Risk Analysis Of Single Point Mooring System Of FPSO And Failure Datebase Design

In the stage of design, construction, transportation, installation, FPSO will be affected by equipment failure, human error, the marine environment and other factors, which inevitably lead to failure of the mooring system. It is a great threat to the operation of FPSO and the safety of offshore oil field. So studying on the risk of FPSO mooring system has become one of the key issues in offshore oil engineering. The precondition of the risk assessment of FPSO is obtaining the probability of failure, besides it is also very necessary to establish the failure database of FPSO.At present, Most of the studies on the risk of the mooring system is about the reliability analysis of the structure of the mooring system in extreme sea condition. But this method still has some defects in the risk analysis of large and complex systems, which can’t take the effects of multiple failure modes into account. This paper combines the methods of the system reliability analysis, and a single point mooring system of FPSO served in typical sea area of china is qualitatively and quantitatively. Meanwhile some proposals to control the risk of mooring system are proposed.To begin with, the types and components of the single point mooring system of FPSO are introduced. The structural characteristics of each part of internal turret mooring system of FPSO are mainly studied. Based on the definition of the system and the functions of the system, a basic reliability model of internal turret mooring system is established, and the risk identification of single point mooring system is completed.Moreover, through the collection and analysis of the various cases of mooring failure,the failure modes and failure causes of mooring system are summarized, and the qualitative risk analysis of mooring system is carried out based on the FMECA (Failure Models Effects and Criticality Analysis, FMECA) method, at the same time, it also provides the basis for the data structure design of the Failure database of FPSO. Based on FTA (Tree Analysis Failure,FTA) method and a large number of investigations, the reason and mechanism of the existence of mooring system are found out. To determine the failure of mooring system as the top target event, subsequently, with various failure mode of equipment as the basic event, the fault tree of the mooring system is created to perform qualitative and quantitative analysis.Finally, based on the above work and reference to the OREDA (Offshore Reliability Data), through the digestion, absorption, optimization and innovation of the OREDA, a failure database of FPSO that with independent intellectual property rights is established.Subsequently, according to the demand analysis, using VB as the main development language,SQL Server 2005 as the background database management system, using C/S structure and the ADO technology to achieve access to the backstage database. Application software of failure database of FPSO is exploited. Faults query and faults information management of FPSO are realized, which accumulates valuable experience and data for the future risk assessment of FPSO.