Interaction Between Active Components Of Crude Oil And Emulsifiers

As one of the most important energy sources,petroleum is mostly exploited in the form of oil-water emulsions.In the secondary oil recovery stage,the crude oil recovery rate is significantly improved by using enhanced oil recovery technologies.However,with the application of tertiary oil recovery technology,the high water content in the produced fluid the economic benefits of oil extraction,and the large part of the remaining heavy oil is not easy to be extracted due to its high viscosity and poor fluidity.In response to this situation,viscosity reduction by chemical emulsification have become a research hotspot in heavy oil production.Therefore,in-depth research on the properties,composition and structure of crude oil and emulsifiers affecting the stability of emulsions-provides effective theoretical guidance for emulsion formation and its stability.In this paper,the toluene solutions of Gudao crude oil and its three components such as oil fraction,resin and asphaltene abtained by solvent separation method are used as oil phase of emulsion,The basic properties of crude oil and its components were determined,and the stability effects on crude oil emulsion were investigated.The effects of the concentration of four emulsifiers（AC-1810,OP-10,TX-100,SDBS）on the stability of simulated emulsions of crude oil and its components and the expansion viscoelasticity of oil-water interface were studied;The interaction between emulsifiers and components were investigated by Ultraviolet visible absorption spectroscopy and infrared spectroscopy.The research results show that in the separation of crude oil components and the determination of basic properties,it is shown that Gudao crude oil is a heavy oil with less water content.Its molecular weight and heteroatom content in descending order are asphaltene,gum,crude oil,and oil.The sulfur content of asphaltene and gum is as high as 6.69%and 3.05%,indicating that the composition of asphaltene and gum is more complex than that of oil.Through the investigation of the stability of the emulsion,the results show that in the crude oil component W/O type simulated emulsion,Asphaltene has the least water output,which is 10%,indicating that the asphaltene has the strongest interfacial activity;After adding emulsifiers,when the concentration of the three non-ionic emulsifiers increases to 0.3%,the water output value of crude oil and component emulsions is below 95%～100%,indicating that the three non-ionic emulsifiers interact with gums and asphaltenes to a certain extent,so that the surface activities of the two are inhibited to a certain extent.The water effluent rate of crude oil and component emulsions decreases with the increase of SDBS concentration;in the crude oil component O/W type simulated emulsion,through particle size test,the selected four emulsifiers all improve the stability of the emulsion When the concentration of non-ionic emulsifier TX-100 is increased to 0.3%,the particle size of the simulated emulsion formed with asphaltene is 77 nm,and the emulsification effect is the best;By investigating the influence of different concentrations of emulsifiers on the expansion modulus of crude oil and its components,the results show that the expansion modulus and elastic modulus of crude oil and its components increase with the increase of the expansion frequency;By investigating the influence of different concentrations of emulsifier and crude oil and the expansion modulus of the oil-water interface of each component,the results show that:in the nonionic emulsifier,the lipophilic group has a benzene ring,and the benzene ring has a short chain alkane group,which has a larger oil-water interface expansion modulus;compared with the nonionic type,The influence of hydrophilic groups on the expansion modulus of oil-water interface is greater than that of lipophilic groups;the ultraviolet-visible light absorption experiment on asphaltene toluene solution shows that the initial associative concentration of asphaltene components in Gudao crude oil is 75mg/L,After adding four emulsifiers,the initial precipitation point changes from 15%to 30%,40%,45%,and 55%.It shows that the four emulsifiers have a dispersing effect on asphaltenes;Through the comparison of the infrared spectra,the results show that the infrared spectra of the mixed system of the emulsifier and the crude oil system change mostly at 1000 cm^-1-1800 cm^-1,indicating The interactions between emulsifiers and crude oil and components are mostly reflected in heteroatom groups.The infrared spectrum of the emulsifier with benzene ring and the mixed system of the components changes more,and the interaction between the two is strong.