胶凝原油启动波传播及压缩特性研究

发布时间：2019-02-16 22:34

【摘要】：为解决现有研究中在胶凝原油停输再启动模型建立方面存在的问题,更好地指导工程实际,本文利用室内管流实验装置对胶凝原油停输再启动过程进行了实验研究,进而依据相关理论编程模拟探究压缩特性和启动波传播特性。(1)蠕动泵启动初期流量从零增长到额定值需要一定时间,采用实验研究和编程模拟相结合的方法,求得蠕动泵启动瞬时流量变化过程;研究发现,启动频率越大,达到额定流量时间越长,启动流量变化过程属于蠕动泵的一项机械性能,启动频率相同,泵启动初期流量瞬变过程也相同;流量从零线性增加到额定值的假设与实际作用效果相同,计算结果可用于之后模拟研究中。(2)选用新型四参数双曲触变模型,提出了依据全局最优化原理同时求解触变模型中各参数值和启动屈服应力的新方法;程序采用粒子群优化算法来求解,收敛速度快;本触变模式的求解方法克服了以往研究中的缺陷,可靠性较高,对后文的模拟研究有很大意义。(3)引入低压当量压缩系数表征胶凝结构压缩性的大小,改进建立了恒流量启动过程低压当量压缩系数的计算模型;计算可知在一定范围内温度越低、停输时间越长、预剪切速率越低、静态降温幅度越大,会使低压当量压缩系数越大;应用LS-SVM回归方法,建立起一种新的胶凝原油低压当量压缩系数预测模型,与多元回归算法建立的模型相比,该模型回归和预测精度较高,可进行工程实际应用。(4)提出一种求解启动波速的计算方法,计算结果表明,启动波速随着启动时间的延续先快速增大,后逐渐减小,其初期快速上升过程是由泵启动初期流量瞬变过程造成的;启动波速远小于声速和瞬变压力波速,与胶凝原油结构特性和启动条件密切相关;以低压当量压缩系数、启动流量和启动时间为自变量,回归样本数据得出启动波速求解公式,该公式拟合效果较好,有一定的参考价值,但缺乏理论基础,后续研究可对公式进一步的修正。
[Abstract]:In order to solve the problems existing in the existing research in establishing the model of stopping and restarting of cementitious crude oil, and to guide the engineering practice better, this paper has carried out an experimental study on the process of stopping and restarting of cementitious crude oil by using an indoor pipe flow experimental device. Then according to the relevant theoretical programming simulation to explore the compression characteristics and start wave propagation characteristics. (1) it takes a certain time to increase the initial flow rate from zero to rating of the peristaltic pump. The method of combining experimental research and programming simulation is adopted. The transient flow change process of creep pump is obtained. It is found that the higher the starting frequency, the longer the rated flow time, the process of starting flow is a mechanical property of peristaltic pump, the starting frequency is the same, and the transient process of initial flow is the same. The assumption that the flow rate increases from zero linear to rated is the same as the actual effect. The calculated results can be used in the subsequent simulation study. (2) A new four-parameter hyperbolic thixotropic model is selected. A new method based on the principle of global optimization is proposed to solve the parameters and initial yield stress of the thixotropic model simultaneously. Particle swarm optimization (PSO) algorithm is used to solve the program. This thixotropic model overcomes the shortcomings of previous studies and has high reliability, which is of great significance to the simulation study later on. (3) introducing low pressure equivalent compression coefficient to characterize the size of the compressibility of cementitious structures. The calculation model of equivalent compression coefficient of low pressure in the process of constant flow start-up is improved. The calculation shows that the lower the temperature, the longer the stop time, the lower the preshear rate and the greater the static cooling range, the larger the equivalent compression coefficient of low pressure. By using LS-SVM regression method, a new prediction model of low pressure equivalent compression coefficient of cementitious crude oil is established. Compared with the model established by multivariate regression algorithm, this model has higher precision of regression and prediction. It can be used in engineering practice. (4) A method for calculating the starting wave velocity is proposed. The results show that the starting wave velocity increases rapidly with the extension of startup time, and then decreases gradually. The initial rapid rising process is caused by the transient process of the initial flow rate of the pump. The start-up wave velocity is much smaller than the sound velocity and the transient pressure wave velocity, which is closely related to the structural characteristics and start-up conditions of the cementitious crude oil. With low-pressure equivalent compression coefficient, starting flow rate and start-up time as independent variables, regression sample data are used to obtain the formula of starting wave velocity. The formula has good fitting effect and has certain reference value, but it lacks theoretical foundation. The formula can be further modified by further study.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE832.31

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