Reliability Research Of Subsea Emergency Shutdown System

As the core part of the subsea control system,the reliability level of subsea emergency shutdown system determines whether the subsea oil and gas production can be carried out safely.Foreign countries have blocked the core technology in the field of subsea production.The domestic subsea reliability engineering is in the initial stage of development,and there are problems such as low accuracy of reliability model and ignoring the time-varying characteristics of failure rate of subsea equipment during long-term operation in harsh environment.When studying problems such as lack of failure data and easy to be missing,the uncertainty of reliability index is usually only considered instead of failure rate parameter.This paper is supported by the High-tech Ship Research Project of the Ministry of Industry and Information Technology of China,the reliability study of subsea emergency shutdown system is carried out for the above problems in order to achieve the purpose of improving the safety and reliability of subsea production.The main research contents are as follows:(1)Reliability analysis of the subsea emergency shutdown system based on time-varying failure rate model.The reliability block diagram model of the system and the time-varying failure rate model including the cumulative failure rate parameter are established,and the reliabilities of the systems under the time-varying failure rate model and the constant failure rate model are simulated and calculated.The comparison results show that the time-varying failure rate model can effectively eliminate the reliability evaluation error caused by constant failure rate,and is consistent with the actual engineering.(2)Modifying the time-varying failure rate model and analyzing uncertainty in the reliability of subsea emergency shutdown system.The statistical-fuzzy knowledge is used to extend the cumulative failure rate parameter to interval value,and a statistical-fuzzy model of this parameter is established.The parameter model is used to modify the time-varying failure rate model,and the theorem of upper boundary existence for failure rate region and its numerical example are presented and proved.The reliabilities of the systems under the time-varying failure rate model before and after modification are calculated to prove the accuracy and generality of the model modification method and theorem.The modified model eliminates certain parameter subjectivity and effectively modifies the reliability interval containing uncertainty,and the results are consistent with engineering experience.(3)The reliability allocation of subsea emergency shutdown system is carried out by analytic hierarchy process.Based on the analysis of the principle and purpose of system reliability allocation,the reliability block diagram model of the system is equivalently simplified and the analytic hierarchy model is established.The judgment matrix of each level is scientifically constructed by expert knowledge to obtain the allocation coefficients of units.Multiple allocations are made on the basis of one allocation,and the results of allocation provide guidance for the localization design of subsea emergency shutdown system.In this paper,the time-varying failure rate model is innovatively established and modified based on the time-varying characteristics of failure rate of subsea emergency shutdown system.The degree of influence from the uncertainty of parameter to the uncertainty of system reliability is deeply studied,and the reliability allocation from system to equipment is realized,which lays a foundation for promoting reliability engineering and application in the field of subsea production.