KR20140077181A - A method of recovering a deposit from the sea bed - Google Patents

Abstract

The present invention relates to a water ship 20 from which a rope is released from the sea floor and first and second suction vehicles 27 and 30 connected to the watercraft by suction of sediments by the seabed and by respective flexible risers 26 ), A sediment slurry is transported from a suction vehicle to a water ship along a flexible riser. The method comprises moving the first and second suction vehicles back and forth across the seabed at a plurality of lanes so that the suction vehicles move substantially further than the watercraft, And turning each vehicle at the end of each lane in such a way that they are adjacent to each other. Only a suction vehicle is placed on the seabed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering sediments from a seabed,

The present invention relates to a method for recovering sediments from the sea bed.

A method of implementing this is disclosed in WO 2010/000289. This includes the watercraft and the suction vehicle that moves the seafloor. The suction vehicle is attached to the watercraft by a flexible riser and the slurry of sediment is transported from the suction vehicle to the watercraft along the flexible riser.

To be economically feasible, the production process should be as efficient as possible. This means that the highest possible production rate should be implemented with the least possible cost. Many factors, such as pumping capacity and speed of the suction vehicle, affect production rates, but operating costs are largely determined by energy costs.

The range of suction vehicles for the watercraft (ie, the horizontal distance that can be moved away from the watercraft) is determined by the length of the flexible risers. Longer flexing risers provide a greater range, but they also have drawbacks such as increasing the weight of the suction vehicle and also providing resistance and inertia to the suction vehicle during movement and steering.

The most direct way to retrieve sediments is to follow the water craft by simply moving the suction vehicle along a single waterway. Under such circumstances, however, the suction vehicle must travel at the same speed as the water craft. This is undesirable if safety is involved by attracting the riser system through water at relatively high speeds. This can easily damage the suction vehicle if the suction vehicle falls over.

"Data Gathering and Gap Analysis for Assessment of Marine Diamond Mining Activities on the BCLME Region" (Project BEHP / CEA / 03/02), Chapter 4: Mining Methods, pages 165-168; Published in March 2008; The Pisces Environmental Services (Pty) report on the subject Benguela Current Large Marine Ecosystem Program (available at www.bclme.org) is launching the use of submarine submarine crawlers. However, the vehicle is driven by a driver using a joystick to steer the vehicle. Then you will not follow a well-defined pattern.

Are included in the scope of the present invention.

According to the present invention, there is provided a method for recovering sediments from a seabed using a first and a second suction vehicle which are connected to a watercraft by suctioning sediments by moving the watercraft and undersea from which the rope is released, To move the first and second suction vehicles back and forth across the seabed from the plurality of lanes so that the suction vehicles move substantially farther away than the marine vessel and to allow the lanes to be adjacent to each other Wherein the sediment slurry is transported along a flexible riser from a suction vehicle to a water ship, wherein the slurry is transported along a flexible riser.

In the present invention, the suction vehicle no longer needs to match the speed of the watercraft. In addition, by mining the seabed in adjacent lanes, the seabed area can be covered without spacing, improving the operating efficiency.

The use of more than one suction vehicle is advantageous in that it provides continuity of operation. Spare suction vehicles can remain on the deck of the watercraft, and if one suction car fails, they can be replaced with spare cars while other vehicles or vehicles continue to operate. The recovered vehicle is then repaired while normal operation is in progress. Although described with two such vehicles, the present invention may also be applied to two or more vehicles.

1A shows a suction vehicle 1 having a mouse at one end thereof. Which travels along the first lane 2 and then turns at 180 [deg.] In the turning circle 3 and returns along the second lane 4. The suction vehicle 1 makes another passage, but this time moves along the third lane 5 to the second turning circle 6. [ As can be seen in FIG. 1A, there is a significant overlap 7 between the two turning circles 3, 6, and the time operation of the suction vehicle in the turning circles is not optimal. 1B shows a second vehicle 8 having a suction mouse at one end. Instead of rotating at 180 [deg.], The vehicle 8 is simply retracted to the adjacent lanes 11, 12 while still reaching the end of the first lane 9, 10 and still looking in the same direction. As is apparent from Fig. 1B, the suction vehicle misses the regions 13 and 14, and the suction operation becomes inefficient. As a result, in order to maximize the recovery efficiency, the turn number of the mining pattern must be minimized.

Thus, preferably, the method comprises moving a first suction vehicle traversing a first grid covered by a vehicle moving in a first lane longitudinally from a first end to a second end of the grid, Moves slightly along the adjacent lane before returning in the longitudinal direction of the first lane; Repeatedly moving in this manner between the two ends along the adjacent lane next to the previous lane each time until the first grid is finished; Simultaneously moving the second suction vehicle in the same manner in the adjacent second grid next to the first grid so that the lateral spacing between the first and second suction vehicles is maintained substantially constant throughout; And after the first and second grids are finished, moving the first and second suction vehicles to the third and fourth grids respectively adjacent to the first and second grids respectively in the longitudinal direction, and in the same manner as the first and second grids To cover the third and fourth grids.

This provides an efficient lightening pattern in that the first and second vehicles can be maintained at a substantially constant distance apart, thereby eliminating collision and entanglement possibilities.

Secondly, since the suction vehicles move longitudinally adjacent first and second grids adjacent to each other, the utilization of the riser length is optimized and the lanes become longer, so that the suction vehicles are more efficient than the light- Can be improved.

The watercraft can simply keep moving in the longitudinal direction to keep up with the suction vehicle as the suction vehicles move through the third and fourth grids and gradually move to another grid. Preferably, however, the method comprises moving the watercraft in a lateral direction while the suction vehicle is moving to the first and second grids, and moving the watercraft in the longitudinal direction as the suction vehicle moves to the third and fourth grid, Further comprising the steps of: As the watercraft moves sideways as the suction vehicles pass the grid, the width of the grid can be increased for any given riser length. This effectively enables the use of shorter risers. Since the watercraft moves in the longitudinal direction as the suction vehicles move to the third and fourth grids, the suction vehicles as a whole generally require that the watercraft be at the midpoint of the adjacent grid, generally the length of one grid, It is only necessary to move about half the speed of the suction vehicles so as to move the length of the two grids effectively while moving from one end of one grid to the other end of the second grid.

Upon reaching the ends of the first and second grids, the suction vehicle can then be moved transversely across the entire width of the grid to begin covering the next transverse next grid that covered the previous grid. Preferably, however, small lateral displacements occur in the first and second grids from the respective third and fourth grids in the opposite transverse direction. Inevitably, this means that the adjacent grid in each longitudinal direction is covered in the transverse direction to the previous grid. This provides a more efficient mining pattern and less lateral movement of the water craft.

For the second preferred pattern, the method preferably comprises moving the watercraft in the longitudinal direction and moving the first and second suction vehicles in the lateral direction. With this pattern, the watercraft can move along a much simpler path as the suction vehicle moves in the lateral direction. As such, this pattern can be used if more complex control of the marine vessel is considered undesirable.

In this pattern, the watercraft may further include moving each of the suction vehicles to one side of the watercraft. Alternatively, the method may further comprise moving each suction vehicle to both sides of the watercraft. The step of moving each suction vehicle to one side of the water ship has the advantage that the two suction vehicles each move to their own space while the step of moving each suction vehicle to both sides of the water ship is longer Provide lanes and thus reduce turn count.

For the third preferred pattern, the method preferably further comprises moving the first and second suction vehicles to an arcuate path substantially centered about the point at which the flexible riser is attached to the water vessel. This has the advantage that the "extent" of each riser remains substantially constant and also enables longer lanes than the transverse arrangement.

Again, the method may further include moving each suction vehicle to one side of the watercraft, or moving each suction vehicle to both sides of the watercraft.

Each suction vehicle can have a mouse at one end, in which case the vehicles are moved substantially between the ends of the grid looking in the same direction. Preferably, however, the method further comprises the step of actually turning each suction vehicle to 180 ° each time it reaches the end of the lane before returning to the opposite end. This method can be used in vehicles with a single suction that can be simpler, cheaper and lighter in design.

Are included in the scope of the present invention.

Examples of methods according to the present invention are described with reference to the accompanying drawings:
Figures 1a and 1b are schematic plan views illustrating problems encountered at the end of a waterway.
Figure 2 is a schematic cross-sectional view of the recovery system.
3A to 3D are schematic plan views showing the steps of the first lighting pattern.
4 is a schematic plan view of the second lighting pattern.
5 is a schematic plan view showing a change in the second lighting pattern.
6 is a schematic plan view showing a change in the third light pattern.

An overall system with a marine vessel 20 equipped with a pumping system 21 and a slurry treatment system 22 is shown in FIG. The riser system has a floating tank 24 and a rigid riser bundle 23 partially supported by a flexible conduit 25 leading to the water craft. While the first flexible riser 26 leads to the first suction vehicle 27 moving from the rigid riser bundle 23 across the underside 28 while the second flexible riser 29 is connected to the second suction vehicle 30). The watercraft has a dynamic positioning system that can stay in place and follow predetermined tracks.

In use, the suction vehicle sucks up the surface sediments and moves the seabed, and the sediments are then conveyed to the water vessel through the rigid riser bundle 23 and the flexible conduit 25 along the flexible risers 26, 29 Where the deposits are processed in the processing plant 22 and then shipped to the shore for another process. The wastewater is pumped by the pump system 21 beneath the disposal riser system adjacent to the seabed. This application is related to the characteristics of the mining pattern and will not be described in more detail here. For a detailed description of the lyser bundle 23, reference is made to the pending application (Attorney Docket No. 113711GB00), and the suction vehicles 27, 30 are described in the application (Attorney Docket No. 113709GB00). The overall system is also described generally in WO 2010/000289.

In Fig. 2, the transverse direction is shown by the arrow 31, while the longitudinal direction is the inward and outward directions of the ground. This is shown in arrow 32 of FIG.

The mining pattern will be described with reference to Fig. Referring first to FIG. 3D, the mining pattern is divided into a first grid 33, a second grid 34, a third grid 35, and a fourth grid 36. The first and second grids 33, 34 are adjacent to each other laterally and are simultaneously covered by the first suction vehicle 27 and the second suction vehicle 30. The third and fourth grids 35 and 36 are adjacent to each other and longitudinally to the first and second grids 33 and 34, respectively. The third and fourth grids 35 and 36 are simultaneously covered in succession to the first grid 33 and second grid 34 areas as will be described in more detail below.

It will be readily appreciated that the description below relates primarily to the formation of four grids, but that the process is intended to be repeated continuously until a certain area is completed. Generally, each lane has a gap of about 2 meters between adjacent lanes and is 10 to 15 meters wide. Each grid is several hundred meters in length and width. Prior to initiating the recovery operation, the seabed is the object of the survey that causes the optimal path to be presented to provide as many straight lines as possible. This will provide optimal coverage while avoiding large-scale undersea features. Sensors may be installed in two vehicles as described in the above-referenced co-pending application (Attorney Docket No. 113709GB00), so that small scale obstacles can be avoided by the suction vehicle. In these circumstances, the vehicle follows the path around the obstacles and then returns to the lanes described below as soon as possible.

When the water ship 20 reaches the end of a long run, it turns around a large light pattern determined from the survey and starts again on the new path using the light pattern described below. This path may be a course adjacent to the path just covered or in a completely different direction.

Thus, the following description deals with basic building blocks of mining patterns that are repeatedly and repeatedly repeated to cover possibly thousands of square kilometers of undersea.

The first suction vehicle 27 and the second suction vehicle 30 start collecting sediments from the first and second grids 33 and 34 by moving along the first longitudinal path 37 first. When the vehicles reach the end of the grid, they either turn completely to either side as shown in FIG. 1A, or if the suction vehicle has a suction mouse at either end, reverse the direction as shown in FIG. Move to lane. At each end of the grid to operate in an adjacent lane, this rotation and backward process is repeated until the first and second grids are covered (until just after the position shown in Fig. 3B).

There is no need to have two cars at exactly the same location along their lanes at any one time. One vehicle may be moved in one direction, for example, while the other vehicle is moved in the opposite direction. It is important to note that since the lanes are essentially in the same direction, the vehicle generally moves on parallel lines, so that as the vehicles move, the vehicles generally do not approach each other.

Initially, the first vehicle 27 is at a maximum (i.e., horizontally as far from the watercraft as the riser 26 allows), and the second vehicle 30 is at a minimum range. As the recovery process proceeds, the suction vehicle 27 becomes closer to the watercraft, while the second suction vehicle becomes further away until it reaches the position shown in FIG. 2, and the second suction vehicle 30 Moves towards maximum range. At this time, the marine vessel 20 moves step by step so that the suction vehicles finish the first and second grids 33 and 34 (as shown by the line 38 in FIG. 3D). The suction vehicle reaches the first end of the last lane of the first and second grids (shown in Figure 3B). The watercraft 20 is turned to move in the longitudinal direction, and the path thereof is indicated by a path 39 in Fig. 3D. The turn will not suddenly change, as shown in Figure 3D, but in fact it is a gentle curve. Due to the flexibility of the riser, any incense deviations from the ideal path shown in Figure 3d are compensated. As the water vessel 20 moves along this path, the two suction vehicles 27 and 30 continue to run along the longitudinal path 40 after completing the species lanes of the first and second grids 33 and 34, 3 and the fourth grid 35,36. In this way, the watercraft 20 can move at a speed about half the speed of the suction vehicle 27, 30.

The suction vehicles 27,30 are then moved in the opposite direction to the lateral movement direction of the first and second grids 33,34 except that the transverse direction is laterally opposite to the lateral movement direction of the first and second grids 33,34, And is advanced to cover the third and fourth grids 35, 36 in the same manner as described above for the first and second grids 33, 34. At this time, the water vessel 20 is also moved transversely in the same manner as described above with the lateral movement indicated by the line 41 in Fig.

As shown in FIG. 3D, in the third and fourth grids 35 and 36, the suction vehicles 27 and 30 are moved forward in the longitudinal direction and, as described with reference to FIGS. 3A and 3B, 2 Begin covering the successive grids in exactly the same way that they cover the grid.

A second example of a mining pattern is shown in Fig. In this case, the water vessel 20 moves in the longitudinal direction. The first suction vehicle 27 moves back and forth in the lateral direction at one side of the water marine vessel 20 while the second suction vehicle 30 moves back and forth in the lateral direction at the opposite side of the water marine vessel 20. The suction vehicles 27 and 30 turn at the end of the lane as shown in Fig. 1A. The marine vessel 20 moves essentially linearly while the two suction vehicles move to the maximum extent allowed by their risers 26 and 29. [

Fig. 4 shows the operation of the suction vehicle so that the suction vehicles approach each other at positions close to the watercraft. Alternatively, they can operate at substantially regular intervals, so that when one vehicle approaches the marine vessel, the other vehicle is at the farthest position from the marine vessel. This means that there is no entanglement problem near the watercraft and that the patterns covered by the two suction vehicles can become more similar.

A modification of this pattern is shown in Fig. Again, the watercraft 20 moves in the longitudinal direction, while the suction vehicles 27, 30 move laterally. In this case, all of the suction vehicles move much longer lanes that extend to both sides of the watercraft. As seen in FIG. 5, increasing the distance of the lanes reduces the inefficiency associated with the turn count. On the other hand, more careful control of the position of the suction vehicle is required to prevent collision and entanglement of the flexible risers 26,29 with the umbilicals 50,51.

A third pattern is shown in Fig. This is because the suction vehicle 27,30 is shown in the top view of the pattern of Figure 4 except that the risers 26,29 follow an arcuate path generally centered around the point 52 attached to the water vessel 20, similar. In fact, this is in fact the case where the risers 26, 29 (as shown in FIG. 2) are located at the lower end of the rigid riser bundle 23 because the rigid riser bundle 23 is just below the point 52 or slightly below it due to the drag on the rigid riser bundle 23 And becomes a point attached to the bottom of the rigid riser bundle 23.

When the suction vehicles 27 and 30 reach a certain point on the far end of the lane moving in the same longitudinal direction as the water ship 20, the water ship 20 moves in the small lengthwise direction (approximately 10 meters). The suction vehicles 27 and 30 are then returned to the destination. The vehicles are moved at right angles to the direction of movement of the watercraft 20 at the opposite end of their lanes so that the watercraft 20 can be moved while the suction vehicles are turning to move to the next path, Lt; RTI ID = 0.0 > slightly < / RTI > As shown in FIG. 6, it is shown that when the vehicle is farthest away, it is retracted at one end of the lane and turns at one end of the path when the vehicle is nearest to each other. Equally, ships can perform this pattern by turning at both ends or backing at both ends. The arcuate lanes shown in Fig. 6 can also be achieved in a manner similar to Fig. 5, so that each suction vehicle 27, 30 effectively follows the semicircular path on both sides of the water vessel 20. Again, this is a tradeoff between reduced turn count and control reinforcement needed to prevent collisions.

Claims (12)

A method of recovering sediments from a seabed using a first and a second suction vehicle which are connected to a watercraft by suctioning sediments by moving the watercraft from the sea floor and the seabed and releasing the sediments by respective flexible risers,
To move the first and second suction vehicles back and forth across the seabed from the plurality of lanes so that the suction vehicles move substantially farther away than the marine vessel and to allow the lanes to be adjacent to each other And turning each vehicle at the end of each lane,
A method for recovering sediments from a seabed where a sediment slurry is transported along a flexible riser from a suction vehicle to a waterborne vessel and only a suction vehicle is placed on the seabed. The method according to claim 1,
Moving a first suction vehicle across a first grid covered by a vehicle moving in a first lane in a longitudinal direction from a first end to a second end of the grid and moving the first suction vehicle across the lane adjacent the first lane, Moves slightly to the side before returning in the longitudinal direction; Repeatedly moving in this manner between the two ends along the adjacent lane next to the previous lane each time until the first grid is finished;
Simultaneously moving the second suction vehicle in the same manner in the adjacent second grid next to the first grid so that the lateral spacing between the first and second suction vehicles is maintained substantially constant throughout; And
After finishing the first and second grids, the first and second suction vehicles are moved to the third and fourth grids respectively adjacent to the first and second grids respectively in the longitudinal direction, and in the same manner as the first and second grids And covering the first, second, third, and fourth grids. 3. The method of claim 2,
Moving the watercraft in a lateral direction while the suction vehicle is moving to the first and second grids and moving the watercraft in the longitudinal direction as the suction vehicle moves to the third and fourth grids, Method of collecting sediments. 4. The method according to any one of claims 1 to 3,
Wherein the small transverse movements in the first and second grids occur in opposite transverse directions from respective third and fourth grids. The method according to claim 1,
Further comprising the step of moving the watercraft in the longitudinal direction and moving the first and second suction vehicles in the lateral direction. 6. The method of claim 5,
Further comprising the step of moving each suction vehicle to one side of the watercraft. 6. The method of claim 5,
Further comprising the step of moving each suction vehicle to both sides of the watercraft. The method according to claim 1,
Further comprising the step of moving the first and second suction vehicles in an arcuate path substantially centered about the point where each flexible riser is attached to the water vessel. 6. The method according to claim 1 or 5,
Further comprising the step of moving each suction vehicle to one side of the watercraft. 9. The method of claim 8,
Further comprising the step of moving each suction vehicle to both sides of the watercraft. 11. The method according to any one of claims 1 to 10,
Further comprising the step of turning each suction vehicle to 180 < RTI ID = 0.0 > t < / RTI > when the end of the lane is reached. 12. The method according to any one of claims 1 to 11,
Each suction vehicle having a mouse at each end, the method further comprising the step of reversing each such ship when it reaches the end of the lane.

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