Gulf of Mexico platform, pipelay work heats up

The refurbished pipelay-derrick barge Hercules has been working for Amerada Hess in the gulf this fall (Fig. 1).

Increased Gulf of Mexico activity is reflected in recent contracts executed for major gulf operators.

In October 1997, Global Industries Ltd., Houston, used its pipelay-derrick barge Hercules in salvage operations for Amerada Hess Corp. And in November 1997, Global was scheduled to complete pipelay work for Shell Pipe Line Corp., Houston.

Upgraded vessel

Global mobilized its pipelay-derrick barge Hercules (Fig. 1) in October to undertake salvage operations in Vermillion Block 310 and West Cameron Block 572. The work involved salvaging two 8-pile platforms, Vermillion 310A and Vermillion 310B, and a 4-pile well protector platform West Cameron 572A.

Each Vermilion platform consisted of a jacket weighing more than 2,800 tons with grouted piles and a 1,600-ton deck. The West Cameron platform included a 550-ton jacket excluding the piles and a 722-ton deck.

Water depths in both areas were approximately 200 ft.

The Hercules had just completed the first phase of a multimillion dollar upgrade, according to Global. This refurbishment included installation of dynamic positioning and conventional pipelay capabilities.

The vessel's specially designed cantilever stinger will allow it to lay concrete-coated pipe up to 42 in. in water depths to 4,000 ft.

The second phase of the conversion, scheduled to begin in 1998, includes installation of a 110-ft diameter reel capable of spooling FBE-coated pipe, pipe bundles, insulated pipe, and pipe-in-pipe systems of up to 18 in. OD.

Global says that when the vessel has completed its refurbishment, it will be a multipurpose vessel laying virtually all types of pipelines in water depths to 8,000 ft.

Pipelay

A fleet of other Global vessels is completing this month a contract to install approximately 40 miles of 20-in. crude oil pipeline connecting a platform riser in Main Pass 289 to Shell's Delta pipeline in Main Pass 69 in water depths to approximately 350 ft.

Installation of the pipeline will be from Global's derrick-pipelay barge DLB 323. Operating from bury barges Tonkawa and Cherokee, the company will subsequently perform riser tie-ins and bury sections of the pipeline.

Approximately, 50,000 ft of pipeline will be buried to 3 ft, and an additional 15,000 ft of line, crossing a fairway, will be buried to a depth of 10 ft.