Feasibililty Assessment Of Air Injection EOR For Xinjiang Oilfield In Low Permeable Reservoirs

There are many low-permeability, low-porosity, high-pressure and low-temperature light oil reservoirs in Xinjiang oilfield. It is difficult to be produced efficiently. This paper studies the feasibility of air injection for the four low-permeability blocks Cai 9, Shi Nan 4, Sha Qiu 5 and Lu 9 from theoretic calculations, laboratory experiments and experience. Results show that the four target blocks can all be suited to be produced through air injection. Among them, Cai 9 is selected for further evaluation and field experiment design.In theoretic calculations, this paper analyzed the factor to air injection from a large amount of actual example in abroad and internal, established the index which be used to screen reservoirs and corroborated the index's extent by theory and practice, acquired the weight of index by the method of fuzzy gradation analysis, evaluated the air injection's congruence of reservoirs by fuzzy synthetic evaluation and conducted simple economic analysis. Finally the screen software is formulated by VB and used to screen the candidate target blocks.In laboratory experiments, the four candidate blocks are studied about the reaction activity of crude oil and air by static oxidation experiments. Also temperature, pressure and clay content are studied about how they affect the reaction rate. Finally results show that Cai 9 is optimum for air injection. Next Cai 9 is further studied through dynamic flooding experiments and EOR experiments. Results show that the oxygen can be consumed and the recovery can be improved in reservoir conditions. The screen model is also proved to be correct by the laboratory experiments.