Synthesis of Copolymer OMA as Pour Point Depressant for an African Crude Oil

Octadecylmethacrylate/maleic anhydride/acrylamide copolymer was synthesized by solution polymerization in toluene and lots of copolymer samples were prepared under varying synthetic conditions and investigated for depressing pour point of an African crude oil and establishing the parameters of treating technology.The African crude oil was taken from an crude oil storage park else where in China,contained 18.3% wax,14.7% resin,and practically no asphaltene and had density of 0.8996 g/cm3 and pour point of 38.5℃.A most suitable copolymer,notated as OMA-6-2,was prepared by copolymerization of the above mentioned three monomers in molar ratio 3:1:1,which was initiated by 1.0% PBO at 80℃,self-accelerated with temperature exothermically rised to 95℃ and conducted at 80℃ in 3 hrs,and had weight and number average molar mass of 13600 and 9200,respectively,as obtained by a GPC technique.With OMA-6-2 introduced at dosage 200 μg/g at temperature 70℃,the pour point of the crude oil was depressed by 9.4℃.The statistical data analysis of micrograms showed that the number of wax crystallites increased from 100 to 1300 and the standard deviation of wax crystallite diameter,expressing the uniformity of crystallite size distribution,decreased by 67% in the crude oil treated by OMA-6-2 in comparison with that in the original crude oil.