Research on Microemulsion Flooding System for Low Permeability Reservoirs in Daqing

Daiyin Yin, Tingting Jiang

Abstract


Based on the problems of the low recovery caused by the conventional water flooding and the great risks to improve the development effect in the low permeability reservoirs, the microemulsion system is prepared to enhance the oil recovery. The interfacial tension and adsorption properties of different surfactants are evaluated, and the cetyl hydroxyl-sulfobetaines surfactant (THSB) is selected as the main surfactant in the microemulsion system with the low interfacial tension and the critical micelle concentration is 0.9%. According to the advantages of compounding the same type of surfactants, sulphobetaine series SB4 and SB11 are added into the selected system to form compound systems, respectively, and the later one can reach a better performance. When the mole ratio is 6:4, the ultra-low interfacial tension can be reached and the critical micelle concentration (CMC) is reduced to 0.5%. Meanwhile, the effect of alcohol type and concentration on the microemulsion system are investigated. When the concentration of n-decyl alcohol is 1.2%, the compound system interfacial tension decreased significantly. Meanwhile, the results are explained and illustrated in solid theoretical basis. At last, an indoor flooding experiment is conducted to evaluate the performance of microemulsion system. The results show that the compound system with THSB-SB11 and n-decyl can improve the recovery by 11.36%. According to the experimental results, this microemulsion flooding system can be widely used in the low permeability reservoirs in Daqing.


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