GB2202879A - Underwater saddle - Google Patents

Abstract

A saddle 16 for carrying fluids across from one part of a seabed oil and/or gas production complex to another has a framework 17 carrying one or more loops of pipe 18 with open ends at the bottom. Connector caps 20 on the pipe ends are designed to mate with connector hubs 15 on blocks 11, 12 of the seabed complex and a hydraulic system of lines, valves and actuators allows the connector caps to be locked and unlocked independently. The hydraulic system may have two sets of shuttle valves, one set for locking and the other for unlocking. The hydraulic lines connecting the sets of valves may run through an attachment point 25 of the saddle for a running tool, the lines being completed by passages through the running tool or an isolation plug associated with the attachment point. <IMAGE>

Description

UNDERWATER SADDLE This invention relates to a saddle for carrying fluids across from one part of a sea bed oil and/or gas production complex to another.

Oil or gas production complexes on the sea bed are becoming more common. Each underwater well may have a sea bed valve block above it and the oil and/or gas produced through the block may be transferred to another block for despatch with or without further processing.

Published UK Patent Application 2 174 442A, for example, describes and claims a subsea oil production system comprising a three-dimensional template framework enclosing one or more production bays, each bay having a well slot and a manifold slot, a well head and tree module above each well slot and a manifold selector head and manifold module above each manifold slot. The modules are linked by a production bridge formed of an upper tree block and an upper manifold block with piping connecting the blocks. In operation, oil flows from each well up a well tree module, across the production bridge and down and away through the adjacent manifold module.

As described in GB 2 174 442A, the production bridge with its connecting pipework is assembled as a unit and in assembling the complex, it is run and landed as a unit. While this reduces the number of steps required in assembling a complex, the production bridge is the heaviest component of the complex and determines the size and lifting capacity of the surface vessel or rig required to assemble the complex.

In one embodiment of the present invention, therefore, the saddle of the present invention may form part of a production bridge according to GB 2 174 442A which is not a single integral unit, but which consists of three separate units, viz an upper tree block, an upper manifold block and a connecting saddle. This allows the production bridge to be run and landed as smaller, lighter units, similar in weight to the other units of the complex, thereby reducing the maximum lifting capacity of the surface vessel or rig employed in assembling a complex. In the same way retrieval of the units for service or repair is facilitated. It may be possible to use a simple monohull vessel rather than a larger semi-submersible vessel or rig.

The specification of UK Patent Application No 8707307 entitled "Sea Bed Process Complex" describes a development of the sea bed complex of GB 2 174 442A in which oil may be both produced and processed in a sea bed complex. In this development there may be for each well, three pairs of blocks, a pair of well blocks, a pair of oil production blocks, and a pair of gas production blocks. Each of these pairs of blocks may be connected by a saddle according to the present invention.

As used in the above two complexes, the saddle links the blocks at their tops. This leads to other advantages, described in more detail hereafter, as compared with other methods of pipe connections used in other sea bed complexes, which may be some distance down from the tops of the blocks being connected. By suitable design of the blocks, saddles of the present invention could be used to replace such connectors and it is to be understood that saddles of the present invention may be used for carrying fluids from any part of a sea bed oil and/or gas production complex to any other adjacent part, and is in no way limited to use in the two examples of sea bed complexes described above. The saddle can be run and landed or retrieved vertically, which also facilitates assembly or dis-assembly, allowing, as indicated above, the use of a monohull vessel.

According to the present invention, a saddle for carrying fluids across from one part of a sea bed oil and/or gas production complex to another comprises (a) a framework carrying at least one loop of pipe, said loop having spaced apart open ends at the bottom of the framework, (b) a connector cap associated with each of the pipe ends, (c) a hydraulic system of lines, valves and actuators so that a connector cap at one end of a loop of pipe may be locked or unlocked independently of the connector cap at the other end, and (d) optionally, an attachment point at the top of the framework for lowering or raising the saddle.

There may be two loops of pipe on a saddle so that it may connect the normal annulus and production pipes of sea bed oil production blocks. There may, if required, be more than two loops of pipe if it is desired to connect other fluid-carrying pipes e.g. hydraulic fluid control lines.

The pipe ends of a loop or loops are at the bottom of the framework and are spaced apart so that they can mate with corresponding pipe ends at the top of the blocks to be connected.

Such pipe ends in the blocks will have connector hubs matching the connector caps of the saddle so that the pipe ends of the saddle and blocks can be hydraulically locked and unlocked using known connector hub and cap latches. The saddle pipe ends preferably have a vertical axis, as do the pipe ends of the blocks, thereby facilitating the connection of the pipe ends using the hubs and caps. To give some play and to tolerate some slight misalignment between the connector caps on the saddle and the connector hubs on the blocks, the pipes in the blocks leading to the connector hubs may be coiled so that they act, in effect, as springs.

The vertical alignment of the pipe ends and their connectors also makes it possible, on satellite wells, to have launching chambers on the saddle for the insertion of pigging or workover tools into the pipe work.

If there are two loops of pipe in a saddle the loops may be interconnected by cross-over pipe work with cross-over valves so that the saddle can be used to switch fluid flows from the annulus side pipe work to the production side pipework and vice versa.

The connector caps may have mechanical override rods extending up to spigots near the top of the framework, so that the connector cap latches can, in an emergency, be actuated mechanically by a remotely operated vehicle.

The saddle may have one or more buoyancy chambers filled with a suitable foam to reduce the weight of the saddle in water.

If there is an attachment point at the top of the framework, it may be of any convenient form so that the saddle can be attached to a running tool at the end of a pipe or cable and can thus be raised or lowered through the water. It may be a vertical, hollow cylinder with J-slots, the running tool on the end of the pipe or cable having corresponding latch pins for the J-slots. Alternatively, and preferably, the cylinder may have an internal groove capable of receiving hydraulically operated latching dogs on the running tool.

The cylinder may have a guide funnel at the top to facilitate the insertion of the running tool. The running tool may have passages in it mating with ports in the attachment point so that the running tool can complete the hydraulic system of the saddle, as described in more detail herafter.

If the saddle is to be used in a sea bed complex having a three-dimensional framework such as is described in GB 2 174 442A, the saddle framework may be adapted to fit within the template framework and parts of the saddle framework (e.g. a horizontal member) may align with the template framework to complete it.

The hydraulic system may comprise two sets of two shuttle valves.

In one of the sets, one valve is connected by hydraulic lines to the unlock side of one connector cap of a pipe end and the other valve is connected by hydraulic lines to the unlock side of the connector cap at the other pipe end of a loop of pipe. In the other set, two further shuttle valves are connected in like manner to the lock sides of the connector caps. The valves may be actuated by hydraulic pressure acting through couplers between the saddle and the blocks and the hydraulic system may be completed, if desired, by linking the two unlock shuttle valves and the two lock shuttle valves through ports in the attachment point and passages in the running tool or an isolation plug.

The invention is further illustrated and described with reference to the accompanying drawings in which, Figure 1 is an end view of a saddle, in place and connecting two modules of a sea bed complex.

Figure 2A is a side view of a saddle at right angles to Figure 1.

Figure 2B is a detail view showing the bottom part of a saddle when attached to a module; Figure 3A shows an attachment point for a saddle and a running tool for use with the attachment point and Figure 3B shows an isolation plug for use in the attachment point.

Figure 4, 5 and 6 show different ways in which the saddle and its associated modules may be raised or lowered.

Figure 7 is a flow diagram of a hydraulic system for locking and unlocking the saddle connector caps, and Figures 8A, B, C and D illustrate various sub-sea oil production complexes in which the saddle of the present invention is used.

Figure 1 shows a three dimensional framework of a template of a sea bed oil production complex. The framework has side members 8, a cross member 9 and top member 10. Within the framework are modules of an oil production complex. Module 11 may be, for example an upper tree block according to GB 2 174 442A and module 12 an upper manifold block. Each module has a cap 13 and each also has pipe work 14 within it extending up to connector hubs 15 indicated by dotted lines.

A saddle indicated generally at 16 connects the two modules.

Saddle 16 has a main frame 17 shaped to fit over and around template cross member 9. The frame supports two loops of pipe in the form of an inverted U,. One only is shown in Figure 1 marked at 18. The other, 19, is behind loop 18 and can be seen in Figure 2. Each end of each loop of pipe is surrounded by a connector cap 20. Connector caps 20 are loosely located within subsidiary shoe frames 27. Override rods 21 extend up from the connector caps 20 to override spigots 22 above main frame 17.

The saddle has a buoyancy chamber 23 filled with foam and tie rods 24 extend up from main frame 17 to an attachment point 25. These rods are loaded by springs 26 within housings above the main frame so that the saddle has a limited vertical freedom of movement relative to the rods and attachment point.

Figure 2A, which is a view at right angles to Figure 1, shows more clearly the duplication of the loops of pipe 18, 19, and their associated connector caps 20 and mechanical override rods 21, and ROV spigot 22. It also shows that there are two tie rods 24 and that attachment point 25 is within a template filler member 28 which completes the template framework in the plane at right angles to framework member 10 of Figure 1.

Figure 2A also shows between the loops of pipe 18 and 19 a set of hydraulic and electrical coupler stabs 29. There are two sets on either side of the saddle, which are mounted on floating plates 30 and which are spring loaded by springs 34 so that they can be latched into corresponding sets of coupler receptacles on modules 11 and 12, such latching being automatic on lowering the saddle onto the modules.

Suitable automatic couplers have been described, for example, in earlier-filed UK Patent Applications, viz UK Patent Application No 8622024 entitled Underwater Electrically Conductive Coupling, and UK Patent Application No 8722007 entitled Fluid Coupling.

Figure 2B is a detail of the bottom part of saddle 16 showing it latched onto a module, viz. module 12 of Figure 1. Module frame 31 has a hub alignment frame 32 attached to it by spring-loaded bolts 32A. Alignment frame 32 has base plate 32B through which the bolts pass and superstructure 32C which guides and aligns the shoe frame 27 of the saddle. Pipes 14 and connector hubs 15 extend up above the module so as to mate with connector caps 20. Also, above module frame 31 and forming part of the alignment frame 32 of the module 12 is a set cf hydraulic and electrical coupler receptacles 33 corresponding with the set of coupler stabs 29 on the saddle.It will be seen that the act of landing the saddle on the modules has pushed coupler stabs 29 and floating plate 30 up against the action of springs 34 (Figure 2A), this action being part of an automatic engaging mechanism latching coupler stabs 29 with coupler receptacles 33. It will be appreciated that saddle 16 has a second set of coupler stabs 29 at the end of the saddle which contacts module 11 and that module 11 also has a set of coupler receptacles equivalent to coupler receptacles 33 of module 12. There are thus hydraulic and electrical connectors from both modules 11 and 12 into saddle 16.

Figure 3A shows the detail of the attachment point. It consists of a hollow vertical cylinder 35 in template filler member 28.

Cylinder 35 has groove 36 cut into it. The top of the cylinder widens out into guide funnel 37. The bottom part of the cylinder is slightly narrower and it has two ports 38, 39 extending through it.

A hydraulic running tool 40 to be used in combination with the attachment point is indicated above the attachment point. It is shaped to fit into cylinder 35, and has hydraulically actuated dogs 41 which can engage the groove 36 of cylinder 35. Running tool 40 can be attached to the end of a suitable lowering string, e.g. lengths of drill pipe or a cable, with a suitable umbilical and it will be seen that it can be inserted into cylinder 35 and that by hydraulic action, the latch dogs 41 can be locked into groove 36. Thus the whole saddle can be raised or lowered using tool 40 and can be locked or unlocked from the tool hydraulically.

Running tool 40 has two passages 42, 43 running through its lower end and these passages are separated by three ring seals 44. The passages are positioned so that they line up with ports 38, 39 when the tool is locked into cylinder 35. Ports 38 and passage 42 thus provide pathways for hydraulic fluid from running tool 40 to a pair of shuttle valves 45, 46 and ports 39 and passage 43 provide pathways from running tool 40 to a second pair of shuttle valves 47, 48. Ring seals 44 ensure that there is no leakage of hydraulic fluid when fluid is passed through the ports and passages. Passage 42 may be supplied with hydraulic fluid by an umbilical running down the pipe or cable holding the running tool and passage 43 may be supplied similarly by a separate line.

When running tool 40 is in position in cylinder 35 there is direct communication between shuttle valves 45 and 46 and between valves 47 and 48. There is thus hydraulic control between the valves during the lowering and landing of the saddle or when retrieving it.

When the running tool is not in place, however, there is no hydraulic lock and the valves can act independently as discussed in detail hereafter with reference to Figure 7. While it would be possible to leave cylinder 35 open and ports 38, 39 exposed, it is, nevertheless, preferred to use an isolation plug 50 which seals the ports without forming a hydraulic lock.

Thus, when it is not proposed to use running tool 40 for lowering or raising saddle 16, or when the running tool 40 is otherwise not in place, ports 38 and 39 in cylinder 35 may be sealed by isolation plug 50 which is shown in Figure 3B. Plug 50 has the same general shape as the running tool, thus fitting closely within cylinder 35. It has three ring seals 51 similar to seals 44 on the running tool 40 so that ports 38, 39 are protected against ingress of dirt or sea water. It also has passages 74, 75 corresponding to passages 42, 43 in running tool 40 with a vent line 76 from them to the bottom of the plug, this vent line being protected by a check valve 77 against ingress of water.Vent line 76 from passages 74, 75 ensures that there is no hydraulic lock between the pairs of shuttle valves 45, 46 and 47, 48 when they are operating independently, as described hereafter with reference to Figure 7. Plug 50 has spring shear pins 52 near its base acting as a latch. Pins 52 allow plug 50 to be easily inserted into cylinder 35 but hold it against accidental removal. Plug 50 can, however, be pulled out of the cylinder if a reasonable pulling force is applied to the top 53 of the plug by a suitable latching mechanism. Pins 52 are sheared by the over-pull and the plug 50 can thus be removed.

Independent action of shuttle valves 45, 46, 47 48 is effected using the two other hydraulic lines leading to each of the valves shown diagrammatically in Figure 3A. Their use and functioning is described hereafter with reference to Figure 7.

Figures 4, 5 and 6 show how the valves and hydraulic system can be used for running and retrieving modules 11 and 12 and the saddle 16.

Taking Figure 4 in the running mode it shows that module 11 has already been run and landed as a separate operation, using a module running tool. Figure 4 shows module 12 and saddle 16 already locked as a unit. This assembly can be run using module running tool 49 and without any running tool 40 in the saddle. Once landed a signal from module 12 can lock the unlocked connector caps of the saddle onto the connector hubs of module 11.

Taking Figure 4 in its retrieving mode, a signal from module 12 will unlock the saddle from module 11 by unlocking the connector caps. Module 12 and the saddle, still locked together, can then be lifted as a unit leaving module 11 still in place. If required, module 11 could then be retrieved as a separate operation.

Figure 5 shows the reverse of Figure 4, viz that module 12 can be landed first and then module 11 and the saddle together. It also shows that module 11 and the saddle can be retrieved as a unit leaving module 12 in place to be retrieved subsequently.

If it is assumed that modules 11 and 12 and the saddle together form a production bridge according to GB 2 174 442A, Figures 4 and 5 show that only two landing operations are required to form the bridge and that the whole bridge can also be retrieved in two steps, despite the fact the bridge consists of three individual units.

Figure 6 shows, however, that it is possible to land and retrieve each unit separately, modules 11 and 12 being run and landed in succession in either order followed by the saddle and that the saddle can be retrieved separately leaving both modules in place, for separate retrieval if required.

The actual alternatives and how they are effected are described with reference to Figure 7 read in cooperation with Figures 4, 5 and 6.

Reverting to Figure 4 in the running mode, the connector caps of saddle 16 are locked to the connector hubs of module 12 on the drilling rig or surface vessel before running. Couplers 29 on saddle 16 will also be automatically latched to couplers 33 on module 12.

Module 12 and saddle 16 are run using module running tool 49, which will be supplied with hydraulic fluid via the module running tool umbilical. As module 12 and saddle 16 are landed, couplers on the left hand side of the saddle will automically latch with couplers on module 11 and the left hand side connector caps of the saddle will fit over and around the connector hubs of module 11. The connector caps cannot be locked with the hubs on module 11 directly, however, because module 11 has no supply of hydraulic fluid. Locking is, therefore, effected from module 12. As shown in Figure 7, a coupler 55 between module 12 and saddle 16 is actuated to supply hydraulic fluid to lock shuttle valve 48 via line 56. (This coupler 55 and the other couplers of Figure 7 may be couplers of the set of couplers 29, 33 of Figure 2).The valve is pushed to the left allowing fluid to flow along line 57 to the lock side of the left hand production and annulus connector caps 20, thereby locking the caps.

During this running operation there will be no saddle running tool in cylinder 35 of the saddle. Instead cylinder 35 will have isolation plug 50 in it. Passage 75 and vent line 76 in plug 50 will be connected to line 58 so that movement of the shuttle of valve 48 to the left is not prevented. Displaced hydraulic fluid in connector caps 20 is also free to flow back through unlock line 61 to unlock shuttle valve 46 and thence to vent through line 62, isolation plug passage 74 and vent line 76 or back through coupler 59.

Once saddle 16 has been locked to module 11, the modules and the saddle will form a linked production bridge. Module running tool 49 can then be released from module 12 and pulled back to the surface.

In the retrieving mode, Figure 4 shows the removal of module 12 and saddle 16. Module running tool 49 is run and landed and locked to module 12. This time coupler 59 between module 12 and the saddle 16 is actuated allowing hydraulic fluid to flow via line 60 to unlock shuttle valve 46. Again the shuttle of valve 46 is pushed to the left, so that fluid can flow along line 61 to the unlock side of the left hand production and annulus connector caps 20. The isolation plug 50 in cylinder 35, with its passage 74 and vent line 76 connected to line 62 allows the shuttle of valve 46 to move. Displaced hydraulic fluid in the connector caps 20 flows back through lock line 57, valve 48 and line 58 to the isolation plug vent 76 or line 56 through coupling 55.

Once the connector caps have been unlocked from the connector hubs of module 11, module 12 and saddle 16 can be retrieved by raising pipe 54.

Figure 5 shows the reverse operation, viz running or retrieving module 11 and saddle 16 with module 12 in position. For running, coupler 63 between module 11 and saddle 16 is actuated so that hydraulic fluid flows via line 64 to move lock shuttle valve 47 and hence allow flow via line 65 to the lock side of the right hand production and annulus connector caps 20.

For retrieving, coupler 67 is actuated, fluid flowing via line 68 to move unlock shuttle valve 45 and allow flow via line 69 to the unlock sides of the right hand production and annulus connector caps 20.

A third set of couplers shown in Figure 7, 71 on the right hand side and 72 on the left hand side, are directly linked by line 73.

These are hydraulic control couplers for the modules and provide a hydraulic linkage between modules 11 and 12 across saddle 16 for operational purposes. These do not form part of the locking and unlocking hydraulic system. They are shown for purposes of illustration and it will be appreciated that there could be several sets of couplers, as well as one or more sets of electrical couplers directly linking the modules if required, as well as electrical couplers linking electrical functions on the saddle with the modules 11 and 12 or vice versa.

Figure 6 shows saddle 16 being run or retrieved as a separate operation. In the running mode, Figure 6 shows that modules 11 and 12 have already been run and loaded separately using a module running tool. This time, saddle running tool 40 has been fitted into cylinder 35 of the saddle attachment point and locked in by dogs 41 fitting into groove 36. As previously explained the pipe or cable from which tool 40 is hung has two separate hydraulic lines running to passages 42 and 43 in the running tool to operate the tool and the shuttle valves.

For the running and landing operation, lock passage 43 is used.

When saddle 16 has landed with the right hand connector caps fitting over the hubs of module 12, and the left hand connector caps fitting over the hubs of module 11, hydraulic fluid supplied to passage 43 will flow through ports 39 to both of the lock shuttle valves 47 and 48 via lines 66 and 58 respectively. The shuttle of valve 47 will be moved to the left and the shuttle of valve 48 to the right. Hydraulic fluid can thus flow from valve 47 through line 65 to the lock side of the right hand connector caps, and from valve 48 through line 57 to the lock side of the left hand connector caps. All connector caps are thus locked simultaneously. Hydraulic fluid in lines 64 and 56 leading from valves 47 and 48 will allow the shuttles of valves 47 and 48 to move from left to right respectively by venting through couplings 63 or 55.

Once the saddle 16 has been locked to modules 11 and 12, the saddle running tool 40 can be released by withdrawing dogs 41 from the groove 36 and it can be pulled up. Isolation plug 50 can then be fitted to protect the hydraulic system against sea water and to provide a vent line 76 if required.

For retrieving the saddle according to Figure 6, isolation plug 50 is removed, and then the saddle tool is run, landed into cylinder 35 and locked by moving dogs 41 into groove 36. Hydraulic fluid supplied this time to passage 42 will be fed through ports 38 to unlock shuttle valves 45 and 46, pushing the shuttles to the left and right respectively. Hydraulic fluid can then flow via line 69 from valve 45 and via line 61 from valve 46 to the unlock sides of both the right hand and left hand side connector caps. Once unlocked the saddle can be pulled up to the surface.

The shuttle valves and their associated hydraulic systems will give the maximum flexibility for running or retrieving modules 11 and 12 and saddle 16 as individual units or with saddle 16 already locked to either module 11 or module 12.

As previously indicated, the saddle of the present invention may be used to link any two parts of a subsea oil and/or gas production compled whether of the types described in UK Patent Applications 2174442A and 8707307 or not. Figures 8A, B, C & D show four types of examples of deepwater diverless complexes using saddles of the present invention.

In Figure 8A a satellite well has a well head 78 supported through a permanent guide base 79 by a mud mat drilling template 80.

The well head has above it, in conventional manner, lower tree 81, upper tree 82 and control cap 83 which is actuated via a control receptacle 84 and umbilical 85.

Saddle 16 on this complex links upper tree 82 with a flow line isolation module 86. Oil or gas produced is led out through module 86 and flow line 87 to a central gathering point.

Figure 8B illustrates such a gathering point supported on template 88. Oil or gas flows in from the satellite wells through flow line 87 to a flow line module 89, having a control cap 90.

Umbilicals 85 lead back from this control cap to each satellite well.

In this complex, saddle 16 is used to bring the oil or gas from flow line module 89 into a manifold assembly which controls the despatch of the oil or gas. This assembly has a choke module 91, manifold module 92 and bus bar 93 and is controlled by control module 94 and control tray 95.

Figure 8C shows a cluster well assembly. This assembly is similar in some respects, to the satellite well of Figure 8A, but has additional controls, including a choke. Thus on template 96 is a well head 78 with lower and upper well trees, 81, 82 surmounted by a high pressure cap 97. Saddle 16 brings oil or gas over from upper tree 82 to a choke module 91 above flow line isolation module 86 from which flow line 87 leads. The assembly is controlled by control cap 83, control receptacle 84 and umbilical 85.

Figure 8D shows a gathering point for a series of cluster wells of Figure 8C. Again the gathering point has similarities to the satellite well gathering point of Figure 8B, but without choke control since this is in the cluster well assembly. The gathering point of Figure 8D is also double backed, illustrating how a large number of cluster wells could be connected to a single gathering point.

In Figure 8D, template 88 supports two flow line modules 89, each receiving flow lines 87 from cluster wells. The modules have control caps 90 with umbilicals 85 leading back to the cluster wells. Saddles 16 link the flow line modules to manifold modules 92 and bus bars 93 which are joined at 97 to give a single outflow pipe bundle from the gathering point. The assembly is controlled by control modules 94 on top of each manifold module 92, with control tray 95 feeding hydraulic and electrical power and control signals to the control modules 94.

Claims (9)

Claims

1. A saddle for carrying fluids across from one part of a sea bed oil and/or gas production complex to another comprising (a) a framework carrying at least one loop of pipe, said loop having spaced apart open ends at the bottom of the framework, (b) a connector cap associated with each of the pipe ends, (c) a hydraulic system of lines, valves and actuators so that a connector cap at one end of a loop of pipe may be locked or unlocked independently of the connector cap at the other end, and (d) optionally, an attachment point at the top of the framework for lowering or raising the saddle.

2. A saddle as claimed in claim 1 having two or more loops of pipe.

3. A saddle as claimed in claim 1 or 2 wherein the pipe ends have a vertical axis and the connector caps are adapted to mate with vertically aligned connector hubs on blocks of the sea bed complex.

4. A saddle as claimed in claim 1, 2 or 3 wherein the loops of pipe have connecting cross-over valves and/or launching chambers for the insertion of pigging tools.

5. A saddle as claimed in any of claims 1 to 4 wherein the connector caps have mechanical override rods and spigots.

6. A saddle as claimed in any of claims 1 to 5 wherein the attachment point is a cylinder adapted to receive a running tool.

7. A saddle as claimed in any of claims 1 to 6 wherein the hydraulic system has two sets of two shuttle valves, one set being connected to the lock sides of the connector caps and the other set being connected to the unlock sides.

8. A saddle as claimed in claim 7 wherein the valves are actuated by hydraulic pressure acting through couplers between the saddle and blocks of the seabed complex.

9. A saddle as claimed in claim 7 or 8 wherein the saddle has, within the attachment point cylinder, an isolation plug having a hydraulic vent line.