大庆胶凝原油的循环剪切实验研究

摘要

Because of the three-dimensional network of wax in gelled wax-bearing crude oil, the wax-bearing crude has complex rheological property. The rheological property of gelled crude oil is the key point and the hot point in research. Many scholars have carried out particular and in-depth study on the property of gelled crude oil, but the studies mainly focus on the constantly rate of shear, and there is little research about the continuous shearing. In this paper, by the experiments, the thixotropy law of the gelled wax-bearing crude was studied under this loading condition that shearing rate first increased linearly and then linearly decreased. The law of thixotropy was also researched by controlling different rates of temperature fall and changing rate of shearing rate. The experimental results indicate that the shearing stress is higher at lower rate of temperature fall, but the shearing stresses of different cooling rates approach one another and have no difference at the end;In the different changing rate of shearing rate, the higher the changing rate, the higher the shearing stress at the same shearing rate.%胶凝含蜡原油由于其蜡晶的三维网状空间结构，具有复杂的流变性。胶凝原油的流变性质一直是研究的重点和热点。很多学者对胶凝原油的性质做了详细而又深入的研究，但这些研究一般集中在恒定剪切速率上，对胶凝原油的变剪切的研究较少。通过实验，研究了胶凝含蜡原油在剪切速率先线性增大后线性减小这一循环加载条件下其触变特性。通过控制不同降温速率和剪切速率增加的速率，来研究胶凝原油的触变性规律。试验结果表明，对于不同的降温速率，低降温速率时期剪切应力开始比较大，但随着剪切速率的增大，其应力逐渐靠拢，到最后无明显区别；而改变剪切速率增加的速率时，当剪切速率变化率越大时，在同一剪切速率下，其应力就愈大。