Decommissioning of the Ekofisk I platforms
Authors: Jørgensen K.O. 
Published: October 2008

Abstract
14 platforms with various functions have been made redundant as a result of the Ekofisk II project, and although some of them will continue to operate some years after startup of Ekofisk II, a common Cessation plan and an Impact Assessment will be prepared for decommissioning and disposal of these platforms. Four main disposal options are being evaluated, with several alternatives for each option currently subject to various feasibility studies. Decommissioning of the first platform, Cod, is scheduled to start later this month, and it is expected that all wells on this platform will be plugged by fall 1998. The disposal methods for the Ekofisk Complex North are currently being studied, and preparatory cleaning and decommissioning will start once the changeover to Ekofisk II has been completed.

The Ekofisk Cessation Project
The Ekofisk II Plan for Development and Operation (PDO) included a commitment to decommission and dispose of these installations in a safe, environmentally responsible and cost efficient way and according to the appropriate regulations. Platform decommissioning is a relatively new activity in the Norwegian North Sea, and the Odin platform (Esso) and the North-east Frigg (Elf) are the two only examples so far. None of these had been removed or disposed of at the time of Ekofisk II PDO approval in 1994. A project team was therefore organized late that year and named the Ekofisk Cessation Project (ECP). Their mandate was to address the decommissioning issues of the redundant Ekofisk I installations and to evaluate any and all possible methods of decommissioning and disposal - and to relate this to the regulatory regimes in Norway, the OSPAR area (North Sea and North East Atlantic) and to international conventions (IMO). The conceptual studies were completed mid-1996, and outlined options to carry forward into more detailed feasibility studies. In the same period, the Norwegian Authorities drafted a new version of the Petroleum Act, which addressed field abandonment and disposal in considerably more detail than the previous law, and came into effect mid-1997. One of the new requirements in this law that the license group need to submit a Cessation Plan five years before the end of the license period or two years before cessation of operations of a platform. For Ekofisk I, the date for plan submittal has been agreed to third quarter of 1999 with an anticipated response from the Authorities two years later. This schedule implies that the installations will be shut down, cleaned and prepared for a "cold" phase from 1998/99 and until the final disposal option has been decided by the Norwegian Parliament. At the same time, there is considerable activity among the European countries involved in OSPAR to arrive at common guidelines for platform disposal in the North Sea area, which certainly also will have an effect on the options available for platform disposal on the Norwegian Continental Shelf. It is anticipated that the 16 OSPAR countries will reach an agreement on the Ministerial level in June 1998.

Ekofisk I Platforms to be decommissioned
The 14 redundant Ekofisk I platforms to be decommissioned starting August 1998 are identified on figure 1.