Comprehensive Research on Foam-Assisted Oxygen-Reduced Air Flooding in Changqing Triassic Extra-Low Permeability Reservoirs

Abstract

For Changqing Triassic extra-low permeability reservoirs,due to poor reservoir physical property, high filtration resistance, existing natural micro-fractures, water flooding development has great difficulty. Foam-assisted oxygen-reduced air flooding technology has distinct advantages for extra-low permeability reservoirs on improving oil recovery and it combines the advantages of foaming flooding and air flooding with low cost and obvious incremental oil effect. In the meantime, injection of oxygen-reduced air could reduce explosion risks which is significant for field implement. Recent years, based on the water flooding development, foam-assisted oxygen-reduced air foam flooding tests have been conducted. Relying on these tests, the micro-displacement mechanisms have been deepened, flooding systems have been developed for extra-low permeability high salinity reservoirs, and the matching injection-production parameter optimization technologies and safety monitoring and controlling system have been formed, the explosion limits and oxygen reduction limits have been determined, an overall technological process which is integrated and effective covering from the injection to the production has been established, and obvious effect has been obtained. The main purpose of this paper is to summarize achievements and knowledge of researches and tests and form a technical system, which has crucial significance to the further promotion in extra-low permeability reservoirs of Changqing oilfield, and also provides a certain degree of references for the development of similar reservoirs in the world.