Angus Lugsdin, business development manager at Tritech International, outlined the value of multibeam sonar technology for real-time integrity monitoring at a technical session on structural integrity at Aberdeen’s Offshore Europe Conference in September.
Prior to its acquisition by Tritech in 2009, SRD’s proprietary multibeam technology RAMS were initially developed as integrity monitoring systems.
The RAMS system was first developed for BP, and was shown to be 100% effective in detecting a bend stiffener failure while deployed Teekay’s Petrojarl Foinaven FPSO, operating on a BP deepwater oil field approximately 190km (118mi) off the west coast of Shetland.
According to Lugsdin, multibeam sonar technology allows operators to have real-time, 24/7 information on the presence and position of mooring chains, risers and umbilicals.
Multibeam sonar systems provide autonomous alarms in the event of mooring line or bend stiffener failure. The accurate sonar data can be used for further fatigue analysis, assisting in the planned maintenance schedule.
Unlike other acoustic techniques, multibeam sonar does not require additional sensors mounted to each mooring chain or riser, therefore removing the need for regular maintenance, servicing and power source replacement by ROVs. Although useful in allowing detailed examinations, ROV-performed annual inspections do not provide real-time information.
In 2015, the unique technology will be permanently deployment on a newbuild FPSO, also entering service in the North Sea.
In addition to detecting mooring line and bend stiffener failure, studies show that when correlated with environmental and motion information, RAMS data can be analyzed to allow the operator to validate mooring line performance against design criteria. The information assists with future designs and more accurately predicts infield life and time between failures.
Systems capable of recording a vessel’s motion and offset and environmental conditions have shown to be useful in determining the extent of extreme and fatigue conditions experienced by riser and mooring systems. There have been documented cases where such data has been used to reduce conservatism in the assumed design and to justify extended operations.
Tritech recently added a visibility and modeling software module that allows operators to simulate the sonar performance beneath an FPSO turret during a project’s FEED stage to ascertain if this system would enhance their operations. It also allows operators of existing FPSOs to establish if RAMS could be retrofitted to an existing asset through a spare I-tube to provide a real-time monitoring solution, enhancing safety as part of a life extension program
Future developments include examining the possibility of combining RAMS sonar data with third party sensor data to calculate mooring line tensions in real-time.
For more information on RAMS, including a video, visit www.tritech.co.uk/gallery/rams-the-real-time-360-riser-and-anchor-chain-integrity-monitoring-for-fpsos.
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