Effect of modified ethylene vinyl acetate copolymers pour point depressants on flow properties of crude oil and corresponding mechanism analysis

In order to explore the influences of the alkyl chain length and type of polar groups of the PPDs (pour point depressants) on the crystallization characteristics and flow ability of crude oil, a series of new maleic anhydride derivative graft modified EVA (ethylene vinyl acetate) copolymers PPDs were synthesized. All the new copolymers were characterized by fourier transforms infrared (FT-IR) spectrum analysis, proton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). The results showed that all the new PPDs exhibited better performance in improving the fluidity and delaying the gelling of crude oil than EVA PPD. Moreover, copolymer containing alkyl chain with 18 carbon atoms exhibited better performance than those bearing alkyl chains of other carbon number in depressing the pour point, a pour point drop up to 19 ℃ was obtained by using 0.1 wt% of that PPD, which was conductive to co-crystallization of PPD molecules and wax molecules. However, copolymer containing benzene ring exhibited the best performance in depressing the pour point by 22 ℃ at the concentration of 0.1 wt%, which can change the growth characteristics of wax crystals and delay the aggregation of asphaltene and resin, thus effectively improve the flow ability of crude oil.