大庆-俄罗斯混合原油流变规律实验研究

Experimental Study of Rheological Behavior of Daqing-Russian Mixed Crude Oil

采用差示扫描量热和流变测试方法对大庆-俄罗斯混合原油的凝点、黏度、触变性、屈服值和析蜡特性进行测试分析。结果表明:相比于大庆原油,混合原油的流变性有所改善,随掺混俄油比例的增加,混合原油的析蜡点、析蜡峰温和含蜡量均呈下降趋势,导致其凝点、表观黏度、屈服值降低幅度逐渐增大,触变性明显减弱。庆-俄油混合比例为4∶4时,与大庆原油相比,混合原油的析蜡点降低7.9℃,析蜡峰温降低6.1℃,含蜡量降低13.9%。此时,混合原油平均降凝率为50.0%,不同剪切速率下的平均降黏率为96.3%,触变实验中的剪切应力总衰减率为14.0%,屈服值衰减率为97.0%。根据DSC测试结果,掺混俄油后不仅仅降低了原油含蜡量,同时也改变了蜡的结晶特性,这是导致混合原油流变性改善的主要原因。

In this study,the pour point,viscosity,thixotropy,yield value and wax precipitation characteristics of Daqing-Russia mixed crude oil have been tested by using differential scanning calorimetry and rheological test method.The result shows that compared to Daqing crude oil,mixed crude oil rheology proves to be improved.With the increase of the mixing proportion of Russian crude oil,the wax precipitation point,the wax precipitation peak temperature and the wax content of the mixed crude oil gradually decreased.This leads to the fact that pour point,apparent viscosity,and yield value of the mixed crude oil decreased,and thixotropy decreased significantly as well.Compared with Daqing crude oil,Daqing-Russian crude oil with the mixing ratio of 4∶4,the mixed crude oil wax precipitation point reduced by 7.9℃,wax precipitation peak temperature 6.1℃,and paraffin content 13.9%.At this time,the average decrease rate of pour point of the mixed oil is 50%,the average reduction rate of viscosity under different shear rate 96.3%,the total shear stress decay rate 14.0%,and the yield value of the decay rate 97.0%.According to the results of DSC test,the crude oil mixed with Russian oil not only reduces the wax content of crude oil,but also changes the crystallization characteristics of wax.This is the main reason for the improvement of rheological properties of mixed crude oil.