Risk Assessment Methods Study Of Internal Turret Single Point Mooring System

In the stage of design,connection,service,FPSO will be affected by marine environment,human operating errors,equipment failures,structure failure factors and other factors,which inevitably lead to failure of FPSO single point mooring system.Once the failure occurs,it will affect the FPSO single point mooring system itself and the oilfield safety.In this paper,the risk assessment of the Internal Turret single Point Mooring System is carried out,which is of certain reference significance to the marine engineering risk assessment and research,and has important engineering significance for ensuring the safety of the single-point mooring system and avoiding the occurrence of major risks.In this paper,large and complex internal turret single point mooring system,focusing on its structural features,combined with historical failure cases,carried out risk identification.On the basis of risk identification,taking into account the impact of a variety of failure modes,the fault tree method is selected for risk analysis of the structural system.Through the combination of expert scoring and fuzzy theory,taking into account the change of the probability of the event over time,the fault tree is solved based on the matrix method,and the fault tree is qualitatively and quantitatively analyzed.For the operation of the internal turret single point mooring system,the connection operation steps are divided.On this basis,the possible sources of danger in each operation step are analyzed,and the existing control measures are discussed to establish a single point connection job safety analysis form.Probability of occurrence and consequence severity of dangerous sources in each operation step unit are analyzed,and the risk evaluation is carried out according to the risk matrix.In view of the risk of sinking buoy in the internal turret,taking a FPSO in the South China Sea as an example,the stress of buoy under a sea condition in a hundred years is calculated based on hydrodynamics.The probability of occurrence of risk is given by fitting the result of probability distribution.The results show that there are many first-order minimum cut sets in the fault tree of the internal turret mooring system,which will easily lead to system failure and serious consequences.Therefore,more attention should be paid to the safety of key structures.Operational safety analysis is applicable to a large number of personnel,equipment,structure of the operating activities,single point connection operations,winches and suspension facilities and other equipment is an important equipment,in the event of failure will result in work directly obstruction of such equipment and facilities need to work Prior to the focus of investigation,at the same time to work out in the event of such equipment failure after the emergency measures.Personnel injuries,personnel errors in the operation process is the need to focus on the risk events,and must take systematic control measures to reduce staff risk.In ensuring a sufficient pre-tightening force,the probability of buoys falling off is small,in an acceptable range.In the design,select the appropriate cable location,can effectively reduce the risk of sinking.