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

The recovery of heavy crude oil is essential in the petroleum industry due to its richness in the world. The features of high viscosity, high density and poor flowability in Tahe heavy crude oil have brought great obstacles in production and transportation. In this thesis, an attempt to explore an effective viscosity reducer, with good ability to decrease the viscosity and improve the fluidity of heavy oil, has been investigated.Firstly, we analyzed the constituents of Tahe heavy crude oil. The results indicated that heavy components involving the gum and asphaltene play a critical role in determining the high viscosity and density of heavy crude oil. Meanwhile, the mobility and the reason of high viscosity of heavy crude oil were systematically studied.Secondly, octadecyl methyl-acrylate, an important monomer of copolymer viscosity reducer, was synthesized via a melting esterification method with precursors of methacrylic acid and octadecyl alcohol, in which the effecting factors on the quality of the product were investigated. The 90% yield of the monomer can be achieved following the conditions with ratio of methacrylic acid to octadecyl alcohol of 1.2, 1.0% toluene-p-sulfonic acid, and 0.7% hydroqninone, after incubation for 6 h. Then, a solution-polymerization strategy was proposed towards the synthesis of oil-soluble multinary copolymer viscosity reducer with monomers of octadecyl methyl-acrylate, styrene, maleic anhydride, and acrylamide. The affecting factors such as the proportion of reagents, initiator dosage, reaction time, temperature were studied in detail. The proper ratio of monomers 10∶3∶3∶1, quantity of initiator 1.0%, reaction time 5 h, reaction temperature 80℃. In addition, the test on reducing heavy oil viscosity using copolymer alone was performed, and the possible mechanism of which was presented. However, the results of reducing viscosity with the only use of copolymer are not satisfying. Therefore, a composite strategy with the combination of copolymer and surfactants, exhibiting enhanced performance in reducing the viscosity of the heavy oil, is further developed. For example, the addition of 1.0% of the composite viscosity reducer to heavy crude oil can decrease the amount of diluted oil at least by 25%. This feature may mean the present technique has promising applications in reducing the heavy oil viscosity, and gaining better economic profits.