This book comprises a new mathematical study of multiphase multicomponent flows in heterogeneous porous media. The goal is to develop analytical models of the recovery processes from heterogeneous reservoirs based on the exact analytical solutions of equations of flow in porous media. The analytical models developed describe chemical and hot waterflooding, injection of gases and solvents in oil and gas condensate reservoirs. Analytical modelling allows a wide comparative study of application of different recovery technologies in any actual hydrocarbon reservoir and permits a detailed sensitivity study. Analytical solutions of inverse problems allow the determination of the properties of reservoirs and fluids from field test data and laboratory data. Applications of analytical models in feasibility studies, in the development planning and design, and in reservoir characterization are given with respect to numerous CIS oil and gas condensate fields. While a review of classical problems is included, the bulk of the book deals with original, unpublished material and new research. The book will be useful for researchers in petroleum engineering and reservoir modelling, for software engineers, for practical reservoir engineers and managers of reservoir studies.