Tahiti Project Pushes Riser Monitoring to a New Level

The most comprehensive riser and flowline monitoring (RFM) contract ever has been given to 2H Offshore Inc., an Acteon company, by Chevron’s Tahiti Project. Riser monitoring instrumentation covers production riser hang-off and touchdown regions and provides strain and motion measurements.

The flowline monitoring system measures flowline buckling shape and local temperature and hoop and axial strain.

The 2H contract involves system design, equipment supply, integration, and deployment and is the first of the latest generation of on-line riser monitoring systems. The riser monitoring system has been configured with careful consideration to the analytically predicted riser response and to the requirements for data processing. Decisions on transducers specification and location were preceded by detailed studies also executed by 2H Offshore to ensure that the monitoring objectives were met. These objectives include capturing riser VIV response, wave and current response and providing information on riser to seabed interaction.

The “state of the art” on-line SCR monitoring system is gathering riser response information at 10 Hz frequency, processing it in real-time and providing feedback to the Tahiti controls systems. The RFM system is fully integrated with Tahiti’s data network, which allows data monitoring from shore. The 2H monitoring system provides critical information on riser response, confirming riser structural integrity and facilitating riser integrity management. Data gathered by the system will also be very valuable for general understanding of riser behaviour and development of design practices.

“Breaking down an involved system into simple manageable blocks ensures integration of RFM system with complex offshore project development,” said Metin Karayaka, Chevron RFM Project Coordinator. He added, “Close cooperation with Tahiti’s integrated project team enabled us to optimize the RFM system for robustness and reliability”.

The criticality of the monitoring systems and the need to deliver reliable data is appreciated and consistent with previous 2H instrumentation applications. The RFM system design life requirement of 10 years is an industry first. Only the most reliable components, designs and system architecture can withstand such a requirement. All the subsea sensors, electronics systems and communication cables are configured with double redundancy. “2H has supplied several on-line monitoring systems during the last few years, but the Tahiti RFM requirements are severe, thus we are very excited to work on this project,” said Mateusz Podskarbi, 2H Integrity Monitoring Manager.
The system architecture maximizes the use of 2H’s field-proven INTEGRI pod™ technology coupled with successful long-term component track record, and utilizes existing Tahiti project infrastructure in its communications. The design of the system emphasizes data reliability and ensures that single point failure does not result in the loss of system functionality and collection of the required data.

Curtiss Blankenship, Chevron RFM Technical Advisor, observed that, “The strategy of involving subcontractors during the early stages of the FEED enabled us to significantly improve the system and engineer it to the point where data integrity is assured.”