Preparation And Performance Evaluation Of Oil-soluble Viscosity Reducer For Heavy Oil

There are great challenges to the exploitation and transportation of the heavy oil due to its high viscosity and density.In order to reduce the viscosity of the heavy oil,several methods including dilution,heating,and emulsification have been used,but there are a variety of inevitable shortcomings for every method.Recently,the oil soluble viscosity reducers have obtained much attention and showed a good development prospect for its stable viscosity reduction efficiency,low cost and simple operations.In this work,heavy oil of the Shengli Oilfield was taken as the experimental sample.The physicochemical properties and four component contents of the heavy oil have been analyzed.The infrared spectroscopy was used to analyze the asphaltene that extracted from the heavy oil.The results indicated that the heavy oil has high viscosity,high density and high contents of asphaltene.The asphaltene contains a large number of aromatic rings and polar groups,which caused the poor fluidity of the heavy oil.We defined the method and condition of heavy oil viscosity reduction experiment.Based on the viscosity mechanism of heavy oil,the functions of three key groups in the viscosity reduction process of heavy oil were analyzed,and two different oil soluble viscosity reducers OEP(octadecyl acrylate-methyl eugenol-vinyl pyrrolidone terpolymer)and OEA(octadecyl acrylate-methyl eugenol-acrylamide terpolymer)were designed and synthesized.The net viscosity reduction rate of OEP was 28.7%,when the monomer ratio of n(octadecyl acrylate): n(methyl eugenol): n(vinyl pyrrolidone)is 4:2:1,the quantity of initiator was 1.0%,the reaction time was 5 h,the reaction temperature was 70℃,and the dosage of viscosity reducer was 1000 mg/kg.The net viscosity reduction rate of another viscosity reducer OEA was 36.90% when the monomer ratio of n(octadecyl acrylate): n(methyl eugenol): n(acrylamide)was4:2:0.4,the quantity of initiator was 1.2%,the reaction time was 6 h,the reaction temperature was 70℃,and the dosage of viscosity reducer was 1000 mg/kg.The different net viscosity reduction rate of the two viscosity reducers mainly due to the difference of the environment of N element and steric hindrance.Finally,the viscosity reduction mechanism of oil soluble viscosity reducers was deeply explored.And the properties of the asphaltene that extracted from heavy oil before and after viscosity reducers treatment were studied by infrared spectroscopy(IR),thermo gravimetric analyzer(TG),differential scanning calorimetry(DSC),dynamic light scattering(DLS),scanning electron microscopy(SEM)and dispersion experiments.The results demonstrate that the addition of viscosity reducers can effectively disperse asphaltene aggregates,reduce the size of asphaltene aggregates,increase the dispersion of asphaltene,and then reduce the viscosity of heavy oil.