Experience of deepwater SCR applications in the Gulf of Mexico (GOM) shows that fatigue is usually one of the most challenging feasibility issues for SCR design. Wave loading fatigue contributes significantly to the total fatigue damage, through wave induced vessel motions. This is particularly true for large diameter SCRs.

 

The objectives of this two-phase study included the development of an international database of SCRs and a methodology for assessment of the reliability and integrity of large-diameter SCRs for ultra-deepwater applications. Effects of fatigue, corrosion, and wear associated with terminations at the platform or at sea floor touch-down were studied. Methods of accounting for uncertainties in structural, material, and environmental parameters were also investigated. The study produced a database of international SCR for MMS internal use as well as report document detailing the methodology for assessing the reliability and integrity of SCRs for:

1. SCR hang-off strategies and hull riser tie-in;
2. Effect of flexible joint aging on weld fatigue at hang off;
3. Improved stress recovery for VIV analysis;
4. Wave loading fatigue and coupled vessel/mooring/riser analysis; and
5. Soil pipe interaction and effect on SCR fatigue and extreme response.

The project was completed in July 2006.  In addition to providing the attached final report, Intec presented preliminary findings at the 2006 Offshore Technology Conference in Houston, TX.