Tahiti Project Pushes Riser Monitoring to a New Level


A comprehensive riser and flowline monitoring (RFM) contract has been awarded to 2H Offshore Inc., an Acteon company, for Chevron's Tahiti Project. The RFM system design life requirement of 10 years is an industry first and all the subsea sensors, electronics systems and communication cables are configured with double redundancy.

2H will provide riser monitoring instrumentation for production riser hang-off and touchdown regions and strain and motion measurements. The flowline monitoring system will measure flowline buckling shape and local temperature and hoop and axial strain.

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

The 2H contract involves system design, equipment supply, integration and deployment and is the latest generation of on-line riser monitoring systems. The riser monitoring system has been configured for analytically predicted riser response and data processing. Transducers specification and location were preceded by detailed 2H studies to ensure that the monitoring objectives were met. These objectives include capturing riser vortex induced vibration (VIV) response, wave and current response and information on riser- to-seabed interaction.

The high tech on-line steel catenary risers (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.

"2H has supplied several on-line monitoring systems during the last few years, but the Tahiti RFM requirements are the most critical, 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(TM) technology coupled with a 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 front-end engineering design (FEED) enabled us to significantly improve the system and engineer it to the point where data integrity is assured."