Removal of old oil filled submarine cables in the Oslo Fjord 2016/2017

摘要

The Transmission System Operator (TSO) of the Norwegian energy system, completed a new 13 km submarine cable connection across the Oslo Fjord in 2014. The old out-of-service 420 kV submarine oil-filled cables from 1981 was removed in 2016-2017. This paper describes the requirements for the removal project, the project scope, the project execution with engineering, preparation work, removal of the installations and disposal of the cables. The removal project scope consisted of; 70 km of single core 420 kV submarine oil-filled cables at maximum 320 meters water depth in a sailing lane with heavy traffic, removal of oil-pressure systems and termination facilities, recycling of all parts and cable lengths. The project showed that with proper planning and well-prepared procedures, it was managed, together with the chosen contractors, to perform a successful removal and disposal project without any HSE incidents. Due to high metal prices, the project net cost was well within the original budget. The way this removal project was carried out may be to some guidance for other utilities that has old out-of-service oil-filled submarine cables they consider to remove.