基于嵌套网格的环空流体内旋转杆柱与井筒碰撞特性研究

Study on Collision Characteristics of Rotating Rod Strings in Annulus Fluid With Wellbores Based on Nested Grids

针对浸没在流体中杆管柱间相互接触问题,基于嵌套网格技术,该文建立了环空流体内旋转杆柱与井筒间碰撞的数值求解方法.将环空流体域分为相互嵌套的子区域:背景网格和组件网格,推导了各嵌套区域流场边界传递信息的插值计算公式,采用分域方法对环空流体域与杆柱固体域耦合进行求解.通过静止流体中球形颗粒与壁面正、斜碰撞实验对比,验证该文数值方法的正确性.研究了不同流体黏度、杆柱旋转速度条件下杆柱与井筒的碰撞特性,结果表明:1)杆柱与井筒碰撞的碰撞力、速度随黏度增大而降低,即杆柱与井筒碰撞的剧烈程度与流体黏度负相关;2)随着杆柱旋转速度增大,杆柱与井筒的碰撞力、速度也增大,即杆柱与井筒碰撞的剧烈程度与转速正相关.

To solve the contact problem between the rod string immersed in annulus fluid and the wellbore,a numerical solution method for the collision was established based on the nested grid technology.The annulus fluid domain was divided into 2 sub⁃domains:the background grid and the component grid.Then,the interpola⁃tion calculation formula for the flow field boundary transferred information in each nested domain was derived and the coupling between the annulus fluid domain and the rod solid domain was solved with the subdomain⁃based method.Through comparison of the frontal and oblique collision experiments on spherical particles and wall surface in stationary fluid,the correctness of the proposed numerical method was verified.The results show that,the force and velocity of the collision between the rod string and the wellbore decrease with the flu⁃id viscosity,i.e.,the collision intensity is negatively correlated with the fluid viscosity.Moreover,the force and velocity of the collision between the rod string and the wellbore increase with the rotation speed of the rod,i.e.,the collision intensity is positively correlated with the rotation speed.