Marathon Introduces Semisubmersible For Gulf Of Mexico Environment

Marathon LeTourneau Offshore Company of Houston recently announced its new GranGulf® Class semisubmersible drilling unit that is rated to drill in water depths up to 3,000 feet and can carry a deck load of 4,000 tons. As the leading U.S. producer of offshore drilling units, Marathon developed this new design to fill the offshore industry's need for a semisubmersible drilling rig that is specifically suited to the deepwater Gulf of Mexico operating environment and other areas with similar conditions.

Recent Department of the Interior deepwater lease sales in the Gulf of Mexico have added promising new acreage in water depths ranging from 500 to 2,500 feet. Newly built, large North Sea class semisubmersibles, some of which have been relocated to the Gulf, are constructed for much harsher operating environments, and represent a less than cost-effective option for oil and gas exploration in these new deepwater tracts.

The GranGulf offers optimum payload for a semi of this size and weight. In addition, its design incorporates a unique lower hull configuration, for which a patent is pending, that gives the unit superior storm response characteristics, less transit resistance, and better wave clearance, all without loss of normal station-keeping performance while drilling.

The new design semi is a four-column stabilized unit. There is the option for propulsion assist or dynamic positioning capabilities. As a statically anchored unit, its maximum water depth is 2,000 feet; equipped with optional dynamic positioning, it can drill in water depth up to 3,000 feet.

Overall length is 280 feet and overall beam is 195 feet; height to main deck is 96 feet. Maximum storm conditions are: wave height, 100 feet; wind velocity, 100 knots; current, 3 knots.

As the leading builder of jackup drilling rigs for 30 years, Marathon LeTourneau has historically provided new designs for increasing water depths and for the harsh and hostile environments of newly opened frontier drilling areas. The company's most recent new jackup designs, the Gorilla and Super 300 bottom-supported rigs with Slotlever ® capabilities, are currently extending the range of self-elevating units into remote areas with water depths of 450 feet. The introduction of the GranGulf Class semi continues this trend of providing new mobile offshore drilling units intended for new operating environments. Marathon's line of jackups ranges from large, deepwater, hostile environments to compact, shallow-water units for mild environments. The company also builds other types of offshore drilling vessels, including semisubmersibles, drillships, and tenders, and performs repair and modification work on all classes of offshore drilling units. Marathon has rig construction facilities in Vicksburg, Miss.; Brownsville, Texas; and the Republic of Singapore. Marathon is a Penn Central company-

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