Successful Scanning of Flexible Risers In Situ Makes Subsea History

Operator Hess Limited, working with flexible pipe specialist flexlife and partners AGR Field Operations, have made industry history by the successful scanning of flexible risers in situ for the first time.

Hess Limited commissioned the inspection of flexible risers on the Triton FPSO, which produces oil and gas from the Bittern and Guillemot West Area fields, using breakthrough technology, as part of campaign to investigate and assess riser integrity on its North Sea assets.

The work was successfully carried out in February and involved three companies combining forces and utilized flexlife's patented ultrasonic scanning technology delivered by AGR Field Operations' Neptune device, carried by Film-ocean's inspection class ROV.

flexlife, recent winners of the Subsea UK Best Newcomer award 2009, launched the scanning technology in partnership with AGR Field Operations last year. The AGR Neptune is the only subsea operated technology able to scan for a flooded annulus and flexible pipe armour wire corrosion, factors that significantly affect the service life of flexible risers.

John Marsden, flexlife director who oversaw the work offshore, said, "This is the first time in the 40 years since flexibles were brought into service that it has been possible to inspect risers for a flooded annulus and be absolutely certain of the results. Hess Limited were the first operator to commission work from us using the AGR Neptune and, in a matter of days, we gathered the 100% accurate data on flooding for them. Our pioneering, safety-conscious solution has attracted a huge amount of interest from the industry and we are scheduled to carry out similar scanning work for more clients shortly.

"The AGR Neptune can be used down to 6,000 meters meaning it can go anywhere in any environment required by the oil and gas industry. By using this technology, operators can detect if they have a breached outer sheath and flooded annulus on a flexible riser or flowline. We can now see the armour wires through the outer sheath and measure levels of corrosion or damage, greatly reducing the risk of major leakage of hydrocarbons and associated environmental, personnel and production impact. There is the potential for the technology to help extend the lifespan of flexible pipes -- an attractive option, especially during the current period of reduced oil prices."

Glenn Wilson, Hess' North Sea Facilities Engineering Manager, said, "Having seen the results achieved in onshore trials, Hess was sufficiently confident to commission the flexlife-AGR partnership to undertake the first commercial scanning operation using this innovative technology. The operation provided valuable new information about the condition of our risers, contributing to our ongoing integrity management program and the long term safety of our facilities."

High-resolution images were obtained by scanning through the riser outer sheath showing the armour wires underneath. Deployment, attachment, detachment and recovery were performed to meet strict safety and integrity conditions. The ROV was deployed from the FPSO and testing was carried out in depths of 20-30meters and currents approaching one knot.

The results were recorded using AGR's proprietary Technology Design™ software and delivered to the client in real time.

"We are now looking forward to assisting other flexible operators obtain a clearer picture of their flexible integrity," said Matthew Kennedy, manager of AGR Integrity UK.

FPSOs are the main users of flexible pipe -- with some 300 FPSOs in operation now and approximately 200 more expected to come on stream within the next four years, nearly all using flexible risers, potential worldwide demand for the application is enormous.


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