The Gulf of Mexico is a unique region when it comes to the operational aspect of moored mobile offshore drilling units (MODUs). There is vigorous tropical activity in the area, combined with a dense infrastructure that is not found elsewhere in the world. Additionally, there is a wide variety of different size and types of companies who operate in the Gulf of Mexico, with varying levels of acceptable risk based on their own company's risk model. This paper outlines the guidance that the Minerals Management Service (MMS) provides to lessees and operators who conduct drilling, workover, or completion operations on the Outer Continental Shelf (OCS) in the Gulf of Mexico using moored MODUs during hurricane season.

Information includes the regulatory requirements, along with further guidance given to operators. The MMS approval process is described, along with how MMS uses the data in the approval process. MMS uses risk assessments in the approval process and information is shared in that regard. Statistics and analysis from the 2008 hurricane season are provided - types of mooring equipment, return periods of the mooring systems, risk assessments results, etc. A brief synopsis, outlining the resultant damage from the 2008 hurricane season, is also included.


As part of its mandated responsibilities, the Minerals Management Service (MMS) regulates offshore oil and gas drilling, completion, and workover operations on the Outer Continental Shelf (OCS). In keeping with the agency's regulatory objectives to ensure that operations are safe and that marine and coastal environments are protected, the MMS is looking very closely at the fitness of moored mobile offshore drilling units (MODUs) during hurricane season in the Gulf of Mexico. The hurricane season for the Gulf of Mexico is June 1 through November 30 every year.

The effects of Hurricanes Ivan, Katrina, and Rita during the 2004 and 2005 hurricane seasons, along with Hurricanes Gustav and Ike in the 2008 hurricane season, were detrimental to oil and gas operations on the OCS in the Gulf of Mexico. Fortunately, these hurricanes did not cause any loss of life or significant pollution because of industry's ability to secure wells and evacuate personnel successfully. There were moored MODUs that experienced station-keeping failures, along with jack-up rigs that were unable to keep station, and platform and pipeline damage. MMS is concerned about the loss of these facilities, as well as the potential for catastrophic damage to key infrastructure and the resultant pollution from future storms.

In an effort to reduce these effects, real and potential, the MMS Gulf of Mexico OCS Region sets forth guidance to ensure compliance with the regulations and to improve performance in the area of moored MODUs and their station-keeping ability during the environmental loading that may be experienced during hurricanes.

Regulatory Requirements.

The regulation at 30 CFR 250.417(a) states what must be provided if an operator plans to use a MODU. The operator " must provide information and data to demonstrate the drilling unit's capability to perform at the proposed drilling location. This information must include the maximum environmental and operational conditions that the unit is designed to withstand.??

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