聚合物驱油过程中形成油墙的动力学机理研究

A kinetic mechanism study on oil bank forming during polymer flooding

目前关于聚合物驱油过程是否形成油墙可以根据产出液含水率曲线的变化特征进行推断,也可以通过在物理模拟模型上直接动态监测含油饱和度的方法判断,这些方法没有从理论上系统说明油墙形成的原因和过程。为了从理论上系统研究油墙的形成,利用分流理论,在分流方程的基础上,建立了聚合物驱油过程中形成油墙的动力学机理数学模型,根据聚合物驱油的基本规律,利用所建立的形成油墙动力学机理数学模型,证明了水驱过程含油饱和度表现出非增的现象,不会形成油墙;而在聚合物驱过程中,含油饱和度表现出增加的现象,有油墙形成。利用所建立的油墙形成动力学机理数学模型可以研究聚合物驱油过程油墙形成的时机,油墙规模大小的影响因素,从而为聚合物驱油过程分子量和注入浓度的选取提供科学的理论依据。

Presently, there are mainly two methods to be used to determine whether oil bank will form during polymer flooding： one method is to observe the change characteristics of water cut curve for produced liquids, and the other one is to directly monitor the oil saturation in physical model. All these methods could not systematically explain why oil bank forms in polymer flooding. In order to study oil bank forming mechanism through a theoretical way, in this paper, a kinetic mathematical model for oil bank forming during polymer is established based on fractional flow theory and fractional flow equations. According to the model, it is demonstrated that for water flooding, the oil saturation exhibits nonincremental phenomenon without oil bank forming, but for polymer flooding, the oil saturation displays an obvious in- creasing phenomenon with oil bank forming. The model can also be used to predict when oil bank forms, and to analyze the factors influencing oil bank forming for polymer flooding. So, it can be applied to screen the polymer molecular weight and the polymer concentration during polymer flooding planning.