This title covers a wide range of topics related to the Pressure Volume Temperature (PVT) behavior of complex hydrocarbon systems and documents the ability of Equations of State (EOS) in modeling their behavior. The main objective of this book is to provie the practicing engineer and engineering student with tools needed to solve problems that require a description of the PVT of hydrocarbon systems from their compositions. Because of the dramatic evolution in computational capabilities, petroleum engineer can now study such phenomena as the development of miscibility during gas injection, compositional gradient as a function of depth and the behavior near critical hydrocarbon systems with more sophisticated EOS models.