The traditional evaluation on wave induced fatigue of subsea wellhead does not consider the chan-ges in the composition of subsea wellhead structure at different drilling stages,resulting in limited accuracy in wave induced fatigue evaluation of subsea wellhead.A fine evaluation method for wave induced fatigue of subsea well-head in full drilling process based on global-local interaction analysis was proposed.A local fine model for subsea wellhead with complex structure and a global model for platform-riser-subsea wellhead-conductor coupling system in the full drilling process were built.The interaction mechanism between global model and local model was studied.The transitive relation between global model and local stress was constructed to finely evaluate the wave induced fa-tigue damage of subsea wellhead in full drilling process.The results show that the changes in the composition of subsea wellhead structure have almost no effect on the wave induced fatigue of the riser system and the conductor far away from the mud line in full drilling process,but have a significant impact on the wave induced fatigue of local part of subsea wellhead and the conductor near the mud line.At the second stage of drilling,the wave induced fa-tigue damage to the subsea wellhead is the most severe,and the bottom of the subsea wellhead is always at the fa-tigue limit position.The conclusions are helpful in judging the fatigue of subsea wellhead during drilling and ensu-ring the safety of drilling operations.
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