Analysis Of Viscosity Reduction And Stability Of Viscous Crude Oil With Polyoxyethylene Surfactant Compound System

When it comes to the development and application of viscous crude oil resources,high viscosity and poor fluidity are often the most difficult constraints we need to address.Many scholars have proposed different solutions in reducing the viscosity of viscous crude oil.Among them,heavy oil emulsification method is often used to improve the recovery of heavy oil.However,due to the stability of heavy oil emulsion is difficult to control,its application in heavy oil pipeline transportation is scarce.Therefore,it is necessary to study polyoxyethylene surfactant compound system for emulsification of heavy oil.A new approach to the selection of surfactant compound is given.And it is benefic to increase the safety and economy of heavy oil pipeline transportation.In this paper,firstly,the physical properties of heavy oil produced in Liaohe Oilfield was analyzed.Then,the physical conditions of the heavy oil emulsification were determined.Secondly,the application of surfactant emulsification for heavy oils were researched.The viscosity reduction and stability of the heavy oil emulsion were evaluated by measurement of viscosity,interfacial tension(IFT)and particle size distribution.Surfactants used in the experiment include nonionic surfactant alkylphenol polyoxyethylene(9)ether(APE-9)and alkylphenol polyoxyethylene(4)ether(APE-4),anionic surfactant sodium dodecyl sulfate(SDS)and sodium oleate,amphoteric surfactant dodecyl dimethyl betaine(BS-12).The alkaline agent includes inorganic sodium carbonate and sodium hydroxide,organic alkali ethanolamine,diethanolamine and triethanolamine.The results of the surfactant compounding experiment are shown as follows.The viscosity of the emulsion prepared by the APE-9/SDS initially increased with time and then gradually decreased after 20 min.The final viscosity was 469.3 mPa·s.When APE-9 and BS-12 were compounded,the viscosity of emulsion decreased firstly with time and then gradually became constant after 18 min.The final viscosity was 510.8 mPa·s.The viscosity of viscous crude oil was relatively stable with time when APE-9 compounded with APE-4.The viscosity of became constant and reached lowest viscosity value of 276.3 mPa·s.This indicates that the emulsion of the system has good dynamic stability and the emulsion viscosity is the lowest among the three compound systems.The addition of ethanolamine further reduced the viscosity to 35.11 mPa·s.The IFT study showed that when the reduction in IFT is the highest,the interface is the most active.Emulsion is easier to emulsify and its viscosity reduction rate is increased.The droplet particle size distribution study showed that the APE-9/APE-4 and APE-9/SDS binary compound systems stabilize the emulsion with a small particle size.The ternary compound system of ethanolamine and APE-9/APE-4 showed dynamic stability of the particle size of the emulsion over time.