OFFSHORE MATERIAL HANDLING SYSTEM AND MATERIAL HANDLING METHOD

Abstract

An offshore material handling system including an offshore crane carrying vessel(4), an installation structure (1) fixed to the seabed and projecting above the sea level is described. The installation structure(1) includes a material handling distribution system on board the installation structure(1). The material handling system includes an independent platform structure(3) for temporary attachment to the installation structure(1) and temporary use on the installation structure (1) for load transfer.

Claims

1. An offshore material handling system comprising: a suitable offshore crane carrying vessel; an installation structure fixed to the seabed and projecting above the sea level, which installation structure includes a material handling distribution system on board said installation structure; and wherein said material handling system includes a crane onboard said vessel arranged to lift an independent platform structure from said vessel and onto said installation structure for temporary attachment to said installation structure and temporary use on said installation structure.

2. The offshore material handling system according to claim 1, wherein said material handling distribution system onboard the installation structure includes lifting appliances able to elevate or lower a load from or to said independent platform structure.

3. The offshore material handling system according to claim 1, wherein said lifting appliances onboard the installation structure is either a gantry crane, slewing crane, alternative crane structure, winches, or other lifting appliances able to elevate or lower a load from or to different levels internally on the installation structure.

4. The offshore material handling system according to claim 1, wherein said offshore crane carrying vessel is a supply vessel, a service vessel or any suitable vessel.

5. The offshore material handling system according to claim 1, wherein said installation structure is either an unmanned wellhead platform (UWP), or any offshore installation fixed to the seabed.

6. The offshore material handling system according to claim 1, wherein said independent platform structure is a corner platform structure.

7. The offshore material handling system according to claim 1, wherein said independent platform structure is attached to the installation structure some distance above the sea level.

8. A method for offshore material handling between an offshore crane carrying vessel and an installation structure fixed to the seabed and projecting above the sea level, which installation structure includes a material handling distribution system on board said installation structure, characterized in that said method comprises the following steps: a) the offshore crane on said crane carrying vessel brings an independent platform structure from said vessel onto said installation structure for temporary use as a load station on said installation structure; b) said crane on said offshore crane carrying vessel brings a load from said vessel onto said independent platform structure; and c) said material handling distribution system brings said load to predetermined level and location on said installation structure.

9. The method according to claim 8, wherein said method includes the following step: d) said crane on said offshore crane carrying vessel brings a second load from said vessel onto said independent platform structure and continues according to step c) above.

10. The method according to claim 8, wherein said method includes the following step: e) said crane on said offshore crane carrying vessel releases and brings said independent platform structure back from said installation structure and onto said vessel.

11. Independent platform structure for temporary attachment to said installation structure and use on said installation structure according to claim 1, wherein said independent platform structure includes attachment means in form of hooks or other fixation means to be attached onto said installation structure.

12. The independent platform structure according to claim 11, wherein said independent platform structure includes a ladder or gangway to enable forming a walkway from said platform structure onto said installation structure.

13. The independent platform structure according to claim 11, wherein said independent platform structure is a corner platform structure.

14. (canceled)

Description

EXAMPLE OF EMBODIMENT

[0027] While the various aspects of the present invention has been described in general terms above, a more detailed and non-limiting example of an embodiment will be described in the following with reference to the drawings, in which:

[0028] FIG. 1 is a perspective view of the installation structure, the vessel with offshore crane and the independent platform structure, and standard load carrier;

[0029] FIG. 2 is a perspective view of the crane on vessel being used to lift the independent platform structure from vessel for temporary attachment on the installation structure;

[0030] FIG. 3 shows the independent platform structure attached to the installation structure;

[0031] FIG. 4 shows lift between vessel and the installation structure;

[0032] FIG. 5 shows the independent platform structure attached to the installation structure with standard load carrier ready for internal material handling;

[0033] FIG. 6 is perspective views of the installation structure with the independent platform structure attached thereto, gantry crane for internal material handling between the independent platform structure to landing area ready to lift standard load carrier;

[0034] FIG. 7 show the top deck with gantry carne, ready for internal material distribution of standard load carrier;

[0035] FIG. 8 shows an alternative crane structure onboard the installation structure; and

[0036] FIG. 9 shows in perspective view an alternative embodiment if the invention showing a corner platform structure to be installed on a corner of the installation structure.

[0037] Reference is firstly made to FIG. 6 Showing a perspective view of an offshore installation structure 1 of a type called Subsea on Stick. The installation structure 1 is made up as an open trusswork structure projecting above the surface of the sea. A Gantry crane 2 is located on top of the installation structure 1 and is straddling over a top deck of the installation structure 1. The

[0038] Gantry crane 2 is moveable on rails back and forth, while a traverser carriage with lifting gear and hook, is running traverse to such back and forth direction, in order to be able to put off loads at any point all over the top deck.

[0039] FIG. 3 shows the installation structure 1 according to FIG. 6 with the detail of the independent detachable platform structure 3 attached to the installation structure 1 some distance above the sea level. The platform structure 3 illustrated, is provided with two spaced apart heavy hooks designed to hook onto a substantially horizontal truss bar on the installation structure 1.

[0040] FIG. 2 shows the various components of the system according to the invention. The system includes a supply boat 4 having a crane 5 onboard, in addition to the above described installation structure 1 and the detachable independent platform structure 3.

[0041] FIG. 1 shows a first step of performing the method steps according to the invention. A hook 6 on the crane 5 is connected to the platform structure 3 lifted off the boat deck at this stage. The hook 6 is more clearly shown in FIG. 2 when the platform structure 3 is lifted a distance above the deck of the supply boat 4 ready for the transfer over the boat rail.

[0042] FIG. 2 shows the platform structure 3 after having been swung out over the rail and to the proximity of the installation structure 1. The next and last step is shown in FIG. 2 where the platform structure 3 is hooked onto a horizontal truss beam 6 on the installation structure 1.

[0043] In FIG. 3 the platform structure 3 is securely attached to the installation structure 1. The lower part of the platform 3 is resting against two respective inclined truss beams 8a, 8b by means of a substantially horizontal thrust bar 9 on the platform 3 structure. A ladder or ramp gangway 10 is shown to the right hand side on the platform structure 3. As shown in FIG. 3, the gangway 10 can be pivoted to establish a walkway over to a staircase structure on the installation structure 1.

[0044] Preferably, the platform structure 3 and interface on the installation structure 1 is to be standardized such that one and the same platform structure 3 can be used on several installation structures 1.

[0045] Next step is to bring a load 11, or several loads, from the supply vessel 4 over to the platform structure 3, as illustrated in FIGS. 1 and 4. This is done in a per se conventional manner.

[0046] FIG. 4-7 shows sequential internal transportation steps on board the installation structure 1 from the platform structure 3 to the top deck of the installation structure 1. This is done by means of the Gantry crane 2.

[0047] FIG. 8 shows a situation where a number of loads have been transferred to the top deck of the installation structure 1 by repeated transportation steps as indicated by FIGS. 4 to 7. Also an intervention equipment 12, or tool, has been installed and erected on the top deck of the installation structure 1 with alternative crane structure onboard the installation structure 1.

[0048] FIG. 9 shows in perspective view an alternative embodiment if the invention showing a corner platform structure 3A to be installed at a corner of the installation structure 1.

[0049] As in the FIG. 3 embodiment, the independent and detachable corner platform structure 3A is attached to the installation structure 1 some distance above the sea level. The platform structure 3A is provided with two spaced apart heavy hooks 3C designed to hook onto respective horizontal truss bars 6, which respective horizontal truss bars 6 are located on respective sides of the installation 1.

[0050] In FIG. 9, the platform structure 3A is securely attached to the installation structure 1. The lower part 3B of the platform structure 3A is resting against a corner column extending in an inclined direction from the sea and to the top of the installation structure 1. A ladder or ramp gangway (not shown) can be installed in order to establish a walkway over to a staircase structure on the installation structure 1.