Abstract:

Ethylene vinyl acetate copolymer (EVA) is one of the most widely used polymer pour point depressants commercially. It can disperse wax crystals by changing the crystallization process of wax crystals, effectively inhibit the formation of three-dimensional network structure of wax crystals, and improve the low-temperature fluidity of wax oil. Therefore, the research on the application of EVA pour point depressant in the field of crude oil pour point depressant has far-reaching significance. This paper summarized the research and application progress of EVA and its modified polymer in improving the low-temperature fluidity of waxy crude oil in recent years, introduced EVA pour point depressant and its effect after chemical, nano hybrid and synergistic modification, and expounded the pour point depressant mechanism and influencing factors. Compared with the traditional EVA pour point depressant, the pour point depressant after chemical modification, nano hybrid and cooperative modification can further change the morphology and structure of wax crystals and disperse wax crystals, thus significantly improving the pour point and viscosity reduction effect of crude oil. With the rise of long-distance pipeline transportation, repeated heating resistance and shear resistance were still important factors restricting the practical application of pour point depressants. Therefore, nano hybrid EVA was still the main research direction in the future.

Key words: ethylene-vinyl acetate copolymer, waxy crude oil, low temperature fluidity, crystal, viscosity, gels

摘要：

乙烯-醋酸乙烯酯共聚物（EVA）是商业化应用最为广泛的一种聚合物型降凝剂，能通过改变蜡晶结晶过程分散蜡晶，有效抑制蜡晶三维网状结构的形成，改善蜡油的低温流动性。因此，对EVA降凝剂在原油降凝领域应用的研究具有深远意义。本文综述了近年来EVA及其改性聚合物在改善含蜡原油低温流动性问题的研究和应用进展，介绍了EVA降凝剂及对其进行化学、纳米杂化、协同改性后的作用效果，同时对降凝机理及影响因素等方面进行了阐述。相较于传统的EVA降凝剂，经化学改性、纳米杂化、协同改性后的降凝剂能进一步改变蜡晶的形貌结构和分散蜡晶，从而显著提升对原油的降凝降黏效果。随着长距离管道输送的兴起，抗重复加热性和抗剪切性依然是制约降凝剂实际应用的重要因素，因此纳米杂化改性EVA仍然是今后主要的研究方向。

关键词: 乙烯-醋酸乙烯酯共聚物, 含蜡原油, 低温流动性, 结晶, 黏度, 凝胶