WO2008048852A2

WO2008048852A2 - Subsea installation systems and methods

Info

Publication number: WO2008048852A2
Application number: PCT/US2007/081105
Authority: WO
Inventors: Donald Wayne Allen; Christopher Steven West; William Andrew West
Original assignee: Shell Oil Company; Shell Internationale Research Maatschappij B.V.
Priority date: 2006-10-13
Filing date: 2007-10-11
Publication date: 2008-04-24
Also published as: GB2456686A; BRPI0720510A2; US20100050921A1; NO20091843L; WO2008048852A3; AU2007312981A1; AU2007312981B2; GB0904576D0

Abstract

There is disclosed a system comprising a vessel floating in a body of water, a line comprising a first portion connected to the vessel and a second portion in the body of water, a tool connected to the second portion of the line, the tool in the body of water below the vessel, a stationary apparatus connected to the second portion of the line, the stationary apparatus in the body of water below the vessel, and a mechanism on the vessel connected to the first portion of the line, the mechanism adapted to keep the line taut as the vessel heaves up and down.

Description

SUBSEA INSTALLATION SYSTEMS AND METHODS

Field of Invention:

The present disclosure relates to subsea installation systems and methods. In particular to installation systems and methods for use on subsea structures from a surface vessel. Background:

Structural elements can be installed at sea from a floating vessel using a J- lay configuration where the structural element is held vertically on the vessel and dropped vertically into the water and then when it reaches the bottom of the body of water, it lays horizontal, or alternatively structural elements can be installed in a S-lay configuration where the structural element is held horizontally on the vessel, drops to vertical through the body of water, and then rests on the bottom of the body of water in a horizontal configuration. Other configurations for installing a structural element from a vessel in a body of water are also known.

Some time after a structure has been installed in the water, it may be desired to perform additional operations on the structure, for example to install VIV suppression devices, install sacrificial anodes, fly over the structure to ensure integrity and perform necessary repairs, install insulation or coatings, and other operations as are known in the art.

Often, it is convenient to control the subsea operations from a surface vessel. However, as the surface vessel heaves up and down, it may cause subsea elements connected to the vessel by a line or tether to also heave up and down. Referring now to Figure 1 , there is illustrated system 100. System 100 include vessel 110 floating in a body of water 112, which has bottom 113. Vessel 110 has lowered tool 122 by winch 120 on line 118. In some embodiments, line 118 may be a rope, cable, umbilical, or wire. Tool 122 may be a remotely operated vehicle, a storage facility for other tools, or a holder for vortex induced vibration suppression devices. Tool 122 is used to perform work or provide materials for work done to subsea structure 114. Subsea structure 114 may be a riser, a tendon, or flowline, or an umbilical. Subsea structure may have a surface structure 116 attached to it, for example a host, a FPSO, a platform, a TLP, or a spar. As vessel 1 10 heaves up and down as shown by the arrows, tool 122 will also heave since it is connected directly to heaving vessel 1 10.

U.S. Patent Number 6,695,539 discloses apparatus and methods for remotely installing vortex-induced vibration (VIV) reduction and drag reduction devices on elongated structures in flowing fluid environments. The apparatus is a tool for transporting and installing the devices. The devices installed can include clamshell-shaped strakes, shrouds, fairings, sleeves and flotation modules, installed by a clamshell-shaped tool. U.S. Patent Number 6,695,539 is herein incorporated by reference in its entirety. There is a need in the art for an improved apparatus and method for performing subsea operations on a structure. There is another need in the art of apparatus for and new and improved methods of performing subsea operations on a structure from a surface vessel. There is another need in the art for new and improved systems and methods to compensate for heave of a surface vessel. There is another need in the art for new and improved systems and methods to compensate for heave of a surface vessel connected to a subsea tool by a tether or line.

These and other needs of the present disclosure will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.

Summary of the Invention

One aspect of the invention provides a system comprising a vessel floating in a body of water, a line comprising a first portion connected to the vessel and a second portion in the body of water, a tool connected to the second portion of the line, the tool in the body of water below the vessel, a stationary apparatus connected to the second portion of the line, the stationary apparatus in the body of water below the vessel, and a mechanism on the vessel connected to the first portion of the line, the mechanism adapted to keep the line taut as the vessel heaves up and down. Another aspect of the invention provides a method comprising connecting the tool to a line connected to the vessel, connecting a stationary apparatus to the line, activating a mechanism on the vessel to keep the line taut as the vessel heaves. Advantages of the invention include one or more of the following: an improved apparatus and method for performing subsea operations on a structure; an apparatus for and new and improved methods of performing subsea operations on a structure from a surface vessel; new and improved systems and methods to compensate for heave of a surface vessel; and new and improved systems and methods to compensate for heave of a surface vessel connected to a subsea tool by a tether or line. Brief Description of the Drawings

Figure 1 illustrates a system working on a subsea structure.

Figure 2 illustrates a system working on a subsea structure.

Figures 3a and 3b illustrate a system working on a subsea structure.

Figure 4 illustrates a system working on a subsea structure. Figure 5 illustrates a system working on a subsea structure.

Figure 6 illustrates a system working on a subsea structure. Detailed Description of the Invention Figure 2:

Referring now to Figure 2, in some embodiments, system 200 is illustrated. System 200 includes vessel 210 floating in body of water 212, having bottom 213. Vessel 210 heaves with the wave action as shown by the arrows. Vessel 210 includes winch 220, to lower tool 222 on line 218. Weight 224 is provided on bottom 213 also connected to line 218. Tool 222 is releasably connected to line 218 at a fixed location. Winch 220 is a constant tension winch, which acts to keep tool 222 stationary, by keeping tension on line 218 while vessel 210 heaves. Tool 222 may be used to work on or provide materials for subsea structure 214, which may have a surface structure 216 attached to it. Figure 3:

Referring now to Figure 3a, in some embodiments, system 300 is illustrated. System 300 includes vessel 310 which heaves up and down with waves and currents as shown by the arrows. Vessel 310 is in body of water 312, with bottom 313. Vessel 310 includes winch 320 which may be used to lower tool 322 by line 318. Buoyancy 324 is provided above tool 322, and weight 328 is provided on bottom 313 below tool. Tool 322 may be clamped to line 326 between buoyancy 324 and weight 328, so that tool remains stationary, as line 318 has sufficient slack to provide for heave of vessel 310. Tool 322 may be used to work on and/or provide materials for subsea structure 314. Surface structure 316 maybe attached to subsea structure 314.

Referring now to Figure 3b, in some embodiments, buoyancy 324 is attached to and/or integral with tool 322. The rest of system 300 is the same as shown and described for Figure 3a. Figure 4: Referring now to Figure 4, in some embodiments, system 400 is illustrated.

System 400 includes vessel 410 which heaves up and down with the wave action as shown by the arrows. Vessel 410 is in body of water 412 having bottom 413. Subsea structure 414 is in body of water 412, and may have surface structure 416 attached to it. Tool 422 is provided to work on and/or provide materials for subsea structure 414. Vessel 410 has winch 420 which lets out line 418 to lower weight 424 to bottom 413. Tool 422 is then lowered down line 418 by winch 421 and line 419. Once Tool 422 is in desired location alone line 418, tool 422 may be releasably attached to line 418 to keep tool 422 in one location along line 418. Line 419 may be let out so that is no longer taut. Winch 420 may be a constant tension winch which can take up and release line 418 as vessel 410 heaves to keep tool 422 stationary.

To retrieve tool 422, tool 422 may be released from line 418, and winch 421 operated to retrieve line 419 and tool 422. Figure 5: Referring now to Figure 5, in some embodiments, system 600 is illustrated.

System 600 includes vessel 610 in body of water 612, which has bottom 613. Subsea structure 614 is in body of water 612 and may have surface structure 616 attached to it. Vessel 610 heaves up and down with the waves as shown by the arrows. Vessel 610 includes winch 620 which lowers out line 628 to lower clamp 626 to desired location alone structure 614. Clamp 626 may then be attached to structure 614. Line 618 hangs from clamp 626 with weight 624 on bottom 613. Tool 622 may be attached at the desired location alone line 618, so that tool 622 may be used to work on and/or provide materials for subsea structure 614. After clamp 626 and tools 622 are in the desired location, winch 620 can let out additional line so that line 628 is loose and does not interfere with clamp 626 or tool 622 when vessel 610 heaves up and down. Figure 6: Referring now to Figure 6, in some embodiments, system 700 is illustrated.

System 700 includes vessel 710 in body of water 712, having bottom 713. Subsea structure 714 is in body of water 712, and may have surface structure 716 attached to it. Vessel 710 has winch 720 to lower line 718, with clamp 724 connected to line 718. Clamp 724 is attached to the desire location along subsea structure 714. Line 718 also has attached tool 722 and buoyancy 726. Tool 722 maybe releasably attached at a desired location alone line 718. Buoyancy 726 may be used to keep line between buoyancy 726 and tool 722 taut. The portion of line 718 above buoyancy 718 may be loose by letting out additional line from winch 720 so that buoyancy 726 and tool 722 do not move when vessel 710 heaves up and down. Alternative Embodiments:

In some embodiments of the invention, tool 222 may be used to install VIV and/or drag reduction devices around structural element 214 according to the method disclosed in United States Patent No. 6,695,539, which is herein incorporated by reference in its entirety.

In some embodiments of the invention, tool 222 may be used to install VIV and/or drag reduction devices about structural element 214 according to the method disclosed in United States Patent No. 6,561 ,734, which is herein incorporated by reference in its entirety. In some embodiments of the invention, tool 222 may be used to install VIV and/or drag reduction devices about structural element 214 according to the method disclosed in United States Patent Application Publication No. 2003/02131 13, which is herein incorporated by reference in its entirety.

In some embodiments of the invention, the outside diameter of structural element 214 may be from about 10 to about 50 cm.

In some embodiments of the invention, structural element 214 may be cylindrical, or have an elliptical, oval, or polygonal cross-section, for example a square, pentagon, hexagon, or octagon. In some embodiments, body of water 212 has a depth of at least about 1000 meters, at least about 2000 meters, at least about 3000 meters, or at least about 4000 meters. In some embodiments, water 212 has a depth up to about 10,000 meters. In some embodiments of the invention, structural element 214 may be a pipeline, a crude oil flowline, a mooring line, a riser, a tubular, or any other structural element installed in body of water 212. In some embodiments, structural element 214 may have a diameter from about 0.1 to about 5 meters, and a length from about 10 to about 200 kilometers (km). In some embodiments, structural element 214 may have a length to diameter ratio from about 100 to about 100,000. In some embodiments, structural element 214 may be composed from about 50 to about 30,000 tubular sections, each with a diameter from about 10 cm to about 60 cm and a length from about 5 m to about 50 m, and a wall thickness from about 0.5 cm to about 5 cm. In some embodiments, tool 222 may be a transport tool to carry devices subsea, which may be used in conjunction with an installation tool, such as an ROV, to attach the devices to the tubular.

In some embodiments, devices may be attached to tool 222 on vessel 210 by hand. The tool 222 may then be launched from the vessel 210 and lowered to a depth where the devices are to be installed. Illustrative Embodiments:

In one embodiment, there is disclosed a system comprising a vessel floating in a body of water, a line comprising a first portion connected to the vessel and a second portion in the body of water, a tool connected to the second portion of the line, the tool in the body of water below the vessel, a stationary apparatus connected to the second portion of the line, the stationary apparatus in the body of water below the vessel, and a mechanism on the vessel connected to the first portion of the line, the mechanism adapted to keep the line taut as the vessel heaves up and down. In some embodiments, the stationary apparatus comprises a clump weight. In some embodiments, the stationary apparatus comprises a clamp attached to a subsea structure above the tool. In some embodiments, the stationary apparatus comprises a clamp attached to a subsea structure below the tool. In some embodiments, the tool is adapted to perform work on and/or transport materials for a subsea structure. In some embodiments, the system also includes a buoyancy module above the tool and connected to the second portion of the line. In some embodiments, the system also includes a remotely operated vehicle (ROV), the ROV adapted to work with the tool on a subsea structure. In some embodiments, the tool comprises buoyancy. In some embodiments, the line is selected from the group consisting of a rope, a cable, an umbilical, and a wire. In some embodiments, the tool is adapted to carry vortex induced vibration suppression devices to be installed on a subsea structure. In some embodiments, the mechanism on the vessel comprises a constant tension winch. In one embodiment, there is disclosed a method comprising connecting the tool to a line connected to the vessel, connecting a stationary apparatus to the line, activating a mechanism on the vessel to keep the line taut as the vessel heaves. In some embodiments, the method also includes connecting the line to a buoyancy module above the tool and below the vessel, wherein the buoyancy is at a sufficient depth so that the buoyancy is not subject to heave. In some embodiments, the method also includes installing VIV suppression devices on a subsea structure from the tool. In some embodiments, the method also includes launching an ROV from the vessel to work with the tool.

In one embodiment, there is disclosed a system comprising a vessel floating in a body of water; a line comprising a first portion connected to the vessel and a second portion in the body of water; a tool connected to the second portion of the line, the tool in the body of water below the vessel; a subsea structure in the body of water near the second portion of the line; and a stationary apparatus connected to the second portion of the line and the subsea structure, the stationary apparatus in the body of water below the vessel. In some embodiments, the stationary apparatus comprises a clamp connected to the second portion of the line and the subsea structure at a location above the tool. In some embodiments, the system also includes a weight connected to the second portion of the line at a location below the tool. In some embodiments, the stationary apparatus comprises a clamp connected to the second portion of the line and the subsea structure at a location below the tool. In some embodiments, the system also includes at least one buoyancy module connected to the second portion of the line at a location above the tool. Those of skill in the art will appreciate that many modifications and variations are possible in terms of the disclosed embodiments, configurations, materials and methods without departing from their spirit and scope. Accordingly, the scope of the claims appended hereafter and their functional equivalents should not be limited by particular embodiments described and illustrated herein, as these are merely exemplary in nature.

Claims

C L A I M S

1 . A system comprising: a vessel floating in a body of water; a line comprising a first portion connected to the vessel and a second portion in the body of water; a tool connected to the second portion of the line, the tool in the body of water below the vessel; a stationary apparatus connected to the second portion of the line, the stationary apparatus in the body of water below the vessel; and a mechanism on the vessel connected to the first portion of the line, the mechanism adapted to keep the line taut as the vessel heaves up and down.

2. The system of claim 1 , wherein the stationary apparatus comprises a clump weight.

3. The system of claim 1 , wherein the stationary apparatus comprises a clamp attached to a subsea structure above the tool.

4. The system of claim 1 , wherein the stationary apparatus comprises a clamp attached to a subsea structure below the tool.

5. The system of one or more of claims 1 -4, wherein the tool is adapted to perform work on and/or transport materials for a subsea structure.

6. The system of one or more of claims 1 -5, further comprising a buoyancy module above the tool and connected to the second portion of the line.

7. The system of one or more of claims 1 -6, further comprising a remotely operated vehicle (ROV), the ROV adapted to work with the tool on a subsea structure.

8. The system of one or more of claims 1 -7, wherein the tool comprises buoyancy.

9. The system of one or more of claims 1 -8, wherein the line is selected from the group consisting of a rope, a cable, an umbilical, and a wire.

10. The system of one or more of claims 1 -9, wherein the tool is adapted to carry vortex induced vibration suppression devices to be installed on a subsea structure.

1 1. The system of one or more of claims 1 -10, wherein the mechanism on the vessel comprises a constant tension winch.

12. A method of insulating a subsea tool from heave of a surface vessel, comprising: connecting the tool to a line connected to the vessel; connecting a stationary apparatus to the line; and activating a mechanism on the vessel to keep the line taut as the vessel heaves.

13. The method of claim 12, further comprising connecting the line to a buoyancy module above the tool and below the vessel, wherein the buoyancy is at a sufficient depth so that the buoyancy is not subject to heave.

14. The method of one or more of claims 12-13 further comprising installing VIV suppression devices on a subsea structure from the tool.

15. The method of one or more of claims 12-14, further comprising launching an ROV from the vessel to work with the tool.

16. A system comprising: a vessel floating in a body of water; a line comprising a first portion connected to the vessel and a second portion in the body of water; a tool connected to the second portion of the line, the tool in the body of water below the vessel; a subsea structure in the body of water near the second portion of the line; and a stationary apparatus connected to the second portion of the line and the subsea structure, the stationary apparatus in the body of water below the vessel.

17. The system of claim 16, wherein the stationary apparatus comprises a clamp connected to the second portion of the line and the subsea structure at a location above the tool.

18. The system of one or more of claims 16-17, further comprising a weight connected to the second portion of the line at a location below the tool.

19. The system of one or more of claims 16-18, wherein the stationary apparatus comprises a clamp connected to the second portion of the line and the subsea structure at a location below the tool.

20. The system of one or more of claims 16-19, further comprising at least one buoyancy module connected to the second portion of the line at a location above the tool.