Feasibility study on high-pressure air injection for EOR in light oil reservoirs

Air injection has been considered to be an effective enhanced oil recovery (EOR) process for light oil reservoirs.During the process,compressed air is injected into a high-temperature light-oil reservoir,and the oxygen in injected air is intended to react with a fraction of reservoir oil and results in an in-situ generation of flue gases and steam.Therefore,the residual oil that is immobilized by water flooding could be driven towards producer wells.The displacement mechanisms are highly related to the oxidation behavior of crude oil.Relevant studies were involved in this paper to discuss the merits of high-pressure air injection(HPAI) in light oil reservoirs,and to demonstrate the influence of water saturation and residual oil volume on displacement efficiency.According to the investigation,a feasibility study of HPAI was conducted based on the oxidation mechanisms associated with field applications.The results shows that air injection could be technically applied for EOR in water flooded reservoirs,especially in those highly water-saturated reservoirs.An insufficient residual oil volume could universally lead to low displacement efficiency;under this circumstance,adding an appropriate content of nitrogen or absorbing particles into injected air could stabilize oxidation reaction and thus improve displacement efficiency.In addition,there still exists sorts of security concerns during field applications,so more emphases should be placed on the air breakthrough in the producers.