井下气液分离器的模拟与优化

发布时间：2019-07-09 08:27

【摘要】：针对高气液比油井防气问题,目前最有效的措施是安装井下气液分离器。自井下气液分离器应用以来,对于其结构和分离机理的研究从未间断。大多数学者主要从分离器结构角度来研究影响分离器分气效率的因素,而对于分离器工作条件的界定却比较缺乏；同时在井下气液分离器的CFD仿真方面,分离器出口边界条件的选择存在一定的不足。针对以上问题本文开展了如下工作： (1)基于垂直管中气液两相流型,对比分析了Mixture模型、Volume of Fluid模型和Eulerian模型的适应性,优选出适合分离器模拟的Eulerian多相流控制模型以及PBM气体控制模型。 (2)井下气液分离器的工作行为主要受抽油泵抽汲过程的影响,本文借助动网格技术模拟抽油泵抽汲过程,创建了更真实的分离器工作环境。同时,结合分离器的井下行为设定了压力入口边界条件和泵运动出口。 (3)在重力沉降式气液分离器结构、机理分析基础上,建立了该分离器的物理模型,通过仿真分析,对割缝入口和小孔入口影响分离器进液量的问题进行了研究,并对小孔数量和分离筒内中心管的偏心位置进行了研究和优化。模拟表明：小孔入口结构优于割缝入口,当中心管偏心量大于分离筒半径1/2时效果较好。 (4)工况和流体物性同样影响分离器的分气效率,本文分别对沉没压力、气油比、抽汲速度以及粘度对分离器性能的影响进行了研究和分析,推荐沉没压力为4MPa左右、采用长冲程低冲次。 (5)螺片倾角能够有效的改变螺旋分离器内部流场分布,本文从速度场、压力场以及云图分析了螺旋倾角和普通倾角之间的区别,推荐螺旋倾角为15°。 (6)井下螺旋分离器能否起到螺旋分离的功能主要取决于流体的流速,本文对分离器上下冲程行为进行了模拟,并对上下冲程过程中流体的流场分布进行了分析和研究,模拟表明：当螺旋片上流体流速达到0.45m/s时才能产生螺旋分离效果。
文内图片：

图片说明：NW直管气液两相典胡流巧(3)过渡流
[Abstract]:In order to solve the problem of gas prevention in oil wells with high gas-liquid ratio, the most effective measure at present is to install downhole gas-liquid separator. Since the application of downhole gas-liquid separator, the research on its structure and separation mechanism has not been interrupted. Most scholars mainly study the factors that affect the efficiency of separator gas separation from the point of view of separator structure, but lack of definition of separator working conditions. At the same time, in the CFD simulation of downhole gas-liquid separator, there are some shortcomings in the selection of outlet boundary conditions of separator. In order to solve the above problems, the following work has been done in this paper: (1) based on the gas-liquid two-phase flow pattern in vertical tube, the adaptability of, Volume of Fluid model and Eulerian model of Mixture model is compared and analyzed, and the Eulerian multiphase flow control model and PBM gas control model suitable for separator simulation are selected. (2) the working behavior of downhole gas-liquid separator is mainly affected by the swabbing process of the pump. In this paper, the swabbing process of the pump is simulated by using the auxiliary grid technology, and a more real working environment of the separator is created. At the same time, combined with the downhole behavior of the separator, the boundary conditions of the pressure inlet and the pump outlet are set. (3) on the basis of the structure and mechanism analysis of the gravity settling gas-liquid separator, the physical model of the separator is established. Through simulation analysis, the influence of the slit inlet and the small hole inlet on the liquid intake of the separator is studied, and the number of holes and the eccentric position of the central tube in the separation cylinder are studied and optimized. The simulation results show that the structure of the small hole entrance is better than that of the slit entrance, and the effect is better when the eccentricity of the central tube is larger than the radius of the separation tube 1 / 2. (4) the working conditions and fluid physical properties also affect the gas separation efficiency of the separator. In this paper, the effects of sunk pressure, gas-oil ratio, swabbing speed and viscosity on the performance of the separator are studied and analyzed. It is recommended that the sunk pressure is about 4MPa and the long stroke is low stroke. (5) the screw inclination angle can effectively change the flow field distribution in the spiral separator. In this paper, the difference between the spiral inclination angle and the ordinary inclination angle is analyzed from the velocity field, pressure field and cloud image, and the spiral inclination angle is recommended to be 15 掳. (6) whether the downhole spiral separator can play the function of spiral separation mainly depends on the flow rate of the fluid. In this paper, the upper and lower stroke behavior of the separator is simulated, and the flow field distribution of the fluid in the upper and lower stroke process is analyzed and studied. The simulation shows that the spiral separation effect can only be produced when the fluid velocity on the spiral plate reaches 0.45m/s.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE931.1

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