聚合物老化降解是影响油藏中聚合物驱效果的重要因素.聚合老化降解表观上是其特征黏度和黏度降低的过程,实质是聚合物分子量断裂引起的大分子向小分子降解的过程,聚合物降解过程中分子量分布发生变化,但其总质量浓度不变.假设聚合物由多个不同分子量的纯组分构成,建立的多组分模型可以描述聚合物老化降解过程中各组分质量浓度变化的过程.基于组分模型的构建思想,将多组分模型进行简化处理,构建了聚合物降解的两组分模型.假设聚合物老化降解发生在两组分之间,平均分子量较大的高组分聚合物向分子量较小的低组分聚合物降解.通过拟合具体的实验数据得到两组分模型的两个参数:低组分聚合物特征黏度和降解系数,进而通过两组分模型描述聚合物降解过程中特征黏度的变化过程,再结合特征黏度与黏度的半经验公式表征聚合物降解过程中黏度的变化.相对于多组分模型,两组分模型的参数更易获取,也不失对聚合物降解机制的体现,可以通过两组分模型描述聚合物的老化降解过程.
Aging degradation refers to the reduction of intrinsic viscosity and apparent viscosity, but the essence of this phenomenon is the breakage of large polymer molecules. During degradation, the distribution of polymer molecular weight changes, but its total mass concentration remains unchanged. If the polymer solution is made up of several pure components with different molecular weights, then a multi-component model can be used to describe the process of polymer degradation. Based on this idea, a twocomponent model of polymer degradation is established. In this model, polymer degradation occurs between two-components, large molecule component and small molecule component. Intrinsic viscosity and degradation coefficient of the latter component are obtained from laboratory experiment. These two parameters are used in the two-component model to describe the change of intrinsic viscosity during degradation. Furthermore, apparent viscosity change is obtained using semi-empirical relationship between intrinsic viscosity and apparent viscosity. Compared with the multi-component model, the two-component model not only reflects the polymer degradation mechanism but also the two parameters required are easier to obtain.
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