高压高产气井油管柱特殊螺纹密封动力学研究

针对高产气井中油管柱振动问题建立特殊螺纹接头密封面在动载荷作用下接触应力的力学模型。分析密封面接触应力、密封球面半径、密封面表面摩擦系数对特殊螺纹密封性能的影响。针对油管柱的高频振动,提出特殊螺纹密封面之间将会产生微振磨损,并基于能量耗散模型,分析不同螺纹锥度情况下,振荡载荷对油管柱接头能量耗散的影响。结果表明:公接头密封球面半径越小,接触应力越集中,接触应力也就越大,密封接触宽度也越小;同时,螺纹密封面锥度越小,密封面能量耗散值也越小,而当密封面锥度小于11°时能量耗散几乎与锥度无关;建议在高压高产气井中,应适当减小特殊螺纹密封面锥度,且密封面结构优先采用锥面对锥面密封结构形式,其次采用球面对锥面结构。

Study on sealing dynamics about tubing premium connections in high-pressure and high-production gas wells

Aiming at the vibration of tubing string in the high production gas well,the mechanical model of contact stress in the premium connection s sealing surface under the dynamic load was established.Furthermore,the effects of contact stress,radii of sealing sphere surfaces,and frictional coefficient of the sealing surface on the premium connection s sealing performance were discussed.Aiming at the vibration of tubing string with a high frequency,the fretting wear in the sealing surface was put forward.Based on the energy dissipation model,the influence of vibrational load on the premium connection sealing surface s energy dissipation was analyzed when the sealing surface has different cone angles.The results show that,the smaller the spherical radius on the pin s sealing surface is,the bigger contact pressure on the sealing surface is,and the smaller the contact length is.Moreover,the smaller taper of the sealing surface is,the smaller energy dissipation is.At the same time,the smaller taper leads to a smaller energy consumption.Especially when the taper is less than 11°,the taper almost has no influence on the energy dissipation.It is suggested that,in the gas well with a high pressure and a high production,appropriately reducing the taper of sealing surface s structure designing is preferred.Furthermore,the cone-to-cone sealing structure is highly recommended,and the sphere-to-cone structure is the second hand choice.