Natural gases have so many industrial applications that a major challenge is to develop a thermodynamic model able to predict the phase equilibrium of these mixtures. Such predictions are indeed essential for the processing of natural gases and the design of transportation facilities. The most commonly used models for this purpose are cubic equations of state (EoS) and especially the ones issued from the Redlich-Kwong and Peng-Robinson classes. The SAFT-type models are a promising class of EoS emerging since the late 1980s. Although no industrialized version of SAFT EoS really exists nowadays, proof has been given that the Perturbed-Chain-SAFT EoS can be successfully used to model natural-gas phase envelopes. The goal of this chapter is to describe and analyze the various EoS models usable for the correlation and prediction of phase-equilibrium and energetic properties (enthalpy, heat capacities, etc.) of natural gases. In the last part of this chapter, some of these models are compared on the basis of the reproduction of experimental phase-envelope data of real or synthetic natural gases