锥面-锥面特殊螺纹接头密封面处能量耗散有限元分析

Finite Element Analysis of Energy Dissipation at the Sealing Surface of Cone-cone Premium Connection

特殊螺纹接头在井下服役时,当开关井、压裂液注入和产气时,因井口装置和井底封隔器的约束及井筒中流体变化的作用,特殊螺纹接头密封面处将会产生滑移。通过有限元法,建立锥面对锥面特殊螺纹接头有限元模型,分析在不同内压与轴向循环载荷作用下,特殊螺纹接头密封面处能量耗散情况。结果表明:当接头所受内压一定时,轴向循环载荷幅值越大,密封面处能量耗散值越大,密封面处接触压力降低幅值越大;当接头轴向循环载荷一定时,随着内压的增大,接头密封面处能量耗散值越大,但其接触压力幅值降低越小;随着接头锥度的增加而增加,密封面处能量耗散值增加,接触压力幅值降低越小。因此,在特殊螺纹接头服役过程中应适当增加内压,减少轴向载荷即增加减震装置,并采用锥度较小的特殊螺纹接头。

When the premium connection is in service underground,when opening and closing the well,fracturing fluid injection and gas production,due to the constraints of wellhead device and bottom hole packer and the effect of fluid changes in the wellbore,the sealing surface of the premium connection will slip.Therefore,the energy dissipation model at the sealing surface of special thread based on the shear layer model was established.Through the finite element method,the finite element model of cone-to-cone premium connection was established to analyze the energy dissipation at the sealing surface of premium connection under different internal pressure and axial cyclic load.The results show that when the internal pressure of the joint is constant,the greater the amplitude of axial cyclic load,the greater the energy dissipation at the sealing surface,the greater the reduction amplitude of contact pressure at the sealing surface,and the worse the sealing performance.When the axial cyclic load of the joint is constant,with the increase of internal pressure,the greater the energy dissipation value at the sealing surface of the joint,but the smaller the decrease of the amplitude of contact pressure,the better the sealing performance.With the increase of joint taper,the energy dissipation at the sealing surface increases,and the smaller the decrease of contact pressure amplitude,the better the sealing performance.Therefore,in the service process of premium connection,the internal pressure should be appropriately increased to reduce the axial load,that is,to increase the damping device and the premium connection with small taper should be used.