WO2007026149A1

WO2007026149A1 - Damping device

Info

Publication number: WO2007026149A1
Application number: PCT/GB2006/003218
Authority: WO
Inventors: Malcolm Duell
Original assignee: Malcolm Duell
Priority date: 2005-09-01
Filing date: 2006-08-31
Publication date: 2007-03-08
Also published as: GB2429730B; GB0617085D0; GB2429730A

Abstract

The present invention relates to sub-surface recovery or exploration apparatus (10) . In an embodiment, the apparatus comprises a conductor guide (13) and a conductor tube (14) received through a guide space defined by the conductor guide. A damping device (28) is disposed in the guide space between the conductor guide and the conductor tube. The damping device comprises a plurality of resilient bodies disposed along the conductor tube.

Description

Damping Device

The present invention relates to sub-surface recovery or exploration apparatus having a damping device and a method of damping movement in sub-surface recovery or exploration apparatus .

In a number of industries, subsurface wells are drilled to provide for recovery of raw materials. After a fresh well has been drilled, it is usual to install a conductor pipe in the top of the wellbore.

The conductor tube (or conductor casing as it is also known) is cemented in place at the top of the wellbore and secures the open hole to prevent collapse. The bore of the conductor tube provides access to the well and equipment to be used in the well is introduced via the conductor tube. The tube typically comprises thick- walled casing and thus can also provide support for valve tree equipment, which is used in controlling operational conditions of the wellbore. In offshore applications, the conductor tube usually extends from the top of the wellbore at the seabed to above the sea surface. In such applications, the conductor tube is often installed and supported from a wellhead platform on or above the water surface. The conductor tube may then be guided to the wellbore from the wellhead platform through a series of conductor guide tubes fitted to the platform.

The conductor guide tubes have a greater diameter than the conductor tube to accommodate protrusions on the conductor tube, for example between adjacent conductor tube sections. The conductor guide tubes are usually cylindrical and have a funnel-shaped mouth to provide for ease of reception of a conductor tube in the conductor guide tube.

When a conductor tube is installed, the conductor tube is typically located passively within the conductor guide tube. The larger diameter conductor guide tube allows for limited lateral movement of the conductor tube within the conductor guide tube.

There are problems associated with this arrangement. More specifically, the conductor tube is subject to movement caused by wind and sea, which can lead to impacts between the conductor guide tube and the conductor tube, resulting in damage to the conductor tube.

In order to prevent impacts, existing techniques involve use of a clamp arrangement attached to a support member of the platform. In such a case, the clamp typically grips the conductor tube above the guide tube to rigidly secure the conductor tube to the platform in a near- central position within the guide tube.

However, such clamp arrangements are susceptible to damage due to vibrations of the conductor tube caused by the motion of the sea. In addition, installation of such clamp arrangements may require removal of components of the guide tube to secure the clamp in place. For example, the funnel-shaped mouth of the guide tube or "tundish" may need to be removed. Accordingly, installation operations can be time consuming and costly.

In other cases, shims are located in the conductor guide tubes to prevent movement of the conductor tube within the conductor guide tube. However, vibrations and movements of the conductor tube caused by the motion of the sea can be transmitted by way of the shims to the conductor guide tube, thereby causing damage to the conductor guide tube and associated equipment.

Moreover, wave induced movement of the conductor tube can cause large end movements if the conductor tube and the conductor guide tube are rigidly coupled. This can lead to local overstressing of the conductor tube near the rigid coupling points, or for example, in locations where the conductor tube flexes.

It is an aim of the invention to obviate or at least mitigate the drawbacks and deficiencies of existing sub- surface recovery or exploration apparatus. Other aims and objects will become apparent from the description below.

According to a first aspect of the present invention, there is provided sub-surface recovery or exploration apparatus comprising: a conductor guide defining a guide space; a conductor tube received within the guide space and spaced apart from the conductor guide; and a damping device disposed in the space between the conductor guide and the conductor tube, the damping device being configured to damp movement of the conductor tube laterally of the conductor guide, the damping device comprising a plurality of resilient bodies disposed along the conductor tube.

In use, the plurality of resilient bodies damp movement of the conductor tube laterally of the conductor guide. This reduces the likelihood of the conductor tube striking the conductor guide.

More specifically, the damping device may comprise a plurality of resilient bodies disposed around the conductor tube. Thus, the damping device may comprise a mass of resilient bodies in the space between the conductor guide and the conductor tube. The space containing the mass of bodies between the conductor guide and the conductor tube may be substantially annular.

Alternatively or in addition, the damping device may consist exclusively of the plurality of resilient bodies.

Alternatively or in addition, the plurality of resilient bodies may be disposed within the space such that they are movable in relation to at least one of the conductor guide and the conductor tube. In use, this can provide for ease of movement of the conductor guide and the conductor tube in relation to each other axially of the conductor tube. This provides for accommodation of movement that arises, for example, from tidal currents where the apparatus is used in offshore applications.

Alternatively or in addition, each of the plurality of resilient bodies may be of regular shape.

Alternatively or in addition, the plurality of resilient bodies may comprise bodies of different shape.

More specifically, the plurality of resilient bodies may comprise one or more of the following shapes: a prism, a sphere, a cube, a cylinder and a tetrahedron.

Alternatively or in addition, the conductor guide may comprise a substantially cylindrical body having a flared portion defining a mouth of the conductor guide. In use, the flared portion can provide for ease of reception of the conductor tube in the conductor guide.

More specifically, the damping device may be disposed at least in part in the space between the conductor guide and the conductor tube defined in part by the flared portion. Thus, the damping device can be disposed in the space to provide for a damping effect at or around the mouth of the conductor guide.

Alternatively or in addition, the sub-surface recovery or exploration apparatus may be configured to contain the damping device within a portion of the space between the conductor guide and the conductor tube. Configuration of the apparatus to contain the damping device can be of use when the damping device comprises a plurality of bodies that are themselves disposed in an unrestrained fashion in the space between the conductor guide and the conductor tube .

More specifically, the apparatus may comprise a containment apparatus configured to keep the damping means located in the portion of the space.

Preferably, the containment apparatus comprises at least one containment member configured to occlude the space between the space between the conductor guide and the conductor tube from passage of at least part of the damping device. In use, the containment member can obstruct movement of the damping device along the space between the conductor guide and the conductor tube. Thus, the damping device may be configured for disposal in the space between a mouth of the conductor guide and the containment member.

More specifically, the containment member may be configured to occlude the space below an open end of the conductor guide opposing a mouth of the conductor guide.

Alternatively or in addition, the containment member may be configured to so as to leave the conductor tube unobstructed.

More specifically, the containment member may be configured to fit around the conductor tube. More specifically, the containment member may comprise a clamp arrangement for clamping the containment member around the conductor tube.

Alternatively or in addition, the containment apparatus may comprise a second containment member configured to occlude the space defined by a mouth of the conductor guide. In use, the second containment member may prevent escape of resilient bodies of the damping device from the mouth of the conductor guide.

More specifically, the second containment member may be configured to be received in a flared end portion of the conductor guide defining a mouth of the conductor guide.

Alternatively or in addition, the second containment member may be configured so as to leave the conductor tube unobstructed. Thus, for example, the second containment member may be configured to fit around the conductor tube.

Alternatively or in addition, the containment apparatus may be adapted to permit relative movement between the conductor guide and the conductor tube. The relative movement may be at least one of lateral and longitudinal movement .

Preferably, the containment apparatus comprises a containment sleeve configured to occlude a space between an end of the conductor guide tube, which opposes an end configured to receive the conductor tube, and the conductor tube. More preferably, the containment sleeve is fitted to allow axial movement of the sleeve relative to the guide tube. The containment sleeve may be axially slidable relative to the conductor guide tube. The containment sleeve may be fitted around an outer surface of the conductor guide tube. Alternatively, the containment sleeve is slidably fitted on an inside surface of the conductor guide tube.

Preferably, the apparatus is operable to damp movement of the pipe relative to the guide tube of a magnitude similar to that produced during offshore operations.

Preferably, the apparatus is operable to damp movement of the pipe relative to the guide tube in multiple directions.

Preferably, the plurality of resilient bodies comprises at least one resilient body that is movable within the plurality of resilient bodies.

Preferably, the apparatus is configured to permit the at least one resilient body to be movable in relation to the conductor guide and the conductor tube for facilitating movement, and damping of movement, of the conductor tube laterally and longitudinally relative to the conductor guide. In use, the resilient nature of the plurality of bodies can provide for absorption of sudden movement of the conductor guide and the conductor tube in relation to each other, which is liable to cause damage, whilst moveability of the at least one resilient body provides for slower movement of the conductor guide and the conductor tube in relation to each other, slow movement being less liable to cause damage. Preferably, the plurality of resilient bodies comprises at least two resilient bodies that contact each other.

The resilient bodies may be configured to deform elastically. The resilient bodies may be formed at least in part of at least one of the following materials: rubber; neoprene; polyethylene; and foam.

Alternatively or in addition, the plurality of resilient bodies may comprise at least two resilient bodies sized to fit in the guide space laterally adjacent to each other. The at least two resilient bodies may fit in the guide space when the conductor guide and the conductor tube are disposed coaxially.

Alternatively or in addition, a resilient body may have a maximum cross-sectional dimension of between about 1 in and 10 in.

The sub-surface recovery or exploration apparatus may be configured for mineral recovery or exploration, such as of oil or gas.

The sub-surface recovery or exploration apparatus may be configured for at least one of on-shore operation and off-shore operation.

According to a second aspect of the present invention there is provided a seabed installation comprising sub- surface recovery or exploration apparatus according to the first aspect of the present invention. Embodiments of the second aspect of the present invention may comprise at least one feature of the first aspect of the invention.

According to a third aspect of the present invention, there is provided an offshore platform comprising a seabed installation according to the second aspect of the invention.

According to a fourth aspect of the present invention, there is provided a method of damping movement in sub- surface recovery or exploration apparatus, the method comprising: receiving a conductor tube within a guide space defined by a conductor guide such that the conductor tube is spaced apart from the conductor guide; and disposing a damping device in the space between the conductor guide and the conductor tube, the damping device being configured such that it is operative to damp movement of the conductor tube laterally of the conductor guide, the damping device comprising a plurality of resilient bodies disposed along the conductor tube.

Embodiments of the . fourth aspect of the present invention may comprise at least one feature of the first to third aspects of the invention.

According to a further aspect of the present invention, there is provided sub-surface recovery or exploration apparatus comprising: a conductor guide defining an enclosed guide space; a conductor tube received within the guide space and spaced apart from the conductor guide; and a damping device disposed in the space between the conductor guide and the conductor tube, the damping device being configured to damp movement of the conductor tube laterally of the conductor guide.

There will now be described, by way of example only, embodiments of the invention, with reference to the following drawings, of which:

Figure 1 is a schematic cross-sectional view of oil or gas recovery or exploration apparatus according to an embodiment of the invention;

Figure 2A is a schematic cross-sectional view of a containment bracket for the apparatus of Figure 1.

Figure 2B is a schematic cross-sectional view, perpendicular to the view of Figure 2A, of the containment bracket of Figure 2A.

Figure 2C is a plan view of a first half of the containment bracket of Figure 2A;

Figure 2D is a cross-sectional view of the containment sleeve for the apparatus of Figure 1;

Figure 2E is a cross-sectional view, perpendicular to the view of Figure 2D, of the containment sleeve of Figure 2D;

Figure 2F is a plan view of a first half of the containment sleeve of Figure 2D; Figures 3A to 3D represent in cross-sectional views, the apparatus of Figure 1 during successive stages of installation;

Figure 4 is a cross-sectional view of oil or gas recovery or exploration apparatus according to a further embodiment of the invention; and

Figure 5 is a cross-sectional view of oil or gas recovery or exploration apparatus in operation according to a further embodiment of the invention.

With reference firstly to Figure 1, there is generally depicted apparatus 10 for use in oil or gas recovery or exploration. The apparatus 10 comprises a conductor guide tube 12 (which constitutes a conductor guide) . An inner surface of the conductor guide tube 12 defines a cylindrical volume (which constitutes a guide space) through which a conductor tube 14 is received. Furthermore, the tube defines a longitudinal axis 2 and latitudinal axis 4, and upper and lower ends 6,8 of the apparatus.

In addition, the conductor guide tube 12 comprises a flared section 13 and a tubular main section 15. The flared section is known in the art as a 'tundish' and the main tubular section 15 is known as a 'barrel'. The flared section is shaped to facilitate the introduction of the conductor tube through the conductor guide tube, i.e., the wider diameter provides a larger target and makes it easier to locate the conductor tube through the conductor guide tube. The diameter of the flared section 13 decreases progressively from top end 6 toward the bottom end 8 of the apparatus until the flared section meets the main tubular section 15. In the tubular section 15, the diameter remains substantially constant.

Damping material 29 (constituting a damping device) is located in the space between the inner surface of the conductor guide tube 12 and an outer surface of the conductor tube 14. The damping material 29 consists of a mass of resilient balls 28. The damping material acts to damp movement of the conductor tube 14 relative to the conductor guide tube 12.

Toward the lower end 8 of the conductor guide tube 12, there is located a containment member 16. The containment member 16 can be seen in more detail with further reference to Figures 2A to 2F, and comprises a bracket 20 that is clamped to the conductor tube 14. The bracket 20 in turn comprises a body of two semi-tubular halves 201a, b, which can be clamped together. In this embodiment, the two halves of the bracket body are clamped together by means of bolts 18 located through holes in protruding and opposing surfaces 38 of the body halves. A neoprene lining is provided between the conductor tube 14 and surfaces of the bracket 20 that act against the conductor tube 14 to avoid a metal-to-metal contact of the tube and the clamp. The neoprene lining helps to protect the pipe from damage due to clamping of the bracket 20.

The bracket 20 further comprises a containment plate 22 protruding radially at the top of the bracket body. When the bracket is clamped, the containment plate provides a top plate surface 35 that is substantially perpendicular to a longitudinal axis of the conductor tube and is substantially continuous around the circumference of the conductor tube 14.

The containment plate 22 functions to support the damping material 29 near the bottom of the guide tube 12. The containment plate 22 thereby helps to prevent the resilient balls 28 from escaping from the guide space. The guide tube 12 and the containment apparatus 16 acts to contain the damping material in place.

The containment apparatus 16 also comprises a containment sleeve 24 which rests on the top surface 35 of the plate 22 and is partially located around the bottom end of the guide tube 12. The containment sleeve 24 may slide across the surface 35 as the conductor tube moves laterally relative to the guide tube. The containment sleeve 24 is formed from two semi-tubular sleeve halves 241a, b clamped together via bolts 37 in a manner similar to that described above with reference to the bracket 20. When clamped, the containment sleeve 24 comprises a tubular main body 26 with an internal diameter that is similar to the outer diameter of the guide tube 12 at its bottom end to provide a clearance fit around the bottom portion of the main tubular section of the guide tube.

The containment sleeve 24 assists in preventing the resilient balls 28 from escaping the guide space.

In the present configuration, the containment apparatus 16 is arranged with the bracket 20 clamped to the conductor tube 14 in a position near the bottom end 8 of the guide tube 12 such that the bottom end of the guide tube is received within a space defined by inner surfaces of the sleeve 24.

The present arrangement provides a plate gap 32 between a bottom edge of the guide tube 12 and the top surface 35 of the containment plate 22. The plate gap 32 is provided to accommodate axial movement of the conductor tube as indicated by the arrow 39. The axial movement of the conductor tube typically results from flexure of the conductor tube, for example, due to horizontal currents acting on the conductor tube. The plate gap can accommodate a range of relative axial movement of the conductor tube and the guide tube up to around 4 inches.

As the sleeve 24 rests on the containment plate and is movable axially with respect to the guide tube, the sleeve is able to function to provide the required obstruction to the balls at various offsets of the conductor tube relative to the guide tube, i.e., offsets within the range provided for by the plate gap.

It will however be appreciated that in other embodiments, the apparatus could be configured with a gap to accommodate a greater or lesser range of axial movement. In such cases, the axial length of the sleeve may be different, but suitable for preventing escape of the balls.

The apparatus 10 is also provided with a cover arrangement 40 (which constitutes a second containment member) at the top end 6 of the guide tube 12. The cover arrangement 40 comprises a second bracket 44 provided with a second containment plate 42 in a similar manner to the bracket 20 at the opposite end of the guide tube 12. However, in this case, the second containment plate 42 rests on the top edge of the flared section, and the second bracket 44 is merely fitted around the conductor tube 14.

The bracket cover arrangement is formed in two semi- tubular halves and clamped together using bolts to provide a clearance fit around the conductor tube. This allows the conductor tube to move axially relative to the guide tube, while the second containment plate 42 can remain in position on the flared section to prevent dislodgement of the damping material 29 and resilient balls 28 from the top of the guide tube 12.

The damping material 29 comprises discrete balls 28 with resilient properties. The damping material 29 acts to damp relative movement of the conductor tube 14 and the conductor guide tube 12. The mass of balls 28 located within the guide tube function together to resiliently damp the relative movement.

The resilient balls 28 are of similar dimensions and are sized to fit in the guide space between the conductor tube and the tubular main section 15 of the conductor guide tube. In other embodiments of the invention the balls may have an maximum dimension of between 1 and 7 inches. It will be appreciated however, that balls with maximum dimensions outside this range could be used. Between the individual resilient balls, there exist pockets 46 of the guide space. Upon the exertion of a force (i.e. from a moving conductor tube), for example due to movement of the conductor pipe within the conductor guide tube, the resilient balls 28 may displace, deform and move relative to each other within the guide space, into and around the pockets 46. This allows the conductor tube 14 to move laterally and axially within the conductor guide tube whilst preventing the conductor tube from touching the conductor guide tube sides. The mass of resilient balls 28 behave elastically, i.e. the material of the bodies allows the conductor tube to displace relative to the conductor guide tube before tending to return the conductor tube to its original or equilibrium position within the conductor guide tube .

In this case, the balls are formed of neoprene material. In other embodiments however, the balls could be formed from plastic or rubber materials. More specifically, the balls may be formed from materials such as nylon, Teflon®, Kevlar®, aramids, polyethylenes, or any other suitable resilient material. In addition, the damping material 29 could comprise spheres, cubes, cylinders or any other appropriately sized prismatic body.

The mass of balls 28 displaces as the conductor tube moves within the conductor guide tube, and surrounds the conductor tube as it moves within the conductor guide tube to thereby provide support. This helps to prevent damage to the apparatus which could otherwise arise from sudden movement of the conductor tube.

A sub-set of balls located in the guide space of the flared section of the guide tube can also act as a back- up reservoir of balls that can replace and fill the space left by any balls that for any reason become removed from the guide space, e.g., under extreme or irregular operating conditions.

In another embodiment of the invention, the damping apparatus 100 of Figure 4 shows a conductor guide tube 102 is fitted to an offshore platform. In this case, the guide tube 102 is, as known in the art, attached and fixed to tubular members 114 of a platform, and the tubular members 114 are in turn fixed to and supported from a support structure 112 of the platform.

In this configuration, a conductor tube 104 extends from a well at the seabed through the conductor guide tube 102 fixed to the platform structure. The ocean environment causes vertical and horizontal components of movement of conductor tubing. For example, waves, wind and tides can cause the conductor tube to move within the conductor guide tube, and the present damping apparatus 100 is adapted to accommodate such movement in both latitudinal and longitudinal directions, whilst damping sudden movements that could cause damage.

The apparatus 100 is otherwise configured in a similar manner to the apparatus 10 described above, although the apparatus 100 is provided with a sleeve 108 that is located on the inside of the guide tube 102. The sleeve 108 comprises two semi-tubular halves, which can be clamped together in a similar manner to the sleeve described above. However, in this case, bolted opposed surfaces protruding radially from the clamp are provided toward the bottom end of the sleeve. An outer surface of the sleeve is slidably located against the inside surface of the guide tube 102. The sleeve axially slidable relative to the guide tube 102, and provides a similar function as the sleeve 24 of apparatus 10 in preventing balls 28 from exiting the guide space from the bottom end of the guide tube 104. The containment plate is located on the conductor tube such that the protruding surfaces of the sleeve when resting on the containment surface, do not interfere with or prevent slidable axial movement of the conductor tube and sleeve relative to the guide tube.

In use, the present sub-surface recovery or exploration damping apparatus may be installed on an offshore platform near a well to which access is required from the platform.

A conductor guide tube is fitted to the platform and a conductor tube is introduced into the flared section of the conductor guide tube and inserted through the conductor guide tube and into the top portion of the well. The lower end of the conductor tube is secured in place at the top of the well. The top end of the conductor tube is accessible at the platform.

The bracket 20 is clamped to the conductor tube near the bottom end of the conductor guide tube and the containment sleeve 24 is movably located around the bottom end of the conductor guide tube. This sleeve 24 is positioned so that it rests on the top surface of the containment plate of the bracket 20. The sleeve is slidably located on the top surface in order that it can move across the surface and accommodate lateral movement of the conductor guide tube relative to the conductor tube. Furthermore, the sleeve is sized and the bracket attached to the conductor tube, such that the top edge of the sleeve body, when resting on the plate top surface, overlaps the bottom edge of the conductor guide tube. Furthermore, the bracket is positioned such that there is provided a gap between the bottom edge of the conductor guide tube and the top surface of the plate to accommodate vertical components of motion of the conductor tube relative to the conductor guide tube.

The damping device, which consists of a plurality of resilient balls 28, is introduced into the guide space between the guide tube and the conductor tube. With reference to Figures 3A to 3D, the conductor tube 14 is in Figure 3A located through the guide tube 12 defining a guide space 301 for introduction of damping material. In Figure 3B an initial set of the balls 281 are introduced in a first accessible portion of the guide space 301 while the conductor tube 14 is located off-centre in the guide space. The conductor tube moves to another off- centre position, in the case of Figure 3C forcing the first set of balls 281 into a squashed position, and a further set of balls 282 is introduced into the guide space 301 at a second accessible portion of the guide space. As the conductor tube moves away from the off- centre position, for example, due to external influences or by deliberately moving the tube, the balls 281 and 282 tend to settle around the conductor tube, providing damping and tending centralise the conductor tube within the guide tube as shown in Figure 3D.

The bracket 20 and sleeve 24 act to keep the plurality of balls 28 in location in the guide space and prevent the bodies from escaping. The plate supports the resilient bodies near the bottom of the conductor guide tube and corresponding guide space .

Furthermore, a top cover arrangement (which constitutes a second containment member) is located over the top end of the conductor guide tube to prevent the resilient balls 28 from escaping out of the top of the apparatus.

Movement of the water at the offshore locality produces forces acting against the platform and/or conductor tube that may cause movement of the conductor tube relative to the conductor guide tube. This movement will in general comprise vertical and horizontal components, and the present apparatus damps such movement by means of the resilient balls 28.

With reference to Figure 5, example sub-surface recovery or exploration damping apparatus according to a further embodiment is depicted generally at 600. The apparatus 600 comprises a conductor guide tube 601, through which a conductor tube 604 is received. The apparatus has a mass of balls 606 contained in the guide space between inner surfaces of the guide tube and an outer surface of the conductor, in a manner similar to other embodiments described above.

Figure 5 further provides an illustration of the apparatus 600 during operation after forces acting on the conductor tube 604 have caused the tube to move into an off-centre position within and relative to the guide tube 602 as indicated by arrows 610. The centre axis of the guide tube is indicated by reference numeral 605. The mass of resilient balls 606 act to accommodate the lateral displacement of the conductor tube. In this case, a first set of balls 608a become compressed against the inner surface of the guide tube facing the direction of movement of the conductor tube. This set of balls 608a tends to absorb movement of the conductor tube and tends to resiliently oppose the movement of the conductor tube, pushing it toward an equilibrium position in the centre of the guide tube.

A second set of balls 608b fall from a reservoir of balls in the funnel portion, according to arrows 612, into the guide space behind the conductor tube as it travels laterally, thus keeping the space filled with resilient balls. In this case, a number of balls fit laterally adjacent to each other in the guide space.

When the conductor tube returns to its equilibrium position, the balls 608b will then compress and/or displace relative to each other in response to the return motion, while supporting the conductor tube.

In general, the balls will move up and down, in and around the guide space to fill the space, and move into and out of gaps according to the motion of the conductor tube, whether including lateral and/or longitudinal components of motion.

Accordingly, the balls allow the conductor tube to be fully supported and "caressed" as it moves, in a manner similar to a "bean bag", and then moved back into an equilibrium position. As the conductor tube moves from side to side, the motion of the conductor tube is damped without damaging impacts occurring. The present invention is advantageous as it is able to efficiently damp motion of a conductor pipe induced in a vertical and horizontal direction. This can reduce damage to conductor tube and conductor guide tube equipment as typically used in harsh offshore environments and can help to prevent damage of other equipment, such as wellhead valve tree piping, that is typically supported by the conductor tube.

In addition, the present apparatus can be installed relatively easily and non-destructively, e.g., without having to remove components of existing guide tube equipment.

Various modifications and improvements may be made without departing from the invention herein described.

Claims

1. Sub-surface recovery or exploration apparatus comprising: - a conductor guide defining a guide space; - a conductor tube received within the guide space and spaced apart from the conductor guide; and - a damping device disposed in the space between the conductor guide and the conductor tube, the damping device being configured to damp movement of the conductor tube laterally of the conductor guide, the damping device comprising a plurality of resilient bodies disposed along the conductor tube .

2. Sub-surface recovery or exploration apparatus as claimed in Claim 1, wherein the damping device comprises a plurality of resilient bodies disposed around the conductor tube.

3. Sub-surface recovery or exploration apparatus as claimed in Claim 2, wherein the damping device comprises a mass of resilient bodies in the space between the conductor guide and the conductor tube.

4. Sub-surface recovery or exploration apparatus as claimed in Claim 3, wherein the space containing the mass of bodies between the conductor guide and the conductor tube is substantially annular.

5. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 1 to 4, wherein the damping device consists exclusively of the plurality of resilient bodies.

6. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 1 to 5, wherein the plurality of resilient bodies is disposed within the space such that they are movable in relation to at least one of the conductor guide and the conductor tube .

7. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 1 to 6, wherein each of the plurality of resilient bodies is of regular shape .

8. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 1 to 7, wherein the plurality of resilient bodies comprises bodies of different shape.

9. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 1 to 8, wherein the plurality of resilient bodies comprises one or more of the following shapes: a prism, a sphere, a cube, a cylinder and a tetrahedron.

10. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the conductor guide may comprise a substantially cylindrical body having a flared portion defining a mouth of the conductor guide.

11. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the damping device is disposed at least in part in the space between the conductor guide and the conductor tube defined in part by the flared portion.

12. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the sub-surface recovery or exploration apparatus is configured to contain the damping device within a portion of the space between the conductor guide and the conductor tube.

13. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the apparatus comprises a containment apparatus configured to keep the damping means located in the portion of the space.

14. Sub-surface recovery or exploration apparatus as claimed in Claim 13, wherein the containment apparatus comprises at least one containment member configured to occlude the space between the space between the conductor guide and the conductor tube from passage of at least part of the damping device.

15. Sub-surface recovery or exploration apparatus as claimed in Claim 14, wherein the damping device is configured for disposal in the space between a mouth of the conductor guide and the containment member.

16. Sub-surface recovery or exploration apparatus as claimed in Claim 14 or Claim 15, wherein the containment member is configured to occlude the space below an open end of the conductor guide opposing a mouth of the conductor guide.

17. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 14 to 16, wherein the containment member is configured to so as to leave the conductor tube unobstructed.

18. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 14 to 17, wherein the containment member is configured to fit around the conductor tube.

19. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 14 to 18, wherein the containment member comprises a clamp arrangement for clamping the containment member around the conductor tube .

20. Sub-surface recovery or exploration apparatus as claimed in Claim 13 or Claim 14, or any of Claims 15 to 19 when in dependence on Claim 14, wherein the containment apparatus comprises a second containment member configured to occlude the space defined by a mouth of the conductor guide.

21. Sub-surface recovery or exploration apparatus as claimed in Claim 20, wherein the second containment member is configured to be received in a flared end portion of the conductor guide defining a mouth of the conductor guide.

22. Sub-surface recovery or exploration apparatus as claimed in Claim 20 or Claim 21, wherein the second containment member is configured so as to leave the conductor tube unobstructed.

23. Sub-surface recovery or exploration apparatus as claimed in Claim 22, wherein the second containment member is configured to fit around the conductor tube .

24. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the containment apparatus is adapted to permit relative movement between the conductor guide and the conductor tube.

25. Sub-surface recovery or exploration apparatus as claimed in Claim 24, wherein the relative movement is at least one of lateral and longitudinal movement.

26. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the containment apparatus comprises a containment sleeve configured to occlude a space between an end of the conductor guide tube, which opposes an end configured to receive the conductor tube, and the conductor tube.

27. Sub-surface recovery or exploration apparatus as claimed in Claim 26, wherein the containment sleeve is fitted to allow axial movement of the sleeve relative to the guide tube.

28. Sub-surface recovery or exploration apparatus as claimed in Claim 26 or Claim 27, wherein the containment sleeve is axially slidable relative to the conductor guide tube.

29. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 26 to 28, wherein the containment sleeve is fitted around an outer surface of the conductor guide tube.

30. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 26 to 28, wherein the containment sleeve is slidably fitted on an inside surface of the conductor guide tube.

31. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the apparatus is operable to damp movement of the pipe relative to the guide tube of a magnitude similar to that produced during offshore operations.

32. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the apparatus is operable to damp movement of the pipe relative to the guide tube in multiple directions.

33. Sub-surface recovery or exploration apparatus as claimed in any one of Claims 1 to 32, wherein the plurality of resilient bodies comprises at least one resilient body that is movable within the plurality of resilient bodies.

34. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the apparatus is configured to permit the at least one resilient body to be movable in relation to the conductor guide and the conductor tube for facilitating movement, and damping of movement, of the conductor tube laterally and longitudinally relative to the conductor guide.

35. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the plurality of resilient bodies comprises at least two resilient bodies that contact each other.

36. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the resilient bodies are configured to deform elastically.

37. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the resilient bodies are formed at least in part of at least one of the following materials: rubber; neoprene; polyethylene; and foam.

38. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the plurality of resilient bodies comprises at least two resilient bodies sized to fit in the guide space laterally adjacent to each other.

39. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein a resilient body has a maximum cross-sectional dimension of between about 1 in and 10 in.

40. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the sub-surface recovery or exploration apparatus is configured for mineral recovery or exploration.

41. Sub-surface recovery or exploration apparatus as claimed in any one of the preceding claims, wherein the sub-surface recovery or exploration apparatus is configured for at least one of on-shore operation and off-shore operation.

42. A seabed installation comprising sub-surface recovery or exploration apparatus as claimed in any one of Claims 1 to 41.

43. An offshore platform comprising a seabed installation as claimed in Claim 42.

44. A method of damping movement in sub-surface recovery or exploration apparatus, the method comprising: - receiving a conductor tube within a guide space defined by a conductor guide such that the conductor tube is spaced apart from the conductor guide; and - disposing a damping device in the space between the conductor guide and the conductor tube, the damping device being configured such that it is operative to damp movement of the conductor tube laterally of the conductor guide, the damping device comprising a plurality of resilient bodies disposed along the conductor tube.

45. A method as claimed in Claim 44, wherein the sub- surface recovery or exploration apparatus is an sub- surface recovery or exploration apparatus as claimed in any one of Claims 1 to 41.