Riser Management System Performance in Ultra-Deep Water With Rapidly Changing Current

The largest loading in terms of bending for a top tensioned riser in ultra-deep waters, subject to strong and rapidly changing ocean currents, are found to be close to the upper and lower extremeties. This has been demonstrated by the analyses of various dynamic current scenarios including strong cross currents and currents with rapidly changing direction, resembling eddies and loop currents based on metocean data from Brazilian waters. The riser response in terms of deflections and bending is not found to be critical at any location along the riser for the investigated load cases. Monitoring a riser based on the upper and lower flex-joint angles are hence sufficient to safely operate and control the drilling riser under such conditions. This implies that Riser Management Systems (RMS) that are widely used in intermediate and deep waters with slowly varying currents can safely be applied for top tensioned risers in ultra-deep waters with strong and rapidly changing currents. In fact they may prove to be more important under these conditions, to reduce the wear and tear, improve safety, and as a decision support tool for when to safely disconnect the riser.