Introduction - Why Redevelopment of Ekofisk
Authors: Holhjem Arne 
Published: October 2008

Abstract
The Ekofisk Field, discovered in 1969, was the first field to be developed on the Norwegian Continental Shelf. Currently in the order of 550,000 bbls of oil and 2 bcf of gas is being handled at Ekofisk. However, after more than 20 years of production the Ekofisk Field started to show its age. Facilities were no longer modem, operating costs were increasing and safety standards did not meet latest requirements. In addition compaction of the producing reservoir caused the seabed to subside resulting in a future need for rebuilding or replacing many of the platfonns. These were the technical (and economical) challenges given to the evaluation team. In addition the remaining license period was short and the oil price outlook was not the best. Today these challenges have been overcome. The redeveloped Ekofisk will start operations later this year. This paper discusses the difficult path to arriving at a decision which was right both for the license holders as well as for the country of Norway.

Introduction
Ekofisk has been the pioneer of the Norwegian oil and gas era. And, even though Ekofisk is the longest producing field on the Norwegian Continental Shelf, it is not a dull and uneventful operation. Ekofisk could well be a pioneer also in the future. As per today the new fifty slot wellhead platform (214 X) with dual rig capabilities has been producing oil and gas for more than a year. Eventually it will replace three of the existing platforms. The processing and transportation platform (2/4 J) is undergoing run-in tests and is ready for operations in August of this year. This platform will eventually replace six of the existing platforms. Being the first field to be developed on the Norwegian Continental Shelf, it is not surprising that Ekofisk is one of the first fields that sees a need for a major upgrading. However, it will not be the last field to experience this as all fields eventually mature. There is a clear indication that the Norwegian oil and gas industry is moving into a new era as the original giant fields age.

History
To put todays situation at Ekofisk into perspective, it is necessary to go back and touch on some of the history. The giant Ekofisk Field discovered in 1969, is located in the southern part of the North Sea, approximately equal distance from the coasts of Norway, Denmark and the UK (Fig 1). The reservoir rock is cretaceous chalk, fractured, with high porosity but low matrix permeability. The field is estimated to contain more that 8 billion barrels of oil equivalents in place, however the low matrix penneability results in a field with a long producing life (Fig 2). Ekofisk was brought on production in 1971, only eighteen months after the initial discovery, by the means of four subsea completed wells producing to the Gulftide jack-up. During this temporary production phase permanent facilities were being constructed. Most platforms on the Ekofisk Field tself, including the Ekofisk Complex, were installed during the first half of the 1970's. Following development of the Ekofisk Field, six other fields in the area were developed and tied into the Ekofisk Complex.