Mad Dog Project: Regulatory Approval Process for the New Technology of Synthetic (Polyester) Moorings in the Gulf of Mexico

Abstract

This paper summarizes the responsibilities between the Minerals Management Service (MMS), United States Coast Guard (USCG), the American Bureau of Shipping (ABS), and BP Exploration & Production, Inc. (BP) as the Operator for gaining regulatory approval on the new technology of synthetic (polyester) moorings. More specifically, the Mad Dog Project received the first approval for the permanent use of polyester moorings in the Gulf of Mexico. Authors present the regulatory strategy and corresponding structure in regard to the Mad Dog Truss Spar Taut Leg Mooring System. This paper chronicles the Operator's roadmap in engaging the MMS, USCG, and ABS upon making the decision to use polyester through obtaining the necessary regulatory concurrence. Introduction The offshore industry in the Gulf of Mexico (GoM) has expanded to water depths in the 10,000' range. Technology has also expanded to take on the ever-increasing challenges presented in the harsher conditions, one such innovation being the use of synthetic moorings. Polyester moorings have been successfully used on floating facilities in offshore Brazil in water depths over 4000 feet. Also, BP ran a test case on a Mobile Offshore Drilling Unit (MODU) to test handling, installation, and recovery procedures, as well as functionality testing and testing of recovered lines. While the latter was in the GoM, it was set as a temporary mooring configuration. In order to gain approval for the permanent use of polyester mooring in the GoM, the regulations as set out by the MMS and USCG, as well as the delegations of responsibility resulting from the Memorandum Of Understanding (MOU)1, had to be satisfied or equivalencies established. ABS was also involved in the process, with their role being to satisfy Classing requirements and provide third party verification. This concept was considered new and unusual for the GoM, although acknowledgement existed that the constituent parts of this concept were indeed proven technologies. However, since the common established mooring practice for floating facilities is steel rope and wire chain, it was necessary for BP as the Operator to demonstrate that polyester provides an equivalent or better level of operability. This paper summarizes the methods and strategies used in positively engaging the regulatory agencies with this new technology and eventually gaining the necessary consensus approvals, all within a relatively short time period and with a tight project schedule. Mad Dog Truss Spar and Mooring Configuration The Mad Dog Truss Spar is located approximately 190 miles south of New Orleans, Louisiana in Green Canyon (GC) Block 782. The nominal water depth is 4500' and the field runs along the Sigsbee Escarpment (where the bottom is 6500'). The local regulatory offices are the MMS Houma District as part of the MMS GoM Region and the USCG Morgan City Marine Safety Office as part of the USCG Eighth District. The hull is 128' in diameter, 555' long, and has an 11-line taut mooring configuration. There are three mooring line groups - two with four lines and one with three lines. Technical paper OTC 16589 details this further2.

Anchor loads for shallow water mooring of a 15 MW floating wind turbine—Part II: Synthetic and novel mooring systems

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“…Polyester fibre ropes have been used for mooring deep-water offshore platforms for many years now (De Pellegrim, 1999;Bugg, 2004;Haslum, 2005) and extensive fatigue testing has shown that their fatigue performance is better than equivalent steel components (Banfield, 2000). The idea of using nylon ropes for long-term mooring lines is relatively new as there is little available knowledge on the durability behaviour of such structures.…”

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