The Oseberg Flowline Bundles were installed during July 1988. The first end connection was performed to the Oseberg B Platform by the J-tube pull method. This paper describes the design and construction of the bundles as well as theoretical examination of actual observed J-tube pull forces.
The two Oseberg Flowline Bundles each comprising one 8-inch oil line and one 2-inch service line connect the two satellite wells B-49H and B-50H located approximately 6 kilometers North of the Oseberg Field Centre to the two platforms.
The Oseberg Field, consisting of blocks 30/6 and 30/9 in the Norwegian Sector, was in 1979 and 1982 decided to be developed by Norsk Hydro and its five partners. The development of the field was to take place in stages, with the first stage to be completed by April 1, 1989. First oil produced was 1.December 1988, 4 months ahead of schedule.
Norsk Hydro, as operator for the group, designed fabricated and installed one drilling platform (steel jacket) with a bridge to a process platform (concrete gravity base structure) and a 28 inch pipeline for oil transportation into an oil terminal at the west coast of Norway. Additionally, a subsea development scheme was undertaken, in order to recover oil reserves beyond the reach of the platform.
The subsea development was initiated in late 1984 with a final decision on number of wells taken summer 1985. The two single slot wells were placed approximately 6 km away from the platforms. Each well was developed with one production and one service line to be connected to the steel jacket via J-tubes and one umbilical connected to the concrete p1atform via a J-tube. The routing of the different lines are shown in Fig. 1.
The detailed engineering of the flowlines started early spring 1986, reviewing various installation scenarios such as bottom tow, off-bottom tow or the use of flexible pipes, before selecting the conventional installation method using carbon steel pipes. Detailed material and installation specifications were completed in autumn 1986. By summer 1987 all contracts pertaining to the purchase of materials, insulation application and installation were placed. The flowlines were completed and hydrostatically tested in late summer 1988.
The flowlines will be used to transport oil with a throughput of up to 25000 BPD from each well.
The partners of Norsk Hydro Production a. s in the Oseberg development are: Den norske stats oljeselskap (Statoil), Total Marine Norge A/S, Elf Aquitaine Norge A/S, Saga Petroleum A/S, Mobil Development Norway A/S.
In January 1986 Norsk Hydro awarded the detail engineering contract for the Oseberg Flowlines to A.R. Reinertsen of Trondheim, Norway.
Pipeline hydraulic studies were made for various flow conditions and line sizes, and the costs for the different alternatives estimated. On the basis of forecast production an 8-inch 1ine in two-phase flow appeared to be the most practical solution for the production line.
