普适性结蜡模型研究

Unified wax deposition model

根据原油在管道内流动特性及析蜡规律,提出了有效析蜡量的计算方法。利用F检验法筛选了原油结蜡的主要影响因素,包括原油黏度、管壁处剪切应力、温度梯度及管壁处蜡晶溶解度系数。利用9种原油室内环道结蜡实验数据,按照逐步线性回归的方法,得到了含蜡原油的普适性结蜡模型。该模型不需进行结蜡模拟实验,只需根据原油的黏度、析蜡特性及密度等物性参数就可预测原油的结蜡规律。在未进行室内结蜡模拟实验的情况下,利用普适性结蜡模型预测了中宁—银川输油管道不同工况下沿线结蜡分布,并和现场运行参数进行了对比,平均误差为6.32%,最大误差为20%,预测结果为现场清管作业提供了依据。

The calculation method of effective wax precipitation content was proposed according to the flow property of crude oil and wax precipitated mechanism. The main factors affecting the wax deposition were selected by using F testing method. The affecting factors include the viscosity of crude oil, shear stress on tube wall, temperature gradient and the dissolved fraction of wax mass on tube wall. The unified wax deposition model was presented by using line correlation method and wax deposition data of 9 kinds of crude oils on flow loop. In the application of this model, the wax deposition experiment on the flow loop was not needed. The wax deposition could be predicted by using viscosity, wax precipitation property and density of crude oil. The wax deposition along the Zhongning-Yinchuan pipeline was predicted by using this unified wax deposition model, instead of the wax deposited experiments on flow loop. The prediction result was compared with the field data. The relative average error is 6.32%. The maximum relative error is 20%. This method can be used to determine the period of pigging.