Influence of Axial Vibration on Friction Reduction and Buckling Characteristics of Pipe String in Near-Horizontal Hole
In order to solve the problem of friction increase and even buckling deformation of the pipe string af-ter compression in the near-horizontal long borehole,the axial vibration method for friction reduction and pipe bucking prevention is propose.The mechanical analysis model of axial vibration friction reduction is established,and the internal mechanical mechanism of vibration friction reduction is analyzed.Moreover,the finite element model of vibration friction reduction is established,and the influence of excitation force and frequency on the ef-fect of friction reduction is studied,which is verified by field tests.The results show that there is a phenomenon of direction change in the friction between the pipe string and the hole wall in a single vibration period,which re-duces the average friction in a single vibration period.The greater the excitation force is,the better the friction reduction effect is.When the amplitude and frequency of axial vibration force reach a certain threshold value,it can effectively prevent the buckling deformation of the pipe string and reduce the swing of the pipe string.For a 200 m long wireline drill pipe string with a diameter of 89 mm,when the excitation force is greater than or equal to 5 kN,it can greatly reduce the friction between the pipe string and the hole wall and prevent the buckling of the pipe string.The relationship between the average friction and the vibration frequency is inverse logarithmic.With the increase of the excitation frequency,the average friction first decreases and then becomes stable.The effect of friction reduction tends to be stable after the excitation frequency is greater than or equal to 6 Hz.The research results have guiding significance for the development of friction reducing and buckling resistant drilling tools and drilling engineering construction.
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NSTL
万方数据
维普
