Deck mounted pull riser tensioning system

Abstract

A deck mounted pull riser tensioning system for a floating platform or vessel includes at least two cylinders having a cylinder body supported at an upper or lower end on a deck or tensioner support structure of the platform or vessel in spaced apart relation with the cylinder rods extending downwardly from the cylinder body, or vice versa. A load structure member is connected to lower ends of the cylinder rods or bodies and has an opening therethrough for receiving a portion of a riser extending from the seafloor. A vertically adjustable riser attachment supported on the load structure member over the opening attaches to a portion of the riser extending through the opening and generally centrally between the cylinders. The cylinders pull upwardly on the load structure member to exert an upward tensioning force on the riser at the location of the riser attachment.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims priority of U.S. Provisional Patent Application Ser. No. 60 / 835,655, filed Aug. 3, 2006.BACKGROUND OF THE INVENTION [0002] 1. Field Of The Invention [0003] This invention relates generally to riser tensioner systems for offshore floating platforms and vessels, and more particularly to a deck mounted pull riser tensioning system for use on floating platforms and vessels that incorporates direct acting cylinders having cylinder rods connected with a load structure member that has a riser attachment which attaches to a riser extending therethrough and generally centrally between the cylinders whereby the cylinders exert an upward tensioning force on the riser. [0004] 2. Background Art [0005] Marine riser systems are employed to provide a conduit from a floating platform or vessel at the water surface to the blowout preventer stack or, production tree, which is connected to the wellhead at the sea floor. A tensioning ...

AI Technical Summary

Benefits of technology

[0019] One of the advantages of the present system is that the tensioner cylinder arrangement uses multiple, direct acting cylinders configured in a manner to minimize the overall footprint of the system and to achieve maximum tensioner stroke with minimum overall length of the cylinders.

[0020] Another advantage of the present system is that the tensioner cylinder configuration incorporates an accumulator system to achieve a desired stiffness variation with cylinder stroke, and in applications where multiple riser tensioning systems are deployed on the platform or vessel, the accumulator system may be shared between tensioner cylinders.

[0021] Another feature and advantage of the present system is that the rods of the tensioner cylinders are connected to a common load structure member that in turn supports a riser attachment which is attached to the riser itself and allows the attachment to the riser be variably adjusted vertically thereon to accommodate variations in the riser stack-up relative to the seafloor.

[0022] Another feature and advantage of the present system is that the interface between the riser and the load structure member may be rigidly fixed, or supported by a spherical bearing connection to offer a degree of relative rotational freedom.

Problems solved by technology

Typically these types of tensioner units require frequent maintenance due to the constant motion producing wear and degradation of the wire rope members and occupy a relatively large space on the supporting structure.

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