剪切和降凝剂作用对含蜡原油流变性的影响

为了研究管输过程中降凝剂及管流的剪切作用对含蜡原油的流变性的影响,在不同剪切速率下对加降粘剂与未加降粘剂的原油进行了对比实验.研究表明,降凝剂作用和剪切作用都能使蜡晶的形状、大小以及结构等发生变化从而影响原油的流变性能,剪切作用和降凝剂作用对含蜡原油的流变性存在交互性影响.油样凝点由加剂前的16℃降低到加剂后的-10℃,降低了26℃;未加剂油样反常点温度为30℃,加剂油样的反常温度为26℃,降低了4℃;加剂前后油样析蜡点的温度基本没有变化;相同温度相同剪切速率下所测两油样粘度值差别比较大,总体上未加剂油样的粘度比加剂油样的粘度低.剪切作用对未加剂油样流变性能的影响明显大于对加剂原油流变性的影响;剪切作用对加剂原油流变性能的影响程度跟剪切速率和剪切温度有很大关系;加剂原油粘度下降幅度随剪切作用的增强而逐渐减小,当剪切作用超过一定范围时,对加剂原油粘度将不再产生影响.

Influences of shearing action and depressant on the rheological property of waxy crude

In order to study the influences of the depressant and shearing action on the rheological property of waxy crude,the properties of the crude oil with depressant and without depressant are measured under different shearing rates.It is shown that depressant and shearing action can all make the morphology,size and structure of wax crystal changing and therefore influence the rheological property of waxy crude;the depressant and shearing action can influence each other.The condensation point of the waxy crude decreases by 26℃,it is 16℃ before the depressant is added and-10℃ after depressant is added;the anomalistic point of the waxy crude decreases by 4℃,from 30℃ to 26℃;wax precipitation point basically does not vary.There is greater difference between the viscosities of the crude samples without depressant and with depressant,and as a whole,the viscosity of the former is lower than that of the latter.The influence of shearing action on the rheological property of the crude sample without depressant is clearly greater than that of the crude sample with depressant;the influence degree of shearing action on the rheological property of the crude sample with depressant is greatly related to the shearing rate and temperature;the reduction of the viscosity of the crude sample with depressant decreases with the increase of shearing action strength,and it will not decrease when the shearing action exceeds certain range.