含凹坑缺陷稠油热采井口用四通管的冲蚀数值模拟研究

The erosion numerical simulation analysis of the four-way pipe with pit defect used in the heavy oil thermal production wellhead

为研究凹坑缺陷对稠油热采井口四通管冲蚀失效的影响,采用计算流体力学(CFD)对四通冲蚀过程进行了数值仿真试验。计算流体力学仿真采用欧拉-拉格朗日气固两相流模型耦合试验分析修正的含砂颗粒冲蚀模型。首先,通过实际的井口四通管失效案例与冲蚀仿真结果的对比,验证了该模型的有效性;然后,利用该CFD模型研究了井口四通管的凹坑缺陷位置对四通管冲蚀损伤速率及损伤发展的影响规律。研究结果显示,当初始凹坑缺陷位于非易冲蚀部位(直管段)时,对四通管的冲蚀速率的影响不大;凹坑缺陷位于易冲蚀部位(肩部位置)且缺陷较浅时,四通管最大冲蚀速率将成倍增加;随着缺陷深度加深,最大冲蚀速率则逐渐降低;而随着肩部缺陷底面边长增加,最大冲蚀速率呈现先增大、后减小的趋势。

To investigate how the pit defects would affect the erosion of the four-way pipe used in the heavy oil thermal production wellhead,a series of the numerical simulation experiments were conducted by the computational fluid dynamic(CFD)method.Euler-Lagrange gas-solid two-phase flow model and sand erosion model modified by experimental analysis were used in CFD simulation.Firstly,the effectiveness of the model was verified by comparing the actual wellhead four-way pipe failure cases with the erosion simulation results.Then,the CFD model was used to study the influence of the pit defect location on the erosion damage rate and damage development of the four-way pipe.The results show that there would be little effects on the erosion rate of the four-way pipe when the pit defect is not located in the erodible site.On the contrary,when the pit defect is located in the erodible site and shallow,the erosion rate would increase exponentially.The maximum erosion rate would decrease when the depth of the defect increases;and the maximum erosion rate first increased and then decreased with the increase of area of the defect.