GB2355746A - Device and method for removing sediment - Google Patents

Abstract

A method for removing sediment material S, which has gathered on the water floor 7 around the support structure 3 for a drilling platform 1, where a remote controlled dredging vehicle 10 is lowered down the outside of the support structure so that once on the floor the vehicle can be manoeuvred under the support structure and remove the material. The material may be discharged by means of a pump 40, arranged on the vehicle, and a line 15 to above the water surface. The vehicle may be lowered and raised with the help of a frame 13 which is hung from the platform or another relatively statically positioned body. A vehicle with propelling means which comprises at least two worm rollers 20 is also disclosed.

Description

2355746 Device and method for removing sediment material from a water

floor.

The invention relates to a device and method for removing sediment material from a water floor. The invention particularly relates to the removal of drilling sludge, which is released in submarine drilling activities and is situated on and around the well mouth in the shape of an often metres thick layer and which is polluted with oil and heavy metals, but also with objects such as end hooks, chain parts, cables, tools fallen from the drilling platform, and sometimes even containers.

When the drilling activities of a drilling platform have come to an end it is more and more required, not only in view of maritime safety-that the drilling platform is removed for a large part, but also in view of the environ ment that no polluting remains are left on the sea floor.

The removal of the polluted sludge and objects in it usually takes place when the platform is still there, after all use can then be made of its support and of the conveniences on it with the help of people and means that are lowered from the drilling platform, within the jacket construction.

Here the jacket construction is used for providing support where needed.

The jacket construction, however, has the disadvantage that the freedom of movement and the room for passing on material are limited. The ac tivities to be carried out are operationally complex and require a lot of time and therefore are costly.

It is an object of the invention to improve on this. From one aspect the invention to fhat end provides a method for removing sediment material from a water floor, such as for instance waste material from oil or gas exploration or exploitation by means of a drilling platform supported on a support construction placed on a water floor, which material has ac cumulated on the water floor within, underneath and possibly around the support construction, in which a dredging vehicle is lowered outside past and/or around the support construction, the vehicle being remotecontrolled in order to move under the support construction from aside to the material and subsequently remove the material.

With the method according to the invention the jacket construction is not hindering when lowering/raising equipment and carrying out the activities.

The movement around the outside of the jacket construction renders the process more easily controllable. Hydraulic lines and power cables, as well as discharge lines can also hang freely around the jacket construction from the platform or a location near it and the vehicle, without said lines getting stuck in it. The method can be used from the drilling platform itself, but possibly also from a floating platform, for instance a pontoon equipped fro that purpose, or a dredging ship, in particular when the drilling platform is not accessible or unsuitable.

The material preferably is discharged by means of pump means and a line connected thereto also extending underneath and outside around the support construction to above the water surface, to receiving means or a further line situated above water surface. In this way a continuous removal of the waste material is possible, in which the support construction cannot hinder either.

Preferably use is made here of pump means arranged on the vehicle, as a result of which the discharge line extending from the vehicle can be flexible, as the delivery pressure will be able to compensate the water pressure.

Preferably use is also made here of an operation line for the vehicle which is guided outside of the support construction, so that also for said line there is no danger of getting stuck and for that matter a quick lowering and raising of the vehicle is possible.

Preferably the vehicle is lowered and raised with the help of a frame which is hung from the platform or another relatively statically positioned body, which frame itself is provided with a stock-length of the operation line of the vehicle and with a control unit, such as a hydraulic or pneumatic pressure source, for operating the several functions of the vehicle via the 10 operation line. As a result the length of the operation line, in which several sub lines are accommodated, can be kept as short as possible, as a result of which the chances of damage and thus failure are reduced. From another aspect the invention provides a vehicle for removing material 15 from a water floor, comprising means for removing the material and means for conveying the material from the removal means to elsewhere, as well as means for propelling the vehicle over the water floor, in which the vehicle comprises a longitudinal axis and the propelling means comprise at least two worm rollers provided with opposing pitch that are placed on 20 either side of the longitudinal axis of the vehicle. In this way a condition is provided for a low construction height, which is advantageous to the deployability of the vehicle. In particular the needed burial depth, when moving from aside below the bottom edge of the 25 support construction, is kept small. Moreover in case the vehicle has become buried in by soil or sediment (waste) material, the vehicle is able to simply move on as, unlike in case of wheels and caterpillar tracks, the movement direction on the upper side is the same as on the lower side. As a result also movement under the edge of the support construction is 30 promoted.

The feasibility of a low construction height is further improved in case the vehicle comprises a chassis, in which the worm rollers extend on either side outside of the chassis. The space between the worm rollers can be used for other functions of the vehicle. Preferably the worm rollers extend at least almost entirely outside of the chassis.

The worm rollers are preferably of such a dimension that the chassis generally extends to a lower level than the worm rollers.

In order to promote the controllability in the horizontal plane it is preferred that drives are provided for the worn rollers, which can be adjusted independently from each other. In order to promote the controllability in the vertical plane it is preferred that the worm rollers are bearing- mounted on suspensions attached to the vehicle, which suspensions can be adjusted as to height independent from each other. 15 Preferably the worm rollers are bearing-mounted in suspensions attached to the vehicle, which suspensions are moveable for liftin g the lower side of the worm rollers above the lower side of the chassis, preferably by means of independently powered driving means. Thus in case of a power cut for 20 the operation of the worm rollers, the worm rollers can be lifted out of engagement with the underground, so that the vehicle is substantially supported on the chassis and can be pulled away more easily. In order to limit the occupation of space, it is advantageous for when the 25 worm rollers are provided with internal spaces, in which at least a part- of the drive of the worm rollers is accommodated. In a further development of the vehicle according to the invention the removal means comprise excavation rollers having excavation screws, 30 which are substantially symmetrically positioned on either side of the longitudinal axis, having casing surfaces that are oriented to the fore and aside in an oblique manner. In this way it is achieved among others that 5- during propelling the vehicle, a sideward force is exerted on large and hard objects that are encountered, such as cases and containers, so that the excavation path is cleared again. This is additionally promoted in case the translation direction of the screws of the excavation roller in question is to the outside.

Preferably the excavation rollers comprise two outer rollers, which are positioned in an inclined manner such that the outer edges of their casing surfaces extend sidewards beyond their bearing, as a result of which said suspension is under the lee of said roller and will get damaged less easily by hard objects the vehicle encounters.

The space that can be left over therebetween as a result of the oblique positioning of the aforementioned excavation rollers can be occupied by a middle roller, which has a double conical surface, on which excavation screws with respective opposing pitch are provided.

Furthermore it is advantageous for limiting the occupation of space when the excavation rollers are provided with internal spaces, in which at least a part of the drive for the excavation rollers is accommodated.

Preferably the conveying means comprise one or more suction mouths and a pump placed behind the suction mouths, on or in the chassis, which pump discharges the excavated dredged material to a pressure line.

Suction mouths can be provided on either side of the longitudinal axis of the vehicle, which suction mouths are in connection to the pump via separate suction lines. Preferably the suction mouths have adaptable passage apertures, so that the dredge operator can each time realize an optimal mixture composition, also in case of one of the suction mouths being blocked. The positioning of a pump on the vehicle makes it possible to use a flexible discharge hose, as delivery pressure can compensate the water pressure.

In a first further development the pump is an axial pump placed in a parallel manner between the worm rollers. As a result of its elongated shape, such a pump is very suitable for placement between the drives situated on the longitudinal sides of the vehicle, such as the worm wheels, as a result of which the construction height can remain determined by said drives.

In an embodiment the suction lines of opposing sides debouch substantially transverse to the inlet of the axial pump, so that the driving shaft of the pump does not need to be bearing-mounted in the wall of the suction line.

The bearing can take place at the upstream end of the axial pump, in which both suction lines as seen in axial direction debouch adjacent to it in the axial pump.

In a second further development the pump is a centrifugal pump provided with a vertical axis of rotation, so that it can be accommodated in a lying position between the drives of the vehicle and the construction height of the vehicle can remain limited. Moreover, a much higher delivery pressure can be achieved with a centrifugal pump, so that also in larger depths of water a booster station can be left out in the pressure line.

The construction height here is kept limited, in case the inlet and the discharge of the pump extend in parallel planes, transverse to the axis of rotation. The inlet preferably is radial/tangential to the pump here.

In this way the advantageous condition is provided for the measure, that the drive of the pump is placed within the volute, so that further oc cupation of space is reduced.

In an advantageous manner the inlet is then situated vertically above or below the impeller, and debouches in an annular inlet chamber which merges into an annular distribution chamber to the impeller, in which preferably the inlet chamber and the distribution chamber are vertically in line with each other. The inlet chamber here already forms some kind of distribution chamber, in which the flow of dredged material can move to the distribution chamber for the impeller in a smooth manner with an axial direction component and losses of speed are kept limited, which is favourable to the discharge head of the pump.

Preferably the distribution chamber is situated under the inlet chamber, so that gravity promotes the inflow of the dredged material from the inlet chamber to the distribution chamber for the impeller.

Preferably a curved guiding plane is formed at the lower radial inner edge of the distribution chamber for promoting the inflow of the dredged material to the impeller.

The presence of an inlet chamber having a distribution function, can be benefitted from by using a part of the distribution chamber for the impeller for enlarging the blade surface, by providing the impeller with blades extending radially inwardly into the distribution chamber. 20 Further economizing on space can be realised when the inlet and the discharge at least partly coincide, as seen in a vertical plane of projection. The construction height can further be kept limited when the inlet chamber, the inlet and the suction lines have a rectangular crosssection. A 25 rectangular cross-section of the suction lines may not be optimal from a hydraulic point of view, but said part of the line is very short, whereas with the rectangular shape an favourable condition is provided for a flat inlet chamber, in which a transition resulting in loss of power can be left out30 Loss of power can further be kept limited when two inlets are provided instead of an inlet on which two suction lines debouch. Preferably both inlets debouch in the inlet chamber in directions having a same tangential component.

With the low construction height thus obtained it is preferable that any worm rollers extend until above the pump, so that the pump is situated under the lee of the worm rollers.

The invention also relates to a centrifugal pump provided with one or several of the aforementioned particular characteristics.

In a third further development the pump is an axial plunger pump. From a further aspect the invention provides a vehicle of the kind described above, provided with a suspension bracket attached to the chassis, to which a suspension wire can be connected, in which the suspension 15 bracket can be moved between an upright lowering and raising position and a collapsed working position. Thus the suspension bracket will not be able to be in the way of the excavation activities, in particular does not form a protruding part which may impede the progress of the vehicle. 20 Preferably the vehicle is provided with means that are remote releasable, preferably self-locking means, for locking the suspension bracket in the working position, so that when the vehicle moves a part of the jacket construction cannot engage under the suspension bracket and then urge the suspension bracket upwards into the raising position and a further 25 movement of the vehicle would be impeded. From a further aspect the vehicle according to the invention is provided with at least one microphone through which it can be established when the vehicle encounters a hard object such as a container and the correct 30 measures in the controlling of the vehicle can be taken.

Preferably the vehicle is provided with remote control means for operating -9 the driving means and the excavation means and the conveyor means.

From a further aspect a device is provided for lowering and raising a vehicle according to the invention, comprising a frame provided with a suspension means and means for detachably holding the vehicle, in which the frame further comprises a reel for a combined control, operation and feeder line for the vehicle. Thus a low situated stock-length of said line is provided, so that said stock-length can be kept limited and the reel therefore as well.

Said simplicity can be increased in case at the location of the suspension means a connection is present for a feeder line and in which the frame is provided with a hydraulic unit operable by means of the feeder line, which unit is in hydraulic communication to the drives in the vehicle via hydraulic lines in the combined line.

Preferably the frame is provided with a guide for a dredged material discharge line coming from the vehicle, with which the submarine presence of the frame can be used for orienting the discharge line.

Preferably the means for detachably holding the vehicle comprise a suspen sion wire for the vehicle that preferably can be wound and unwound.

Below the invention will be elucidated on the basis of a number of exemplary embodiments shown in the attached drawings, in which:

Figure 1 schematically shows an arrangement of a drilling platform, in which the device according to the invention is operative; Figure 2 is a detail of figure 1 of the vehicle according to the invention in operation; Figure 3 is a top view on an embodiment of the vehicle according to the invention; Figure 4 is a side view on the vehicle according to the invention; Figure 5 is a top view on a centrifugal pump for the vehicle according to the invention; Figure 6 is a cross-section through the centrifugal pump of figure 5; Figure 7 is an alternative embodiment of a vehicle according to the inven tion; Figure 8 is a schematic view in cross-section on the pump in the vehicle of figure 7; Figure 9 is a view on a auxiliary device for the vehicle according to the invention; and Figure 10 is a top view on the vehicle of figure 2 in operation. In figure 1 a water body 5 is shown and a drilling platform 1 placed in it, having a top structure 2 extending above the water surface 6 and a jacket or support structure 3, which is -founded in the water or sea floor in a 25 known manner by means of posts near the corners. The jacket construction 3 is a truss construction, of which the bottom transverse pipes 8 are situated near the bed 7. Within the truss construction 3 a hill S of waste sediment is present on the bed 7, mainly consisting of so- called drill cutting, in particular soil polluted with oil and heavy metals Priginating from 30 the drilling process carried out with the drilling platform 1. The hill S here extends to beyond the truss construction.

The top construction 2 is provided with an outrigger 17, having guidance 16 for systematically indicated -flexible pressure line 15 leading to pump 19 in the top construction 2, and from there, but not shown, to a dis charge- or storing means, such as a hopper ship to be moored near the top construction 2.

The outrigger 17 furthermore carries guide 18 for a cable 14, which does not only serve as suspension for a suspension frame 13 yet to be further described, but also has a function in the power supply for the dredging vehicle 10 which has been lowered on the water floor 7. From the suspen sion frame 13 a suspension wire 12 extends towards the vehicle 10, as well as a combined service line 11, in which hydraulic lines and electric lines for operating the several functions of the vehicle 10 are accom modated.

The vehicle is, as shown in figure 3, assembled in a characterizing manner, in which for starters the worm rollers 20a, 20b can be mentioned that - are placed on either side of the chassis 60, which rollers are provided with screws 30a, 30b, -of opposing pitch which are rotated in the directions B and C. The worm rollers 20a, 20b are substantially hollow, and offer room for their drives that are not further shown, which are preferably hydraulically operated, via the multiple function line 11.

The drives for the worm rollers 20a, 20b can be operated independently from each other. By for instance letting the worm roller 20a rotate and holding the worm roller 20b still, the vehicle 10 can be made to make a left turn.

Furthermore it is special that the worm rollers 20a, 20b at their ends are bearing-mounted in outriggers 21 a, 21 b and 22a, 22b protruding sidewards from the chassis 60, in which at least the outriggers 21 a, 21 b are hinging about a horizontal axis 23a, 23b and by means of driving means that are -12 not further shown, can be selectively placed in a wanted rotated position.

In this way while the vehicle 10 is operative the selected worm roller 20a or 20b can be placed in a tilted position with respect to the direction A of progress, so that also the working direction of the vehicle 10 can be influenced as seen in the vertical plane. If necessary, the outriggers 21 a, 21 b and 22a, 22b can be rotated upwards to such an extent that the worm rollers 20a, 20b come to lie above the lower side of the chassis, the screws being free from the floor, so that the retraction of the vehicle 10 in case the drive of the worm rollers 20a, 20b no longer functions, is facilitated. To that end a separate feeding for the movement of the outrig gers may be provided, preferably in the shape of a (hydraulic) battery present on the vehicle.

In figure 3 it is further shown that the vehicle 10 at its front is provided with three excavation rollers 24a, 24b and 25, in which the rollers 24a, 24b are positioned inclined to the outside and are provided with screws 31 a, 31 b on their cylindrical casings and with the help of driving means accommodated in the rollers 24a, 24b, which just like the driving means for the worm rollers 20a, 20b are hydraulically operated, are driven in directions D and E, respectively. The conveyance directions past the front will as a result have a component directed to the outside. The excavation rollers 24a, 24b are journalled. on either side in outriggers 26a, 27a and 26b, 27b arranged on the chassis 60. Because of the inclined position of the excavation rollers 24a, 241b the bearings on the outriggers 26a, 26b will be present under the lee of the excavation rollers 24a, 24b.

Spraying means can be provided at the excavation rollers for supporting the excavation process and the conveyance by means of spraying water jets.

At the front end of the vehicle 10 the excavation roller 25 is bearingmounted in outriggers 28a, 28b, which are a continuation of the outrigger 13 29 which is connected to the chassis 60. The excavation roller 25 is built up from two truncated conical casings 25a, 25b that are placed against each other with their largest planes. On the casing 25a a screw 32a is provided and on the casing 25b a screw 32b, which has an opposing pitch to the one of screw 32a. Now as well driving takes place by means of driving means that are accommodated in the excavation roller 25, with the help of which the roller 25 is rotated in the direction F. The shape chosen for the excavation roller 25 results in objects touching it being urged aside of their own accord and the vehicle 10 not being unwantedly stopped by such an object.

Seen in the working direction behind the excavation rollers 24a, 24b suction chambers 33a, 33b are present which may each be provided with an adjustable visor in order to adjust the size of its access opening behind the excavation rollers 24a, 24b. To that end drives and operation lines are provided that are not further shown, which via the multiple function line 11 to the suspension frame 13 and via the cable 14 are in connection with the operation centre in the top construction 2.

The suction chambers 33a, 33b debouch in the suction lines 34a, 34b which via the flange connections merge into inlet lines 35a, 35b to a pump 40, which debouches in pressure line 15 via outlet 41.

A closable lid 62 is furthermore shown in figure 3, for a space which can be used for possible further control elements, and hinge connections 51a, 51 b for the bracket 61 which here is shown in collapsed position locked to the chassis 60, and at its end is connected to suspension wire 12.

In figure 2 it can be seen in detail how a vehicle 10 having little height moves in the direction A under the bottom transverse pipe 8 of the truss construction 3, at a location between the corners of the truss construction, so that the movement can take place there free of obstacles on and above the see floor. The suspension wire 12, the combined function line 11 and the flexible discharge line 15 here remain outside of the truss construction 3. When propelling in the direction A the vehicle 10 encounters the heap of waste material S in order to remove it and the discharge it to discharge line 15 by means of excavation and pump means yet to be described. In figure 4 it is clearly shown that the construction height of the vehicle 10 is determined by the worm rollers 20a, 20b. In this way the vehicle 10 need not dig itself in too deeply in order to move under the transverse pipe 8 of the truss construction 3 and it encounters the heap S at a level which is almost equal to the lower boundary of said heap.

The low construction height is also made possible by the location of the pump between the driving members for the vehicle 10.

In figure 5 and 6 the centrifugal pump 40 is shown, which corresponds to the one accommodated in the vehicle 10 of figure 3. The centrifugal pump 40 is able to realise such a discharge head that also in deep water (for instance 150 rn deep) dredging material can be pressed upwards above the water surface 6 without a booster station. As can be seen in case of com20 bination of the figures 5 and 6, there is an annular inlet chamber 48, in which the rectangular inlet lines 35a, 35b debouch. The flow direction is clockwise, in which during flowing around the dredged material goes to the distribution chamber 49 according to the direction component J, which distribution chamber is situated exactly below the inlet chamber 48, and 25 form as it were one large annular chamber therewith. At the radial outside of the distribution chamber 49 a number of blades 50 are present, which are rotated in the direction H by means of a hydraulic drive 47 which with driving axis 45 and driving housing 44 is bearing-mounted by means of bearings 46 in the pump housing and is accommodated in the axial space 30 43 which is realised within the chambers 48, 49.

The blades 50 can be extended to the inside in portions 52, in which they extend into the distribution chamber 49. The radial lower-inner edge of the distribution chamber 49 can designed in a rounded off manner, as is shown.

At the radial outer side of the blade space the usual volute-shaped chamber 51 is situated, which merges in pressure line 41, which is connected to the discharge line 15 with flange 41 a. On the basis of the various flow directions shown and the shown arrangement it is noted that the flow takes place substantially parallel to the horizontal plane, except for the direction 10 component J for movement from inlet chamber 48 to the distribution chamber 49. As a result, the direction transitions, in case there are any, are smooth. A flat construction, including inlets and outlets, is possible. Moreover it is advantageous that the inlet lets in dredged material at a location which is relatively at a large distance from the rotation centre 15 point.

The centrifugal pump 40 can be simply adapted for letting through parts of a size of 100 mm.

In the figures 7 and 8 an alternative is shown of the vehicle according to the invention, now vehicle 110 having axial pump 140, which pump is also situated between the rollers 120a, 120b and in which suction lines 134a, 134b debouch in inlets 135a, 135b, that are transverse to the housing 136 of the axial pump 140. The axial pump 140 has a number of helical blades 25 150, which are driven by an axle 145, which is driven by means of a hydraulic or electric motor 165. During operation the dredged material enters in the directions K and L in order to subsequently be urged in the direction M via pressure end 141 into the discharge line 15. 30 In figure 9 the suspension frame 13 is shown, which is suspended from the top construction 2 by means of cable 14 guided over the guide roller 18 attached to the outrigger 17 of the top construction 2, in which a winch for the cable 14 is present. The lower end of the cable 14 is. shaped like a chock 72 which at the location of the hinge connection 71 is at tached to the upper side of the frame 70 of the suspension frame 13. The suspension frame 13 is further provided with an outrigger 73, in which guide rollers for the.discharge line 15 and a guide roller for the multiple function line (umbilical) 11 are present. For the cable 11 a reel 74 is arranged in the frame 13, on which the cable 11 can be wound in one plane, that is to say that the windings are situated on each other in radial sense.

It can be seen that the hydraulic lines 11' are branched off before they enter the reel 74. The hydraulic lines 11' are wound separately, via a number of tension pulleys 78a, 78b, 78c, on reel 80, in which the pulley 78a can be moved up and down by means of leverage rod 75 and cylinder assembly 76. With such an in itself known construction the length of the hydraulic lines 11' is stored within the frame 13, without a rotating hydraulic passage being needed. Furthermore the winch 79 is shown, with which the suspension wire is being

hauled in and paid out, which wire is attached to the upper end of the bracket 61 of the vehicle 10.

A hydraulic compression source 77 is also schematically shown, which source is fed by the power line in the cable 14 and which ensures hydraulic pressure in the lines 11'. Because of the low placement in the system the hydraulic lines can be kept short, which is advantageous from a handling point of view.

When the heap S has to be removed from under a drilling platform the frame 13 is lowered on the cable 14 past the outside of the truss shaped support construction 3 of the drilling platform, until the vehicle 10 has ended up adjacent to the construction on the sea floor 7. During lowering 17 the discharge line 15 is paid out.

Subsequently the winch 79 is released, as well as the reel 74, and the cable 14 is held back a little. Via the electric operation line which is accom modated in the cable 14 various functions in the frame 13 can be operated from the top construction Of the drilling platform. The operation signals are transmitted to the vehicle 10 via the multiple function cable 11. Said vehicle 10 is operated such that it digs under the bracing 8 towards the heap S. Use is made of the excavation capacity of the excavation rollers 24, 25 at the front of the vehicle 10. Via.the suction mouths and the pump the excavated material -first bed material, then polluted dredged material- is discharged via the discharge line 15.

While the vehicle 10 moves under the bracing 8 the bracket 61 can be urged downwards as a result and by means of locking means that are not shown the bracket 61 can be secured in its flat position to the chassis 60.

The vehicle 10 is now operated to dig off the heap S, as shown in figure 10. The worm rollers 20a, 20b are here controlled to let the vehicle 10 move according to an optimal path for the removal process.

During the process of digging off the heap S it may happen that the vehicle also gets material on top of itself, however this need not impede the progress of the activities as the conveyance direction on the upper side and on the bottom side of the worm rollers 20a, 20b is the same.

When the heap S has been removed -also the portion outside of the construction 3, to which end the vehicle 10 is also moved under the right hand bracing- the vehicle 10 can be retrieved, by driving the worm rollers 20a, 20b in reverse mode, and, which can also be done in case of an emergency, retracting the wire 12. Because of the locking of the bracket 61 the correct direction of the tensile force exerted is guaranteed. When the vehicle 10 has come outside of the support construction 3 again, below the outrigger 17, the bracket 61 is unlocked via the multiple function cable 11, after which the bracket 61 is turned upwards by exerting a tensile force on the pulling wire 12. Subsequently the frame 13, which has been kept at some distance above the see floor, is lowered while simultaneously hauling in the multiple function line 11 and the suspension wire 12. When the frame 13 has reached a position with respect to the vehicle 10 as shown in figure 9, the winches and reels on the frame 13 are fixed, which can also be remote controlled from the top construction, and the cable 14 and the discharge line 15 are hauled in.

It will be understood that the vehicle according to the application can be deployed in other work in which a low construction height is advantageous to the performance of the activities. The centrifugal pump with its flat shape as shown can similarly be used on other locations where the space to be used is or has to be small. Furthermore the frame with its remote hydraulic power source can be used elsewhere. The application also regards such uses.

I --- I _/ 1 6f

Claims (44)

Claims

1. Method for removing sediment material from a water floor, such as waste material from oil or gas exploration or exploitation by means of a drilling platform supported on a support construction placed on the water floor, which material has accumulated on the water floor within, under neath and possibly around the support construction, in which a dredging vehicle is lowered outside past and/or around the support construction, the vehicle being remote-controlled in order to move under the support construction from aside to the material and subsequently remove the material.

2. Method according to claim 1, in which the material is discharged by means of pump means and a line connected thereto also extending underneath and outside around the support construction to above the water sOrface, to receiving means or a further line situated above water surface. 15

3. Method according to claim 1 or 2, in which use is made of pump means arranged on the vehicle.

4. Method according to claim 1, 2 or 3, in which use is made of an 20 operation line for the vehicle which is guided outside of the support construction.

5. Method according to any one of the claims 1-4, in which the vehicle is lowered and raised with the help of a frame which is hung from the 25 platform or another relatively statically positioned body, which frame itself is provided with a stock-length of the operation line of the vehicle and with -20 a control unit, such as a hydraulic or pneumatic pressure source, for operating the several functions of the vehicle via the operation line.

6. Method according to any one of the preceding claims, in which the vehicle is lowered from the drilling platform.

7. Vehicle for removing sediment material from a water floor, comprising means for removing the material and means for conveying the material from the removal means to elsewhere, as well as means for propelling the vehicle over the water floor, in which the vehicle comprises a longitudinal axis and the propelling means comprise at least two worm rollers provided with opposing pitch that are placed on either side of the longitudinal axis of the vehicle.

8. Vehicle according to claim 7, comprising a chassis, in which the worm.

rollers extend on either side outside of the chassis.

9. Vehicle according to claim 8, in which the worm rollers extend at least almost entirely outside of the chassis.

10. Vehicle according to claim 7, 8 or 9, in which the chassis generally extends lower than the worm rollers.

11. Vehicle according to any one of the claims 7-10, provided with drives for the worm rollers, which can be adjusted independently from each other.

12. Vehicle according to any one of the claims 7-11, in which the worm rollers are bearing-mounted on suspensions attached to the vehicle, which suspensions can be adjusted as to height independent from each other.

13. Vehicle according to any one of the claims 7-12, in which the worm rollers are bearing-mounted on suspensions attached to the vehicle, which suspensions are moveable for lifting the lower side of the worm rollers above the lower side of the chassis, preferably by means of independently excitable driving means.

14. Vehicle according to any one of the claims 7-13, in which the worm rollers are provided with internal spaces, in which at least a part of the drive of the worm rollers is accommodated.

15. Vehicle according to any one of the claims 7-14, in which the removal 10 means comprise excavation rollers having excavation screws, which are substantially symmetrically positioned on either side of the longitudinal axis, having casing surfaces that are oriented to the fore and aside in an inclined manner, in which the translation direction of the screws preferably is to the outside. 15

16. Vehicle according to claim 15, in which the excavation rollers comprise two outer rollers, which are positioned in an inclined manner so that the outer edges of their casing surfaces extend sidewards beyond their bearing. 20

17. Vehicle according to claim 15 or 16, in which the excavation rollers comprise a middle roller, which has a double conical casing surface, on which excavation screws with respective opposing pitch are provided. 25

18. Vehicle according to claim 15, 16 or 17, in which the excavation rollers are provided with internal spaces, in which at least a part of the drive of the excavation rollers is accommodated.

19. Vehicle according to any one of the claims 7-18, in which the con30 veying means comprise one or more suction mouths and a pump placed behind the suction mouths and on or in the chassis, which conveying means discharge the excavated dredged material to a pressure line.

20. Vehicle according to claim 19, in which suction mouths are provided on either side of the longitudinal axis, which suction mouths are in connection to the pump via separate suction lines.

21. Vehicle according to claim 19 or 20, in which the pump is an axial pump placed in a parallel manner.between the worm rollers.

22. Vehicle according to claim 20 and 21, in which the suction lines of opposing sides debouch substantially transverse to the inlet of the axial 10 pump.

23. Vehicle according-to claim 19 or 20, in which the pump is a centrifugal pump provided with a vertical axis of rotation.

24. Vehicle according to claim 23, in which the inlet and the discharge of the pump extend in parallel planes, transverse to the axis of rotation.

25. Vehicle according to claim 23 or 24, in which the inlet is radial/tangential to the pump. 20

26. Vehicle according to claim 23, 24 or 25, in which the drive of the pump is placed within the volute.

27. Vehicle according to any one of the claims 23-26, in which the inlet is 25 situated vertically above or below the impeller, and debouches in an annular inlet chamber which merges into an annular distribution chamber to the impeller, in which preferably the inlet chamber and the distribution chamber are vertically in line with each other. 30

28. Vehicle according to claim 27, in which the distribution chamber is situated under the inlet chamber and preferably at the lower radial inner edge forms a curved guiding plane.

29. Vehicle according to claim 28, in which the impeller has blades exten ding radially inwardly into the distribution chamber.

30. Vehicle according to any one of the claims 23-29, in which the inlet and the discharge at least partly coincide, as seen in a vertical plane of projection.

31. Vehicle according to any one of the claims 23-30, in which the inlet chamber, the inlet and the suction lines have a rectangular cross-section.

32. Vehicle according to any one of the claims 23-31, in which two inlets are provided which preferably debouch in the inlet chamber in directions having a same tangential component.

33. Vehicle according to any one of the claims 23-32, in which the worm rollers extend until above the pump.

34. Centrifugal pump as described as part of the vehicle according to any one of the claims 23-33.

35. Vehicle according to claim 19 or 20, in which the pump is an axial plunger pump.

36. Vehicle according to any one of the claims 7-33 or 35, provided with a suspension bracket attached to the chassis, to which a suspension wire can be.connected, in which the suspension bracket can be moved between an upright lowering and raising position and a collapsed working position.

37. Vehicle according to claim 36, provided with means that are remote releasable for locking the suspension bracket in the working position.

38. Vehicle according to claim 37, in which the locking means are selflocking.

39. Vehicle according to any one of the claims 7-33 or 35-38, provided with at least one microphone.

40. Vehicle according to any one of the claims 7-33 or 35-39, provided with remote control means for operating the driving means and the excavation means and the conveyor means.

41. Device for lowering and raising a vehicle according to any one of the claims 3-33 or 35-40, comprising a frame provided with a suspension means and means for detachably holding the vehicle, in which the frame further comprises a reel for a combined control, operation and feeder line for the vehicle. 15

42. Device according to claim 41, in which at the location of the suspension means a connection is present for a feeder line and in which the frarne is provided with a hydraulic unit operable by means of the feeder line, which unit is in hydraulic communication to the drives of the vehicle via the hydraulic lines in the combined line.

43. Device according to claim 41 or 42, in which the assembly is provided with a guide for a dredged material discharge line coming from the vehicle.

44. Device according to claim 41, 42 or 43, in which the means for detachably holding the vehicle comprise a suspension wire for the vehicle.