剪切作用对添加降凝剂后新疆混合原油流变性的影响

EFFECT OF SHEAR ON RHEOLOGY OF XINJIANG CRUDE OIL TREATED BY FLOW IMPROVER

系统地研究了模拟管流的中低速剪切持续时间对添加降凝剂的新疆混合原油流变性的影响.研究表明,在原油析蜡高峰区2～20℃的温度范围内.将以1312s^(-1)高速剪切加剂原油的凝点及剪切温度以下的表观粘度大幅度上升.增加降凝剂的加入量反而会加剧剪切引起的流变性的恶化.如果高速剪切后温度保持恒定,则该温度下的(表观)粘度不受影响.25℃以上的高速剪切对凝点及2℃时的原油的表观粘度均无影响.不论原油加降凝剂与否,经历动冷后原油的屈服值远小于静冷的原油.

Effect of different shear conditions on rheology of Xinjiang crude treated by flow improver is investigated systematically, including low to medium shear simulating pipeflow, high shear simulating pipeflow in pump, and high shear temperature and time. The results show that at the wax-crystallizing temperatures (2-20℃), high shear at shear rate of 1312s-1 makes pour point and apparent viscosity of the treated crude oil below shear temperature increase dramatically. Increasing dosage of the additive intensifies the shear effect, but no viscosity variation is observed, provided that the oil is kept isothermally after high shear. On the other hand, high shear above 25℃ shows no obvious effect on both pour point and apparent viscosity at 2℃. Whether the crude is treated by flow improver or not, yield value of dynamically cooled crude is much lower than that after static cooling.