Structure For Transporting, Commissioning and Decommissioning the Elements of a Fixed Oil Platform and Methods For Implementing Such a Structure

• US 20080131209A1
• Filed: 12/30/2004
• Published: 06/05/2008
• Est. Priority Date: 01/28/2004
• Status: Active Grant

• Current Assignee: Technip France (Technip)
• Original Assignee: Technip France (Technip)
• Inventors: Thomas, Pierre-Armand
• Granted Patent: US 8,070,388 B2
• Time in Patent Office: Days
• US Class Current: 405/198
• CPC Class Codes: B63B 35/003 for transporting very large loads, e.g. offshore structure modules construction methods for artificial islands mounted on piles E02B17/00; for transporting marine vessels B63B35/40; docks B63C1/00
• CPC Class Codes: E02B 17/021 with relative movement between supporting construction and platform
• CPC Class Codes: E02B 17/0818 with racks actuated by pinions lifting jacks B66F3/02 - B66F3/06
• CPC Class Codes: E02B 2017/0047 using a barge
• CPC Class Codes: E02B 2017/0052 Removal or dismantling of offshore structures from their offshore location
• CPC Class Codes: E02B 2017/006 with lattice style supporting legs

Abstract

The invention relates to a structure for transporting, installing and dismantling a fixed oil platform provided with framework elements which are substantially formed by a bridge and at least one supporting pillar. The inventive structure comprises a floating U-shaped shell provided with at least three lifting legs adapted for resting upon the bottom of the sea and a shuttle movable along the lifting legs for displacing a platform element. Said shuttle consists of at least three elements each of which is associated with the lifting leg and is provided with mechanical means for driving on the corresponding lifting leg in a manner independent of the shell of the structure and with means for connecting to displaceable framework element. Methods for transporting, installing and dismantling the bridge or the supporting pillar of a fixed offshore oil platform are also disclosed.

Claims

1. A structure for decommissioning and transporting an offshore fixed oil production platform comprising framework elements substantially formed by a deck and at least one supporting column, said structure comprising:

a U-shaped floating hull fitted with at least three lifting legs for this hull, adapted to rest on the seabed, each lifting leg being associated with mechanical displacement means housed in a bearing framework of said hull, and

a shuttle which can be displaced along the lifting legs and intended to displace one of the framework elements of the platform, wherein said shuttle is formed of at least three elements each associated with a lifting leg and each comprising, on the one hand, mechanical drive means on the corresponding lifting leg independent of the hull of the structure and, on the other hand, connecting means with the framework element to be displaced of said platform.

2. The structure as claimed in claim 1, wherein each element of the shuttle includes a vertical guidance branch on the corresponding bearing framework of the hull, whose top section comprises a horizontal branch supporting the mechanical drive means of said element on the corresponding leg.

3. The structure as claimed in claim 1 wherein the mechanical drive means of each element comprise, on the one hand, two opposing plates supported by each chord of the corresponding lifting leg each featuring, on each lateral face, a series of teeth and, on the other hand, at least two opposing assemblies, supported by the horizontal branch of said element and each formed of a pinion driven rotationally and cooperating with one of the series of teeth.

4. The structure as claimed in claim 1, wherein the connecting means with the framework element formed by the deck of the platform comprise at least a horizontal plate supporting this deck and positioned on the bottom part of the vertical branch of each element of the shuttle.

5. The structure as claimed in claim 1, wherein the connecting means with the framework element formed by a supporting column of the platform comprise, for each element of the shuttle, a linear, vertical traction device, formed of a chain or cable and two locking assemblies of said traction device, one of said assemblies being supported by said element and the other of these assemblies being supported by the hull for a gradual vertical displacement of the supporting column by successive locking of said locking assemblies.

6. The structure as claimed in claim 5, wherein each locking assembly is formed of two opposing locks that can tilt vertically toward one another between a position releasing the traction device and a position blocking this traction device.

7. The structure as claimed in claim 1, wherein it includes an independent branch for sealing the hull opening that is lockable on said hull.

9. A method of transporting and commissioning a framework element of a fixed oil platform, formed of a deck, between a quay or a barge and a production site, wherein a structure is used as claimed in claim 1.

11. A method of transporting and commissioning a framework element of a fixed oil platform, formed of a section of supporting column, between a quay and a production site, wherein a structure is used as claimed in claim 1.

8. A method of decommissioning and transporting a framework element of a fixed oil platform, formed of a deck, between a production site and a quay for disassembling the deck, characterized in that it consists of the following stages:

positioning beneath the deck a transport structure comprising a U-shaped floating hull fitted with at least three lifting legs for this hull and a shuttle which can be displaced along these legs independently of said hull,

applying the lifting legs onto the seabed,

lifting the hull and the shuttle to bring said shuttle into contact with the deck,

locking the shuttle onto the lifting legs,

lowering the hull to float it,

separating the deck from its supporting column,

raising the deck via the intermediary of the shuttle under the rising action of the lifting legs,

displacing the structure supporting the deck to release said deck from the supporting column,

lowering the shuttle supporting the deck to bring it onto the hull,

floating the structure supporting the deck to the disassembly quay or to a site for unloading onto a barge,

applying the lifting legs onto the bottom to stabilize the hull,

releasing the deck from the structure, and

unloading the deck onto the quay or the barge.

10. A method of decommissioning and transporting a framework element of a fixed oil platform, formed of a section of a supporting column, between a production site and a quay for disassembling the supporting column, wherein it consists of the following stages:

positioning around the supporting column, a U-shaped floating hull fitted with at least three lifting legs for this hull and a shuttle formed of at least three elements that can each be displaced along one of said legs independently of the hull,

applying the lifting legs onto the seabed,

lifting the hull and the elements of the shuttle,

connecting each element of the shuttle to the section of supporting column via a linear traction device,

separating the section of supporting column from the rest of said column,

locking each traction device to each element of the shuttle,

raising the elements of the shuttle to lift the section of supporting column,

locking the traction devices alternately to the elements of the shuttle and the hull and lowering and raising said elements to gradually lift the section of supporting column,

bringing the shuttle supporting the section of supporting column into contact with the hull,

lowering the shuttle and the hull to float it,

continuing the descent of the hull to cause the lifting legs of the structure to ascend by reaction,

displacing the structure supporting the section of supporting column to remove this section from the production site and bring it to a loading site on a barge,

applying the lifting legs on the unloading site on the seabed,

lifting the hull and the shuttle to raise the section of supporting column above the water level,

positioning the barge in the structure beneath said section,

lowering the hull and the shuttle to place the section of supporting column onto the barge,

detaching the traction devices from the section of supporting column, and

bringing the barge carrying the section of supporting column to the disassembly quay and repeating these stages for other sections of said supporting column.