运用可靠性方法，基于概率分析设计了单轴和双轴疲劳可靠性试验，得到了套管柱的单轴和双轴概率疲劳特性，推导出套管钻井的P — S — N曲线方程。
The reliabilitytests both the axialfatigueand the biaxial fatigue of casing strings were designed by means of examination and numerical simulation, and the P-S-N curves were obtained.