Study On Interfacial Property And Oil-water Separation Of Crude Oil Emulsion

As an important energy source,oil is mostly exploited in the form of crude oil emulsion.Due to the application of enhanced oil extraction technology and the increase of the content of asphaltene and resin in crude oil,the viscosity of the extracted liquid and the stability of the emulsion are enhanced,which makes the production,transportation and processing of crude oil more difficult.Therefore,through in-depth studies of the property,composition,structure of crude oil and the factors affecting the stability of crude oil emulsion,we can provide effective theoretical guidance for solving important practical problems.This article takes Hekou crude oil as the research object,the crude oil is divided into three components:oil,resin and asphaltene by solvent separation.The asphaltene and resin are divided into five subcomponents of A₁^A₅ and three subfractions of R₁^R₃ according to polarity.The basic properties of crude oil and its components and subcomponents are determined.The contribution of components and subcomponents to the stabilities of crude oil,asphaltene and resin emulsion respectively are inspected.The effects of the water phase pH,partially hydrolyzed polyacrylamide?HPAM?concentration and HPAM molecular weight on the simulated emulsions stabilities and Zeta potential at oil-water interface of crude oil and its fractions,asphaltene subfractions and resin subfractions are studied.The variation of interfacial dilatation viscoelasticity with the expansion frequency of the crude oil and its components and subcomponents is investigated.The results show that the Hekou crude oil is heavy oil with high water content,acid value and density.The composition of the asphaltene and the resin is very complex.The content of heavy components and heteroatom in A₁^A₅ and R₁^R₃ are all higher.The interfacial tension of crude oil and its components decreases with the increase of solute concentration.The interfacial film pressure of crude oil and its components increases with the decrease of the interface area.The effective particle size of asphaltene,A₅ and R₃ in crude oil components,asphaltene subcomponents and resin subcomponents are the least.The stabilities of the simulated emulsions of the crude oil and its components increase with the increase of the water phase pH.The ability of the crude oil and its components to form emulsion is enhanced with the increase of HPAM concentration,at the same time,the intermediate phase is produced,and the water quality is worse,but the influence degree of the different components is different.The ability of crude oil and components to form emulsion decreases with the increase of HPAM molecular weight,and when the molecular weight is low,the ability to form emulsion is stronger than that of deionized water.The addition of HPAM makes the demulsification of crude oil and its components emulsion difficult.The absolute value of Zeta potential in the emulsion of the crude oil and each component decrease first and then increase with the increase of water phase pH,and the Zeta potential is turned from positive to negative.When the pH value is higher or lower,the change of the Zeta potential of the oil and water interface is more obvious.The absolute value of Zeta potential in the emulsion of the crude oil and each component increase with the increase of HPAM concentration and the Zeta potential is negative.The change of Zeta potential is significant at low concentration.The absolute value of Zeta potential in the emulsion of the crude oil and each component decrease with the increase of HPAM molecular weight and the Zeta potential is negative.When the molecular weight is low,the stability of the emulsion is stronger and the stability of the emulsion is weaker when the molecular weight is higher.The dilation modulus and elasticity modulus of crude oil and its components increase with the increase of the dilational frequency.When the frequency is low,the growth rate is small,and the increase is larger when the frequency is high.The viscosity modulus and phase angles of the crude oil and its components decrease with the increase of the dilational frequency.When the frequency is low,the amplitude is larger and the amplitude is smaller when the frequency is high.