Traditional landfalls with pipelines along the coast of Norway are performed with concrete plugs in a subsea pull-in chamber and by use of divers. These solutions have caused a long construction period and assume the pulling winch is placed at the pipe laying vessel. It has also been performed a landfall with vertical eruption to sea bed, which was very costly.
Multiconsult has in co-operation with Statoil made a new low cost effective land fall concept for pipelines. The solution includes horizontal drilling to sea bed without the use of concrete plugs and with pulling winch placed in the pull-in chamber. Drilling to sea bed and pull-in is performed through a special cylinder construction, named seal tube. Use of divers is avoided.
Scope of work
Construction of site was performed according to plan.
Performed work: design, tender documents, mechanical requisition, working procedures, assistance with follow-up the contracts, pictures animation, tender evaluation
The new solution has the following advantages compared with the traditional land falls:
- Short performance and little lie time for the vessel
- Considerably cost reduction
- High grade of security for personnel and for execution
- No divers necessary during operation and without submarine welding
- All operations have back-up solutions and can at any time be reversed
- Space for new land fall in the same cavern/ pull-in chambers
- Flexible with regards to future pipe size and choice of pipe line direction on sea bed and in the pull-in chambers
- Piercing the sea bed may be performed close to existing pipelines, since blast is not necessary