of state are used to model the Amal phase behaviour. In addition, 1-D slim-tube model is built using commercial compositional simulator to simulate four slim tube experiments. The outcome revealed that conventional PVT data will not reect the proper phase behaviour model when it was used to simulate the slim tube experiments. Therefore, further eorts are giving to EOS tuning. Also, the lumped compositional model was not so perfect to simulate the hump phenomenon in slim tube experiments like extended model did. Perfect match of all slim tube experiments from immiscible to miscible conditions at pressures of 2000, 3000, 3600 and 4000 psia were achieved indicating the validity and reliability of the realized phase behaviour model.