基于密封性能要求的超深井钻柱极限提升力的确定

为了评估大轴向载荷作用下的钻杆接头密封性能，保证钻杆接头的使用性能，采用三维有限元方法建立了双台肩钻杆接头高精度有限元模型，研究了钻杆接头的密封机理，并分析了其在上扣扭矩和轴向拉力作用下的力学特性。研究结果表明，双台肩钻杆接头的密封以主台肩、副台肩为主，只有当上扣扭矩使主、副台肩上产生一个合理的接触压力后，才能保证接头的密封性能；轴向拉力的作用将降低主、副台肩上的接触压力，从而影响接头的密封性能；当轴向拉力超过2 500 kN时，主、副台肩将失去密封性能，从而增加接头发生应力腐蚀的风险。该研究结果对超深井钻杆接头使用性能的提高和钻柱极限提升力的确定具有一定的参考价值。

Determination of ultimate lifting capacity of drill string for ultra-deep wells based on sealing performance of tool joint

In order to evaluate the sealing performance of tool joint in large axial load and ensure the usability of tool joint, a precision finite element model of double shoulder tool joint was established using three-dimensional finite method to describe the sealing mechanism of tool joint. This model could analyze mechanical characteristics of tool joints under actions of make-up torque and axial tension. The results showed that: The sealing performance of double shoulder tool joint was mainly with the primary and secondary shoulder, and rational contact pressure which was produced by the primary and secondary shoulder guaranteed the sealing performance of tool joint; Axial tension may reduce the contact pressure on the primary and secondary shoulder, which weakened the sealing performance of tool joint; When the axial tension reaches to 2 500 kN, the primary and secondary shoulder would lose their sealing performance, which increased the risk of stress corrosion of tool joint. These results could be taken as a reference in determining the ultimate lifting capacity of drill string and improving the performance of tool joint.