存在岩屑床的水平环空钻井液紊流CFD模拟

CFD simulation of turbulent drilling fluid flow in horizontal annuli with cuttings bed

 王克林¹ 刘洪涛¹ 程红伟² 张雪松¹ 王艳¹ 周鹏遥¹

中国石油塔里木油田分公司油气工程研究院，新疆 库尔勒 841000 中国石油长庆油田分公司第一采油厂，陕西 西安 751500）

 在钻井过程中，由于钻井液携岩效率的限制，在水平井段极易形成岩屑床。利用CFD（计算流体动力学）软件来模拟环空成床后的钻井液紊流流动规律，模拟结果与已发表的实验数据对比，验证了所选模型的正确性。环空岩屑床的存在将减小流核区的速度，但会增加岩屑床面附近的速度，有助于床面岩屑起动；增加岩屑床高度，环空摩擦压降会减小；随着岩屑床壁面粗糙度增加或岩屑床高度减小，钻井液流动时作用在床面上的切应力减小，不利于床面岩屑的起动；且在钻柱与床面交汇处容易形成屏蔽效应。

 During drilling operations, cuttings bed in the horizontal segment may be formed due to the low fluid carrying capacity. In this study, CFD software is used to simulate the turbulent flow characteristics in the annuli, and the published experimental data have been used to check the choosing models. The simulation results show that flow core decreases due to the existence of bed, but velocity increases near the bed surface, which contributes to incipient particle motion. Increasing bed height will lead to decreasing pressure drop in the annuli. With the increase of bed surface roughness or the decrease of bed height, the shear stress acting on the bed surface decreases and the particle is difficult to be transported by fluid flow. Also, the shear stress increases gradually from pipe to wellbore, and a shielding effect is formed between pipe wall and bed surface.

10.6056/dkyqt201701026