WO1990003491A1

WO1990003491A1 - Submerged umbilical connection arrangement

Info

Publication number: WO1990003491A1
Application number: PCT/GB1989/001106
Authority: WO
Inventors: Alan Bradbury Wilson; John Ernest Lawson; Stephen Anthony Hatton
Original assignee: Mobil Oil Corporation; Fssl Limited; Cameron Offshore Engineering Limited
Priority date: 1988-09-22
Filing date: 1989-09-21
Publication date: 1990-04-05
Also published as: GB8822267D0

Abstract

A submerged control umbilical pull-in arrangement (10) (Fig. 1) comprises a control hub assembly (22) attached to an umbilical (23) lowered laterally of a subsea structure bed (11) and a hauling gantry (30), separately lowered to the bed on conventional guide wires (15), including a pair of dependent hauling cables (41, 42) which pass about, and terminate at, cable guide pulleys (40, 41) on support legs (34, 35) spaced apart at opposite edges of a platform (25) which is adjacent the positions occupied by a laterally facing hub (18) of a valve tree (16) lowered to the support bed. A remotely controlled vehicle (56) draws the cables (41, 42) from the gantry (36) and couples them to the hub assembly (22) which is then hauled by the cables onto the platform and secured. The vehicle uncouples the hauling cables permitting the gantry to be removed. The umbilical hub assembly carries a hub plate (21) movable relatively to the platform to and from mating engagement with a cooperating plate (20) on the valve tree to permit tree replacement with the hub assembly on the platform and the cooperating hub plates are slidable transversely to each other and direction of approach and cooperate with guide surfaces (68, 69 Fig. 7) to align as they are moved together.

Description

SUBMERGED UMBILICAL CONNECTION ARRANGEMENT

This invention relates to submerged valve arrangements and particularly to the connection of an electro-Tiydrauiic control umbilical or the like to such an arrangement submerged at a depth where operation has to be conducted by remotely controlled machinery.

Sub-sea wells for the production of hyrdocarbons are often sited at the sea bed and capped with a variety of controllable flow control, safety and other valves and equipment organised in a so-called Christmas tree to which hydrocarbon-extracting flow lines are connected.

Such a valve tree assembly is constructed within a partially protective framework for transport to and from the submerged site and when positioned thereat a control umbilical, containing channels or lines along which electrical and/or hydraulic power and tree-control signals are provided from some remote source, is connected with corresponding control lines within the tree structure. For convenience in this specification such control lines are referred to generically as electro-hydraulic lines irrespective of the control medium carried.

Such valve trees are complex and the umbilical channels usually numerous. The tree structure is normally lowered onto a prepared structure bed at the well head from a surface vessel and located on fixed upstanding structure bed guide posts to which it is guided by means of guide wires extending from .the post tops to the surface vessel and operations on the lowered tree structure which are not readily performed automatically are normally performed manually by a diver, such as the attachment or detachment of electro-hydraulic umbilical lines or manipulative operations on, or replacement of, control items on the tree.

When items requiring attention are too complex or too large for a diver to handle then it is usual to shut down the well and raise the Christmas tree structure by the same guide* wire arrangement for surface attention. The complexity and cost of the operation in addition to lost well production is tolerated as being the most cost-effective with present apparatus and procedures.

However, one procedure not readily, if at all, ' performable solely by a diver is the pull-in of the multiple channel control umbilical to the structure for coupling therewith, the drag of an average deployed length being considerable irrespective of any buoyancy provided, and mechanical pull-in assistance to the diver is required. Not only is such umbilical pull-in necessary in initial construction of the valve tree arrangement but requires to be performed each time that other tasks require its disconnection for returning the valve tree to the surface.

Hydrocarbon production is now being carried out in seas where the sea bed is beyond the range of divers, so that more tasks require retrieving the Christmas tree, and in seas where weather conditions and sea states place greater constraints on Christmas tree retrieval for surface working. Present working practices are far from suited to such conditions. It is well known to use remotely operated submersible vehicles (ROVs) to perform simple operations on submerged structures in place of divers. However, such ROVs are limited both in their manipulative ability and load-carrying or force-exerting ability, even when docked to the structure against which the operating forces react and cannot, at least at present, be considered as a complete substitute for a diver in deep sea operation.

Electrohydraulic umbilical connection requires not only the aforementioned overcoming of drag-forces in pulling the umbilical to the connector position but also the accurate positioning of termination hubs of umbilical and valve tree lines prior to, and for, connection and furthermore requires the exertion of mating or joining forces to overcome an effective separation force inherent with self-sealing line terminations which confirms the unsuitability of known ROVs for performing the whole task. The pull-in and mating of control umbilical termination can be considered as broadly similar in nature to the pull-in and mating of flow lines, despite a difference in scale and detail of the lines to be mated, and principles of tools-which operate unattended underwater, that is, completely automated or in response to surface controls, and which have been developed to effect such flowline pull-in operation can be adapted to the connection of electrohydraulic umbilicals.

Examples of typical arrangements for effecting flowline pull-in and connection are found in US patents Noε. 3,298,092, 4,457,378 and 3,716,100 and share features of construction and operation which restrict the form of subsea structure with which they can be used and the provision of remotely recontrolled operation- involves construction complexity with inherent expense and reliability problems.

In general, the pull-in and connection arrangements of the above-mentioned prior art comprises a carrier attached to a terminating hub of the flowline, pulling apparatus adapted to be lowered onto the subsea structure and a hauling cable connected between the carrier and a pulling winch, either on the pulling apparatus or on a surface vessel, in the latter case being threaded by way of a pull-in tube on the pulling apparatus. The pieces of apparatus and hauling cable are assembled and connected at the surface with the pulling apparatus and flowline lowered together connected by the hauling cable, the flowline hub and carrier being deposited on the sea bed laterally of the structure and the pulling apparatus being deposited on the structure. The carrier is then winched to the pulling apparatus by the hauling cable and orientated thereby if necessary in order to mate with a flowline in the structure for attachment,^• the pulling frame, carrier and hauling cable which joins them thereafter being detached automatically by remote control to free the pulling frame carrier and hauling cable for retrieval to the surface. Such arrangement, apart from the obvious complexity needed to effect remote operation, particularly latchings .and unlatchings, with reliability, clearly requires a complex deployment procedure of both pulling apparatus and coupled flowline and no obstructions to the downward passage of not only the pulling apparatus and carrier but also the interconnecting hauling cable. It is sometimes desired to protect the structure from

- physical damage by other subsea equipment and/or provide workover ability by means of a skeletal framework around the structure but the inclusion of cross-bracing members impedes the lowering of the connected hauling cable as the pulling apparatus is deployed on the tree inside the framework and the flowline is deposited outside and presents problems to the implementation of aforementioned schemes.

Furthermore such arrangements do not cater for situations such as, for example, where the flowline has to be disconnected from, and reconnected to, the structure requiring it to be returned without the surface and the whole deployment, pull-in and connection procedure repeated.

There are differences in practice between dealing with production flowlines and electrohydraulic control umbilicals in which the plurality of lines do have to be terminated at a plurality of individual ports arrayed at a connection face of a termination hub so that the mating alignment of the hub is particularly significant.

It is an object of the present invention to provide a subsea valve arrangement including a connection arrangement for an electrohydraulic umbilical which is simpler, cheaper and more reliable to implement and more versatile than known arrangements.

According to one aspect of the present invention a subsea valve arrangement includes (a) a subsea structure bed,

(b) a valve tree unit locatable on the structure bed having an electrohydraulic control line connection hub in the form of a tree hub housing and facing laterally thereof a tree hub plate carrying control lines terminations, (c) a platform carried by the structure bed and disposed laterally of the valve tree unit location adjacent a position assumed by the line connection hub of the tree unit, (d) hauling means including (i) a surface vessel, (ii) a winch arrangement, (iii) a pair of hauling cables depending from the winch arrangement and (iv) a hauling gantry arranged to be transported between the surface vessel and the structure bed and including a pair of legs disposed to locate at the structure at each side of the platform, each leg carrying hauling cable guide means about which one of the depending hauling cables passes and terminates for gantry transport,

(e) an electrohydraulic control umbilical, (f) a control umbilical hub assembly attached to an end of the electrohydraulic control umbilical comprising (i) a hub carrier attached to and housing individual electrohydraulic control lines of the umbilical, (ii) carrier fastening means operable to secure the carrier to the platform, (iii) an umbilical hub including a hub plate carrying terminations of the electro¬ hydraulic control lines and an umbilical hub housing therefor disposed on the carrier such that with the carrier on the platform the umbilical hub plate is facing, but spaced from, the tree hub plate, (iv) umbilical hub housing drive means operable to move the umbilical hub housing with respect to the carrier on the platform to displace the hub plates into aligned engagement with each other and, (v) hauling coupling means disposed at each side of the carrier adapted to be releasably coupled to the ends of the hauling cables, and (g) a manipulation machine operable to couple the terminations of the hauling cables from the lowered gantry to the coupling means of a carrier displaced laterally of the structure bed, permitting the hub assembly carrier to be hauled onto the platform by winching of the hauling cable, and operable to decouple the hauling cables from the carrier secured to the platform, permitting the gantry to be transported relative to the structure.

According to another aspect of the present invention a method of pulling-in and making a submerged electrohydraulic control umbilical to a submerged valve arrangement comprises

(a) providing a platform on a sea bed structure laterally of a position at which the submerged valve arrangement locates on the structure,

(b) lowering a control umbilical carrying a hub assembly at which the umbilical lines terminate to the sea bed laterally of the sea bed structure,

(c) lowering onto the structure a hauling gantry in which depends a pair of hauling cables fed about and terminating at guide means spaced at opposite edges of the platform,

(d) drawing the terminations of the hauling cables from the hauling gantry and coupling them to the umbilical hub assembly by a remotely operated submersible vehicle,

(e) pulling in the hauling cables to draw the hub assembly onto- the platform between the hauling cable guide means,

(f) securing the hub assembly to the platform, (g) uncoupling the hauling cables from the hub assembly by he remotely operated submersible vehicle,

(h) raising the hauling gantry from the subsea structure and

(i) displacing the umbilical line terminations with respect to the platform to mate with corresponding ones of the valve arrangement.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which:-

Figure 1 is a perspective view of a subsea valve arrangement including a subsea structure, an electrohydraulic umbilical and apparatus for connecting the umbilical to the valve arrangement shown at the beginning of the connection procedure with a hauling gantry carrying hauling cables being lowered to the subsea structure. Figure 2 is a side elevation view of the arrangement of

Figure 1,

Figure 3 is a side elevation similar to Figure 2 but showing the hauling gantry supported at a platform of the subsea structure, Figure 4 is a side elevation similar to Figure 3 showing the hauling cables coupled to the umbilical hub, Figure 5 is a side elevation of a portion of the arrangement showing the umbilical hub assembly being hauled onto the platform by the hauling gantry,

Figure 6 is a sectional elevation showing the arrangement of Figure 5 with the hub assembly attached fully to the platform and the hauling gantry removed, and an umbilical hub line termination carrying plate spaced from a corresponding plate of the valve tree hub, and the internal configuration of the hub assembly, and Figure 7 , is a side elevation of the arrangement disposed as in Figure 6 but showing the umbilical hub termination carrying plate displaced to mate with the valve tree hub plate.

Referring to Figures 1 and 2 a subsea valve arrangement 10 comprises a subsea structure bed 11 having upstanding perimeter guide posts 12 for receiving a valve tree unit 13 thereon. The guide posts 12 are connectable to a surface vessel 14 by guide wires 15 down which the valve tree, having guide funnels 16 slidable over the guide posts, is lowered and located on the bed.

The valve tree unit has a number of fluid power and control lines therein (not individually shown) which control the various valves of the tree, the lines spreading from a control module 17 to which a plurality of electrical and/or hydraulic control lines are input by way of a tree hub 18 which comprises a tree housing 19 and facing laterally thereof a tree hub plate 20 carrying the control lines terminations adapted to mate with corresponding terminations in a hub plate 21 of a hub control umbilical hub assembly 22 carried by a control umbilical 23 and described hereinafter in greater detail.

The subsea structure bed carries a platform 25 disposed laterally of the guide posts 12 adjacent the location assumed by the laterally facing tree hub 18 when the tree unit is lowered thereto. The platform 25 includes a ramp portion 26 by which umbilical hub assembly 22 can be hauled onto the platform .'and fastening means adapted to cooperate with a hub assembly to secure it to the platform.

The subsea structure bed includes a protective framework 27 of tubular steel surrounding the valve tree and designed to protect it from impact by objects moving through the water near the sea bed, such as submarine vessels or, more likely, implements such as anchors or trawls towed by surface vessels. The framework 27 is open-sided to permit access by a remotely operated submersible vehicle (ROV) for working on the valve tree and open-topped to permit lowering and raising of the valve tree, although a protective cap may be fitted over the arrangement when operational. To prevent access to the valve tree by way of the open sides, particularly by implements towed by a dependent rope, cross beams 28 between upstanding posts 29 are provided above the level of the valve tree which serve to vertically deflect such implements as well as brace the framework.

It will be seen however that such cross beams 28 also impede the use of known pull-in arrangements in that when a pull-in gantry coupled to a flowline or umbilical termination hub by hauling cable is lowered with the gantry to the inside of the cross beam and the termination hub outside of the cross beam the termination hub cannot be pulled into location by the gantry. In accordance with the present invention and as shown in Figures 1 to 5, a hauling gantry 30 comprises a pair of spaced guide funnels 31, 32 threaded onto the guide wires 15 and dimensioned to fit onto guide posts 12 atop the valve tree guide funnels 16. The gantry guide funnels are joined by a gantry cross member 33 from which depend a pair of laterally and downwardly extending support legs 34, 35. The lower ends of the legs are formed as guide funnels 34' , 35' and the leg lengths and separation are chosen such that with the guide funnels 31, 32 atop the tree guide posts 12 the legs are supported at the opposite edges of the platform 25 with the leg - guide funnels 34', 35' atop support pins 37, 38 fixed to the platform. Figure 2 shows in side elevation how the hauling gantry is lowered into position through the top of the protection framework and Figure 3 shows the hauling gantry in position on the structure.

The hauling gantry 30 carries at the lower end of each leg hauling cable guide means in the form of grooved pulleys 39, 40 pivoted for rotation in a vertical plane. A pair of hauling cables 41, 42 depend from winching means 147 on the surface vessel 14 and one each about the guide pulleys where they terminate in respective coupling terminals 41', 42'. The guide pulleys are conveniently each provided with guards 43 which permit the free passage of a hauling cable but inhibit the withdrawal of the coupling terminal.

The control umbilical hub assembly 22 comprises . hub carrier 44 which is attached permanently to the end of the control umbilical structure and forms an enclosure for the individual electrohydraulic control lines of the umbilical and their terminal regions. The hub carrier 44 also includes carrier fastening means, described hereinafter, for securing the carrier to the platform 25 and hauling coupling means 45, 46 disposed at each side of the carrier and adapted to be releasably coupled to the coupling terminals 41', 42' respectively of the hauling cables 41, 42. The aforementioned umbilical hub plate 21, having the terminations of the electrohydraulic control lines co-operable and matable with those of the tree hub plate 20, is carried by an umbilical hub housing 48 itself supported on the carrier such that it can slide along one axis orthogonal to the plane of the hub plate, as shown along the extension of the longitudinal axis of the control umbilical, and also to and from the position of the hauling coupling means 45, 46. The umbilical hub housing 48 is caused to slide by umbilical hub housing drive means 49 within the carrier 22, conveniently a ram 50 (Figures 5-7) formed by a piston and cylinder extended by fluid pressure applied by way of an external stab connection 51 or by a line 52 of the control umbilical. The ram may be double acting by pressure applied tβ opposite sides of the piston or single acting and include a spring 53 for retracting the ram to bias the hub housing 4θ in the direction towards the coupling means 45, 46. Functioning of the apparatus and description of the remaining features is made with reference also to Figures 3 to 7. The arrangement includes a manipulation machine designated generally at 55 and comprising, preferably, a^* remotely operated submersible vehicle (ROV) 56. The ROV is substantially conventional in that it has propulsion means 57 for maneouvring it freely within the environs of the subsea structure, television camera 58 for observing the scene in front of the vehicle and an umbilical 59 connecting the ROV to the surface vessel by which visual signals are transmitted to a surface operator and ROV control signals are transmitted to the ROV to control its position and operation of one or more articulated manipulation arms 60 able to perform simple mechanical tasks. In in operation the control umbilical 23 carrying the hub assembly 22 is lowered so that it lies on the sea bed with the hub-assembly displaced from the subsea structure, the manner in which it is lowered and the position it rests at being uncritical as there is no connection with any other apparatus of the arrangement at this stage.

The hauling frame 30 is then lowered with the hauling cables threaded about, but terminating at, the pulley means to be supported on the platform 25 and located on the support pins 37, 38 of the platform, the situation being as shown in Figure 3. Abutment of the hauling cable terminations 42' , 43' with the guide means may enable the hauling cables 41, 42 to be used also for lowering, and subsequently raising, the hauling frame.

Preferably the support legs 34, 35 of the hauling gantry are secured to the platform or support pins by fastening means to prevent undesired upward separation of the gantry. The fastening means may take the form of a latch which automatically functions upon lowering of the gantry legs but requires a manipulation to release or a catch which requires such manipulation both to effect and release. Such manipulation is provided by the ROV 56 and the fastening means conveniently comprises a catch formed by a pin 61 which is inserted in a transverse hole through each leg or leg funnel and support pin 37, 38 by the ROV.

The ROV is then guided to acquire the hauling cable terminal couplings 41' 42', draw each cable from the gantry towards the hub carrier 44. and couple them to the corresponding couplings means » the carrier, as shown in Figure 4.

The ROV operator, having observed the completion of this coupling task, then causes the winch 14' to be operated to haul in the hauling cables 41, 42 thereby drawing the control umbilical assembly 'carrier and the attached umbilical towards and onto the platform ramp 26 and finally onto the platform between the legs of the hauling gantry. It will be appreciated that as the tensions in the hauling cables between the gantry and winch are in an upward direction then there is a tendency for the gantry to be lifted at the guide pulleys but the fastening of the gantry to the platform prevents this.

Figure 5 shows the carrier 44 being hauled onto the platform 25 from ramp 26 and starting to pass between the support legs of the gantry in a direction towards the trep hub assembly 18. The carrier fastening means referred to above is shown at 62 and comprises an elongate tapered pin 63 and corresponding recess 64 carried one each by the platform and carrier and extending substantially parallel to the platform, that is, horizontally, so that as the hauled carrier slides across the platform the pin enters the recess and locates the carrier with respect to the platform both in, and transversely to, its direction of motion towards the tree housing.

The pin includes one or more tangential barbed notches 65 and the carrier has corresponding transverse apertures 66 through which release members in the form of one or more resilient pins extend whereby as the carrier is hauled fully home the pins are splayed by the increasing diameter pin and then locate in the notches to secure the carrier to the platform. The pins are removable by the manipulation machine ^* (ROV) to permit the carrier to slide off the platform if and when desired. It will be appreciated that the fastening means may be of other forms of latch or require the manipulation means to effect the fastening as well as any unfastening.

When the carrier 44 is fastened to the platform 25 the ROV uncouples the hauling cables from the coupling means^"on the

5. carrier and releases the gantry fastening means, pins 61, permitting the hauling gantry to be raised to -Che surface.vessel by winching the hauling cables 41, 42, which are trapped by the guidance means 43 and effect a convenient means of raising the gantry along the guide wires 15, or by winching a separate cable

10 (not shown) attached to the gantry.

The secured control umbilical hub assembly after removal of the hauling gantry is shown in sectional elevation in Figure 6 and side view in Figure 7 which illustrate the construction of the hub assembly and its operation.

15 Referring to Figure 6 the carrier 44 supports hub housing 48 substantially aligned with but spaced from the tree housing 19 with the line termination hub plates 21 and 20 facing each other. The ram 50 in the carrier is then extended by hydraulic fluid pressure in an umbilical line 52 or conveniently

20 by means of the attendant ROV 56 which couples its hydraulic circuit to the ram by way of stab connector 51. The ram then drives the hub housing 48 forward and the hub plates abut mating their corresponding line terminations as shown in Figure 7. Mating is maintained by hub fastening means, such as a pin 67

25 inserted by the ROV independently of the drive ram 50 which may then be de-powered.

Again it will be appreciated that the fastening means may be undone and hubs unmated by withdrawal of the pin 67 by the ROV.

30 It will also be appreciated that the form of hub assembly having relatively movable housing and carrier permits the carrier to be secured to the platform independently of mating of the line and umbilical hubs which hubs can in consequence be mated and unmated many times without the need to -

35 haul the umbilical hub assembly back onto the platform. Also the umbilical hub carrier provides an operationally fixed base and housing for the hub drive means and permits it to take forms other than a simple fluid operable ram.

In particular, by securing the umbilical hub assembly by way of the carrier 44 to the platform which is a part of the structure bed, the valve tree may be lifted from the structure bed for repair or replacement .by simply separating the umbilical hub housing 48 from the tree housing 18 by withdrawal of fastening pin 67 (and possibly actuation of the drive means ram 50), the carrier remaining secured to the structure bed unless its release is also required.

The above described subsea valve arrangement involves several fastening arrangements which need only be of a simple nature, operable with ease by an ROV or manipulation machine of corresponding dexterity, coupled with a form of hauling gantry which is simpler than known devices in not requiring remotely operable latching and releasing mechanisms in respect of its use, thus also being achieved as a simple manipulation by the attendant ROV, and the operating procedure associated with pulling-in the umbilical termination to the valve tree is simplified by use of the ROV, the hauling gantry being lowered independently of the control umbilical and its termination, and it can be used in situations where a surface-coupled arrangement cannot, for example, where a protective framework 27 has cross members 28. The manipulation machine is operable in conditions closed to a diver and the particular elements and their combination are chosen with regard to the requirement for simple manipulation, more effectively provided by a separate manipulation machine of simple abilities than building complex remotely—releasable latches and the like into the individual elements.

It will be appreciated that the manipulation machine may be other than a ROV and could be a similarly remotely operated articulated manipulation arm permanently attached to the subsea structure bed, although it would be necessary to ensure that the control umbilical termination was deposited within reach of the arm to couple the hauling cables thereto. Such an arm could be carried by the hauling gantry for the initial pulling-in and connection of the umbilical hub assembly and any fastening or releasing of fastening means subsequent to removal of the hauling gantry could be provided by a separately deployed ROV or return lowering of the hauling gantry or the like with the manipulation machine thereon.

The above description has concentrated on the performance of mechanical functions and operating procedures which most clearly distinguish the present invention functionally from the known apparatus and will be understood that the various cooperating parts are designed in such a way that as they are brought together for mating alignment is effected.

The use of a hauling gantry with a pair of legs which straddle the platform 25 and a pair of hauling cables which are coupled to the sides of the umbilical hub assembly carrier ensure that the hub assembly is drawn onto the platform with the hub plate substantially facing that of the valve tree irrespective of its initial orientation on the sea bed after deployment. The fastening means 62 may then ensure any further alignment of the carrier on the platform by penetration of the pin 63 along recess 64.

Although the presence of a manipulation machine which provides pictures of the operation to the surface operator enables control of the winching of the hauling cables individually to correct the path taken the platform 25 and/or ramp position 26 may be fitted with upstanding side walls (not shown) to act as a funnel and guide the carrier between the gantry legs in case any difference in hauling cable winching causes a tendency to slew the carrier.

It will also be appreciated that such vision and manipulative ability also permits adaptation of the operation to suit prevailing circumstances. For instance, if the umbilical hub assembly lands inverted the hauling cables may be crossed as- they are coupled by the manipulation machine so that as the umbilical hub assembly is hauled onto the platform it is righted for fastening. Although, as described, the hub plates may be parted to permit raising of the valve tree without releasing the umbilical hub assembly from the platform, if it is necessary to release the assembly by release of the fastening means the assembly or a different one is readily pulled in and secured by lowering the hauling gantry and coupling the hauling cables thereof to it by the manipulation machine without raising the umbilical hub assembly to the surface.

Although the umbilical hub housing is disposed at a known position with respect to the carrier the carrier is constructed separately from the platform to which it is secured and the platform itself may be formed separately from, and secured to, that portion of the structure bed upon which a separately constructed valve tree is deposited. Given the diverse constructions and assemblies involved it will be seen that an accumulation of tolerances make it difficult to guarantee alignment of the hub housings for mating of the plates.

To accommodate a degree of misalignment which may be experienced in practice the tree hub plate 20 and umbilical hub plate 21 are mounted so as to be slidable with respect to their respective housings 19 and 48 transversely to the axis of engagement and separation and to each other. Conveniently, and as illustrated, the umbilical hub plate 21 is slidable in a horizontal plane and the tree hub plate 20 is slidable in a vertical plane, preferably with limited motion in the horizontal plane also.

Plate guide means is provided by cooperating surfaces of the tree hub and umbilical hub assembly which slide the initially separated hub plates into axial alignment as they are brought together.

The guide means may comprise an edge of each plate and an inclined surface which effects a cam that the plate edge follows. As shown, the guide means for the tree hub plate in the main vertical direction is formed as a ramp 68 projecting from the hub plate 21 which ramp operable to engage under the vertically slidable tree hub plate, initially assuming a low position, and lift, it to a higher intermediate position aligned vertically with respect to the umbilical hub housing as housing 48 is moved forward after the carrier is secured in position, irrespective of the vertical relationship between the tree hub housing and umbilical hub housing.

Such ramp may alternatively be carried by the umbilical hub housing 48 or the carrier 44 in relation to which the operative (forward) position of the hub plate 21 is predetermined. In any disposition of ramp 68 with the umbilical housing separated free the valve tree, as in Figure 6, the ramp 68 does not interfere with the raising and replacing of the valve tree.

The umbilical and tree hub plates are aligned laterally by means of guide arms 69 at opposite sides of and projecting forward of, the umbilical hub plate, the arms being inclined to the axis of umbilical hub housing approach, that is, diverging from each other towards the tree hub housing in order to abut, the edge of the tree hub plate upon approach to align the plates. The guide arms may alternatively be fixed either to the umbilical housing, to the tree hub housing or to the tree hub plate, so as to abut an edfe of an unaligned umbilical hub plate which is moved towards the tree hub housing.

The tree hub plate and umbilical hub plate also carry locating pin and funnelled socket arrangement 70 by which final accurate alignment of the line terminations carried by the plates is effected. The plates may be held together mated by a fastening pin 71 extending through the locating pin and socket and removable, and possibly insertable, by the manipulation machine. Such a fastening pia 71 may be in addition to, or instead of, a pin 67 separately fastening the housing 48 on the carrier.

The use of orthogonally movable hub plates permits the alignment to be undertaken more readily in a physically compac - and simple manner in preferance to ensuring the alignment of the whole umbilical hub assembly with respect to the tree housing or of complex mounting of the hub housing to permit aiulti- directional alignment of the housings and providing a locating pin taper and/or socket funnel sufficiently large to accommodate all possible misalignment between them.

It will be appreciated that the mechanical elements and their relationships, such as fastening means releasable by manipulation means and alignment guides, may ^*be changed in respect of alternatives of common use in the trade in addition to other areas where alternatives are possible as outlined above.

The hauling gantry may take any suitable form which permits it to provide two hauling cables pivoted about guide means each side of the platform and need not be supported on the platform as such. For instance a gantry of a form similar to that illustrated may be supported on the main guide posts 12 by guide funnels 31, 32. The hauling gantry may futhermore carry the winching means in place of that 14' on the surface vessel.

The umbilical hub assembly may be hauled onto the platform and secured prior to lowering of the valve tree thereby removing any restrictions on the dimensions of the hauling gantry imposed by the pres^pnce of the valve tree or its use of the guide posts.

One other change to the embodiment illustrated may be the disposition of the umbilical housing to face the side of the tree hub assembly and operatively the side of the platform such that the carrier is drawn across the face of the tree hub plate for securing to the platform and the umbilical hub housing is then driven sideways with respect to the carrier direction to mate with the tree hub.

Claims

Claims: 1. A subsea valve arrangement including

(a) a subsea structure bed,

(b) a valve tree unit locatable on the structure bed having an electrohydraulic control line connection hub in the form of a tree hub housing and facing laterally thereof a tree hub plate carrying control lines terminations,

(c) a platform carried by the structure bed and disposed laterally of the valve tree unit location adjacent a position assumed by the line connection hub of the tree unit,

(d) hauling means including (i) a surface vessel, (ii) a winch arrangement, (iii) a pair of hauling cables depending from the winch arrangement and (iv) a hauling gantry arranged to be transported between the surface vessel and the structure bed and including a pair of legs disposed to locate at the structure at each side of the platform, each leg carrying hauling cable guide means about which one of the depending hauling cables passes and terminates for gantry transport, (*•) an electrohydraulic control umbilical, (f) a control umbilical hub assembly attached to an end of the electrohydraulic control umbilical comprising (i) a hub carrier attached to and housing individual electrohydraulic control lines of the umbilical, (ii) carrier fastening means operable to secure the carrier to the platform, (iii) an umbilical hub including a hub plate carrying terminations of the electrohydraulic control lines and an umbilical hub housing therefor disposed on the carrier such that with the carrier on the platform the umbilical hub plate is facing, but spaced from, the tree hub plate, (iv) umbilical hub housing drive means operable to move the umbilical hub housing with respect to the carrier on the platform to displace the hub plates into aligned engagement with each other and, (v) hauling coupling means disposed at each side of the carrier adapted to be releasably coupled to the ends of the hauling cables, and (g) a manipulation machine operable to couple the terminations of the hauling cables from the lowered gantry to the coupling means of a carrier displaced laterally of the structure bed, permitting the hub assembly carrier to be hauled onto the platform by winching of the hauling cable, and operable to decouple the hauling cables from the carrier secured to the platform, permitting the gantry to be transported relative to the structure.

2. A subsea valve arrangement^' as claimed in ^'claim 1 in which the fastening means operable to secure the carrier to the platform is releasable by the manipulator machine.

3. A subsea valve arrangement as claimed in claim 2 in which the carrier fastening means comprises a pin and recess carried one each by the platform and hub assembly carrier and extending substantially parallel to the platform to be engaged by the hauled carrier sliding across the platform and a release member operable to prevent egress of the pin from the recess and releasable by force applied by the manipulation machine.

4. A subsea valve arrangement as claimed in any one of the preceding claims in which the hub assembly includes hub fastening means operable to hold the engaged hubs in engagement independently of the hub drive means and releasable by the manipulation machine.

5. A subsea valve arrangement as claimed in any one of the preceding claims in which the manipulation machine includes a source of power for, and means to provide it to, the umbilical hub assembly drive means.

6. A subsea valve arrangement as claimed in any one of the preceding claims in which the manipulation machine is a remotely operated submersible vehicle.

7. A subsea valve arrangement as claimed in claim 6 in which the umbilical hub assembly drive means comprises a ram including a piston and cylinder means responsive to fluid pressure from the manipulation machine.

8. A subsea valve arrangement as claimed in any one of the preceding claims in which the gantry legs are supported on the platform.

9. A subsea valve arrangement as claimed in claim 8 in which the gantry legs are secured to the platform by gantry fastening means releasable by the manipulation machine.

10. A subsea valve arrangement as claimed in claim 9 in which the gantry fastening means includes upstanding pins on the platform, recesses in the gantry legs arranged to pass over the pins and releasable means to prevent the legs from lifting off the pins.

11. A subsea valve arrangement as claimed in any one of the preceding claims in which the hauling cable guide means on each leg is a pulley.

12. A subsea valve arrangement as claimed in any one of the preceding claims in which the structure bed has spaced upstanding perimeter guide posts and guide wires extending therefrom to the surface and the gantry has a pair of spaced guide funnels threaded over the guide wires, along which the gantry is transported between the surface and the structure bed, adapted to locate the gantry on the guide posts and a cross member joining the guide funnels from which the spaced legs depend.

13. A subsea valve arrangement as claimed in any one of the preceding claims in which tree hub plate and umbilical hub plate are slidable with respect to each other and to their respective housings transversely to their axis of engagement and separation and the arrangement includes plate guide means comprising cooperating surfaces of the tree hub and umbilical hub assembly operable to slide the separated hub plates into axial alignment as they are brought together.

14. A subsea valve arrangement as claimed in claim 13 in which the plate guide means comprises inclined surfaces formed as a cam to be abutted and followed by a hub plate.

15. A subsea valve arrangement as claimed in claim 14 in which the valve tree hub plate is arranged to slide vertically and assume a lower position under gravity and the guide means includes a ramp projecting from the carrier operable to engage under and lift the tree hub plate to a higher position, in vertical alignment with the umbilical hub plate, as the carrier. of the umbilical hub housing and plate is brought into its secured position on the platform and permit the valve tree .unit to be lifted from the structure bed with the umbilical assembly secured to the platform.

16. A subsea valve arrangement substantially as herein described with reference to, and as shown in, the accompanying drawings.

17. A method of pulling-in and making a submerged electrohydraulic control umbilical to a submerged valve arrangement comprising

(b) lowering a control umbilical carrying a hub assembly at which the umbilical lines terminate to the sea bed laterally of the sea bed structure, (c) lowering onto the structure a hauling gantry in which depends a pair of hauling cables fed about and terminating at guide means spaced at opposite edges of the platform,

(e) pulling in the hauling cables to draw the hub assembly onto the platform between the hauling cable guide means,

(f) securing the hub assembly to the platform,

(g) uncoupling the hauling cables from the hub assembly by he remotely operated submersible vehicle,

(h) raising the hauling gantry from the subsea structure and (i) displacing the umbilical line terminations with respect to the platform to mate with corresponding ones of the valve arrangement.

18. A method of pulling in and mating a submerged electrohydraulic control umbilical to a submerged valve arrangement substantially as herein described with reference to the accompanying drawings.