DORIS was in charge of developing a novel riser concept, meeting the challenges of this deepwater development, the deepest ever off West Africa.
Project outline
- Flowlines: Two 8-inch prod. lines (+ two 2-inch service lines) inside a 30-inch carrier pipe
- Riser towers: Four 8-inch prod. lines along with a gas lift line and two 8-inch injection lines (water or gas)
- Buoyancy tank: 40 m high; ø 8 m; 1,300 m3 displacement
This project was the deepest ever in 1998.
Services delivered by DORIS
The search for a versatile, reliable and cost effective solution opened the way to the Riser Tower Concept. The proposed solution was based on the use of sealine bundles and self-supporting hybrid riser towers housing the production, water/gas injection, gas lift and service lines in a single piece of equipment.
The production flowlines use a new bundle technology whereby two 8-inch production lines are installed inside a 30-inch carrier pipe. Syntactic materials placed inside the bundle provide the required buoyancy as well as a level of insulation.
The towers are connected to the FPSO through flexible jumpers and to the flowlines by jumper spools.
- Concept definition and development within a design competition (1997)
- Front end engineering and preparation of MTO’s for submission to ELF (first half of 1998)
- Detailed engineering (from mid-1998 to 2001)
- Model tests for towing and in-place conditions through DORIS subsidiary OCEANIDE (2000)
- Assistance to AMG for Girassol Phase 2 and Jasmim development (2002)
