Analysis Of The Influence Of Clamping Force On The Effect Of The Drilling Tool

Iron roughnecks are a new type of the mechanized wellhead device in oilfield drilling automation technology.It is an upgrade and replacement product of traditional hydraulic tongs and can be used in the makeup and breakout process of drilling tools.Iron roughnecks have been widely used in all kinds of drilling operations because they have greatly reduced the time to makeup and breakout,improved well construction efficiency and reduced drilling costs.At present,the biggest difficulty of iron roughneck lies in the influence of clamping force on the effect of drilling tool fastening.In this paper,ABAQUS implicit dynamic and static analysis method is used to analyze the nonlinear buckling process of 5 1/2FH type E steel pipe with Φ139.7mm×9.17 mm and NC50 type S steel pipe with Φ127 mm×9.19 mm.The effects of stress magnitude and distribution law,maximum clamping force,maximum torque and friction coefficient on the maximum clamping force of drill pipe and drill pipe joint,as well as the failure forms of drill pipe are obtained,which provides a reference for the study of the failure mechanism of drill pipe and drill pipe joint and practical engineering application.The main conclusions are as follows:(1)The maximum stress value in the makeup process of the spinner increases with respect to the roller loading,and the maximum stress difference is up to 83 MPa.The main reason is that the clamping force causes the deformation of drill pipe and the roller causes its own resistance to the clamp.In the process of roller rotation,the position and value of the maximum stress of drill pipe are dynamically changed,and the dangerous point of stress is transferred to the contact position between the roller and drill pipe.(2)During the buckling process,the failure mechanism of drill pipe is basically the same as that of conventional casing,and the maximum stress occurs from the outer wall to the inner wall when loading.The drill pipe is always elliptical during a full rotation of the roller,and the ovality of the drill pipe is dynamic,fluctuating between 1% and 2.4%.(3)When the clamping force is 150284 N,although there is stress concentration at the contact position between the roller and drill pipe,the maximum equivalent stress does not exceed the yield strength of drill pipe material.After simulation,it is found that the maximum clamping force of 5 1/2FH drill pipe is 221200 N,and that of NC50 drill pipe is 400200 N.In addition,as the friction coefficient increases,the maximum clamping force of the drill pipe decreases.When the friction coefficient increases from 0.15 to 0.27,the maximum clamping force of both drill pipe in this paper decreases by about 12%.(4)The maximum stress value in the fastening process of the punching pliers increases relative to the loading of the pliers teeth,and the maximum stress difference value can reach 215 MPa.The main reason is that the fastening torque in the fastening process increases gradually with the rotation of the pliers teeth.In the process of tooth rotation,the position where the maximum stress occurs on the drill pipe joint remains unchanged,and the maximum stress value increases with the increase of tooth rotation Angle.The dangerous point of stress is at the position where the tooth contacts the drill pipe joint.(5)When the clamping force is 659400 N and the clamping torque is 100 k N · m,although there is stress concentration at the contact position between the pliers teeth and the drill pipe joint,the maximum equivalent stress does not exceed the yield strength of the drill pipe joint material,and the maximum displacement of the pliers teeth is less than 1mm.The simulation results show that the maximum torque transmitted by the 5 1/2FH drill pipe joint is 170 k N · m.(6)A supporting iron roughneck mechanics analysis software is developed,and compare the obtained result of the software with the simulation results of FEM..The results show that the calculation accuracy of iron roughneck mechanics analysis software can meet the requirements of mechanical properties of iron roughneck in oilfield.