基于CFD￣DEM耦合模型的岩屑运移数值模拟分析

Numerical simulation of cuttings migration based on CFD-DEM coupling model

胡金帅 张光伟 李峻岭 陈雨 闫丰平

西安石油大学机械工程学院，陕西 西安 710065

College of Mechanical Engineering, Xi′an Shiyou University, Xi′an 710065, China

为了提高大位移水平井钻井过程中井眼环空的岩屑颗粒运移效率，文中以岩屑颗粒运移速度作为评判运移效率指标，采用CFD￣DEM耦合模型进行数值模拟，分析了钻杆偏心度、钻井液入口流速、钻杆转速和岩屑粒径对岩屑颗粒运移速度的影响规律。模拟仿真结果得出：钻杆偏心度的增大将导致悬浮层岩屑颗粒平均运移速度降低，其中偏心度大于0.50时，岩屑颗粒更易形成岩屑床；岩屑粒径的增大将使得沉降速度增大，从而导致岩屑颗粒运移速度降低，岩屑粒径超过1.5 mm时，岩屑颗粒运移速度降低较为明显；提高钻杆转速，对岩屑颗粒运移速度的提升效果较小，但会使得岩屑滞留量减少；增大钻井液入口流速，能够使得岩屑颗粒运移速度同比例增大。为了减少岩屑床的形成，增大井眼清洁程度，应增大钻杆转速与钻井液入口流速，减小岩屑粒径。文中所建立的耦合模型也可为岩屑颗粒运移的研究提供一定的理论指导。

In order to improve the cuttings migration efficiency of extended-reach horizontal well, this paper takes the average migration rate of cutting particles as the index to evaluate the migration efficiency, uses the CFD-DEM coupling model for numerical simulation, and analyzes the effects of drilling pipe eccentricity, drilling fluid inlet flow velocity, drilling pipe rotary speed and particle size on the velocity distribution of cutting particles. The simulation results show that the increase of the drill pipe eccentricity will lead to the decrease of the average migration velocity of the suspended layer cuttings particles, and the cuttings bed is easily formed when the eccentricity is greater than 0.5. The increase of cuttings particle size will increase deposition velocity, which can decrease migration velocity. When the particle size exceeds 1.5 mm, the cuttings velocity decreases obviously. Improving the rotary rate has little effect on the cuttings particle migration velocity, but it can reduce the cuttings retention. Increasing the drilling fluid inlet velocity can improve the cuttings migration velocity in same propotion. In order to reduce the formation of the cuttings bed and make borehole cleaner, the drilling pipe rotary speed and drilling fluid entrance velocity should be increased, and the cuttings particle size should be reduced. The coupling model in this paper can also provide some theoretical guidance for the study of cuttings particle migration.

10.6056/dkyqt202204021