井筒环形空间液固两相流动特性的数值模拟研究

发布时间：2018-05-21 00:07

本文选题：环空 + 液固两相流　；参考：《东北石油大学》2017年硕士论文

【摘要】：井中岩屑堆积会导致下钻遇阻、蹩泵、卡钻,高扭矩和摩阻压耗等诸多问题,且影响井中岩屑运移的因素有许多,不同因素之间相互作用复杂,因此对于井中环形空间内部的液固两相流动问题进行研究具有工程实际意义。本文基于欧拉-欧拉双流体模型研究液固两相流动,采用k-ε湍流模型对流动进行求解,应用Gidaspow曳力模型模拟液固相相间作用力,并运用UDF实现钻杆的转动,使用FLUENT动网格技术对环空中液固两相流体流动的三维流场进行数值模拟。针对于不同因素对携岩的影响,设置了不同入口液体流速,不同钻杆转速,不同液体密度,不同液体粘度,不同颗粒直径,不同钻进速度,不同流体(牛顿流体及幂律流体),并对环空液固两相流动特性进行理论分析。研究结果表明增大入口流速、钻杆转速度、液体粘度、液体密度、有利于岩屑的运移,但当入口流速增大到一定值时环空压降开始上升,适度的增大有助于岩屑的上返;钻杆旋转可以增加环空液体的紊流度,把运移中的岩屑带入环空高速流核区,但当钻杆转速增大到一定值时,对环空岩屑运移的影响很小;提高液体密度,可提高上返中的液体拖拽岩屑的能力和液体处于静态时的岩屑悬浮能力,有利于岩屑的携带;随着液体粘度的增大,颗粒所受到的相间曳力越大,所以液体的携带能力越强,但并不是粘度越大越好。增大颗粒直径和钻进速度不利于岩屑的运移;增大稠度系数会增加幂律流体的表观粘度,进而增大液固两相之间的曳力。增大流性指数同样会增加幂律流体的表观粘度,且增大流性指数对流体湍动能和湍动耗散率的影响更大。
[Abstract]:The accumulation of cuttings in the well will lead to many problems, such as drilling resistance, pump clamping, high torque and friction pressure consumption, and there are many factors that affect the cuttings movement in the well, and the interaction between different factors is complicated. Therefore, it is of practical significance to study the liquid-solid two-phase flow in annular space. Based on the Euler-Euler two-fluid model, the liquid-solid two-phase flow is studied in this paper. The K- 蔚 turbulence model is used to solve the flow, the Gidaspow drag force model is used to simulate the liquid-solid interaction force, and the UDF is used to realize the rotation of the drill pipe. The three-dimensional flow field of liquid-solid two-phase flow in annulus is numerically simulated by FLUENT dynamic grid technique. Aiming at the influence of different factors on rock carrying, different inlet liquid flow rate, different drilling pipe speed, different liquid density, different liquid viscosity, different particle diameter and different drilling speed are set up. Different fluids (Newtonian fluid and power-law fluid) are used to analyze the characteristics of liquid-solid two-phase flow in annulus. The results show that increasing inlet velocity, drilling pipe speed, liquid viscosity and liquid density are favorable to the cuttings migration, but when the inlet velocity increases to a certain value, the annulus pressure drop begins to rise, and a moderate increase is helpful to the upwelling of cuttings. The rotation of drill pipe can increase the turbulent degree of annulus liquid and bring the cuttings into the high velocity flow core area of annulus. However, when the rotary speed of drill pipe increases to a certain value, the effect of drilling pipe rotation on the annulus cuttings migration is very small, and the liquid density is increased. It can improve the ability of the liquid in the upper return to drag the cuttings and the cuttings suspension when the liquid is in the static state, which is beneficial to the carrying of the cuttings. With the increase of the viscosity of the liquid, the larger the drag force on the particles is, the stronger the carrying capacity of the liquid is. But it's not that the greater the viscosity, the better. Increasing particle diameter and drilling speed is not conducive to cuttings migration, and increasing consistency coefficient will increase the apparent viscosity of power law fluid and further increase the drag force between liquid and solid phases. Increasing the flow index also increases the apparent viscosity of the power law fluid, and the increase of the flow index has a greater effect on the turbulent kinetic energy and turbulent dissipation rate of the fluid.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE31

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