The Experiments Of Cationic Polymer Profile Control And Oil Displacement After Polymer Flooding

Polymer flooding is widely used as a tertiary oil recovery method to make great contribution to oil development. But the decrease of capability of oil production rate maintenance, the rise of water cut and the reduction of oil output appear during the succeeding water displacement in the polymer flooded oil fields. In order to solve these problems and improve the development efficiency, it is urgent to find a new method to improve the oil recovery succeeding polymer flooding. The distribution of residual oil is firstly studied on the basis of Zhong Er-nan block of Gudao oil field so as to make an effective measure. According to the characteristics of the large quantity of remained polymer and the seriously heterogeneous oil layers of the polymer flooded reservoir, three types of profile-control agents are studied, including the cationic and anionic polymer profile-control agent, the cationic and anionic polymer adding coal ash profile-control agent and the crosslinked gel. The last one is a new type block agent based on the polyacrylamide dispersed in water. In order to strengthen the blocking intensity of flocculus in the high permeability reservoir, coal ash is added into the crosslinked system.The dosages of these profile-control agents are optimized through experiments. The blocking strength and the wash resisitance of them are also researched. The cationic polymer of the profile agents also has the ability to improve oil wash efficiency. Its mechanic of oil displacement and the oil displacement efficiency are studied. And the oil displacement efficiency of cationic profile-control agent is also studied in the sand packed pipes with high and low permeability to simulate the heterogeneous reservoir.The results show that the profile-control agents can react with the entrapped polymer to enhance the plugging strength for the large porous channels and improve oil sweep efficiency in the polymer flooded reservoir. And the effective driving manner is to modify the injection profile in the polymer flooded heterogeneous reservoir.