甲基丙烯酸十八酯-顺丁烯二酸酐-醋酸乙烯酯-苯乙烯降凝剂对原油蜡晶形态的影响

用偏光显微镜(PLM)观察甲基丙烯酸十八酯-顺丁烯二酸酐-醋酸乙烯酯-苯乙烯(OMVS)降凝剂添加量对原油蜡晶形态的影响。实验结果表明,随OMVS降凝剂添加量的增加,蜡晶由不规则的棒状和片状逐渐变为粒径小、分散均匀的近似球状的蜡晶;PLM表征结果显示,加入OMVS降凝剂的非洲原油和国产原油的蜡晶颗粒数均由不到100个增至大于1300个和1700个,原先占主导地位的表面积较大(非洲原油150～250μm2和国产原油100～200μm2)的蜡晶个数由超过60%降至1%以内,表面积较小(5～50μm2)的蜡晶个数由不到10%增至90%以上。通过指数回归可确定OMVS降凝剂添加量-蜡晶平均表面积-降凝幅度的内在关系,计算结果与实验结果吻合。

Effect of Octadecyl Methacrylate-Maleic Anhydride-Vinyl Acetate-Styrene Pour Point Depressant on Wax Crystal Morphology of Crude Oil

Effect of octadecyl methacrylate-maleic anhydride-vinyl acetate-styrene(OMVS) pour point depressant on wax crystal morphologies in crude African and domestic oils was observed through micropolariscope. The commonly used OMVS pour point depressant could significantly affect the wax deposition rate and the crystal morphology. The wax crystals in the crude oils transformed from irregular rod-like or flake-like into well-dispersed micro-spheres with smaller size due to increase of the OMVS. The crystal numbers in the African and domestic crude oils increased from both less than 100 to more than 1 300 and 1 700 by means of PLM,respectively. The wax crystals with surface area 5-50 μm2 in the crude oils increased from less than 10% to more than 90%,and those with surface area 150-250 μm2 in the African crude oil and 100-200 μm2 in the domestic crude oil decreased from more than 60% to less than 1%. The relation of OMVS pour point depressant dosage,average surface area of wax crystals and magnitude of OMVS depression could be determined by nonlinear regression,and results were in accordance with the experiments.