In-place disposal of the buried pipelines, the removal of 14 steel platforms and the Ekofisk Tank topsides for onshore disposal – and leave in-place of drill cuttings have previously been given the green light. Nine of the platforms will be removed by the end of 2013, whereas the Ekofisk Tank topsides and preparations for in-place disposal will be completed by 2008. The final useful lives of the Ekofisk 2/4 H, 2/4 Q, 2/4 A, 2/4 B and 2/4 FTP platforms are not known at this stage. The time schedule for the removal of these platforms will be agreed with the Ministry of Petroleum and Energy when the shutdown date is decided.
"It definitely feels good to establish that the planning phase of this special project, which is perhaps the biggest cessation project in the world so far, is finally completed," say Kjell O Jorgensen and Kari Amundsen, who have supervised this extensive work. Phillips has gained support for all of its suggested disposal solutions. The work started, on a small scale, in connection with the Plan for Development and Operation of Ekofisk II in 1993. In 1997/98 the work intensified through a number of studies and consultations, culminating in the submission of the Cessation Plan in October 1999. Since then, preparations for the implementation of the plan have taken place parallel with administrative coordination and decision-making processes in governmental bodies. The in-place disposal of the Ekofisk Tank and the protective barrier wall was also subject to a consultation process among the OSPAR (Oslo-Paris Convention for the Protection of the Marine Environment of the North-East Atlantic) member countries.
The planning of the preparations for the in-place disposal of the Ekofisk Tank and protective barrier is well underway. The main purpose of the preparation is to leave the structures in a condition that does not harm the environment. No complete criteria or requirements for the cleaning conditions exist today. Based on the Norwegian State Pollution Control's guidelines for the classification of environmental quality in fjords and waters close to the coast, Phillips has found an approach to this complex task. In performing this job, the company will work closely with governmental authorities and technical expertise. The work will be revised and updated, as some of the equipment to be used for the task does not exist as of today. The work must be performed under water. The water level in the Ekofisk Tank cannot be significantly reduced as this may threaten the integrity of the structure. "The possibility that other solutions may seem more rational as the preparations progress therefore cannot be ruled out", as the parliamentary bill reads.
The chosen solution involves oil and waste removal from the nine storage cells. The pollution in the bottom sediments in the storages cells will then be removed, and reinjected into the reservoir form the Ekofisk 2/4 X-platform. The sediments accompanying the oil stream from the reservoir were deposited at the bottom of the Tank both when it was used as an oil storage tank – and later, when it was used for separating oil and water. Furthermore, there are two annuli in this structure, an inner annulus between the storage cells and the breakwater wall of the original Ekofisk Tank, and an outer annuls between the Ekofisk Tank and the protective barrier installed in 1989. Some seabed sediments have entered these annuli – and minor discharges of pollution may also have taken place during the structure's installation on the field. These sediments will be covered with sand and gravel to prevent contact with the external environment and to ensure that they do not represent any environmental risk.
A special company will be assigned the job of verifying the preparatory work. Furthermore, Phillips has appointed an independent international scientific group that will monitor the preparation of the Ekofisk Tank and participate in the preliminary work. The team members are experts on maritime environmental issues.
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