Analysis Of Joint Strength And Sealing Performance Of Special Threaded Joints Under Fracturing Dynamic Load

During the large-displacement fracturing operation,dynamic load is generated when the fracturing fluid is injected.As a key part of the downhole tubing connection,premium connections are inevitably affected by this dynamic load.In severe cases,the premium connections may fail or even trip,causing a safety accident.Therefore,this paper uses finite element software to analyze the connection strength and sealing performance of premium connection under fracturing dynamic loading.This paper first analyzes the fracturing dynamic load generated during the injection of fracturing fluid.Then take the premium connection of ?88.9×6.45 mm as an example to establish its three-dimensional finite element model,and use ABAQUS software to simulate it.According to the obtained axial tensile dynamic load,the axial motion is analyzed.The stress distribution of the threaded teeth and the sealing surface of the premium connection under the action of the load,and the regularity of the stress of the premium connection with time;according to the obtained law of the change of the bottom hole pressure with time,the radial internal pressure dynamic load is analyzed.The stress distribution of the premium connection thread and the sealing surface is obtained,and the variation of the stress with time is obtained.Finally,a premium connection shackle test was performed to verify the correctness of the three-dimensional finite element model of the premium connection.The results show that under the action of the maximum buckle torque,the stress distribution on the thread is uneven,and the stress concentration occurs at the sealing surface;during the axial dynamic load period,the axial load increases/decreases,and the thread stress will follow the increase/decrease,the stress at the sealing surface of the premium connection under the axial tensile load becomes small,affecting the sealing effect;the internal pressure increases/decreases during the period of the radial internal pressure dynamic load,the thread and the sealing surface stress Increase/decrease;During the dynamic load cycle,under the same load,the stress on the thread and the sealing surface will show a downward trend,which may lead to joint failure and seal failure.