Study On Vibration Characteristics And Response Of Push-back Automatic Vertical Drilling Tools

With the continuous consumption of oil and gas resources,the difficulty of exploitation of oil and gas resources is gradually increasing.So the development of deep wells and ultra-deep well oil and gas reservoirs has become an irreversible trend.Automatic vertical drilling technology is known as the"crown jewel"especially in recent years.The technology has developed rapidly,but China’s research on automatic vertical drilling tools relative to the international advanced level still has a certain gap.In this paper,the vibration characteristics of automatic vertical drilling tools are studied,including the structural design of automatic vertical drilling tool suspension,the modal analysis of tools,the harmonic response analysis of tools and the fatigue life analysis of suspension bearing groups.Key research methods and findings include:The mathematical model and finite element model of the coupling vibration of the tool shell-inner cylinder-skeleton were established.The first sixteenth-order modes of the tool are solved,and the classification study is carried out according to the vibration type.The results show that under the boundary conditions of free,simple,sliding and fixed boundary conditions at the lower end of the stable platform of the tool,the first sixteenth-order modes of the tool are mainly based on lateral vibration,and the natural frequencies of the tool in the X direction and Z direction are similar.The harmonic response analysis of the tool was carried out,and the response of the tool under different boundary conditions,different maximum excitation loads and different stiffness of the damping ring was mainly studied.The maximum amplitude of the tool in three directions under different working conditions was studied.The results show that the vibration of the tool under the four boundary conditions is mainly longitudinal vibration,and the maximum amplitude of longitudinal vibration is most affected by the boundary conditions.The maximum amplitude of the tool skeleton decreases with the increase of the stiffness of the transverse damping ring,and the amplitude of the tool skeleton is the smallest when the stiffness of the longitudinal damping ring is 2.4068×10~7N/m under the stiffness of the three longitudinal damping rings studied in this paper.The fatigue life of the suspension mechanism bearing group with and without longitudinal vibration damping ring is compared,and the fatigue life of different parts of the tool suspension mechanism bearing group is obtained.Studies have shown that longitudinal damping rings can effectively improve the fatigue life of the bearing group of the suspension mechanism,and the minimum safety factor of the bearing group is increased by 50%.The stress concentration on the upper surface of thrust ball bearings and their rolling elements is the most severe and the area with the shortest life of the suspension bearing set.