This book presents a comparison of different methods for generating PVT properties of volatile oil and gas-condensate reservoir fluids determined that PVT properties generated with the Whitson and Torp method agree the best with full EOS compositional simulation. Also, a new oil-gas ratio correlation for volatile oil and gas condensate reservoir fluids is developed. According to our knowledge, no correlation to calculate oil-gas ratio exists in the petroleum literature. Alternatively, oil-gas ratio had to be generated from a combination of laboratory experiments and elaborate calculation procedures using EOS models. Whitson and Torp’s method was used to generate our database of the MBO PVT curves used in developing our correlation after matching the PVT experimental results with an EOS model. The samples were selected to cover a wide range of fluid composition, condensate yield, reservoir temperature, and pressure. Then multi-variable regression techniques were used to calculate our correlation constants.