A Fatigue Monitoring Strategy And Implementation On A Deepwater Top Tensioned Riser

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA riser fatigue monitoring strategy and implementation on a deepwater Gulf of Mexico Spar top tensioned riser is presented. The paper explains why a fatigue monitoring program is considered necessary to provide the operator with assurance of the riser system performance and integrity in service, the considerations that led to the selection of an appropriate monitoring system and describes in detail the standalone motion logger system adopted.The principles and methods of measurements that permit the monitoring of motions at discrete locations on the riser are presented along with the methods of processing this data such that fatigue damage along the riser can be interpreted.The paper describes how a standalone logger monitoring system has been successfully installed entirely using a ROV, eliminating the need to run the monitoring system during critical path riser installation activities.

Vortex-induced vibration (VIV) effects of a drilling riser due to vessel motion

“…The loggers are strapped to the structure. Typically, motion sensors are made of tri-axial accelerometers and tri-planar angular rate sensors [12], but the angular rate sensors are not active in this experiment.…”

“…Also, the fact that the duration of measurements is only 15 mins adds to uncertainty in the obtained results. Prior works by Tognarelli et al [13] and Thethi et al [12] based on riser monitoring data were focused only on finding the response in the VIV frequency range. Typically, the accelerometers are not accurate at low frequencies, but the vessel displacements obtained by integration is within the range of typical vessel drifts.…”

Simplified model for evaluation of VIV-induced fatigue damage of deepwater marine risers

“…The main properties of the riser [16] and current velocity profiles [17] are shown in Table 3 and Fig. 5.…”

Tahiti Online Monitoring System for Steel Catenary Risers and Flowlines

“…Interpretation of dynamic response of the entire riser from discrete data points is complex and requires careful consideration in the instrumentation design process. The data obtained at discrete locations are extrapolated along the whole riser which requires time domain or frequency domain data processing techniques as discussed in [3], [4] and [5]. A total of 16 measurement stations are installed on the risers.…”