Study On Synthesis And Properties Of Nanoviscosity Reducer In Crude Oil

With the rapid development of the world economy, the demand and consumption of oil increase dramatically. Reserve and exploitable amount of light crude oil are gradually reduced while the world’s crude oil resources are abundant. Therefore, it will mainly rely on the exploitation of crude oil to meet oil growing demand in future. Due to large amounts of paraffin wax, resin and asphaltene in the crude oil, it has the features of high viscosity and poor fluidity, bringing difficulties in both exploitation and transportation. In this case, the key issues to solve the problems in exploitable, transportation and refining of crude oil are reducing the viscosity and improving the fluidity. As an emerging viscosity reducer, oil-soluble viscosity reducer has received much research attention for the advantages of small adding amount, simple process and easy post-processing.In this thesis, the relevant literatures were retrieval and commentary in details first. DaQing crude oil and ShengLi crude oil were chosen for the study. A series of nanoscale viscosity reducers were synthesized by emulsion polymerization and transesterification method. The as-synthesized nanoscale viscosity reducers were characterized with infrared spectroscopy, Raman spectroscopy, transmission electron microscopy and scanning electron microscopy. According to GBT265-1988, kinematic viscosity measurement and dynamic viscosity calculation method for petroleum products, the kinematic viscosities of the the DaQing and ShengLi crude oil before and after adding viscosity reducers were determined by capillary method. The apparent viscosity reduction rate and the pure viscosity reduction rate of the synthetic nanoscale viscosity reducer were calculated and compared with a commercially available EVA. The effect of temperature and dosage on the kinematic viscosity and the polymerization factors on the viscosity reduction efficiency were discussed. The main contents can be summarized as follows:Nanoscale spherical poly(methyl octadecylacrylate)(NOPMA) viscosity reducer with the diameter of200nm was synthesized by emulsion polymerization and transesterification method and applied to study the viscosity reduction performances in DaQing crude oil and ShengLi crude oil. When the optimum dose of300ppm NOPMA was added in40℃, the apparent viscosity of DaQing crude oil was reduced from130.07mm2/s to43.88mm2/s with the apparent viscosity reduction rate of66.26%and the pure viscosity reduction rate of37.59%. Similarly, in40℃, by adding the optimum dose of500ppm NOPMA, the apparent viscosity of the ShengLi crude oil was reduced from803.18mm2/s to236.70mm2/s with the apparent viscosity reduction rate of70.53%and pure viscosity reduction rate of23.04%. Compared with the commercially available EVA, viscosity reduction effects of NOPMA to both DaQing crude oil and ShengLi crude oil are somewhat less than EVA.Poly(divinylbenzene-methyl methacrylate) with the diameter of165nm was synthesized by emulsion polymerization with divinyl benzene and methyl methacrylate as monomers. Three viscosity reducers of poly(divinylbenzene-methacrylate octadecyl acrylate)(DOA), poly(divinylbenzen-methacrylate hexadecylacrylate) and poly(divinylbenzene-tetradecyl methacrylate) with the diameter of165nm were then synthesized by a transesterification method. The as-synthesized viscosity reducers were applied to reduce the viscosities of the DaQing crude oil and ShengLi crude oil. Among the three viscosity reducer, nanoscale poly(divinylbenzene-methacrylate octadecyl acrylate) exhibited the best viscosity reducing effect, while poly(divinylbenzene tetradecyl methacrylate) exhibited worst. When the optimum dose of1000ppm DOA was added in40℃, the apparent viscosity of DaQing crude oil was reduced from130.07mm2/s to35.22mm2/s with the apparent viscosity reduction rate of72.92%and the pure viscosity reduction rate of49.91%. Similarly, in40℃, by adding the optimum dose of500ppm DOA, the apparent viscosity of the ShengLi crude oil was reduced from803.18mm2/s to158.29mm2/s with the apparent viscosity reduction rate of80.29%and the pure viscosity reduction rate of48.54%. The viscosity reduction effects of DOA are better than EVA to both DaQing crude oil and ShengLi crude oil.Nanoscale poly(divinylbenzene-acrylamide-methacrylate octadecyl acrylate)(DAOA) containing strongly polar amide group with the diameter of about150nm were synthesized by emulsion polymerization with acrylamide, divinyl benzene and methacrylate octadecylacrylate as monomers. Considered from the viscosity reducing effect, the best synthesis conditions as a viscosity reducer were stated as follow:molar ratio of methacrylate octadecyl acrylate. divinylbenzene and acrylamide is3:2:1(the amount of methacrylate octadecyl acrylate was5g), the amount of catalyst used was1%wt, the volume of reaction solvent was200ml, the reaction temperature was70℃, the reaction time was2h. As-synthesized DAOA were applied to study the viscosity reduction performances in the DaQing crude oil and ShengLi crude oil. The results showed that DAOA exhibited better viscosity reducing effect on ShengLi crude oil and little effect on DaQing crude oil. In40℃, after adding optimal dose of500ppm DAOA, the apparent viscosity of ShengLi crude oil was reduced from the803.18mm2/s to306.90mm2/s with the apparent viscosity reduction rate of61.79%and pure viscosity reduction rate of56.98%.According to the comparision of the SEM images of the ShengLi crude oil surface before and after the best DAOA dosage, DAOA still exists in nanoscle in the crude oil. The results demonstrate that nanoscale poly(divinylbenzene-methyl octadecylacrylate) with weak polarity is a universal viscosity reducer and can be applied in DaQing crude oil and ShengLi crude oil whose natures are quite different. Nanoscale poly(divinylbenzene-acrylamide-methyl octadecylacrylate) containing strong polar monomers can only be applied to the ShengLi crude oil which is rich in resin and asphaltene and is not fit for waxy riched DaQing crude oil.