Principles of Gas Injection as a Recovery Process

This course covers gas injection as a secondary recovery process. The first part concerns the basis of recovery mechanisms including natural depletion as well as the different driving forces involved in this process. The index drive notion is presented next along with the material balance principle used as a basis for deriving these indices. The second part is devoted to the fundamentals of gas injection methods. The concept of recovery efficiency and the main process parameters involved are examined. Examples are given to illustrate the importance of these parameters. Two methods of gas injection are covered in detail. The first one, the dispersed gas injection method is presented with some illustration. The procedures for using Tarner method as well as some examples are presented next. The second method or external gas injection method is also examined in relation to the frontal displacement theory as applied to gas injection. The last part is devoted to miscible gas injection with application of thermodynamic miscibility and ternary diagram. Examples of high-pressure gas drive and enriched gas drive processes are also presented. Finally, the miscible slug injection theory is introduced and some examples are given as illustrations.