Study On Interfacial Property And Stability Of Emulsion Of Crude Oil Or Its Components

The Gudao 5# crude oil is chosen as the object of study in this paper. The crude oil is separated into asphaltene, resin and oil by solvent extraction. Asphaltene and resin, according to the difference of polarity, are separated into five sub-fractions, A1 to A5 and three sub-fractions, R1 to R3 separately. The influence of partially hydrolyzed polyacrylamid molecular weight, concentration and dilatational frequency on dilational viscoelasticity of oil-water interface is studied. This interface contains surface-active components, crude oil or its components, asphlatene sub-fractions and resin sub-fractions. The influence of resin on stability of the oil-water interface stabled by asphlatene is also studied. And the influence of resin sub-fractions on stability of the oil-water interface stabled by asphlatene or its sub-fractions is researched.The results show that, the Gudao 5# crude oil is heavy petroleum, and the structure of resin and asphaltene is complicated. The percentage and the hetero-atom content of the heavy components from resin or asphaltene are higher. And the structure of sub-fractions is different. With HPAM molecular weight increasing, the stability of interfacial films stabled by components from crude oil or A4 changes slightly, and the stability of oil-water interfacial films stabled by crude oil, asphaltene sub-fractions or resin sub-fractions is strengthened firstly and then weakened. The interfacial activity of A4 is strongest among asphltene sub-fractions.The influence of dilatational frequency on the stability of interfacial films stabled by asphaltene sub-fractions is slightly. As the dilational frequency increasing,the dilational viscoelasticity of crude oil, three components of crude oil or resin sub-fractions shows certain trends-the dilational modulus and the dilational elasticity increase,and the dialtional viscosity and the phase angle decrease.The interfacial activity is strengthened gradually. The interfacial activity of R3 is strongest among resin sub-fractions.As the concentration of HPAM increase, the stability of the oil-water interface stabled by crude oil is strengthened firstly and then weakened, and the stability of the oil-water interface stabled by three components of crude oil is strengthened gradually. The stability of the oil-water interface stabled by asphaltene sub-fractions is higher when HPAM concentration is 500mg·dm-3, while the stability of the oil-water interface stabled by resin sub-fractions is higher when HPAM concentration is 300mg·dm-3.The stability of the oil-water interface stabled by asphaltene or asphaltene sub-fractions is strengthened when the addition of resin or resin sub-fractions is moderate. But the stability of the oil-water interface stabled by asphaltene or asphaltene sub-fractions decreases when the percentage of resin or resin sub-fractions is greater than 1. The influence of different resin sub-fractions on the stability of the oil-water interface stabled by asphaltene sub-fractions is different.