Zentech, Inc.

Amfels, Inc.

Robin Shipyard (pte.) Ltd.

Kenneth P Choate

John S Laird, Ii

Ramesh Maini

Partha Chakrabarti

A taut mooring system for use on a mobile offshore jack-up platform while it is in an elevated operating condition. The elevated operating condition is with the hull jacked up a safe distance above the highest anticipated wave crests, on vertically movable legs which extend to the ocean floor. The mooring system consists of: radially spaced mooring line attachment means on the structure of the platform; suction piles that are radially spaced around the platform, consistent with the radial spacing of the mooring line attachment means; and taut mooring lines which radially connect the suction piles to the attachment means. The flexibility of the taut mooring system provides the ability to coact with the platform's free standing storm resistance capabilities, yielding enhanced capabilities that will enable the platform to safely resist storm induced forces that the platform would not normally be capable of withstanding, and to enable the platform to be used with longer legs in deeper water.

Taut mooring system for jack-up type mobile offshore platforms

An arrangement of a jackup platform's elevating system, leg guides, hull-to-legs load transfer device, and method of operation of the load transfer device for an offshore jackup platform's hull to be supported by legs which have one or more vertical toothed gear racks attached. An apparatus consisting of rectangular blocks with protruding lugs that are shaped for efficient engagement with a portion of the upper faces of the gear rack teeth, that extend vertically on the leg chords of the jackup platform. The rectangular blocks are movable in a direction perpendicular to one side of the gear rack. Powered guide assemblies control movement of the rectangular blocks such that their protruding lugs can move into the spaces in between the gear rack teeth. The protruding lugs of the rectangular blocks can then bear against the gear rack teeth and faces of the rectangular blocks can bear against structure of the hull to transfer hull weight and storm induced interaction forces between the hull and the legs of the jackup platform.

Offshore jackup hull-to-legs load transfer device and elevating and leg

Offshore jackup elevating and leg guide arrangement and hull-to-legs

A locking apparatus and method for an offshore jackup rig having at least one leg extending through the hull and at least one set of rack teeth attached to each of the legs. One or more locking bars are supported from the hull and are movable in a direction substantially normal to the face of the rack teeth. A piston and cylinder power assembly moves the bars towards the teeth and a retention system engages the bars holding them in engagement with the teeth. The elevating system of the rig coacts with the set bars to lock the hull and legs together.

Offshore jackup rig locking apparatus and method

A plurality of vertically extending guide means is carried by the structure of a jack-up type mobile offshore platform. The guide means is spaced about each of the vertically extending legs which engage the floor of a water-covered area and enable the hull, forming part of the structure, to be elevated and supported in position above the water in the water-covered area. A first pair of wedges forms a first wedge means that is movable vertically in each of the guide means, and a second pair of wedges forms a second wedge means that is spaced vertically in each of the guide means relative to the first wedge means. The first and second wedge means are also movable vertically in the guide means. Means interconnect the pair of wedges which form each the first and second wedge means so that one of the wedges of each pair may be moved to engage a vertical leg chord and thereby lock the legs to the structure and distribute loads and more particularly horizontal loads applied to the structure at joints of the vertically extending leg chords, that is, at the intersection of the vertical leg chords with the respective laterally extending braces between the leg chords.

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Houston, TX, United States of America

Kenneth P Choate