This paper presents an investigation of the reliable performance of theoffshore drill strings subjected to separate and combined stick-slipvibration and wave-induced vessel motions, which have never beeninvestigated before. A nonlinear finite element model of the coupled drillstring and drilling vessel was developed to obtain the dynamic stressresponses along the drill string. Reliability assessment was conducted bydefining the normal, low, and high risk zones under different excitationscenarios imposed by operating parameters and environmentalconditions. The study showed that the stick-slip vibration combined withthe drilling vessel motions can significantly reduce the reliableperformance of some regions of the drill string with regard to fatiguefailure.
展开▼
