乙烯-醋酸乙烯共聚物降凝剂对尼罗原油的特殊改性作用规律

利用流变测量手段对尼罗原油添加EVA降凝剂前后流变参数的变化规律进行了研究，结果表明尼罗原油中加入EVA降凝剂后，凝点不变，但低温下的屈服值减小（凝点处降低幅度为70%），反常点由38℃升至45℃，原油的非牛顿流体温度范围向高温方向扩展，此外掺加不同比例轻油的尼罗原油加剂后依然存在反常点升高的现象。最后根据实验数据计算得出相同条件下原油析出蜡晶浓度远小于其实际内相浓度，证明了原油中蜡晶溶剂化层的存在，进一步完善了降凝剂对含有较多极性胶质的高凝易黏原油的改性机理。

Specific action regularity of ethylene-vinyl acetate copolymer(EVA)pour point depressant for Nile crude oil

The rheological properties of Nile crude oil before and after added pour point depressant were studied by rheological methods. The results show that after added ethylene-vinyl acetate copolymer (EVA) pour point depressant, the condensation point of the Nile crude oil keeps the same, but the yield stress at condensation point reduces by 70 %, and the abnormal point increases from 38 ℃ to 45 ℃, so the temperature range of Non-Newtonian liquid extends. Meanwhile, the abnormal phenomena were tested by studying the Nile crude oil after added different content low pour point crude oil. At last, the calculated results show that the volume fraction of the solid crystalline is much lower than the actual volume fraction of the dispersed phase under the same condi-tions, which proves the existence of wax solvation layer. Furthermore the modification mechanism of the pour point depressant for this kind of crude oil containing high content polar resins was improved.