新型气密封特殊螺纹接头抗旋转弯曲疲劳试验研究

Research on Antirotation Bending Fatigue Test of the New Type Hermetic Seal Premium Thread Connection

套管接头在水平井下入过程中承受大量旋转-弯曲疲劳循环载荷,这种循环载荷会导致套管接头螺纹根部产生高应力,导致疲劳损伤和潜在的结构失效,从而对后续油井作业中的管柱接头密封和结构能力产生影响,因此需开展套管特殊螺纹抗旋转弯曲疲劳试验研究。基于API 5C5:2017及API TR5SF标准,通过对某型特殊螺纹套管进行共振弯曲疲劳试验,评价该特殊螺纹接头在疲劳振动载荷下的密封性。结果显示,试验中加载频率越接近试样固有频率,振动越激烈,弯曲应力幅值越大;1^(#)试样在内压60 MPa、弯曲度>20°/30 m的加载条件下,累计加载循环次数54192次后,试样完好,螺纹接头及管体未出现渗漏及破坏;2^(#)试样在内压0.5 MPa、弯曲度>20°/30 m的加载条件下,累计加载循环次数107535次后,试样完好,螺纹接头及管体未出现渗漏及破坏。研究表明,该规格特殊螺纹接头在疲劳振动载荷下仍具有良好的密封性。该试验为共振弯曲疲劳试验方法和相应试验设备在特殊螺纹套管疲劳振动试验领域的深入应用提供了参考。

Casing connection bear a large number of rotation-bending fatigue cyclic loads during horizontal well running.This cyclic loading could result in high stresses in the thread roots of the casing connections,which may lead to fatigue damage and potential structural failure.Therefore,it was necessary to carry out the research on the antirotation bending fatigue test of the casing premium connection.The sealing performance of a premium connection under the fatigue loads was evaluated through resonant bending fatigue test,based on the API 5C5:2017 and API TR 5SF standard.The results show that,vibration and the bending stress was greater when the loading frequency is closer to the natural frequency of the sample in the resonance bending fatigue test.1^(#)samples under the loading condition with internal pressure of 60 MPa and bending degree>20°/30 m had no leakage and damage to the connection and pipe body after 54192 cumulative loading cycles.2^(#)samples under the loading condition with internal pressure of 0.5 MPa and bending degree>20°/30 m had no leakage and damage to the connection and pipe body after 107535 cumulative loading cycles.Therefore,the premium connection of this specification had great sealing performance under resonance bending fatigue load.This test provided a reference on further engineering application of the resonance method and corresponding test equipment in resonance bending fatigue test field of the tubing premium connection.