Analysis on Thread Strength of Tool Joint Under Typical Loads
There are some problems such as insufficient connection strength and torsional resistance when the tool joint is in service,thus leading to troubles like thread sticking,expanding,slipping and breaking.In the pa-per,the ABAQUS finite element simulation method was used to analyze the strength of different tool thread forms under the action of make-up torque load or composite load(tension,torsion,bending),and investigate the mac-roscopic morphology,physicochemical properties,microscopic morphology and bending strength ratio of a failed drill collar sample of a well.The results show that under the action of make-up torque(25.79 kN·m)or compos-ite load,the stress level of the thread near the shoulder of the tool joint is relatively high,and long-term downhole service easily damage the joint.The changes in thread taper and length have great adverse effects on the connection strength of the joint,while the stress relieving structure has obvious significance in improving joint strength and prolonging the service life of drilling tools.The analysis results of failed drill collar also show that the irrational se-lection of drill collar thread leads to mismatched thread type,thus resulting in stress concentration and then the breaking of drill collar joint thread.The research findings provide theoretical basis for the rational use of tool thread.
NETL
NSTL
万方数据
维普
