Latest on FPSO Mooring Line Monitoring Techniques (Updated) - Dr.

  • Published on
    05-Mar-2016

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FPSO

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  • Latest on FPSO MooringLine MonitoringTechniques

    Dr. Zhang Hui2H Offshore

  • Agenda

    Introduction Why monitoring mooring failure Monitoring technology overview Case Study Conclusions

  • Introduction

    Mooring systems keep the floatingplatforms or FPSOs in place

  • Why Monitoring - Mooring Failures

    Total failure in abnormal weather Loss of 1 or 2 lines in mild weather

  • Why Monitoring

    Detection of line failure

    Prediction of line failure

    Planning inspection and maintenance

    Reduction in asset replacement interval

  • Monitoring Technology Overview

    Direct Tension Monitoring Load cell Chain Dynamic Tension Sensor

    Indirect Tension Monitoring Mooring Chain Angle

  • Mooring Chain Dynamic TensionMonitoring

    Measure the mean and dynamic tension For studless chains

  • Mooring Chain Angle Monitoring

    Measure top angle ofeach mooring line

    Angles are convertedinto tension using thechain characteristicequation

  • Case Study: Espirito Santo FPSO

    Subsea turret

    9 Mooring lines

    Chain stopper

  • Monitoring System Design Criteria

    Robust

    Reliable

    Easy to install and operate

    No modifications to chains

    Minimum intervention with subsea equipment

    Redundancy

  • System Configuration

    9 Inclinometers (Loggers)

    3 Acoustic receivers

    Junction box

    Fibre optic cable

    PC with monitoring software

  • Chain Table

    Logger

  • Side view

    Isometric view

    Front view

    Chain Stopper Interface

  • Acousticreceivers

    Chain Table

  • Monitoring Software

    Report mooring line failure

    Measure top angle and calculate tension

    Maintenance and configuration of data loggers

    Evaluate polyester line creep

  • Mooring Software Home Page

  • Mooring line setup Routine togenerate tension

    lookup table

    Set oflookuptablesfor agivenline

    Angle datafrom loggers

    Draft

    Routine tolookup tension

    from table

    Tension

    Tension Calculation

  • Mooring Line Setup

    Chain

    Polyester

  • Mooring Software Line Tension

  • Alarms Notification Screen

  • Mooring line setup Routine togenerate tension

    lookup table

    Set oflookuptablesfor agivenline

    Angle datafrom loggers

    Draft

    Iteratively calculatecorrection( Length)

    Line Creep

    DGPS Data

    Reca

    lcul

    ate

    Polyester Line Creep Iteration

  • Chain

    Polyester

    Polyester Line Creep

  • Conclusion

    Monitoring technology is well advanced and proven

    Mean tension obtained through angle measurement is easy toobtain and provides good value

    Data must be processed through a good understanding ofmooring line response into useful data

    Integrating monitoring as part of an IMR (Inspection,Maintenance and Repair) program adds value

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