The Study Of Enhanced Oil Recovery Technology By Using Active Polymer After Polymer Flooding

To enhance oil recovery after polymer flooding, an active polymer was designed based on the characters of low remaining oil saturation and scattered remaining oil distribution. The synthesis conditions of active macromolecule were optimized with the molecular weight of product as index. The active polymer with 355×104 molecular weight was synthesized and characterized by IR and NMR.The experiment results in doors indicate that the 27 minutes solution time of active polymer is less than HPAM's solution time at the same situation. The viscosity of active polymer aqueous solution is 26.9 mPa.s and lower a little than HPAM when its mass concentration is 1500 mg/L. Compared with HPAM, the viscosity of active polymer aqueous solution can be effected more little by temperature, mineralization of water and shearing. The surface tension of active polymer aqueous solution is 46.03 mN/m and lower than HPAM when its mass concentration is 1500 mg/L. The temperature resistance of the active polymer is more excellent than HPAM. The viscosity of active polymer aqueous solution only reduces 10.1% during 98 days at 70℃.The microstructure of active polymer in water was studied by dissipative particle dynamics simulation, atomic force microscopy, freezing corrosion transmission electron microscopy and scanning electrical microscopy. The results show that the spherical micelle, the tubal micelle and the tridimensional network structure were foamed in turn with the gradually increasing of active polymer concentration. It is clearly that the oil is peeled from bore throat surface by aqueous solution and dispersed in active polymer solution by capillarity and solublization of micelles formed by active polymer molecules.The results of physical simulation flooding experiments indicate that the oil recovery can be increased more than 10% by injecting 0.3PV 1500 mg/L active polymer after HPAM flooding. The scope of EOR by active polymer is more than the second HPAM flooding.After polymer flooding, partial HPAM is resorted in reservoir. The molecular of these HPAM is decreasing with the increasing of residence time. At the same time, its degree of hydrolysis is increasing. The viscosity of solution composed with active polymer solution and HPAM solution is less little than the viscosity of active polymer solution. It indicates that the interaction between active polymer molecule and HPAM molecule is existent.