GB2466992A

GB2466992A - Tool for alignment of subsea equipment during deployment and recovery.

Info

Publication number: GB2466992A
Application number: GB0900817A
Authority: GB
Inventors: Hugh Parker; Allister Fraser; Lev Uryevich Roberts-Haritonov
Original assignee: SUBSEA ENGINEERING SERVICES LT
Current assignee: SUBSEA ENGINEERING SERVICES LT
Priority date: 2009-01-20
Filing date: 2009-01-20
Publication date: 2010-07-21
Also published as: GB0900817D0

Abstract

Camming tool 3 & 18 to orientate subsea equipment 5 when deploying or recovering the equipment between the seabed and surface. The tool comprises two engagable members where one is female 18 the other male 3. One member has a guiding profile 21 for a guide key 30 on the other member. One member is attached to a lifting line 8 and the equipment being launched / loaded with the other member mounted to a frame 1 on a surface vessel. Coaxial movement bringing the two members together rotates the equipment to a correct orientation and locks it in that orientation. The guide profile 21 can be helical. The guide profile and key 30 may be on the male 3 or female 18 member. There can be a locking section of the guide profile (23, fig 2).

Description

TITLE

A tool assembly for alignment of subsea equipment, during deployment and recovery.

DESCRIPTION

Field of invention

The present invention relates to a tool assembly used to align subsea equipment, during recovery and deployment between the sea bed and the surface vessel. The tooling maintains equipment in aligned position while it passes through restricted space in or adjacent to the vessel, thus preventing potential damage due to contact between equipment and the vessel.

Background to the invention

Subsea equipment such as christmas trees, manifolds etc are typically deployed to and recovered to and from the sea bed, using a surface support vessel. On some vessels, the method of deployment and recovery involves utilising the vessel borne crane and/or winch handling system. The deployment and recovery are undertaken either via the vessel moonpool or over the side. The moonpool is a vertical open shaft, typically square or rectangular in cross section, running from the keel of the vessel up to the main working deck. The moonpool provides direct access to the waterline without having to deploy equipment over the side.

The moonpool is typically fitted with two or more vertical guide rails. These rails run the entire vertical distance of the moon pool. These are used for guiding the vertical lowering and retrieval of subsea equipment guide cursor, which runs on these rails.

A guide cursor is used to engage directly or indirectly with subsea equipment and is used to guide that equipment through the moonpool. If deploying/recovering over the side, a guide cursor and rail system may be used.

The winch system is typically comprised of the main lift winch, positioned centrally and up to four outer guide winches. The main winch wire rope is attached to a suitable equipment running tool, itself connected to the equipment being deployed or recovered.

The purpose of the main winch and its associated wire rope is to provide primary means of connection between the equipment running tool/subsea equipment and the handling system. The main winch is used to lower and raise subsea equipment between the vessel and the seabed. The purpose of the guide winches and their associated wire ropes is to provide the subsea equipment with some degree of rotational stability and alignment in the horizontal plane, about the axis of deployment/recovery. This rotational stability is important particularly during deployment and recovery of the equipment while in close proximity of the vessel, where space is normally restricted. [2]

Whether the deployment from, or recovery onto the vessel is achieved via a through-the-deck moonpool, or over the vessel side, it is important to keep the rotation of the equipment to an absolute minimum in the vicinity of the vessel. The four guide wire ropes, which are deployed, from the sea bed to the vessel and typically running in constant tension; provide a means of keeping the equipment from rotating during the deployment and recovery operations.

On a vessel equipped with guidelines, the typical sequence of operation for recovery may be as follows. The equipment and its running tool would be connected to the main winch wire rope. The guide wire ropes running from the surface vessel would also be attached, to the periphery of the equipment. The guide wire ropes would typically be operated in constant tension. The winch and guide lines would pass through the open cursor on the vessel. If the vessel is fitted with a moonpool, the guide cursor would be positioned at the bottom of the moonpool (below the vessel waterline) at the end of the cursor guide rails, ready to accept the recovered equipment. For overboard recovery, the cursor would typically be on the vessel side.

As the main winch lifts the equipment, its rotation would be limited by the guide wire ropes. Once the equipment makes contact with the cursor, both are then recovered together out of the water. During deployment, the sequence is reversed. The cursor provides displacement control for the subsea equipment in the longitudinal and transverse directions and the guide wire ropes providing anti rotation stability and ensure that the equipment is correctly orientated about the vertical axis during deployment and recovery.

The present invention is predicated on the recognition that the guide wire based guidance method does have certain limitations.

Firstly, the inherent nature of guide wire rope systems is that they themselves have limited lateral stiffness. What stiffness they have, depends almost exclusively on the amount of tension applied to them by the winch handling system. The level of lateral rotational stability diminishes further during adverse weather conditions, when greater forces are imparted on the equipment.

Secondly, guide wire rope systems have inherent large clearances between the guide wire ropes and the guide channels in the subsea equipment. This results in a limited guidance and rotational alignment accuracy. There are operational situations where, this level of accuracy is less than required, for effective deployment and/or recovery of subsea equipment.

Thirdly, with the guide wire ropes typically anchored to a seabed structure, surface vessel movement results in an angular offset relative to the guide wire ropes. This diminishes the alignment capability of the guide wires in terms of maintaining a working clearance between the subsea equipment and the vessel.

Finally, the present invention enables effective equipment alignment and guidance during deployment, and recovery, when used with guideline-less systems. [3]

Summary of the invention

With a view to mitigating the foregoing disadvantages and enabling effective alignment of equipment during deployment and recovery without the aid of guidelines, there is provided in accordance with the first aspect of the invention an alignment tool system. The tool system is able to align the equipment about the deployment/recovery axis as it is being deployed or recovered. Once aligned, the equipment is then effectively locked/restrained in the aligned position that prevents it from further rotation about the deployment/recovery axis.

The deployment/recovery alignment tool system is made up of two tools. First tool is the male alignment tool, fitted to the equipment running tool, which is in turn attached to the equipment being deployed/recovered. The other end is attached to the lifting wire rope. The male alignment tool is provided with a guide key, preferably positioned on its outer periphery. Further more, the alignment tool is provided with tapered leading and trailing edges to facilitate guidance into and out of its mating component.

In a further aspect of this invention there is provided a second tool, named the female alignment tool, preferably hollow in section, aligned coaxially with the male alignment tool. The female alignment tool is preferably attached to the guide cursor, which is itself attached on the vessel. The female alignment tool has a three dimensional part helix, part linear guiding profile cut into its bore.

During recovery operations, the male alignment tool, attached to the moving equipment, will engage with the stationary female alignment tool, fixed to the vessel.

The guide key on the outer periphery of one of the tools will make contact with the guiding profile on the alignment sleeve and react against it creating a horizontal and vertical reaction forces with a given resultant force. This resultant force will cause one tool to rotate relative to the other, thus also rotating the equipment attached to one of the tools into a predetermined position defined by the guiding profile geometry. At the end of the rotation part of the guiding profile, another part of the guiding profile effectively locks the rotated equipment in the aligned position. The equipment remains in this restrained position for the next stage of recovery, out of the water and onto the working deck of the vessel.

For deployment operations, the above mentioned sequence will be reversed. The two alignment tools will be fully engaged while the equipment is still on the working deck of the vessel. The guide cursor and the equipment will be deployed over the vessel side, or through the moonpool with the two tools in the fully engaged position.

As such no rotation of the tools and the equipment, relative to the vessel, takes place, until the cursor is lowered to a predetermined position at the bottom of the moonpool or the vessel side and locked in place. From that point on, the two tools will be able to rotate relative to each other, ultimately disengaging and allow the equipment to be lowered away from the vessel.

In a further aspect of the invention, the relative position of the male and female alignment tools can be changed. In such a variant, the male alignment tool would be attached to the guide cursor, which is itself attached to the vessel. The female alignment tool would be attached to the equipment being deployed and recovered and thus be moving. Similarly, the respective guide and guiding profiles can also be [4] interchanged between the tools. In such cases, the method and sequence of deployment and recovery do not change.

Brief description of drawings

The invention will now be described further by way of example, with reference to the accompanying annotated drawings.

Figure 1, Subsea equipment deployment and recovery alignment system Figure 2, Female alignment tool 18 Figure 3, Male alignment tool 3.

Figure 4, Male alignment tool 3, viewed from the opposite side of Guide key 30 showing the Umbilical location groove 29 Figure 5, Scrap view of Male alignment tool 3 engaged with the Female alignment tool 18. For the sake of clarity, the Alignment tool shroud 2, which covers the Female alignment tool 18 and connects it to the Guide cursor frame 1, has been suppressed.

Figure 6, Sequence drawing of subsea equipment recovery, vessel section view-Male alignment tool 3 is about to engage with the Female alignment tool 18, located inside the Alignment tool shroud 2.

Figure 7, Sequence drawing of subsea equipment recovery -Male alignment tool 3 has engaged with the Female alignment tool 18 and the Subsea equipment 5 being recovered is now rotating about the vertical recovery axis, into the final aligned position.

Figure 8, Sequence drawing of subsea equipment recovery -Male alignment tool 3 is fully engaged with the Female alignment tool 18. The alignment rotation has been completed and the equipment is now locked in position. Guide cursor frame 1 and the Subsea equipment S are now ready to be recovered out of the water.

Figure 9, Sequence drawing of subsea equipment deployment -Male alignment tool 3 is fully engaged with the Female alignment tool 18. The Subsea equipment 5 is locked in this position relative to the Guide cursor frame 1. With Subsea equipment S in this position, the Guide cursor frame 1 and the Subsea equipment 5 have been lowered to the bottom of the Moonpool 7, the confined zone of the vessel. At the bottom of the Moonpool 7, the cursor locked in position. The system is now ready for disengagement of the two tools, Male alignment tool 3 and Female alignment tool 18. This is achieved by lowering the Subsea equipment S away from the effectively locked and restrained stationary Guide cursor frame 1.

Figure 10, Sequence drawing of subsea equipment deployment -Having passed through the most confined zone of the vessel, Subsea equipment S is now being lowered away from the stationary and locked Guide cursor frame 1. Male alignment tool 3 is disengaging from the Female alignment tool 18 and the Subsea equipment S being deployed is now rotating about the vertical axis.

Figure 11, Sequence drawing of subsea equipment deployment: -Male alignment tool 3 has fully disengaged from the Female alignment tool 18 on the Guide cursor frame 1. Deployment of Subsea equipment 5 can continue to the sea bed.

Figure 12, Alternative variant of the invention, with locations of the two profiles interchanged between the two tools. Guide key 30 is located on the Female alignment tool 18 (shown in section) and the Guiding profile 21 is located on the Male alignment tool 3.

Detailed description of preferred embodiment

In the present invention, the subsea equipment deployment and recovery alignment system is subdivided into two coaxial tools designed to engage with each other during deployment and recovery operations. In the first part of the present invention, a Male alignment tool 3 is rigidly attached to the Equipment running tool, which is rigidly attached to the Subsea equipment 5, that is the equipment being deployed or recovered It must be stressed although Figure 1 depicts the equipment being a subsea christmas tree, this invention is equally valid to all other types of subsea equipment requiring alignment during deployment and recovery. [5]

The deployment and recovery is by means of a main winch wire rope attached to the Male alignment tool lift point 11 at the top of the Male alignment tool 3.

The Male alignment tool 3 is used to ultimately rotate and align the Subsea equipment 5 in the correct orientation about the axis of deployment/recovery and restrain it from further rotation as it is being recovered either via the moonpool or the over the vessel side.

As shown in Figure 2, Figure 3 and Figure 5, the Male alignment tool 3 has a profiled geometry designed to engage with Female alignment tool 18. It contains several important features. At the top is the Male alignment tool lift point 11, used to secure it to the Main winch line 15. Male alignment tool lift point 11 is connected to the Male alignment tool upper stem 24. The next part is the Male alignment tool upper taper profile 25. This is designed to provide smooth entry of the Male alignment tool 3 into the Lower guide cone 13 and ultimately into the Female alignment tool 18. Figure 1 shows the full assembly, with the Female alignment tool 18 covered by the Alignment tool shroud 2, as it would be normally. The purpose of the Alignment tool shroud 2 is to provide a fixed structural connection between the Female alignment tool 18 and the Guide cursor frame 1.

At the central part of the Male alignment tool 3 is the Male alignment tool central section 28. Its geometry is depicted as being preferably cylindrical in cross section.

It can however also be conical in section as well. This part of the Male alignment tool 3 contains the Guide key 30. The lower part of the Male alignment tool 3 is made up of the Male alignment tool lower taper profile 27 and the Male alignment tool lower stem 26. The Male alignment tool 3 is connected to the Equipment running tool 6 with a suitable connection. Finally, the Male alignment tool 3 is fitted with an Umbilical location groove 29, which locates and protects the Umbilical 9.

The Umbilical 9 passes from the Subsea equipment 5, via the Umbilical location groove 29, through the Alignment tool shroud 2 on the Guide cursor frame I and to the vessel.

The second part of the invention is a Female alignment tool 18, positioned inside the Alignment tool shroud 2, which itself is fixed to the Guide cursor frame 1. The Female alignment tool 18 is hollow and contains a three dimensional Guiding profile 21, cut into its body. The Guiding profile 21 is made up of at least one profile. As an example, Figure 2, shows a twin profile design. In this case, the two profiles can share the same starting point as indicated by Guiding profile start 19 point and the same profile finish point, Guiding profile end 20. This allows the Guide key 30 on the Male alignment tool 3 to engage with the Guiding profile 21, slide up either of line of the Guiding profile 21 and end up at the same Guiding profile end 20 point.

Further more; the Guiding profile 21 is made up of preferably two parts. The first, substantially angled, portion is the Guiding profile-alignment part 22. This part of the Guiding profile 21 is used to rotate the Subsea equipment 5 about the vertical deployment/recovery axis, into a predetermined orientation, relative to the vessel deck. The second, Guiding profile-locking part 23 is more linear in its geometry and it is used to securely restrain the Subsea equipment 5 in its final aligned position, thus preventing it from further rotation. [6]

The method of recovery operation described below assumes a vessel fitted with a moonpool. Although in principle, it is equally valid for over the side and aft methods of recovery.

The Guide cursor frame 1 would be at the bottom of the Moonpool 7 at the base of the Cursor guide rails 10. Guide cursor frame 1 is fitted with Cursor rollers 12, which roll or slide on the Cursor guide rails 10. The progressive recovery sequence is shown in Figure 6, Figure 7 and Figure 8. As shown in Figure 1, the Main winch wire rope 8 is attached to the Male alignment tool 3, which is in turn attached to the Equipment running tool and the actual subsea equipment being deployed or recovered, Subsea equipment 5.

Prior to contact between the Male alignment tool 3 and the Female alignment tool 18, the Subsea equipment 5, could be in any orientation about its vertical axis. As the Subsea equipment 5 is raised, the two coaxial tools, Male alignment tool 3 and Female alignment tool 18 come into close proximity with each other. The first parts of the Male alignment tool 3 to make contact with the inside of the Female alignment tool 18 are the Male alignment tool upper stem 24 and the Male alignment tool upper taper profile 25. The Male alignment tool upper taper profile 25 and the Lower guide cone 13 help to ease the location and start of engagement of the Male alignment tool 3 into the Female alignment tool 18.

With progressive raising of the Subsea equipment 5, the leading, uppermost edge of the Guide key 30 will make contact with the Guiding profile start 19 on the Female alignment tool 18, creating horizontal and vertical reaction force components between them, due to the upward pull of the Subsea equipment 5 being recovered.

The resultant force of these reaction force components will be co-directional with the path of the Guiding profile 21 resulting in the Guide key 30 and the Male alignment tool 3 following the line of the Guiding profile 21.

The Guide key 30 in the Male alignment tool 3 will first be forced to follow the Guiding profile-alignment part 22 of the Guiding profile 21. Given the helix-like geometry of the Guiding profile-alignment part 22, the Male alignment tool 3 and hence the Equipment running tool 6, and the Subsea equipment 5 all being rigidly attached to each other, will start to rotate about the vertical deployment/recovery axis. The rotation of the Subsea equipment 5 will stop once the Guide key 30 reaches the Guiding profile end 20 point on the Guiding profile 21. Once there, the Subsea equipment 5 has been fully aligned in its correct orientation.

Next, by moving along the Guiding profile-locking part 23, the Guide key 30, and hence the Male alignment tool 3 are restrained, and effectively locked in the aligned position. This operation is completed prior to the equipment entering the zone of restricted clearance, be it the Moonpool 7 or the vessel side.

Once the Male alignment tool 3 has reached the Guiding profile end 20 point, the alignment and locking sequence has been completed. The cursor and the aligned/locked equipment are now ready to be recovered out of the water.

In this final position, the Male alignment tool 3 fully engaged in the Female alignment tool 18 and the Guide key 30 fully engaged in the Guiding profile 21 the Subsea equipment 5 and the Equipment running tool 6 are prevented from further rotations. [7]

For deployment operation, the sequence will be totally reversed. The sequence is shown in Figure 10, Figure 11 and Figure 12. The starting point will be the end of above mentioned recovery operation: the Male alignment tool 3 fully engaged in the Female alignment tool 18 and the Guide key 30 fully engaged in the Guiding profile-locking part 23. At this point, the Subsea equipment 5 and the Equipment running tool 6 are firmly restrained against rotation. With the two tools fully engaged relative to each other, the Guide cursor frame 1 and the Subsea equipment 5 attached to it via the two engaged tools, Male alignment tool 3 and Female alignment tool 18, can be lowered into the water. This will be done either through the vessel Moonpool 7 to its very bottom, as shown in Figure 9, or over the side of the vessel. [8]

Claims

CLAIMSThe embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows: 1. A tool assembly for aligning subsea equipment while deploying or recovering between the seabed and the surface characterised in that: A pair of preferably concentric cylindrical or conical tools Male alignment tool 3 and Female alignment tool 18, arranged substantially coaxially along the axis of lift, with; First of said tools being mounted to the hardware on the vessel, with; Second of said tools being connected to the lifting line and the equipment being deployed or recovered; First of said tools, Female alignment tool 18 having a hollow bore and located on the surface of that bore is at least one Guiding profile 21 Second of said tools, Male alignment tool 3 whose outer surface is designed to engage with the bore of the Female alignment tool 18 and on which outer surface is located at least one raised surface profile, Guide key 30, designed to engage with and move relative to a three dimensional profile Guiding profile 21, cut into the bore of the Female alignment tool 18; Whereby the relative coaxial movement between the Male alignment tool 3 and the Female alignment tool 18, the Male alignment tool 3 will be brought in close proximity of Female alignment tool 18, whereby one said tool will be made to engage into the bore of the other with the respective profiles, Guiding profile 21 and Guide key 30 making contact, creating horizontal and vertical reaction forces between them, due to the upward pull of the Subsea equipment 5 being recovered, the resultant force of said reaction forces will be co-directional with the path of the Guiding profile 21 resulting in the Guide key 30 and the Male alignment tool 3 following the line of the Guiding profile 21 resulting in the Male alignment tool 3 and the Subsea equipment 5 attached to it being raised and rotated about the deployment/recovery axis.Relative movement between the tools and the hardware to which they are respectively connected will stop when the Guide key 30 reaches the uppermost point of the Guiding profile 21 at which point the equipment being recovered has been rotated to its correct orientation and locked in that position preventing further rotation relative to the axis of deployment/recovery. [9]
2. A tool assembly for aligning subsea equipment while recovering according to claim 1, where the mounting of the two respective said tools, on the vessel hardware and the equipment being deployed or recovered, can be interchanged.
3. A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, where the Guide key 30 is defined by a raised surface relative to the surface of the Male alignment tool 3.
4. A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, where the surface profile of the Guide key 30 can be of any geometry, limited only to having a width smaller than the width of the Guiding profile-locking part 23 on the Guiding profile 21.
5. A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, where the Male alignment tool 3 contains at least one part tapering section.
6. A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, where depth of the Guiding profile 21 on the Female alignment tool 18 can vary from partial wall thickness to that exceeding the wall thickness of the tool.
7. A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 3, where the leading and/or trailing ends of the Male alignment tool 3 on the Guide key 30 are fitted with rolling or sliding bearings.
8. A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, in which part or all of the said Guiding profile 21 path is generated by wrapping a substantially triangular shape around the cylindrical body of the Female alignment tool 18.
9. A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, in which part or all of the said Guiding profile 21 path is helical in its geometry.
1O.A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, in which part or all of the said Guiding profile 21 has one or more profile paths which can be followed by the Guide key 30.
11.A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, in which said Guiding profile 21 has at least one straight edge.
12.A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, in which said Guiding profile 21 has at least one curved edge.
13.A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, in which part of the said developed Guiding profile 21, Guiding profile-locking part 23 is generated by a straight or curved line.
14.A tool assembly for aligning subsea equipment while deploying and/or recovering according to claim 1, in which the respective Guiding profile 21 and [10] Guide key 30 can be interchanged between their respective tools, whereon the Guiding profile 21 will be recessed in the Male alignment tool 3 and the Guide key 30 will be protruding from the bore of the Female alignment tool 18.