胶凝原油流变学特征

Rheological Characteristics of a Gelled Crude Oil

本文基于Noll流变理论,提出一个新的流变方程;用以描述无弹性触变性含蜡胶凝原油的流变特性。这种液体在剪切过程中,结构变化受两个不相关的过程控制。一方面蜡晶之间弱连结的断裂破坏,这种变化结果使屈服应力值随剪切而衰减,结构状态可用λ_1来表示。另一方面,蜡晶本身在剪切场中的定向作用,这种作用的结果使原油的稠度发生变化,作用程度可用λ_2来表示。通过RV-Ⅱ粘度计实验,得到流变方程中的五个流变参数和四个触变参数。实验证明,用该流变方程描述无弹性含蜡胶凝原油的流变力学特性是令人满意的。

A new rheological equation is presented for evaluating a nonelastic, thixotropic, gelled, waxy crude based on the Noll theory. When crude is sheared, the change of structure is governed by two independent processes, first, the weak linkage between wax crystals will broken, causing the fluid stress to decrease with increasing shear rate. The struture state is denoted by λ1. On the other hand, the wax crystals will rearrange, causing the liquid viscosity to change. The degree of treatment is denoted by λ2. Based on laboratory test, using RV-Ⅱ viscometer, five rheological parameter and four thixotropic parameter for the equation were obtained. It is found that proposed equation correctly predicted the rheological charateristics of above mentioned crude.