Abstract: Gas injection into fractured reservoirs can maintain the formation pressure and improve the displacement efficiency. This paper reviewed the development of EOR by gas injection in fractured reservoirs of the world, and analyzed the general production characteristics during gas injection in fractured reservoirs. It also showed the present laboratory techniques and mathematical simulation techniques in this field, and discussed their limitations. Conclusions were made that the fracture distribution severely affected the gas displacement performance, and that gas breakthrough may not be faster than water breakthrough, and that the sweep efficiency in a gas injection process may be larger than that in water flooding. For the porous media will affect the phase behavior and miscibility and mechanisms during gas displacement, the suggestion were made that further experimental and theoretical researches should be done on gas injection in fractured reservoirs regarding the effects of porous media.

Key words: fractured pool, EOR, gas injection, miscible displacement