Study on Micro-slip Contact Behavior of Sealing Surface of Premium Connection
The premium connection is subjected to the alternating load during downhole,resulting in a micro-slip at the sealing surface of premium connection,which affects the sealing performance.In order to study the micro-slip contact be-havior at the sealing surface,based on the elastic rod vibration differential equation,a micro-slip model of premium con-nection was established,and the critical area of micro-slip and the hysteresis characteristics of load-displacement of the sealing surface of premium connection were analyzed.The finite element model of friction contact of premium connection was established by numerical simulation software,and the change law of contact pressure,relative slip distance and shear friction of the sealing surface of premium connection under the influence of different internal pressure loads,displacement amplitude and friction coefficient were investigated,and the critical conversion range of the micro-slip state at the sealing surface of premium connection was obtained.The results show that the frictional contact finite element model can simulate the micro-slip contact behavior of the sealing surface under the actual working conditions of the downhole.With the in-crease of internal pressure load,the relative slip distance decreases,and the shear friction and adhesive length increase.With the increase of displacement amplitude,the relative slip distance increases and the adhesive length decreases.When the internal pressure load is between 60 MPa and 70 MPa and the displacement amplitude is between 0.02 mm and 0.025 mm,the critical transition of micro-slip state occurs at the sealing surface respectively.With the increase of the friction co-efficient,the relative slip distance of the sealing surface decreases,and the shear friction and adhesion length increase.The research results can provide a reference for the study of the sealing performance of premium connection under dynamic load.
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