GB2327109A

GB2327109A - Method and apparatus for remote connection of fluid conduits

Info

Publication number: GB2327109A
Application number: GB9714491A
Authority: GB
Inventors: William Dennis Loth; James Christopher Pau Waithman
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-07-09
Filing date: 1997-07-09
Publication date: 1999-01-13
Anticipated expiration: 2017-07-09
Also published as: GB0221937D0; GB9714491D0; GB2375381A; GB2375381B; GB2327109B

Abstract

A fluid conduit 5 is connected to a well or other subsea installation with first end connection (fig 4) and to a second well or other subsea installation 8 with second end connection (fig 10). Seals 3, 21, 31, 40 at both connections are loaded with disc springs 19, 27 after seal surfaces are positioned with preinstalled elements. At the first connection, after a lateral guide cone is mated with a post at the first well, the conduit 5 and its connector is swung to engage hooked arms 18 over a shoulder of seal 3, subsequent release of a latch 20 releasing the springs 19 to load the seals 3, 21. At the other connection, a tension member 11 draws a connector 38 with the conduit into a socket on the second well guided by a guide cone and tapered latch finger 29 surfaces. An alignment member 26 is engaged by the connector and is sheared from fixing to the socket, allowing connector ports 35 to align axially with a conduit 7 to the well. After finger 29 latching, a further latch releases the springs 27 for seal loading.

Description

METHOD AND APPARATUS FOR REMOTE CONNECTION OF FLUID CONDUITS This invention relates to connection of flowlines conveying various fluids between wells and other installations associated with the production of hydrocarbons from subsea fields.

Many such sub sea developments incorporate wells spaced around a central facility requiring fluid conduits to be established between the wells and central installation. Other designs require the sub sea wells to be connected directly to a surface facility which may be floating or fixed. In water too deep for diver operations, or in circumstances not suitable for diver operations, these fluid conduits must be connected, at one or both ends, remotely.

Hitherto, these connections have been effected in a two part operation requiring firstly the fluid conduit to be accurately located and secondly to be firmly clamped or otherwise held together with sufficient force to maintain competent, that is leak tight, seals. This normally requires use of one or more specialized tools and often the use of a vessel other than the drilling vessel required to drill and complete the well.

The object of this invention is to provide a connection system in which the connection members provide sufficient provision for alignment and clamping in the absence of other dedicated tooling. A portion of each connection is affixed to the ends of the fluid conduit and the remaining portion affixed to either the central facility or apparatus surmounting the well or other subsea installation.

According to the present invention, a dedicated arrangement is provided for effecting the initial connection, known as the first end, and a second dedicated arrangement for the second connection; the second end connection. The connections are not interchangeable but can be used at either termination of the fluid conduit.

The first connection requires the fixed seabed installation, or well, to be fitted with a passive guidance arrangement located in reasonable proximity to the termination of the fixed installation fluid conduit. Said termination is a circular member prepared with a suitable, plain, sealing surface.

As the fluid conduit is lowered vertically from the surface, with the first end connection attached, the connection is guided to the correct position by the passive guidance arrangements affixed to the fixed installation. Continued lowering causes the connection to be fixed to the installed structure. Further lowering causes the fluid conduit to move towards the seafloor. As the pipe rotates, the connection rotation is guided by a pivoting arm assembly to precisely position the connection, which carries the fluid conduit seal, adjacent and parallel to the seal preparation on the seafloor installation.

As the connection is being positioned adjacent to the seal surface, latching fingers are distended to pass over the protruding edge of the seal preparation. At such time as the fluid conduit has rotated to the horizontal position, the latching fingers spring inwards to lock the connector in alignment and close proximity to the seal preparation.

The final stage of the first end connection is to release the pretensioned disk springs which force the inboard and outboard seal surfaces with the seal carried on the outboard surface, into a stressed contact. This compresses the seal to complete the first end connection.

At the completion of the first end connection, the fluid conduit, which may be either rigid or flexible pipe, is lying on the seafloor and directed generally towards the location of the second end connection.

The second end connection is effected by pulling the prepared fluid conduit end into a preparation on the well or other subsea installation. Motive force is supplied by a tension member extending from the seafloor to the drilling vessel.

The preparation on the end of the fluid conduit is comprised of a protective cover, a receptacle for the remote attachment of the pull-in line, porting to accept flow, a blind end, and two circumferential metal seal surfaces.

The well, or other subsea installation, is fitted with a guidance cone, alignment rod, circumferential seals, provisions for fluid ingress, and a tubular wire guide. The well or other subsea installation is prefitted with a length of flexible tension member extending through the alignment rod, which is shear pinned in position, and fitted at one end with a connection suitable for mating with the receptacle on the flexible conduit and on the other end with a connection suitable for mating with a tension member extending to the drilling vessel.

The second end connection is initiated by mating the flexible tension member coupling installed with the tree or other subsea installation with the receptacle mounted in the free second connection end of the flexible conduit. The coupling and receptacle are mated using a conventional remotely operated vehicle. The same vehicle connects the other end of the flexible tension member to the tension member extending to the drill vessel.

Tensioning the flexible tension member urges the fluid conduit towards the guidance member attached to the well or other sub sea installation. As the connection nears the guidance member the protective cover is removed by the remotely operated vehicle and any required cleaning conducted.

As the fluid conduit is urged forward; the blind end with the flexible tension connector contacts the alignment member. As force is increased, the pins holding the alignment member are sheared. Continued tension urges the fluid conduit and alignment member inwards to expose seal preparations and align porting on the connection and well or other subsea installation. When the connection and alignment have been urged forward to the lirnit set by the shoulder on the fluid conduit preparation, latching fingers which have been distended by the entry of the fluid conduit connection, move to the unflexed locking position. Release of the disk springs causes the seals housed in the well or other subsea installation to be compressed by the seal preparations on the fluid conduit connection and provide sufficient force to resist separating pressure loads.

The flexible tension member extending from the well or other subsea installation is then severed or otherwise disconnected by the remotely operated vehicle to complete the connection process.

A specific embodiment of the invention will now be described by way of example with reference to the following illustrated drawings: Figure 1 Arrangement of Flexible Conduit Connection System Figure 2 First End Connection being lowered Figure 3 First End Connection partially rotated Figure 4 First End Connection fully rotated Figure 5 First End Connection completed Figure 6 Preparation for the Second End Connection Figure 7 End of the fluid conduit for the Second End Connection Figure 8 Commencement of the Second End Connection Figure 9 Intermediate stage of the Second End Connection Figure 10 Further Intermediate stage of the Second End Connection Referring to Figure 1, the connection system is comprised of a first end connection 4, mated to a seal preparation 3 and a fluid conduit 2 mounted on a well or other sub sea installation 1. The fluid conduit 5 extends between the well or subsea installation 1 and other well or subsea installation 8. The well or other subsea installation 8 is mounted on a structure 9 housing the flexible tubular wire guide 10, through which passes the flexible tension member 11. Fluids passing from or to equipment 8 are directed through a conduit 7 to reach the second end connection 6.

Referring to Figure 2, the first end connection 4, attached to the fluid conduit 5, is shown being lowered over the well or other subsea installation 1 in such a manner that the guide cone 12 will land over guide post 13. When the connector assembly 4 is fully down, spring latch fingers 14 will snap into groove 15 securing the assembly.

Referring to Figure 3, first end connection assembly 4 has rotated clockwise as fluid conduit 5 has been lowered. The trajectory is controlled by linkage bars 16 and 17. Spring latch fingers 18 are being distended over seal preparation 3. Disk springs 19 are held in the compressed state by latch 20.

Referring to Figure 4, the first end connection 4 has rotated to the horizontal position, a fluid conduit 5 has been laid on the seafloor. Seal 21 is positioned close to seal preparation 3. Latch fingers 18 have snapped closed to secure the connection 4 to seal preparation 3. The spring disks remain fully loaded and are retained by latch mechanism 20 which is held in place by securing member 22.

Referring to Figure 5, the seal 21 has been compressed by removal of securing member 22. Disk springs 19 urge collar 23 against latch fingers 18 compressing seal 21 between seal preparation 3 and seal carrier 24. The connection is now complete.

The preparation for the second end connection is illustrated by reference to Figure 6.

The well or other subsea installation, 8, is connected to the base, 9, through a flowline 7. The connection housing, 24, is arranged such that ports 32 will coincide with matching ports in the fluid conduit connector.

Flexible tension member, 11, run through tubular wire guide, 10, passing through alignment number, 26, and terminates in latching connector 33. Alignment member 26 is maintained in position by shearable elements 25. Alignment member 26, seals 31, and flexible tension member 11, are installed with the well or other subsea installation. Disk springs 27 are installed in the compressed state and maintained in this state by latch mechanism 30. Spring latch members 29 and guide cone 28 complete the preinstalled elements of the fluid conduit second end connection system.

Referring to Figure 7, the elements of the end preparation for the second end connection which is affixed to the fluid conduit are illustrated. Connection member 38 is permanently affixed to fluid conduit 5. Ports 35 align with the fluid flowpath ports, 32, in the well or other sub sea installation structure 9. Seal surfaces, 40, interface with preinstalled seals, 31, in the well or other subsea structure installation 9. The upset, 39, serves to urge latch finger, 29, over the connection member, 38, so the latch elements, 29, can seat on shoulder 41. Upset 39 also functions to stop inward motion as it impinges on seal carrier 24.

Partition 42 isolates fluid conduit 5 internal flowpath from the nose of the connection member 38. The connection member 38 houses latch preparation, 37, which mates with latch 33 attached to the flexible tension member 11. Protective cover 36 shields seal surfaces 40 and prevents ingress of debris through ports 35 during completion of the first end connection and whilst fluid conduit 5 is being urged to close proximity to the second end connection preparation.

Referring to Figure 8, the second end connection system is illustrated prior to entry of the fluid conduit end preparation into the guide cone. The fluid conduit end preparation has been urged to the position shown by flexible tension member, 11, through mated latch, 33, and latch preparation, 37. Protective cover, 36, can be removed using a remotely operated vehicle. Matching profiles of latch fingers, 29, and the inner surface guide cone, 28, ensures centralization of connection member, 38, as it is urged further inwards by flexible tension member 11.

Referring to Figure 9, the second end connection is illustrated in an intermediate stage: Connection member 38 has been urged inwards by flexible tension member 11. Connection member 38 has been guided by alignment member 26 to avoid damage to seals 31 or seal preparations, 40. Latch 33 has been urged into contact with alignment member 26. Further urging will shear retaining members 25.

Referring to Figure 10, a further intermediate stage of the fluid conduit second end connection is illustrated.. Connection member 38 has been urged inward by flexible tension member 11 and alignment member 26 has been displaced accordingly. Latch elements 29 have been first distended and subsequently returned to their original geometry behind latch shoulder 41. Seal preparations 40, are located against seals 31. Ports 35 have been aligned with the flow path 7 from well or other subsea installation. Release of latch 30 will allow disk springs 27 to load latch elements 29 to urge connection member 38 forward and compress seals 31 against seal preparations 40 to provide competent pressure enclosure and resist subsequent pressure loads. Severing flexible tension member 11 completes the second end connection.

Claims

1. A means for coupling underwater conduits comprised of positioning and sealing mechanisms which can be adapted for either first end, (initially) or second end coupling and connection and do not require dedicated ancillary tooling for operation other than those equipments normally found on a mobile offshore drilling unit.

2. A positioning mechanism as claimed in Claim 1 which by virtue of its geometry positions a moveable seal surface sufficiently close to a fixed seal surface that any final movement and load application to ensure pressure tight sealing can be completed without ancillary tooling.

3. A sealing end positioning mechanism as claimed in Claims 1 and 2 which has as an integral part a mechanism to secure the moveable seal surface carrier in a fixed position with respect to the fixed seal surface.

4. A sealing mechanism as claimed in claim one which houses a plurality of concentric springs capable of loading a seal between moveable and fixed seal surfaces.

5. A sealing mechanism as claimed in claims 1 and 4 which has as an integral part a mechanism which holds the plurality of concentric springs in a compressed state until such time as the seal is to be energised.

6. A sealing mechanism as claimed in claims 1, 4 and 5 which has as an integral part a mechanism to release the plurality of concentric springs in order to compress the seal between moveable and fixed seal surfaces.

7. A positioning mechanism as claimed in claims 1, 2, and 3 which in one configuration houses an alignment pin which is fully engaged before moveable seal surfaces engage seals.

8. A positioning mechanism as claimed in claims 1, 3, 4, 5, and 6 which in one configuration houses primary and secondary alignment via a cone and pin which when fully engaged prevents damage to moveable seal surfaces during assembly.

Amendments to the claims have been filed as follows 1. A means for coupling underwater conduits comprised of positioning and sealing mechanisms which can be adapted for either first end, (initially) or second end coupling and connection and which having been positioned requires only self induced axial movement to complete all connection and seal preload functions.

2. A positioning mechanism as claimed in Claim 1 which by virtue of its geometry positions a moveable seal surface sufficiently close to a fixed inboard seal surface that final movement and load application to ensure pressure tight sealing can be completed without movement of inboard seals or seal surfaces.

3. A sealing end positioning mechanism as claimed in Claims 1 and 2 which has as an integral part an axially moveable mechanism to restrain the moveable seal surface carrier and react subsequently self induced seal preloads.

7. A positioning mechanism as claimed in claims 1, 2, and 3 which in one configuration houses an alignment pin which is fully engaged with the flow conduit before being axially displaced to allow stationary inboard seals to be engaged and preloaded.

9. A means for effecting a second end, pull-in connection as claimed in claims 1, 3, 4, 5, 6, and 8 in which the flexible tension member need not be disconnected or removed to effect conduit connector or sealing.