蜡晶形态结构对原油降凝的影响

EFFECT OF WAX CRYSTAL MORPHOLOGY ON THE POUR POINT DECLINE OF CRUDE OIL

采用偏光显微镜观察了不同条件下蜡晶的形态变化,对蜡结晶过程中的结构、分布状态和生长规律进行了深入的研究,采用气相色谱分析了用52#、62#、80#蜡配制的模拟油中蜡的碳数分布,考察了凝点与蜡含量之间的变化规律,以及沥青质、胶质和大分子降凝剂(PPD)对模拟油降凝、降粘的影响,为改善原油流动性提供理论依据。结果表明,蜡晶的微观形态结构、蜡在油中的溶解性能以及降凝剂的降凝作用与模拟油中蜡的碳数分布密切相关,只有当降凝剂分子结构与油中蜡的结构匹配时,才能达到理想的降凝效果。通过实验确定了模拟油降凝时的临界蜡含量为40%(质量分数),大于该临界值后,凝点随着蜡含量的变化幅度将大大降低。

The variety of wax crystal morphology under different condition was observed by micropolariscope and the wax crystal structure and distribution and grow regulation in crystallizing process were studied. The carbon number and distribution in the wax-containing simulation oils prepared by 52^# , 62^# , 80^# wax were analyzed by gas chromatograph. The relationship of pour point with the wax content was gained. The effect of asphaltene, resin and pour point depressant （PPD） with high molecular mass on the pour point and viscosity decline of the wax containing simulation oil was discovered, which provided the theory basis for effectively improving the oil flow properties. The result of experiments showed that the wax crystal morphology and dissolubility of wax in the oil and effect of pour point decline by PPD were closely related to the carbon number and distribution of wax in the wax-containing simulation oil. The ideal effect of pour point decline was got only when PPD molecule structure well matched with the wax structure in the oil. The critical wax content of wax-containing simulation oil during pour point decline confirmed by the experiments reached to about 40% （mass fraction） over which the range of pour point decline would decrease greatly.