Steel Catenary Risers (SCR) are critical dynamic structures with a complex fatigue response. The offshore industry lacks verification of analytical models with full-scale response measurements. Only a small number of installed SCRs have any instrumentation to monitor dynamic response. This paper describes an on-line monitoring system deployed on one of the Tahiti infield (production) SCRs. Tahiti is a Truss Spar Floater located in 4,000 ft water depth in the Gulf of Mexico. The system is configured with localized strain and motion measurement devices. Emphasis is placed on the selection of number and location of the monitoring devices to characterize vessel induced riser response, VIV induced riser response, riser-seabed interface, and discontinuities at the riser hang-off locations. Monitoring device sensitivity requirements and qualification programs are also discussed. The monitoring system configuration drivers are reviewed in detail such as; monitoring objectives, instrumentation requirements, specification and architecture, field development integration, and installation. Information provided in this paper would be helpful for configuration of complex monitoring systems for deepwater steel catenary rises.

The Riser and Flowline Monitoring (RFM) project deployed one of the most comprehensive subsea structural monitoring systems to date on a Tahiti infield (production) Steel Catenary Riser (SCR) and associated flowline. State-of-the-art motion and strain measurement devices are optimally placed along the SCR to continuously measure and store real-time full scale riser response. In addition, RFM project is the first to implement monitoring devices on a flowline to measure the flowline buckling, a phenomenon that is predicted during repeated start up/shut down. The project goals are two-fold:1. Understand fundamental hydrodynamic behavior of SCRs and flowlines, specifically, floater motion induced response of catenary risers, Vortex Induced Vibration of catenary risers, riser behavior at the pull tube exit region, riser-soil interaction at the touchdown region, flowline buckling, flowline axial walking, and flow assurance characteristics of infield flowlines. The information generated will be used in future riser designs.2. The information will be used to validate Tahiti riser and flowline system robustness and conduct "health checks" on the fatigue critical risers and flowlines, particularly after significant environmental or operational events. This paper describes the monitoring system configuration, the technology deployed, and the installation methods.

The Riser and Flowline Monitoring (RFM) project deployed one of the most comprehensive subsea structural monitoring systems to date on a Tahiti infield (production) Steel Catenary Riser (SCR) and associated flowline. State-of-the-art motion and strain measurement devices are optimally placed along the SCR to continuously measure and store real-time full scale riser response. In addition, RFM project is the first to implement monitoring devices on a flowline to measure the flowline buckling, a phenomenon that is predicted during repeated start up/shut down. The project goals are two-fold:1. Understand fundamental hydrodynamic behavior of SCRs and flowlines, specifically, floater motion induced response of catenary risers, Vortex Induced Vibration of catenary risers, riser behavior at the pull tube exit region, riser-soil interaction at the touchdown region, flowline buckling, flowline axial walking, and flow assurance characteristics of infield flowlines. The information generated will be used in future riser designs.2. The information will be used to validate Tahiti riser and flowline system robustness and conduct "health checks" on the fatigue critical risers and flowlines, particularly after significant environmental or operational events. This paper describes the monitoring system configuration, the technology deployed, and the installation methods.

ATP Oil and Gas Corporation (ATP) is utilizing the MinDOC 3 vessel design for their Mirage, Morgus and Telemark fields. The modeling techniques utilized during the design and verification stages of the project suggest that the production top tension risers (TTR) may be affected by a phenomenon known as Wake Induced Oscillation (WIO). The current modeling techniques are insufficient at predicting the expected amplitude the TTRs will experience due to the WIO and what effect the occurrence will have on the overall fatigue performance of the TTR’s. To acquire a thorough understanding of the effects of WIO, ATP has prudently undertaken an extensive assurance initiative with the purpose of assessing and maintaining structural integrity of their TTRs. As part of ATP’s Integrity Management (IM) program, ATP is monitoring localized strain as well as the motion response of the riser at discrete locations. The paper presents, in detail, ATP’s real-time TTR monitoring system deployed on the ATP MinDOC 3 vessel for their Telemark field. Specific topics to be covered are the monitoring system configuration drivers such as; monitoring objectives, instrumentation requirements, specification, and installation. The paper will cover the number and location of monitoring devices and justification for selection. The data acquired will provide state-of-the-art full-scale riser response information especially during significant events such as hurricanes and loop currents. The goals of the project are: 1. To gain a more in depth understanding of WIO with respect to large diameter hull columns and smaller diameter production TTR’s; 2. Bolster the understanding of the fundamental hydrodynamic behaviour of TTRs and, specifically, vessel-motion induced response of TTRs, and VIV of the TTRs with varying levels of strake fouling. 3. To accurately assess the role of WIO in fatigue damage to the TTR(s).