Risk Assessment Of Deepwater Drilling Riser And Subsea Blowout Preventer

This thesis investigates the reliability failure analysis of deepwater drilling riser and subsea blowout preventer. The risk assessment method for large-scale complex systems is developed and demonstrated. First, the evaluation of the failure-risk probability and failure severity level should be conducted. Then based on failure-risk probability and failure severity level, the grade levels of the corresponding probability and failure severity can be defined respectively. Finally, combined with risk matrix the overall risk assessment of the system is conducted, and according to the decision results the necessary measure should be taken to complete the risk assessment of the large-scale complex system.In view of the situation about the drilling riser’s historical data lack, first investigate the failure cause and failure mode of the drilling riser, then according to the developed failure tree, take account of the importance weight of expert opinion and accumulate the failure probability of individual incident, finally employing the fuzzy analytical hierarchy process, take into account the difference of the expert’s comprehensive ability, and obtain the failure consequences score.In view of the situation about the complete historical data of the subsea blowout preventer, first on the basis of the existing statistical data, conduct the FMECA analysis on the whole blowout preventer stacks, and find out the failure mode of the individual equipment, then in accordance with the statistical data and Bayesian network probabilistic inference rules, acquire the occurrence probability of the basic events, finally measure the consequence after a certain risk accident occurs by loss ratio, and gain the failure consequences score.Finally, according to the risk factors of deepwater drilling riser and subsea blowout preventer, this thesis puts forward a risk-averse method to make sure the long-term stable service of deepwater drilling riser and subsea blowout preventer.