Laboratory Investigation Of Polymer-Surfactant Dual-Compound System And Its Influence On Stability Of Crude Oil Emulsions

In this paper, we introduce the development and research of polymer-surfactant dual-compound system, study on the influence of oil displacement agents on the stability of crude oil emulsions, the formation,stability and demulsification of crude oil emulsion. According to water flooding into later developing period for Gudao oilfield, we studied the polymer-surfactant dual-compand system in lab. However, demulsification of produced fluid became difficulty due to pouring in dual-compound system as oil displacement agent.The effect of oil displacement agents on crude oil emulsion stability were also studied for the sake of further ground processing readily. In order to find out appropriate condition for polymer-surfactant dual-compound produced fluid, the effect of oil displacement agents on crude oil emulsion stability was characterized through oil/water interfacial tension,interfacial shear viscosity, Zeta potential and so on.Sheng Li HPAM and pyrroline dual-compound system was determined in laboratory, and the complex ratio was 3:1, the concentration was 3600 mg·L-1.The viscosity of dual-compound system was 102.5 mPa·s, and the interfacial tension with crude oil was 1.99×10-2 mN.m-1 at 50℃.The indoor performance evaluation indicated that the dual-compound system had good temperature and salt resistance, and other properties. Sheng Li HPAM and pyrroline dual-compound system was in contrast to Wanda HPAM and pyrroline dual-compound system produced by Shengli Academe, the results show that Sheng Li dual-compound system performance was superior to Wanda composite system, which will have good prospects of application in tertiary oil recovery area.For Gudao crude oil and imitated produced liquid, both the demulsifier BSE-238 and BSE-401 have the better effect. We studied the trend of the oil displacement agent's influence on the crude oil emulsion's stability. The experimental result suggested that the addition of single oil displacing agent (surfactant or polymer) decreased the dehydration rate and strengthened the stability of crude oil emulsion. While two kinds of oil displacement agents had obvious synergistic effect which could obviously increase the stability of the crude oil emulsion and make the system have the lowest dehydration rate. The demulsifying condition of the simulation of the binary system flooding was as following, the optimum temperature is 60℃, the concentration of BSE-238 is 50 mg·L-1, the concentration of the acid and the salt is 100 mg·L-1, the final dehydration rate is 84.85%, while the final dehydration rate is 93.33% for crude oil emulsion without oil displacement agent.