水解聚丙烯酰胺溶液松弛时间表征方法研究

Methods for Characterization of Molecular Relaxation Time of Hydrolyzed Polyacrylamide Solutions

松弛时间是表征聚合物溶液黏弹性最重要参数之一,对松弛时间表征方法研究、对聚合物驱油方案设计、聚合物产品质量监督具有重要意义。研究分别采用Carreau模型、爬杆高度(the rod-climbing height)模型、G′和G″交点(G′and G″cross-over point)模型、固定频率松弛时间(relaxation time at a fixed frequency)模型和指数模型计算不同分子量水解聚丙烯酰胺溶液的松弛时间。结果表明,所有方法得到的松弛时间(τ)都与分子量(M)成正比。G′和G″交点模型得到的结果与τ∝M3关系最接近,其次是Carreau和指数模型;CaBER单轴拉伸试验方法在检测分子量分布时更加敏感、简单,根据油田实际建议采用指数模型来计算水解聚丙烯酰胺溶液的松弛时间。

The relaxation time was one of the most important viscoelatic parameters of polymer solution,and investigation on the methods for its characterization was of great significance for designing polymer flooding and supervising the quality of polymer products.The relaxation times of hydrolyzed polyacrylamide solutions with different molecular weights were calculated by Carreau model,Rod-Climbing Height model,G′and G″Cross-Over Point model,Relaxation Time at a Fixed Frequency model and Exponential model respectively.The results indicate that there is direct proportional relationship between relaxation time and molecular weight obtained by using all the methods.The result obtained by G′and G″Cross-Over Point model is the most coincident withτ∝Μ3,the next is Carreau model and Exponential model.The CaBER uniaxial elongation experimental method is more sensitive and simple to detect the molecular weight distribution.According to the practical applications in oilfields,the exponential model is proposed to be used to calculate the relaxation time of hydrolyzed polyacrylamide solutions.