Study On The Synthesis Of Oil-soluble Viscosity Reducer EP/CA/STCL And The Mechanism Of Viscosity Reduction

As the most important energy source in today's world,the resource of conventional crude oil are shrinking after has been continuously exploited.As a kind of unconventional crude oil,the exploitation and utilization of heavy oil will occupy an important position in the energy market.Heavy oil has many problems in the process of exploitation and transportation because of its high viscosity.Therefore,reducing the viscosity of heavy oil and improving its flowing property is the key to exploit and transport heavy oil.Oil-soluble viscosity reducer has been paid more attention because of its small dosage,no change in the self-property of heavy oil and no follow-up water treatment.By analyzing the viscosity-temperature curve of heavy oil and combining with the actual gathering and transportation of crude oil,the temperature of measuring the viscosity of crude oil is detennined to be 50?.Four-component of heavy oil were analyzed and tested.The content C,H,S and N in asphaltene and resin were analyzed by elemental analyzer,and carbon number distribution of n-alkanes in saturated of heavy oil was analyzed by GC-MS,which provided a basis for subsequent molecular design of viscosity reducer.Epichlorohydrin and stearoyl chloride were selected to react with catechol,resorcinol and hydroquinone to obtain three kinds of viscosity reducers which were named VR-1,VR-2 and VR-3.The ability of dispersing asphaltene and resin was analyzed by UV spectrophotometer and laser particle sizer.The test results showed that VR-1 had the ability to disperse asphaltene and resin,VR-2 and VR-3 did not have the ability to disperse asphaltene and resin.Apparent viscosity test results showed that VR-1 had the best viscosity reduction effect.Therefore,VR-1 was selected as the best viscosity reducer.The synthesis conditions of viscosity reducer VR-1 were optimized by single factor method.The optimum synthetic conditions were:epichlorohydrin:catechol:stearoyl chloride=4:4:2,the temperature of main chain reaction was 100?,the reaction time was 8 h,the temperature of grafting reaction was 100?,the reaction time was 10 h,and the addition of promoter was 1.4%(mass fraction).Under the optimum synthesis conditions,the viscosity reduction rate was 52.36%when the temperature was 50? and the dosage of viscosity reducer was 500 ppm.The viscosity reducer was analyzed by GPC,IR,HNMR and EA.The test results showed that a small molecule oil soluble viscosity reducer was synthesized,which accorded with the experimental expectation.The properties of viscosity reducer VR-1 were evaluated.The rheometer test results show that the viscosity reducer VR-1 can reduce the yield stress of heavy oil and improve the fluidity of heavy oil.The effect of viscosity reduction was further improved by the combination of VR-1 and surfactants OP-10.The universality of the VR-1 was explored.Two kinds of heavy oil with different asphaltene content and viscosity were selected.The test results showed that the viscosity reduction rate for 2#heavy oil was 38.18%and the viscosity reduction rate for 3#heavy oil was 44.41%when the dosage of the viscosity reducer is 700 ppm at 50?.The test results showed that VR-1 had a certain effect on these two kinds of heavy oil,which indicated that VR-1 had a certain universality.The mechanism of viscosity reduction of viscous reducer was explored through the effect between viscous reducer and asphaltene/resin/wax.The structure changes of asphaltene,resin and wax before and after adding viscosity reducer were analyzed by XRD.The surface morphology changes of asphaltene and resin before and after adding viscosity reducer were observed by SEM.The phase transformation temperature and enthalpy changes of wax before and after adding viscosity reducer were analyzed by DSC.The test results showed that the viscosity reducer could destroy the stable stacking structure of asphaltene and resin,inhibiting the reaggregation of asphaltene and resin,and reduced the phase transition temperature and enthalpy of wax.The effect of VR-1 on heavy oil system was analyzed by TEM.The test results show that the viscosity reducer can weaken the interaction force between components in heavy oil system,make its structure loose.It is beneficial for each component to disperse into the heavy oil system.