STREAM JIP – An In-Depth Study of SCR Response Based on Field Measurements

Abstract

The objective of the STREAM (Steel Riser Enhanced Analytics using Measurements) Joint Industry Project (JIP) is to provide a measurement-based foundation for Steel Catenary Riser (SCR) modelling to ensure that riser response is assessed with adequate but not overly conservative parameters. Insights from phase 1 of the JIP were presented in a prior OTC paper (OTC-29239-MS). In phase 2 which is the subject of this paper, the JIP has conducted a deep dive into several other aspects of SCR design uncertainty including - combined wave and Vortex Induced Vibration (VIV), Motion Induced Vibration (MIV), and extreme storm response. The paper will describe how field measured riser response events have been categorized into wave, VIV, MIV, and other non-typical response types. Subsequently, fatigue damage rates derived from field measured data (measured fatigue) are compared against global analysis-based predictions. Concurrent wave and VIV response events are assessed to determine whether the industry standard practice of adding VIV and wave fatigue damage rates is adequately conservative. Measured VIV data is utilized to benchmark SHEAR7 and determine the hidden conservatism in it that stems from non-occurrence of VIV in the field despite the presence of sufficiently high currents. MIV response events are characterized, and the impact on overall riser fatigue is evaluated. Finally, observations field measured riser response during the peak of a major hurricane is reported and examined. In an industry first, the STREAM JIP has aggregated and analyzed full scale field data from multiple catenary risers. The JIP results provide insights into riser response characterization with potential applications for life extension and more efficient new designs.