Abstract

Subsea development schemes for oil and gas Fields require reliable riser systems to control production wells and handle high pressure effluents from the sea bottom to floating processing supports. A permanent high pressure multiline riser has been designed to be installed in articulated structures. The riser is able to sustain the more adverse sea conditions of the North Sea without any need for disconnection. The technology of such a riser has been developed in detail. Fatigue and life endurance tests have been performed on full scale protoeype component parts. Test performed on full scale protoeype component parts. Test results confirm that the design may be applied with confidence to industry. The ability to pass high pressure pipelines through the articulation is the specific feature of a riser connected to a column. The technique is based on deflecting pipes passing through an annular universal joint. These pipes are passing through an annular universal joint. These pipes are arranged in a bundle configuration and extend from top to bottom of the column inside a central stack. Deflecting steel pipes are expected to last several years and can easily be replaced from the top deck of the column. The reliability of this riser design led to comprehensive studies for diverse uses of the column: * The use of an articulated structure as a logistic platform to permit daily control and maintenance of subsea wells. * The use of a column acting as a permanent riser an single mooring point for a floating production vessel with the possible alternative of installing production facilities on an isolated column. Water depths up to 400m can be reached with a single articulated structure.

Introduction

The development of the offshore oil and gas industry now advancing in water depths of 100–350m.

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