Study On Sealing Performance And Connection Strength Of Premium Connection And Design Parameter Optimization

During the use of premium connections,accidents such as sealing failure and threaded connection failure will occur due to the combined action of various loads,which will reduce the efficiency of oil and gas exploitation.Therefore,in order to study the influence of premium connections design parameters on sealing performance and connection strength,the finite element analysis was carried out for premium connections with different taper of sealing surface,spherical radius,thread guide surface angle,bearing surface angle and thread tooth width,and the design parameters were optimized.The sealing surface contact mechanics models of cone to cone and sphere to cone were established,as well as the critical load models of tripping failure and shear failure.Through analysis,it can be seen that the range of the main parameters affecting the sealing performance and connection strength of the premium connections is as follows: The sealing surface taper is1/4 to 1/20,the spherical radius is 3mm to 25 mm,the bearing surface angle is-9° to 3°,the guide surface angle is 5° to 40°,and the width of the external thread is 1.45 mm to 3.215 mm.Based on this,a three-dimensional finite element model of the premium connections with different parameters was established,and the equivalent stress distribution of the premium connections as a whole,the thread and the sealing surface as well as the change of contact pressure at the sealing surface were calculated under the combined action of the clamping torque,axial tension and internal pressure.Based on fractal theory,the establishment of the sealing surface roughness,cone to cone premium connections sealing surface of the fractal contact model and finite element model,the fractal analysis of the premium connections sealing performance under different fractal dimension,and the two kinds of different joint sealing form the shackle and experiment was carried out to verify the accuracy of the finite element model of fractal.The results show that when the taper of the sealing surface of the taper to taper premium connections is 1/12 to 1/16,the maximum equivalent stress at the sealing surface is less than the material yield limit,the contact pressure is high,and the sealing performance of the premium connections is good.When the spherical radius of the ball facing the conical surface premium connections is 8 to 16 mm,the sealing surface contact pressure is large,the contact length is long,and the sealing performance is good.When the bearing surface of the thread is-4°?-3°? 3°,the guide surface is 10° to 20°,and the width of the thread is 1.4mm to 2.6mm,the equivalent stress of the thread part is less than the material yield limit and evenly distributed,and connection strength of the premium connections is good.When considering the roughness of the sealing surface,the equivalent stress and contact pressure at the main sealing surface decrease and the contact length increases with the increase of the fractal dimension under the action of the clamping torque.The stress distribution of the joint with different design parameters was obtained by means of finite element method,and the sealing performance and connection strength of the premium connections were further analyzed,which provided a reference for the design,production and field selection of the premium connections.