ABSTRACT

The Glomar Beaufort Sea I was successfully mobilized to its first drilling location, the Exxon Antares prospect in the Alaskan Beaufort Sea, only 13-1/2 months after go-ahead. The paper reviews the completion of construction, describes the site surveys and its characterization, and details mobilization operations from Japan to Alaska.

INTRODUCTION

The Glomar Beaufort Sea I, a Concrete Island Drilling System (CIDS), is a United States Coast Guard certified Mobile Offshore Drilling Unit (MODU) and is classed by the American Bureau of Shipping as a Maltese Cross A-I Caisson Drilling Unit. Its structure is comprised of three basic stacked components:

  • A compartmented A537 steel Mud Base 312 ft in length, 295 ft in breadth and 25 ft deep with raked sides.

  • A central core prestressed and post-tensioned concrete BRICK, octagonal in shape, 234 ft across the flats, 44 ft in height, straight sided.

  • An EH-36 (modified to -60"F) steel deck unit,290.5 ft in length, 274 ft in breadth, and 26 ft deep with raked sides built as two independent deck barges.

The Glomar Beaufort Sea I (CIDS) was installed on its initial Alaskan Beaufort Sea drill site, the Exxon Antares' prospect, only 13.5 months after a letter of intent was signed with the Nippon Kokan (NKK) shipyard in Japan and 10 months after the first concrete was poured. At the peak of activity, 4 shipyards and 2 offsite facilities utilizing over 1600 workers were engaged in fabricating the principal sub-assemblies: mud base, brick, port and starboard deck barges, drill rig, and quarters. Numerous papers and articles have detailed the design (References 1 through 15). This paper summarizes the completion of construction and its mobilization to the drill site.

CONSTRUCTION COMPLETION
Mud Base Construction

Construction of the Mud Base began at NKK's Tsurumi Works on September 28, 1983 and continued until March 13, 1984. The Mud Base was launched by skidding it onto a submersible barge. This created an interesting multiple degree of freedom problem involving variable and offset loads and inclination of the barge coupled with tidal effects that the shipbuilder resolved with a computer controlled barge ballast system. The Mud Base was then launched from the barge and towed 250 miles from the Tsurumi works to the Tsu works to await assembly with the BRICK. After arrival at Tsu, a 3 inch thick asphalt rubber compound was applied hot over the entire top of the Mud Base within the shear curb using conventional road building equipment to evenly distribute the load from the BRICK into the Mud Base structure. The asphalt rubber compound was developed and tested under contract by B.A. Va11erga, Inc. and consisted of 15% asphalt paving grade binder, which contained 20% ground vulcanized rubber, and 85% aggregate, made up of 70% clean dry river sand and 30% Meso1ite.

Keywords:
cid, strength, global marine development inc, exxon production research co, phillips, barge, drilling equipment, concrete brick, operation, seafloor
Subjects:
Drilling Equipment, Offshore drilling units
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1986. Offshore Technology Conference
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