Northeast Frigg Subsea Gas Production System

Abstract

Abstract The North East Frigg (NEF) gas reservoir is a small satellite of the giant Frigg gas field located in the North Sea in 100 meters of water. NEF gas reserves are to be developed using a subsea production system, this being the first major underwater gas production project ever attempted in the North Sea. The purpose of this paper is to describe the NEF subsea development concept, to explain the ration for its selection and to mention possible applications of this system in the development of other marginal fields. The NEF subsea production facilities comprises of four major components:–a subsea template which houses and protects six wells and a manifold–a 16" gas line which links the manifold to the Frigg Field Treatment platform (TCP2)–a Field Control Station (FCS) whose main function is to control the subsea equipment–treatment, metering and boosting modules installed on the TCP2 platform to process the 6 million cubic meters per day of NEF gas. Different development schemes were evaluated during the preliminary selection studies:–conventional fixed steel structure–subsea wells drilled and controlled from a permanent semi submersible platform moored above the wells–subsea wells and manifold remotely controlled from Frigg field–subsea wells remotely controlled from an unmanned articulated column installed close to the well cluster. The last scheme was selected as being the best optimization in terms of:–Operational safety mainly due to separation of critical functions–Reliability of gas production by extensive use of conventional and tested equipment although assembled in a novel configuration–Investment costs–Potential adaptation of the concept to future developments of marginal fields To date, detailed engineering of project components is completed, fabrication and drilling are in progress. The production start-up is scheduled in 1984. Introduction Recent shortages and uncertainties in oil/gas supplies and the related price increases have transformed some unprofitable, marginal and/or difficult fields into commercial ones. In this context Elf Aquitaine Norge (EAN) and its Partners initiated the NEF development studies for producing a satellite of the giant Frigg gas field. This opportunity combined with the present necessity to develop economically attractive concept for producing marginal fields in a difficult environment led to an unconventional approach. Preliminary studies began in 1979 with final decision being made mid 1980. Detailed engineering design of the various sub-systems is now completed. Fabrication of NEF components and the drilling of the wells are in progress. Production start up is expected in 1984.