Precise seabed emplacement of an articulated loading platform in the North Sea
The Statfjord B articulated loading platform is a single point mooring (SPM) consisting essentially of three principal components: gravity base, cylindrical column and rotating head. Built in West Germany and assembled in a Norwegian fjord, the unit was towed to the Statfjord B site and installed precisely adjacent to a seabed valve station and a previously laid sealine in August, 1982. Prior to arrival of the SPM at the site two piles had been driven into the seabed adjacent to the subsea valve station against which the SPM's gravity base was to be docked. Two matching guides had been incorporated in the gravity base for the purpose of mating with the piles. The SPM was maneuvered into position and held steady by three tugboats. A diving support vessel moored on location was equipped with two hydraulic heave compensating winches from which wire ropes were led vertically and fed through sheaves on the valve station to the SPM base. By maintaining constant tension on the pull-in wires and slowly paying out the tug towlines the gravity base was positioned precisely with respect to the horizontal axes and heading by mating the guides with the piles. Touchdown and skirt penetration were achieved by controlled ballasting of the column with water. An integrated acoustic transponder system provided precise real time data on SPM position, base and column angles and under-keel clearance. Final approach was monitored by means of closed circuit television (CCTV). This paper describes the technique developed to install the large structure with a very high degree of precision in two horizontal axes and in azimuth.
- Research Organization:
- Single Buoy Moorings Inc.
- OSTI ID:
- 5436996
- Report Number(s):
- CONF-830514-
- Journal Information:
- Offshore Technol. Conf.; (United States), Vol. 2; Conference: Offshore technology conference, Houston, TX, USA, 2 May 1983
- Country of Publication:
- United States
- Language:
- English
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