套管壁面颗粒冲蚀预测及减弱措施研究

Prediction of the erosion of particles on the casing wall surface

为了准确预测套管壁面的冲蚀及制定相应的减弱措施,采用离散颗粒硬球模型来描述颗粒的运动,用半试验关联式来计算颗粒的冲蚀速率。提出在套管壁面设置一定数量的肋条来减弱冲蚀的方法,并对肋条的几何参数进行优化。结果表明,颗粒在油套环空内的分布呈现不均匀特征;设置肋条不仅可降低套管壁面附近连续相的流速,还可使颗粒以较低速度沿套管壁面聚集,将60%以上颗粒的冲击速度降低到0.5m/s以下,降低颗粒与壁面碰撞的平均速度,极大地提高了套管壁的抗冲蚀性能;当肋条高度为4mm、肋条宽度与间距相同(5mm)时,布置10个肋条就可以收到相对最佳的抗冲蚀效果。

To predict the erosion of the casing wall surface exactly and to make the corresponding measures to weaken it,the model of discrete-particle hard sphere is adopted to describe the movement of the particles and the semi-empirical formations are employed to calculate the flowrate of erosion. It is suggested that ribs be placed on the casing wall surface to weaken the erosion and the geometric parameters of ribs be optimized. The results show that the particles within the tubing-casing annulus are characterized by an uneven distribution. The placement of ribs can not only reduce the flowrate of the continuous phase near the casing wall surface,but also make the particles gather together along the surface at a relatively low speed,reducing the speed of over 60% impacting particles to below 0.5 m/s and decreasing the average speed of particles colliding with the surface. As a result,the anti-impact performance of casing wall is greatly improved. When the rib is as high as 4 mm and the width and distance (5 mm) of ribs remain the same,the relative optimum anti-impact effect can be achieved with ten ribs arranged.