GB2193775A

GB2193775A - Device for positioning or removing an assembly of lines

Info

Publication number: GB2193775A
Application number: GB08715051A
Authority: GB
Inventors: Yvon Castel
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 1986-06-30
Filing date: 1987-06-26
Publication date: 1988-02-17
Anticipated expiration: 2007-06-26
Also published as: GB8715051D0; CA1328216C; GB2193775B; NO872696D0; FR2600710A1; NO180461B; NO872696L; NO180461C; FR2600710B1

Abstract

The present invention relates to a device for positioning and removing a set of lines or a connector block. The device according to the invention is characterised in that it comprises an elongate element 21 which can be positioned by virtue of means 22 onto a base 20. This element comprises guides 27 for the ends of flexible lines. Means 28 for holding the line ends are fitted in these guides. The lines are intended to be connected by a sleeve to the ground lines. The device is particularly applicable to the production of petroleum effluents in an underwater environment. <IMAGE>

Description

SPECIFICATION A device for positioning or removing an assembly of flexible lines BACKGROUND OF THE INVENTION The present invention relates to a device for the remote positioning and removal of an assembly of flexible lines, on an underwater installation resting on the seabed, from a main surface installation.

This invention may more particularly be applied to the field of oil effluent production in polar seas in regions subjected to the passage of icebergs likely to scrape the seabed and in regions subjected to very severe meteorological conditions (wind of 150 km/h, waves reaching 30m), when it is a question of rapidly removing from a critical zone a main surface installation, such as a processing platform, which is coupled to a seabed base or bottom base by flexible lines the removal taking place by leaving solely the bottom installation or installations in position.

SUMMARY OF THE INVENTION The present invention provides a device for overcoming this problem.

Thus, the present invention provides a device for rapidly positioning and removing a set of lines. This device allows lines to be connected to elements fixed to said base.

The device of the invention includes a structure having several guides each cooperating with a line end, each of said guides having means for retaining the line end with which it cooperates and said device having means for positioning said structure on said base.

This structure may include at least one auxiliary guide cooperating with a control line end, a connector integral with said device cooperating with said control line end for connecting, means retaining said line in said guide and means for locking said line on said structure.

The retaining means may be automatic, and they may also be retractible.

The guide lines may each comprise means for connection between said line ends and said control line.

The device of the invention may include locking means adapted for preventing said line from passing through said guide from one side to the other.

These locking means, such as a locking ring, may be disposed in the opening of the guide opposite that through which said end of said pipe is introduced.

The locking means may lose their activity beyond a certain predetermined stress threshold, such as a shearable ring.

The device of the invention may include at least at each of its ends a rotary pivot a fixed part of which is integral with said device and a rotating part is coupled to the lower end of a lifting cable, said pivots having the same pivot axis.

According to the present invention, positioning and locking of said device may be provided by at least one guide and locking assembly having guide posts cooperating with chimneys.

The device of the invention may include lifting means, such as feet actuated by jacks, adapted for separating said device from said base and possibly for separating said ends of said lines from said connection element cooperating therewith.

The device of the invention may include shock absorbers adapted for absorbing the shock during lowering of said device onto said base.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated by the accompanying Figures in which: Figure 1 shows schematically a submarine oil production installation during fitting of a bar, Figure 2 shows a submarine base with a bar and an exploded view of a guide, Figure 3 shows a bar during laying on a base during the lowering phase, Figure 4 illustrates this bar during laying in the final inclined position, Figure 5 shows a flexible line in section during fitting to a base during the phase for belaying this line.

Figure 6 shows a flexible line in section during fitting to a base during the locking phase thereof, Figure 6a shows in detail, in section, the device for locking the control rod, Figure 7 shows schematically the configuration of the flexible line between the bottom and surface installations in different work positions, Figure 8 shows the general configuration of the production device during disconnection from the bottom, Figure 9 illustrates the general configuration of the production device after disconnection from the bottom, and Figure 10 shows the general configuration of the production device during reconnection.

DESCRIPTION OF THE PREFERRED EMBODI MENT In Figure 1, reference 1 relates to the submarine base. This base provides the connection between the flexible lines coming from the main surface installation and bottom lines 2, generally rigid. coming from the different well heads.

Because of the risks of scraping by icebergs, the basw, the bottom lines, and the well heads may be buried in the soil so as not to be damaged.

The dimensions of such a base may be for example 45 x 25 x 9 m and its weight once ballasted may reach 2500 tonnes. The ends of the bottom lines are connected to sleeves 3 which will be connected to the ends of the flexible lines. These ends will be positioned by guides 4 placed on a bar 5, this bar is shown during lowering thereof to the base (Figure 1).

The bar, which may weigh 200 tonnes, has for example, as shown, an elongate shape in ciuding guides 4 for the flexible lines, which guides emerge at the top of the bar for introduction of the flexible lines and have at their lower parts cross sections sufficient for allowing sleeves 3 to pass for connecting the flexible lines with sleeves 3 with which they cooperate. Moreover, these cross sections may be sufficiently limited for retaining the flexible lines during removal of bar 5, and possibly extracting them from the sleeves to which they are connected.

The bar is held in position during lowering thereof to the base by suspension means such as two suspension elements, for example cable thest ends. These cables 6 are fixed to bar 5 by two pivots 7 which also include means for vertically guiding the lowering, such as vertical guide lines 8, about which slide sleeves 9, these guide lines may be mounted at the tops of guide posts 10 providing the final positioning of bar 5 on the base.

The purpose of pivot 7 is to allow angular variations of the bar about the axis passing through pivot 7 during lowering thereof and positioning on base 1. The axis of the pivots is correctly situated with respect to the center of gravity of the bar so as not to cause wrong positioning thereof on base 1.

Figure 2 shows a submarine base 20 having another bar 21, said bar being positioned on base 20 by guide posts 22. The bar is lowered towards the guide post 22 by means of two guide lines 23 about which slide two sleeves 24 placed on pivots 25 at each of the ends of the bar.

The bar is supported at the level of slide sleeves 24 by two suspension elements such as cables 26. Bar 21 includes several flexible line end guides 27 one of which is shown in an exploded view in Figure 2. These guides 27 include means 28 for retaining the ends of the lines with which they cooperate, such as three self locking dogs spaced apart from each other by 1200 in the same plane. Guide 27 may have at its upper part a centering receptacle cone 29.

Figure 3 is an illustration of the position once bar 30 has been lowered during the inclined positioning thereof on base 31. The bar is lowered to the base by vertical guide means such as two guide lines 32 mounted at the end of two guide posts 33, said guide lines and said guides cooperating in turn with two cones 34 which are openable from the moment when the bar is in the raised position to the moment when it is in the lowered position when cones 34 open. These openable cones may be actuated by jacks 39.

During lowering of the bar to the base the bar is supported by sufficient means, such as two cables 48, each being mounted on a pivot 49 at each of the ends of the bar so as to allow rotation of the bar about the axis of the pivots.

The guide lines 32 may be fixed to guide posts 33, by means of independent divers, inhabited submarines or remote control submarines, using a disconnectable lines connection device such as the one described in the patent FR-A-2,497, 899.

For positioning the guide lines on the guide posts, a split centering bicone may be positioned in the upper part of the guide post, said bicone will be withdrawn through its slit once the line has been positioned.

Posts 33 may be fixed to the base whereas the lines, which are tensioned with the surface installation, are positioned at the time of lowering of the bar and are withdrawn by means of a disconnection tool such as one described in the patent FR-A-2,525,682.

The bar also includes, straddling the lines or the guide posts in a substantially horizontal plane, two forks 36 providing, once the openable cones 34 are open, for a certain transverse movement of the bar in the direction of the fork axis 36 while being longitudinally positioned.

The bar has at its lower part lifting means formed of at least four feet, two of which are shown at 37 and 38 in the view of the Figure. These two feet, shown in the extended position, allow the bar to be both lowered when it is desired to immobilize it on the base and lifted when it is desired to remove it from the base. The mobility of the feet may be provided by jacks placed in each of the feet.

These feet jacks and jacks 39 for opening the openable cones may be controlled from the surface by an umbilical line, for example held in position with one of the suspension cables and fixed to the bar. Such control means have not been shown for a greater clarity of the Figures.

Under each of the feet is disposed a shock absorber 40 for attenuating the shock of lowering the bar when it meets the base. Feet 37 and 38 may include rollers 41 which may cooperate with an inclined surface 42 for tilting the bar, once cone 34 is open, towards an inclined position. In Figure 3, the rollers are positioned so that they cooperate with the inclined surface after the shock absorbers have fulfilled their shock absorbing function.

Figure 4 shows bar 21 after tilting and lowering. In the embodiment shown in this Figure the tilting has taken place before lowering.

This latter may be achieved by withdrawing the feet 37 and 38.

Guide and locking means, such as guide posts 43 and 44 cooperating respectively with chimneys 45 and 46, will provide positioning and locking of the bar in its final position.

In the Figure, the guide posts 43 and 44 are of an uneven length so as to provide efficient immobilization of the bar with relatively small lowering thereof.

Reference 47 (Figure 3) shows a bottom line end sleeve which cooperates with flexible line end for providing the connection. Sleeve 47 has two stubs for correctly positioning the end of the flexible line relatively to the sleeve.

The end of the flexible line is positioned by means of a guide 27 (Figure 2) with which it cooperates for belaying it to the bar, for connecting to sleeve 47 and for locking it on the sleeve.

In the embodiment described, the slant of the locking guide posts 43 and 44 as well as that of the sleeves are identical and correspond to the slant it is desired to give to the end of the flexible line once it is connected to the sleeve. This slant is imposed more particularly: by the choice of configuration of the flexible line in the form of an S, by the water depth, by the minimum radius of curvature imposable on the flexible line and by the draft of the main surface installation.

A slant angle of 18 with respect to the vertical satisfies the requirement of a usual bundle of flexible production lines at a depth of 90m in a region with difficult metereological conditions.

Figure 4 illustrates the bar once immobilized on the base. This position is obtained by lowering the bar along the guide lines 50 until it encounters the shock absorbers 40, tilting through releasing the suspension means 51, opening the centering cone for extending the tilting by rollers 41 (Figure 4) rolling on the inclined surface 52 as far as the inclined position, or by withdrawing the feet by draining the lifting jacks and guiding by means of posts 53 and 54 produces positioning of the bar on base 55.

With this positioning finished, the guide lines 50 are raised to the surface whereas the suspension cables 51 are held in position by buoys connected to the surface installation.

Figure 5 shows, after positioning and possibly locking of the bar to the base, the phase for belaying a first end of flexible lines 60 to the base, by means of a first tool 61 placed on a transfer carriage 62 mounted on guides fixed to the base. The bar 63 includes a plurality of guides 64 for the ends of flexible lines 60. These guides are provided with a means for retaining said lines such as self locking dogs 65 releasable by actuating an unlocking jack 66- situated below each of the dogs and the control of which is not shown for the sake of clarity.

Juxtaposed to guide 64 there is provided a first element 67 for the connection of control lines, such as hydraulic lines, for controlling different elements of the flexible lines such as locking of the flexible line end connector 68 to sleeve 47.

The end of the flexible line initially at the surface is lowered towards the guide by means of a fork 70 which may be opened by appropriate means, such as hydraulic jacks, and bearing on a sleeve 69 rotating about the end of the flexible line. This sleeve 69 is secured against translation on the end by two retainer rings 71 and 72.

The guide arm 73 which holds the fork 70, is lowered in,a split tube by means of a cable 74 passing over a guide, such as a lazy pulley 75, before rising to the surface where it is drawn. Arm 73 cooperates with split tube 76 for providing the function of guiding fork 70.

Once the end of the flexible line has reached the bar the guide arm 73 penetrates into a split tube 76 through a truncated cone shaped mouth in a plane which is slanted relatively to the axis of the cone. The groove in tube 76 is positioned angularly so as to open at the lowest point of the free edge of the cone. The guide finger 77, situated on arm 73, cooperates under the action of the tractive force exerted on the cable 74 with the edges of the cone so a to reach the lowest point and engages in the groove of the split tube 76 for then allowing the end of the flexible line to be correctly positioned in its guide 64.

Continuing its travel through the tube, the arm drives the flexible line more deeply into the guide so as to belay it through retainer means 65. Once the line has been belayed, the fork is opened, for example by means of a hydraulic control 79 from the surface and the flexible line is released. To avoid a too severe shock due to release of the line, the line end includes shock absorbing devices 80.

Freed from the flexible line, fork 70 is raised to be used again by means of the lifting cable 81.

The lazy pulley 75 as well as the split tube 76 are both positioned on the inclinabie plate 83 of the carriage which has been previously lowered by guide lines mounted on the guide posts 82. The carriage is guided by openable cones 84 (Figure 6) through which guide lines and guide posts pass.

The slant of the plate is provided by means of jack 85 so that the axes of the split tube 76 and of guide 64 are substantially parallel.

The carriage is movabie over the guides using appropriate means.

The guides may for example be formed of curved or straight rails serving several work stations. Carriage 62 rests through two rows of rollers 87 and 88 on rails 89 and 90. Horizontal guiding of the carriage is provided by rollers with vertical axes huging tighly sides 91 of rail 90. Some of these rollers, driven by motors not shown, may in addition ensure the curviiinear movements of the carriage through the rollers clamping the two opposite sides of the rail which causes an increase in the friction coefficient between them and the rail.

A third engagement rail 92, by cooperating with a clamping system 93 fixed to the carriage, maintains this carriage on base 20, and in addition, this engagement rail 92 and this clamping system 93 immobilize the carriage in a position corresponding to the work position or positions of the tool or tools mounted on plate 83. The clamping system, formed of at least a pair of claws mounted on hinges, imprisons the rail under the action of a jack controlled from the surface. The carriage further includes several deck feet 94 for setting it down once it has been raised to the deck of a surface installation.

Figure 6 shows, after belaying thereof in the guide, the final phase of connecting and locking the connector 101 to sleeve 102 by means of a second tool 103 mounted on the carriage. The functions of this tool 103 are first of all to index the end of the flexible line with sleeve 102, then to cause the end of the flexible line 100 to draw near to the bottom line end sleeve 102 so as to engage them with each other (that is connect them), then connection and locking, on the flexible line, of the control lines which will act among others on connector 101 for causing locking of the flexible line on the sleeve.

Since tool 103 is to provide clamping between the sleeve and the flexible line 100, which has a tendency to rise because of its buoyancy, by pulling on the end of the flexible line 100. it has at its upper part a fork 105 gripping the sleeve 106 which is free to rotate and is secured for translation with the flexible line by means of two retainer rings 107, and has at its lower part a reaction finger 108 which may penetrate into base 109 for providing clamping.

Clamping between the flexible line 100 and sleeve 102 by means of finger 108 and fork 105 is caused by jack 110 which draws the finger and the fork close together by sliding the respective supports one in the other. This assembly formed of fork 105 and finger 108 is positioned along the pulling axis by means of rollers 111 situated in a groove 112 parallel to said axis.

The handling of such an assembly is the same as for the remote connection device described in the French patent application EN 85/15 500.

Engagement of the assembly in the fork is caused by a lateral-translation with respect to the pulling axis of the whole of gantry 113 in which the assembly slides along the pulling axis.

Sliding of gantry 113 over plate 114 is provided by a jack 115 and is guided by grooves formed in plate 114 and cooperating with rollers 116 whose spindles are fixed to the support. The slant of the plate and guiding and movement of the carriage are obtained as in the description illustrated by Figure 5.

Once the fork 105 and finger 108 have been positioned on the flexible line and in the base, a motor 117, such as a hydraulic motor, causes indexation of the flexible line by means of a set of gears including a drive pinion 118, an intermediate pinion 119 and a ring gear 120 integral with the flexible line.

The correct position is for example shown by an indexation key 121 having a pin cooperating with a groove, which key is placed in concordance with the indexation stubs placed on the upper part of sleeve 102.

Control means such as a television camera or position or proximity sensors allow the indexation phase to be followed.

With the indexation terminated, the flexible line 100 is brought closer to sleeve 102, by means of fork 105 and finger 108, until they are connected. At this moment, a rod 122 carrying remote control liness coming from the surface installation is raised by means of a stub on the rod cooperating with an operating fork 123 actuated by means not shown, such as a jack. The rod then penetrates into a correctly indexed opening 124, situated in the ring gear 120, and formed so that the rod may cooperate therewith so as to transmit the control information to the flexible line by means of lines emerging in the opening 124 of the ring gear 120.

These lines 125, which may for example be electric or hydraulic lines (Figure 6a) provide, among other things, locking of connector 101 to sleeve 102. The lines reaching rod 122 are brought either by a cord along the bar lifting cable, or by means of a control flexible line whose end cooperates with a hydraulic or electric multiconnector of the type manufactured by the firm MATRA ACB for providing, once the control flexible line has been belayed, an electric supply for the control lines on the bar.

These control lines, among other things, feed flexible lines through rods 122. The end of rod 122 is provided with a collar 126 for cooperating during removal of the connection tool, with a locking device 127 such as a guillotine normally closed in the rest position, for maintaining the rod in the opening 124 of the ring gear 120.

The device 127 for locking the rod is automatically released by means of a stub placed on the connection tool when the tool is positioned both by its fork 105 on the flexible line and by its finger 108 on base 109. Withdrawal of the tool freeing the guillotine immoblizes the collar 126 integral with the rod between the guillotine and the ring gear.

The control lines emerge at the end of the rod through holes in grooves 123 in the rod which cooperate with the inlet holes -129 for the control lines of the ring gear and 0 seals 130 situated in grooves in the rod for provid ing the connection. Instead of placing the grooves and the 0 seals on the rod they could just as well have been placed in the ring gear.

The lower part of the flexible line guide includes a safety device, such as a ring 131 shearable under a given force, which, assuming that of the end of the flexible line is not released from the sleeve 102 during emergency unlocking thereof, produces a certain force on connector 101 for freeing it without risking damaging the bar and all the other flexible lines present.

In the case of failure, the flexible line is sheared by an appropriate means, such as a hollow bullet charge, placed above the level of the guide. This therefore allows the base, the bar and the flexible lines fixed to the bars to be raised.

A handling cable 132 is mounted at the top of gantry 113 for lowering and raising the tools carrying carriage.

Figure 7 shows schematically the configuration of the bundle 140 of flexible lines between buried seabed installations 141 and surface installations 142 in different wdrk positions.

The behavior of the bundle is assimulated to the behavior of the most fragile line taking into account that, for the same type of flexible line, the minimum possible radius of curvature of the flexible line decreases as its diameter increases.

The mean position of the bundle for which the slant of the bar is calculated is shown with dot dash lines 143 whereas the end positions permitted are shown with a continuous line 144 and a broken line 145.

The end positions are defined by the maximum angle which the end of the bundle attached to base 141 may withstand during service. The minimum radius of curvature of the bundle is close to 9 meters. The pull of the flexible lines on the bar is due to their buoyancy generated by buoys fixed to the flexible lines and situated substantially at the level of the downwardly directed concavity 146 of the flexible line.

According to the different positions, buoy 147 pulls more or less vertically on the suspension means 148. Starting from buoy 147.

the suspension cables are then joined up with the surface installation 142 without being stretched Figure 8 shows the general configuration of the production device during disconnection of base 150 from the surface installation 151.

For disconnecting, each of the connectors is unlocked from its bottom line end sleeve. The vertical pull exerted by the flexible line buoys allows disconnection from the sleeve, but is not sufficient for separating bar 153 from the base.

Bar 153 is then raised by means of feet 37 and 38 (Figure 3) so as to cause unlocking of the base. Finally, a sufficient tractive force is exerted from the surface installation 151 on the suspension means 132 for separating bar 153 from the base 150.

After lifting the bar, partially by means of buoy 154 and by a tractive force exerted on cable 152, the arrangement shown in Figure 9 is obtained where dissociation of the surface installation from that of the seabed allows the surface installation to move away without any risk for it or for the flexible production lines.

Figure 10 shows the general configuration ofthe production device during reconnection.

The surface installation 155 as well as the flexible lines bundle 156 can be seen at the level of the base in a configuration similar to Figure 9. Then the guide lines 157 are lowered from the surface installation through the openable cones 34 (Figure 3) of the bar as far as base 158 where the guide lines are positioned on the guide posts using, for example, a submarine 159.

The bar is then lowered onto the base, while holding the end of the flexible lines in position. it is then positioned as it was the first time when it did not yet comprise the flexible lines. Once locked, as explained by the description of the preceding Figures. the lines are connected and locked as aiready described.

Claims

1. A device forthe rapid positioning and removal of an assembly of lines, said device allowing said lines to be connected to elements fixed to a base, including a structure with several guides each cooperating with a line end, each of said guides having means for retaining the line end with which it cooperates and said device having means for positioning said structure on said base.

2. The device as claimed in claim 1, wherein said structure includes at least one auxiliary guide cooperating with a control line end, a connector integral with said device cooperating with said control line end for connecting, the retaining means of said line in said guide and means for locking said line on said structure.

3. The device as claimed in claims 1, wherein the retaining means are automatic.

4. The device as claimed in Claim 1, wherein these retaining means are retractable.

5. The device as claimed in any one of claims 2 to 4, wherein said line guides each include means for connection between said line end and the control line.

6. The device as claimed in claim 1, including locking means adapted for preventing said line from passing through said guide from one side to the other.

7. The device as claimed in claim 6, wherein said locking means, such as a locking ring, are disposed in the opening of said guide opposite that through which the end ofsaid pipe is inserted.

8. The device as claimed in claim 6, wherein said locking means lose their activity beyond a certain predetermined stress threshold, such as a shearable ring.

9. The device as claimed in claim including, at least at each of its ends, a rotary pivot of which a fixed part is integral with said device and a rotary part connected to the lower end of a lifting cable, said pivots having a same pivot axis.

10. The device as claimed in claim 1, wherein positioning and locking of said device is provided by at least one guide and locking assembly having guide posts cooperating with chinneys.

11. The device as claimed in claim 1, including lifting means, such as feet actuated by jacks adapted for separating said device from said base and possibly for separating said ends of said lines from said connection element cooperating therewith.

12. The device as claimed in any one of claim 1, including shock absorbers adapted for absorbing the shock during lowering of said device onto said base.