某页岩气井连续油管震击器断裂案例分析

Case study on fracture of coiled tubing jar in a shale gas well

某页岩气井连续油管钻磨桥塞过程中发生一起震击器芯轴断裂事故,通过对工具断裂情况进行宏观分析,初步判断为弯扭断裂。结合震击器使用工况和受载特点,利用泵压数据进行傅里叶变换并得到泵压变化频谱,分析并认定是由于使用偏心磨鞋造成了泵压振动频率明显增大,泵压的高频波动增加了震击器芯轴的应力疲劳程度,最终造成了芯轴的断裂,并提出了改进建议。

A jar mandrel fracture occurred during the drilling and grinding process of a coiled tubing plug in a shale gas well.Through macroscopic analysis of the tool fracture,it was initially determined to be a bending and torsional fracture.Combined with the working conditions and loading characteristics of the jar,the pump pressure data was used to perform Fourier transform and the pump pressure change spectrum was obtained.It was analyzed and determined that the vibration frequency of the pump pressure increased significantly due to the use of eccentric grinding shoes,and the pump pressure High-frequency fluctuations increased the stress fatigue of the jar's mandrel,eventually causing the mandrel to break,and suggestions for improvement were put forward.