| Because of High viscosity,high density and poor flow ability of heavy oil,the production and transportation of heavy oil are great difficult.At present,the main ways to reduce the viscosity of crude oil,including viscosity reduction by heating oil or emulsifacation and dilution method by using light oil,have their shortcomings.While the oil-soluble viscosity reducer can be effective under small dosage,avoiding post-processing problems and so on,more and more scholars pay attention to the research of viscosity reducer.On the basis of research situation of viscosity reducer at home and abroad,combining the theroy of molecular structure design and aiming to the character of Xinjiang crude oil with High resin and asphaltene content in this paper.stearyl methacrylate,styrene and acrylic acid were used as monomers of polymerization.We plan to synthesis a terpolymeric oil-soluble viscosity reducer firstly,then to obtain a new cationic viscosity reducer which introduced methacrylatoethyl trimethyl ammonium chloride from the structure of the terpolymers,the optimum synthesis condition of these viscosity reducers were obtained by a series of single factor experiments.The structure and composition of viscosity reducers were characterized by infrared spectra and 1NMR spectra,and a series of properties evaluation had been made and the viscosity reduction mechanism was also investigated.In the experiment,the optimum reaction conditions of cationic viscosity reducer were confirmed as follows:under the protection of nitrogen,monomer mole ratio of stearyl methacrylate,methacrylatoethyl trimethyl ammonium chloride,styrene and acrylic acidis 15:1:6:3?respectively,emulsifier X-100 amount of 5%(mass percent of the sum of total reaction system),monomer concentration of 33wt%,reaction temperature of 65?,reaction time of 4h,initiator(NH4S2O4/NaHSO3)amount of 0.5%(mass percent of the sum of all the monomers),dropping rate of DMC and AA is controlled at 10-1 Is every drop.The effect of these viscosity reducers was investigated,when the properties evaluation of viscosity reducer at 50?,this viscosity reducers were effective for three kinds of Xinjiang heavy oil,such as 114#,118#and 116#,the viscosity reduction rate were 28.90%,29.23%and 29.11%for nonionic viscosity reducer,and 37.37%,39.24%and 38.82%for cationic viscosity reducer,respectively.The effect of viscosity reducer was improved obviously through introducing cationic groups and the viscosity reducer was more effective for crude oil with high water content.When water content of 114#heavy oil is 20%,the rate of viscosity reduction of cationic viscosity reducer reached 46.61%.The combination of viscosity reducer and different surfactants was investigated to show that combination effect of viscosity reducer and sodium dodecyl benzene sulfonic acid was better than others.When the mass ratio of polymer to surfactant was 1:2,the mount of maximum product was 1800mg/L,the best viscosity reduction rate could reach about 46%at 50?,and the reduced viscosity was apprpximate equal to the viscosity of 114#heavy oil at 60 ?.Through IR spectrum and UV spectrum analysis of resin and asphaltene,the TEM of heavy oil,the SEM and absorbance of asphaltene solution with and without viscosity reducer,the mechanism of the viscosity reduction with viscosity reducer was explorated initially.The results shows that the molecules of viscosity reducer could interact with reins and asphaltenes,altering the original micelle structure of crude oil partially,weakening the ability to form hydrogen bonds of aggregate structure formed by resins and asphaltenes and inhibiting the growth and gathered again of the aggregates,so the viscosity of heavy oil is reduced. |
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