Deepwater inspection solutions for hybrid FPSOs/Spars

The development of remote, deepwater oilfields in the Gulf of Mexico, West Africa, and Brazil has posed a challenge to oil companies because of the absence of pipeline infrastructures.

The development of remote, deepwater oilfields in the Gulf of Mexico, West Africa, and Brazil has posed a challenge to oil companies because of the absence of pipeline infrastructures. In these deepwater locations, the favored options are floating production, storage, and offloading (FPSO) vessels, Spar platforms with dry tree and drilling capability, or a combination of both.

There has been much progress in the development of new facilities designed for deepwater production, but the key to acceptability and commercial viability of these assets is the ability to remain on station for 15 to 20 years.

Hull integrity and condition monitoring of these structures is a major consideration when determining if they can fulfill these requirements from safety, environmental, operational, and commercial stand points.

EM&I has developed the concept of asset integrity assurance based on risk-based philosophies for conventional, ship-shaped FPSOs, and has applied these techniques to more than 35 FPSOs worldwide.

The company recently completed an integrity assurance study for a new design, which is a hybrid between the FPSO and Spar concepts. This design is intended for use in remote, deepwater locations. The study showed that using a risk-based approach would allow these assets to remain on station for the required length of time.

The risk-based approach begins with an operational criticality assessment (OCA). The OCA process identifies critical components, their expected performance standards, potential failure modes, and safety and environmental risks. At this stage, the monitoring methods for controlling failures are selected.

An integrity assurance strategy and a detailed inspection management plan are developed, based on the OCA and the failure mode analysis. The inspection periods are likely to be based initially on a five-year cycle, in line with current regulatory requirements. On the basis of the collected inspection results, the inspection frequency may be modified to extend the time period between inspections.

EM&I has developed inspection and maintenance methods, which have been approved and used, to implement inspection schedules without disrupting production. Inspection tools currently used include:

  • CYCLOPS, a helmet-mounted closed circuit television system
  • GLOVE, a flexible glove-mounted ultrasonic probes for piping and process vessel inspections
  • COBRA, a miniature camera for inspecting bottom plating under bell mouths and the inside of pressure vessels
  • SNOOPY, a tool used in water surveys of bottom plating.

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