A method is detailed for fatigue analysis of vortex-induced vibration (VIV)in deep-water drilling riser-wellhead systemsbased on the Weibull distribution.According to the long-term statistical distribution of marine environmental conditions,the load ca-ses of detailed VIV fatigue analysis are divided by using the Weibull distribution theory of random variables,and current profileswith different probabilities of exceedance are obtained.Further,VIV fatigue damage corresponding to each current profile is calculat-ed by using the VIV fatigue analysis program SHEAR7,and the total fatigue damage of the riser system is estimated according to theoccurrence probability.A case study is then conducted for a specific application of the proposed method by combining the design ofriser system and the parameters of sea conditions in an oil well in South China Sea.The results show that VIV-induced fatigue livescalculated from the three single conventional current profiles are only 1.95,0.039,and 0.012 years,respectively,whereas that ob-tained by detailed fatigue analysis based on the Weibull distribution is approximately 40 years.Compared with the conventional meth-od,the proposed method is more suitable for predicting VIV-induced fatigue damage in riser-wellhead system as it complies morewith the real marine environmental conditions and avoids over-conservative riser pre-drilling design.The number of load cases recom-mended for detailed fatigue analysis of VIV is 20-28.
deep-water drillingriser-wellhead systemvortex-induced vibrationWeibull distributionexceedance probability
NETL
NSTL
万方数据
维普
