基于管流式实验的超级13Cr油管变径部位冲蚀研究

Study on Erosion of Super 13Cr Tubing with Diameter Change Based on Tube Flow Experiment

利用自制的模拟水平管道液固两相流冲蚀实验装置,在液固两相流体中,研究了流体速度对超级13Cr油管冲蚀速率的影响。采用扫描电镜的方法分析了超级13Cr油管的冲蚀形貌。实验结果表明,超级13Cr油管冲蚀速率随液固两相流体流速的增大而增长,但在水平油管截面沿圆周方向冲蚀速率分布不均匀,其中油管底部的冲蚀速率较大,油管上部冲蚀速率较小。由于砂浓度沿截面高度方向不均匀,油管底部主要以较为稠密的固体颗粒对管壁的磨损和低角度切削为主,而顶部的冲蚀主要为颗粒冲击和切削管壁。在直冲台肩部位的冲蚀速率和冲蚀形貌类似于30°~45°时喷射式冲蚀实验结果。实验结果为水平井压裂施工冲蚀预测提供了依据。

Erosion behavior of Super-13Cr was investigated by the self-made flow loop of solid-liquid slurry.The slurry contains of 0.35 weight percent Gum solution and ceramic proppants with the diameter of 20/40 mesh.The specimens were put into both the impinging surface of sudden contraction tubing and the locations of straight pipe.Erosion morphologies of specimens were investigated by SEM with increasing the slurry velocity at different locations.It is found that the erosion rate increases with increasing the slurry velocity for all specimens.However,it is different around the circumference of the tubing cross section.The specimen at the bottom of horizontal tubing was abraded more seriously than the top one.The abrasion and sliding erosion are caused in the bottom due to the high particle concentration while the top is just cutting and impinging by dilute particles.The maximum erosion rate occurs at the impinging surface of sudden contraction tubing where the morphologies are like the 30°impingement angle with submerge impact experiments.It is found that the ploughing and metal cutting dominate the erosion mechanism at low impact angle with high velocity by SEM analyses.As a result,these conclusions can give some suggestions for predicting the erosion rate in the horizontal well fracturing work.