柴油稀释对原油流动性及析蜡过程的影响研究

以大庆林源原油和0#柴油稀释剂为研究对象，采用HAAKE RS600流变仪和XP-300C影像分析系统，测试分析大庆林源原油在65℃和/或50℃下添加10%、20%及50%稀释剂前后的流变特性、凝点、静屈服值及析蜡过程，评价它们在降温过程中的15s^-1动态粘温特性及其在终了温度20℃的蜡晶微观形态；采用Ncmivnt图像处理软件，分析蜡晶颗粒数量及其对称性；提出用相同视场下蜡晶颗粒的平均短轴与长轴长度之比来表征其对称性。结果表明：林源原油稀释前后的析蜡点和析蜡高峰温度分别在50～45℃与40～30℃，0#柴油稀释不会改变其析蜡过程与蜡结晶行为；稀释剂加量越大和/或处理温度越高，则蜡晶颗粒的数量越少、对称性越高、分散度越低，原油的低温流动改进效果也就越显著，这为下一步研究降凝剂与稀释剂的协同作用奠定了基础

AN EXPERIMENTAL STUDY OF EFFECT OF DIESEL DILUTION ON FLOWABILITY AND WAX PRECIPITATION PROCESS OF CRUDE OIL

Taking Linyuan crude oil of Daqing oilfield and the diluted 0# diesel as the research object，the rheological behavior，freezing point，static yield stress and wax precipitation process of the crude oil diluted with 10%，20% and 50% diesel at 65℃ and / or 50℃ are measured and analyzed by using a HAAKE RS600 Rheometer and XP-300C Image Analysis System，and the dynamic viscosity-temperature characteristics at 15s^-1 during the temperature dropping and the wax crystal microstructure at the final testing temperature of 20℃ are also evaluated.The numbers and symmetry of wax crystal particles are analyzed by using Ncmivnt software.A method for the symmetry of the crystal particles characterized by the ratio of the average of their short-axis length to that of their long at the same visual field is presented.The experimental results indicate that the wax appearance point and precipitation peak temperature of Linyuan crude oil with and without dilution is 50～45℃ and 40～30℃ respectively；the wax precipitation process and behavior of the diluted crude can not be changed by the diesel treatment，the more the added diesel is and / or the higher the temperature is，the fewer the number of the wax crystals is，and the higher their symmetry is and the lower their dispersion extent is，therefore，the better the improvement of the low-temperature flowability for the treated crude is.All of these provide a basis for the further investigation to the synergetic effect between PPD and the diluent.