Environmental Impact From Removal of Installations: The North East Frigg Field Installations

1.0 Abstract The removal of the Field Control Station (FCS) from the North East Frigg Field was successfully performed in 1996. The preparation started in 1990 and have been a long process. The final Abandonment and removal Plan was approved by the Norwegian Parliament in 1995. This paper presents the decision process by the Authorities of the Operator's Abandonment/removal plan, the approach and the results of the Operator's work to meet the environmental, safety and cost associated targets in accordance with the Authority's abandonment/removal plan, the prevailing legislation and the International legal framework. The additional studies, engineering and risk analysis undertaken allowed the Operator to choose and the Authorities to decide on a combination of different type disposal of parts of the installations. The approved disposal scenarios represents a very satisfying solution for the environment both at sea and in air. Although the NEF field consists of very specific installations, this first case in Norwegian continental shelf attracted considerable interest in term of decision process, contractual and safety-environmental aspects. This was the first case for the Norwegian Authorities to handle and it can be used as an example for the decision process when removal of other platforms is being prepared in the future especially in terms of Environmental Impact assessment, operation safety, Waste Management Program, Third Party Inventory etc. However this does not preclude the need to study each installation case by case. Introduction The North East Frigg (NEF) gas field was a small satellite of the Frigg field (see Fig 1), operated by ELF Petroleum Norge as. When the NEF Subsea Production System (SPS) came on stream 8 December 1983 it was the first multiwell SPS to deliver commercial gas. The field was shut in 8 May 1993 after having produced more than 11 BSCM of gas and was thereafter the first field to be decommissioned in the Norwegian Sector of the North Sea. The abandonment of the wells was performed Summer 1994, the Field Control Station was removed Summer 1996 and the Subsea Template will be removed in Summer 1997. This paper, which is a follow up of the SPE 27 148 paper presented at the conference in Djarkarta January 1994, describes briefly the decision process involved in obtaining the Authority's approval of the Abandonment and Removal Plan, the Operator's measures to meet the requirements set by the Authorities and the final disposal of the installations. 3.0 DESCRIPTION OF THE INSTALLATIONS Figure 1 shows a perspective view of the installations in place on the field for which removal or abandonment have been assessed. They are: A subsea Template with 6 wells. An unmanned Field Control Station (FCS) comprising concrete base, a steel column and a head accommodating an helideck, living quarters area and control equipment. Six umbilicals (hydraulic control lines, injection and service lines) connecting the FCS to the template for direct control of the Xmas trees. Electrical control and power cable from Frigg Field to FCS 16 inch gas pipeline for the transportation of the produced gas to Frigg field. 2" inch methanol pipeline for the transportation of methanol from Frigg field to North East Frigg FCS. An overview of the weights of the different installations as well as a their material content is given in table 1. P. 177^