Navigating the Gulf of Mexico Hurricane Season: Past Lessons and a Path Forward

Abstract

In a body of water commonly traveled by powerful cyclones during hurricane season, weather challenges in the US Gulf of Mexico (GOM) must be met with equally formidable technology. Such technology includes the dynamic positioning of vessels and disconnectible transfer systems; streamlined evacuation, abandonment, and plugging procedures; platform mooring, floaters, and risers; rig and module tie down; post-storm structural inspection; and weather-savvy structure design. Integrity Performance and Data The GOM platform design criteria have become more stringent following the major storms of the past several years. The impact of these storms on oilfield infrastructure has been greater on the GOM continental shelf, where development began in 1947, than on deepwater regions where facilities’ installation began in 1995. Today, shelf development is in decline and deepwater infrastructure is fundamentally different, said Mohammad Rahman, lead analyst for the Gulf of Mexico at Wood Mackenzie. Deepwater platforms are too deep for platform jackets and rely instead on mooring cables for which weather design specifications regarding strength and number have recently become stricter, he said. For example, regarding the comparison of fiber rope mooring systems’ performance testing methods, modeling with Young’s Modulus by Cross Sectional Area with an upper- and lower-bound linear fiber rope stiffness model, compared with modeling the true nonlinear stiffness behavior exhibited by fiber ropes, was presented in paper OTC 20838-MS, “Fiber Rope Mooring Assessment-API RP 2SM Piecewise Linear Stiffness Vs. Nonlinear Stiffness With Integrated Permanent Rope Elongation (E.H. Zimmerman, Delmar Systems, et al, 2010).” The latter nonlinear method also incorporates a function to capture permanent or nonrecoverable rope elongation caused by a hurricane, and its impact on the performance of a mooring system. “By modeling the true nonlinear stiff-ness and being able to capture the permanent nonrecoverable elongation of fiber mooring ropes in a mooring analysis, the designer can more accurately assess the vessel motions during a storm event and more effectively plan component lengths such that retensioning operations will not significantly impact the facility’s ability to operate,” the paper said.