Experimental study on separate injection of combinational polymer slug

Pu I1-4 oil layer in the eastern part of Fault 140 in Naner area of Saertu Oilfield is mainly multisegment, multi-rhythm and positive rhythm.The average porosity of Pu I1-4 oil layer is 30.0%, the average air permeability is 1 980×10^-3 μm².At the end of water flooding, the average water cut is 92%, and its recovery factor is 39.5%.It is planned that polymer flooding will be carried out in this block.According to experiences it is believed that modified injecting polymer technology of combinational slug can improve the cont rolling action of fluidity.How ever, the research is little on how to improve polymer flooding effect and the influence of separate injection time in injection well and injection intensity on development effect. Experimental combination polymer flooding has been carried out through separate injection by modifying injection intensity under different injection time (water flooding stage, water cut decline stage, water cut steady stage and water cut recovery stage) polymer, and modified injection intensity further when the water cut recovery is rise again.Evaluation has been conducted on different flooding scenario by comparing the effect of each flooding scheme.The results show that polymer flooding recovery increases by 19.07% comparing with water flooding when not carrying out separate injection.In addition, separate combinational injection can enhance flooding effect on the basis of not separate injection.Recovery increasing degree by carrying out separate injection in water flooding is the highest, being 26.55%.Recovery increasing degree decrease when the injection time was later.Therefore, the earlier of the separate injection time, the better of the flooding effect.