Pipeline assembly comprising an anchoring device

Abstract

The invention relates to a pipeline assembly and a method of installing a pipeline assembly, wherein the pipeline extends at least in part on a seabed and curves upwardly from the seabed along a curved section thereof, the pipeline extending toward a delivery end provided at the water surface, wherein a connecting device connects the pipeline at a coupling point to an anchoring device at the seabed for preventing the coupling point from moving upward. The invention further relates to a pipeline device comprising at least two pipeline assemblies which are interconnected at a substantial distance from the seabed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 12 / 089,437, filed May 5, 2008, which claims the benefit of the National Stage of International Application No. PCT / NL2006 / 000507, filed Oct. 9, 2006, which in a continuation-in-part of U.S. application Ser. No. 11 / 245,477, filed Oct. 7, 2005, the contents of which is incorporated by reference herein.FIELD OF THE INVENTION[0002]The present invention relates to a pipeline assembly. The present invention further relates to a method for installing the pipeline assembly.DESCRIPTION OF THE PRIOR ART[0003]Pipelines are widely applied in the off-shore industry, for instance for conveying a fluid or a mixture of fluids from an oil well on a seabed to a target device located at a water surface. This target device may be a vessel or a platform, for instance a floating production and storage platform, generally known as an FPSO.[0004]Often, a pipeline is laid which rests on a seab...

AI Technical Summary

Benefits of technology

[0027]The connecting device limits the freedom of movement of the coupling point, thereby substantially reducing movements in the touch-down zone of the pipeline. Hence, fatigue of the pipeline, in particular in the touch-down zone, is substantially decreased.

[0099]The required form and position of the pipeline can be achieved by simply maneuvering the delivery end by the pipeline laying vessel. Hence, no complicated operations at the seabed are necessary.

Problems solved by technology

Every movement of the riser causes an increased fatigue of the pipeline and thus, a loss in lifetime.

A target device located at the water level is generally subject to forces from wind, waves and water currents, which cause movements and rotations of the target device.

If a delivery end of the riser is connected with the target device, the delivery end moves together with the target device, and the movements and rotations of the target device cause fatigue in the riser.

This is generally disadvantageous.

Installing a long anchoring line is generally difficult.

Supporting the delivery end of the riser with a buoyancy device does not prevent all movements of the pipeline.

These forces may still cause movements of at least a part of the riser, thereby causing fatigue.

This causes an increased fatigue in the touch-down zone.

Apart from an increased fatigue, a movement of the touch-down zone results in a risk of the seabed section of the pipeline being damaged, for instance due to wear and tear from the pipe-soil interaction.

The device of U.S. Pat. No. 4,023,517 has a grave disadvantage in that extensive construction work is necessary at the seabed in order to install the flexible hose and connect it to both the horizontal pipeline and the vertical riser.

The device of U.S. Pat. No. 4,023,517 also extends above the water surface, thereby being influenced by forces from wind and waves, which seriously increase fatigue of the riser.

The movement induces strong fatigue in the riser, leading to a short lifetime.

The riser system of U.S. Pat. No. 4,802,431 extends above the water surface, and is thus influenced by forces from wind and waves, which further increases the fatigue of the riser.

The combination of a lazy wave form and a direct connection to a platform at the water surface creates large, varying loads on the riser system, leading to strong fatigue and a short lifetime.

Such a flexible pipeline is only suitable for smaller water depths.

This configuration leads to a strong fatigue of the pipeline, because large dynamic loads may be exerted on the pipeline.

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