【作者】 胡蓉；

【导师】 张国忠；

【作者基本信息】 中国石油大学 ， 油气储运工程， 2007， 硕士

【摘要】 本文以大庆含蜡原油为油样,针对具有一定热历史和剪切历史的大庆胶凝原油在较低温度下的初次裂降过程进行分析,研究各种历史条件下的初次裂降规律。分析了在初次裂降时,单位时间裂降速率受启动温度、静态降温间隔和启动剪切速率的影响。在大量实验的基础上,针对几种用于描述初次裂降曲线的触变模式方程的适用性进行分析,发现双曲模式方程在拟合大庆含蜡原油初次裂降曲线方面效果较好,对双曲模式方程中的各参数进行了进一步分析,并采用多元线性回归的统计方法建立了双曲模型方程中各参数受启动温度、静态降温间隔和启动剪切速率各因素影响的函数关系式;另外,还利用了前馈BP人工神经网络方法对大庆原油的初次裂降过程进行模仿训练,通过设计合理的神经网络,能够以任意精度逼近任意复杂的非线性映射,并且该模型的表达是非解析的。另外,由于初次裂降曲线上最高点及剪切平衡点的特殊性,分别建立了启动剪切应力和平衡剪应力与各影响因素的多元线性函数关系式。更多还原

【Abstract】 The thixotropic properties of Daqing gelled crude oil which has certain heat history and shear history during its first breakdown are studied in this paper. The rate of the crude oil breakdown and its influencing factors such as the restart temperature, the static temperature drop and the restart shear rate are analyzed. A series of thixotropic models are examined based on the experiments to see their fitting effects. The results show that the hyperbolic model is more proper in fitting the experimental curves. The parameters in this model are further discussed. Through the multiple linear regression method, a functional expression describing the relation between the characteristic parameters in the hyperbolic model and the influential factors including the restart temperature, the static temperature drop and the restart shear rate is deduced; Futhermore, a computation method of crude oil thixotropy parameters using feed-forward BP network is put forward. The simulation results show that this method is of high accuracy and not dependent on function form. Besides, the peak point and the equilibrium point on the thixotropic curve are of special importance that the relaitons between these two points and the influential factors are set up respectively.更多还原