A CARRIER FOR SEISMIC NODES

Abstract

The invention relates to a carrier (5) for transporting seismic nodes (9) to and from a sea floor (4), comprising an interior (8) for storing the nodes and a node transfer position (10) for transferring nodes (9) to and from the carrier (5); a support (14) for supporting the nodes (9) in a row (33) between the interior (8) of the carrier (5) and the node transfer position (10); and an endless driven belt or chain (11) with pushers (19) for pushing the row (33) of nodes (9). The invention also relates to a seismic node (9) adapted to use in the carrier (5). Further the invention relates to a method for loading seismic nodes (9) into the carrier (5), and a method for unloading seismic nodes (9) from the carrier (5).

Claims

1-18. (canceled)

19. A carrier for transporting seismic nodes to and from a sea floor, comprising: an interior of the carrier for storing the nodes during the transport; means for moving the nodes into and out of the interior of the carrier; a node transfer position for transferring nodes to and from the carrier; a support for supporting the nodes in a row between the interior of the carrier and the node transfer position; and an endless driven belt or chain with pushers for pushing the row of nodes, a drive wheel or sprocket for driving the belt or chain, and a motor for driving the drive wheel or sprocket.

20. The carrier of claim 19, wherein the node transfer position is on a ramp outside the support.

21. The carrier of claim 19, wherein the node transfer position is on the support.

22. The carrier of claim 19, further comprising a guide for the row of nodes.

23. The carrier of claim 19, wherein the belt or chain is positioned below the support, and the pushers extend above the support.

24. The carrier of claim 19, wherein the pushers are spaced along the belt or chain with a distance corresponding to a length of the node plus a clearance.

25. The carrier of claim 19, wherein the pushers are adapted to push gripping portions of the nodes.

26. The carrier of claim 19, wherein the guide comprises a retaining portion to prevent the nodes from moving perpendicularly off the support.

27. The carrier of claim 19, wherein the support is a longitudinal support and one belt or chain is situated on each side of and below the support, with the pushers extending above the support, the two belts or chains are driven by respective drive wheels or sprockets with a common drive shaft driven by the motor, the pushers are attached to both belts or chains.

28. The carrier of claim 19, further comprising two longitudinal supports for each row of nodes, and the belt or chain is situated between and below the supports, with the pushers extending above the supports.

29. The carrier of claim 19, further comprising a number of rows of nodes.

30. The carrier of claim 19, further comprising exchangeable magazines for the nodes, each magazine comprises at least some components for moving the row of nodes.

31. The carrier of claim 19, being dockable to an ROV.

32. The carrier of claim 19, stackable and dockable to another carrier.

33. A seismic node for acquiring seismic data at a sea floor; comprising sensors for seismic signals, a processor for the seismic signals, a recorder, a memory for storing data representing the seismic signals, and a power source, wherein the seismic node is adapted to use in the carrier of claim 19.

34. A method for loading seismic nodes into the carrier of 20 comprising: placing a node in the node transfer position on the ramp; pushing the node onto the support; starting the belt or chain to make a pusher push the node towards the interior of the carrier; stopping the belt or chain when the node has moved a length corresponding to a length of the node plus a clearance; and repeating the above steps, causing the nodes to form a row between the interior of the carrier and the node transfer position.

35. A method for loading seismic nodes into the carrier of claim 21, comprising: placing a node in the node transfer position on the support; starting the belt or chain to make a pusher push the node towards the interior of the carrier; stopping the belt or chain when the node has moved a length corresponding to a length of the node plus a clearance; and repeating the above steps, causing the nodes to form a row between the interior of the carrier and the node transfer position.

36. A method for unloading seismic nodes from the carrier of claim 19, wherein the nodes are stored on the support in a row between the interior of the carrier and the node transfer position, the method comprises: starting the belt or chain to make the pushers push the row of nodes towards the node transfer position; stopping the belt or chain when a node has arrived at the node transfer position; removing the node from the node transfer position; and repeating the above steps.

Description

[0019] Some embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0020] FIG. 1 illustrates a vessel with a crane lowering an ROV with a carrier for seismic nodes to a sea floor;

[0021] FIG. 2 illustrates the ROV with the carrier for seismic nodes at the sea floor;

[0022] FIG. 3 is a closer view of the front of the ROV and carrier of FIG. 2 seen from the front;

[0023] FIG. 4 illustrates a magazine for seismic nodes; and

[0024] FIG. 5 illustrates another magazine for seismic nodes.

[0025] FIG. 1 illustrates a vessel 1 floating at a sea surface 3 of a sea 2. An ROV 21 has been lowered into the sea 2 by means of a cable 7 from a crane 6. A carrier 5 filled with seismic nodes is located underneath the ROV. The nodes were loaded into the carrier 5 at the vessel, and the carrier was then docked to the ROV before the ROV was lowered into the sea. After being lowered into the sea 2, the ROV 21 is moved in downwards vertical direction 32 to a sea floor 4.

[0026] FIG. 2 illustrates the ROV 21 after the movement to the sea floor 4. The ROV is of a known kind, including a propulsion and positioning system, a manipulator arm 22, a video camera, and lights. The ROV 21 may also include sensors, e.g. pressure sensors, positioning sensors and proximity sensors, and other equipment required to carry out its tasks. The ROV 21 is controlled by a control system which may be in the ROV or on the vessel, or partly in the ROV and partly on the vessel. An operator on the vessel controls the control system. The cable 7 transfers electric power and control signals from the vessel to the ROV, and video signals and sensor signals from the ROV to the vessel.

[0027] The carrier 5 is docked to the ROV by a not illustrated docking system, which includes probes and corresponding receptacles for mechanical attachment of the carrier, and plugs and sockets for transfer of electric power and electric control signals. There may also be hydraulic connectors for transfer of hydraulic power.

[0028] FIG. 3 is a closer view of the ROV and carrier of FIG. 2 seen from the front. The manipulator arm 22 is not illustrated in FIG. 3. Five nodes 9 are located next to each other at the front of the ROV 21 and the carrier 5. Each of these nodes 9 is an outer node or front node in a row of nodes extending between the front of the carrier 5 and an interior 8 of the carrier 5, see FIG. 2, for storing the nodes. A ramp 34 in front of the nodes 9 forms node transfer positions 10, one for each row of nodes 9, for transferring the nodes 9 to and from the carrier 5. The rows of nodes 9 are movable in their longitudinal direction, which will be discussed with reference to FIG. 4.

[0029] With further reference to FIG. 2, the manipulator arm 22 is of a known kind, comprising links and joints and a gripping tool 23 which includes a suction cup with a controllable suction mechanism for gripping and releasing the nodes 9. Alternatively, the gripping tool may include gripping fingers or any other means for gripping the nodes. For the purpose of being gripped, the nodes may have handles or other gripping portions. The gripping tool 23 can reach the nodes 9 in all the node transfer positions 10.

[0030] The manipulator arm 22 can transfer nodes from the carrier 5 to the sea floor 4. When doing that, the gripping tool 23 first grips a node 9 in the node transfer position 10, as illustrated with node 9′ for the rightmost node transfer position 10 in FIG. 2. The manipulator arm 22 then lifts the node from the node transfer position 10 and places it on the sea floor 4 and releases it, as illustrated with node 9″ in FIG. 2. As nodes 9 are transferred from the node transfer positions 10, new nodes 9 can be moved from the row of nodes to the node transfer positions 10, which will be discussed in more detail with reference to FIG. 4.

[0031] The manipulator arm 22 can also transfer nodes from the sea floor 4 to the carrier 5. This is the reverse operation, i.e. the gripping tool 23 first grips the node 9″ on the sea floor 4, then lifts it from the sea floor 4 to the node transfer position 10 and releases it. The node can then be moved from the node transfer position 10 to the row of nodes, which will be discussed in more detail with reference to FIG. 4.

[0032] Each of the five rows of nodes are located in a magazine. Thus, the carrier 5 has five magazines with nodes. The magazines are placed in a frame 30 of the carrier 5. The ramp 34 forming the node transfer positions 10 is part of the carrier, however, the ramp may be part of the magazine, i.e. each magazine may have its own ramp.

[0033] FIG. 4 illustrates an embodiment of an exchangeable magazine 25 for the nodes 9. A portion of the structural parts is cut away for illustrative purposes. The magazine 25 is oriented in the position in which it is used in FIG. 3, and references to “upper”, “lower”, “above”, “below” and similar terms related to relative location, should be understood in this way, ref. downwards vertical direction 32.

[0034] The magazine comprises two longitudinal side plates 15 held together and stiffened by structural members 24. Two endless chains 11 extend substantially over the length of the magazine 25, and have lower portions near a bottom of the magazine 25, upper portions approximately in the middle of the magazine 25, front portions arranged on respective free running sprockets 12 near a magazine front end 31, and rear portions arranged on respective not illustrated drive sprockets near an opposite, not illustrated rear end of the magazine 25. The free running sprockets 12 are rotatably mounted on an axle 13 extending between and attached to the side plates 15 of the magazine 25. The drive sprockets are mounted on a not illustrated common drive shaft, which in turn is driven by a not illustrated electric or hydraulic motor.

[0035] A support 14 made of a plate or rail connected to the structural members 24 extends in the longitudinal direction of the magazine 25 between the chains 11. The upper portions of the chains are located below the support 14. Pushers 19 are attached to the chains 11 at intervals, and extend above the support 14.

[0036] The nodes 9 are arranged in a row 33 and slidably carried on the support 14, with a pusher 19 between each node 9. The intervals between the pushers 19 correspond to the length of the nodes 9 plus a clearance. “The length of the nodes” means the outer dimension of each node in a longitudinal direction 16, 35 of the magazine 25. The clearance is as a minimum the distance required for a practical placement of the nodes 9 on the support 14, and may be between 2 and 20 mm, typically 8 mm. In other words, the intervals between the pushers 19 are adapted to the nodes 9 and the way they are placed on the support 14.

[0037] The row 33 of nodes extends in the longitudinal direction 16, 35 of the magazine 25, from its front end 31 to a location away from the front end in the interior 8 of the carrier 5, see FIG. 2. Since the pushers 19 are located between the nodes 9, the pushers push the row 33 of nodes along the support 14 when the chains 11 are moved. When the motor driving the chain 11 is run in a first direction, the upper portion of the chain 11 moves inwards in direction 35, and the pushers 19 push the row 33 of nodes 9 inwards along the support 14 towards the magazine rear end. When the motor driving the chain 11 is run in a second direction opposite the first direction, the upper portion of the chain 11 moves outwards in direction 16, and the pushers 19 push the row 33 of nodes 9 outwards along the support 14 towards the magazine front end 31.

[0038] Upper portions of the side plates 15 form guide plates 27 that keep the nodes 9 laterally in place in the row 33 and guide the nodes 9 during their movement in the magazine 25. The guide plates 27 have top portions 29 bent in right angles towards the row 33 of nodes 9. When the carrier 5 is on the sea floor 4, and during lowering and raising of the carrier 5, the nodes 9 will be kept in place on the support 14 by the gravitation acting in vertical direction 32, see FIGS. 1 and 2. However, if the carrier 5 is undesirably tilted, the guide plates' top portions 29 prevent the nodes from moving perpendicularly off the support 14, away from the support 14. Openings 26 in the side plates 15 and openings 28 in the guide plates 27 reduce weight and allow flow-through of water.

[0039] FIG. 5 illustrates an alternative embodiment of both the magazine 25 and the nodes 9. This magazine has similar longitudinal side plates 15, structural members 24, sprockets 12, axle 13 and not illustrated drive sprockets and motor as the magazine in FIG. 4. Like FIG. 4, a row 33 of nodes 9 is slidably carried on a support 14 arranged between the chains 11, i.e. one chain 11 is arranged on each side of the support 14. Further, upper portions of the chains 11 are located below the support 14, and pushers 19 attached to the chains 11 extend above the support 14. The pushers 19 are, however, different.

[0040] The pushers 19 of FIG. 5 are smaller and located with much smaller intervals than in FIG. 4. The nodes are also different. The nodes generally have a square shape, which is insignificant to the invention. Further, the undersides of the nodes 9 have gripping portions formed by alternating cogs 17 and notches 18. When the node 9 is placed on the support 14, the pushers 19 enter the notches 18 and abut the cogs 17, and when the chains 11 move, the pushers 19 thereby push the nodes 9.

[0041] Further, unlike the magazine 25 of FIG. 4, in the magazine of FIG. 5 the node transfer position 10 is on the support 14 in the magazine front end 31. This means that the magazine of FIG. 5 can be used in a carrier 5 without the ramp 34. There are no guide plates 27 with top portions 29 at the location for the node transfer position 10, which enables a manipulator arm 22 to lift nodes 9 to and from the node transfer position 10 on the support 14. Both the embodiment with the node transfer position 10 on the support 14 and the embodiment with the pushers 19 engaging gripping portions in the undersides of the nodes are shown in FIG. 5. This does, however, not mean that these two embodiments are linked to each other.

[0042] When loading seismic nodes 9 into the carrier 5 with the magazine of FIG. 4, the magazine is located adjacent the node transfer position 10 on the ramp 34. The manipulator arm 22 places a node 9 in the node transfer position 10 on the ramp 34, as discussed above. Assuming there initially are no nodes in the magazine 25, there will be empty space on the support 14 at the magazine front end 31. Further, it is assumed that the pushers 19 have a position and movement where they do not block the access to the support 14 from the node transfer position 10. This can be achieved by the chains 11 being stopped and one pusher 19 being located at the sprockets 12 between and below the node transfer position 10 and the support 14, and the next pusher being located a distance from the magazine front end 31. The manipulator arm 22 then pushes the node 9 onto the support 14 at the magazine front end 31. For this purpose, the manipulator arm 22 may use the gripping tool 23 or another suitable tool mounted on the manipulator arm. Alternatively, the manipulator arm 22 may initially place the node 9 partly on the support 14, to ease the transfer of the node 9 from the node transfer position 10 to the support 14. The chains 11 are started, and a pusher 19 contacts the node 9 and pushes it towards the interior 8 of the carrier 5. The chains 11 may be started before the node 9 has been completely pushed onto the support 14, to provide a smooth transfer of the node 9 from the node transfer position 10 to the support 14. When the node 9 has moved a length corresponding to a length of the node 9 plus the clearance (the clearance is discussed above) the chains 11 are stopped. Then there will be an empty space on the support 14 at the magazine front end 31, and the magazine is ready for receiving another node 9. The manipulator arm 22 places another node 9 in the node transfer position 10, and the above steps are repeated as long as desired. Consecutive transferred nodes 9 thereby form a row 33 starting in the node transfer position 10 and extending towards the interior 8 of the carrier 5.

[0043] When loading seismic nodes 9 into the carrier 5 with the magazine of FIG. 5, since the node transfer position 10 is on the support 14, the ramp 34 in the carrier 5 may be dispensed with. The manipulator arm 22 places a node 9 directly in the node transfer position 10 on the support 14. The magazine of FIG. 5 also shows the alternative with the pushers 19 engaging gripping portions in the undersides of the nodes 9, and therefore, during placing of the node 9 on the support 14, it must be ensured that the pushers 19 enter the notches 18. For this purpose, the chain 11 with the pushers 19 may be moved simultaneously. In other respects, loading seismic nodes 9 into the carrier 5 with the magazine of FIG. 5 is the same as loading with the magazine of FIG. 4.

[0044] In another not illustrated embodiment, the alternative with the pushers 19 engaging gripping portions in the undersides of the nodes 9 may be used together with the node transfer position 10 being located on the ramp 34. In this case it may be advantageous to move the chains 11 when moving the nodes from the node transfer position to the support 14, to ensure that the pushers 19 enter the notches 18.

[0045] Unloading of seismic nodes from the carrier 5 is the same for both the magazine of FIG. 4 and FIG. 5. It is assumed that the nodes 9 initially are stored on the support 14 in a row 33 between the interior 8 of the carrier 5 and the magazine front end 31, with no node in the node transfer position 10. The chain 11 is started and run in direction 16 to make the pushers 19 push the row 33 of nodes 9 towards the node transfer position 10. The chain 11 is stopped when a node 9 has arrived at the node transfer position 10. For the magazine of FIG. 4, this means that the front node 9, i.e. the node in the magazine front end 31, is pushed off the support 14, onto the ramp 34. For the magazine of FIG. 5, this means that the front node 9 stays on the support 14. The node is then removed from the node transfer position 10 by means of the manipulator arm 22. Then the chain 11 is started to bring a new node 9 to the node transfer position 10, and the above process is repeated as long as desired.

[0046] The start/stop of the motor for the drive sprockets is controlled by the control system or the operator. For this purpose, a sensor which detects presence of a node 9 in the node transfer position 10 is in communication with the control system, and when unloading nodes from the carrier 5, the motor for the drive sprockets may thereby be started automatically when the node transfer position 10 is empty. Alternatively, the operator may use a camera on the ROV to visually detect the presence of a node in the node transfer position 10.

[0047] Desired weight distribution in the carrier 5 can be achieved by a suitable sequence of transfer of the nodes from the various node transfer positions 10 and suitable movement of the nodes 9 inside the carrier 5. Further, some nodes may be kept in the rear portion of the magazine 25, i.e. the interior 8 of the carrier.

[0048] Before deploying the nodes, when the carrier is on the vessel or on shore, the nodes will be loaded into the magazines, and the magazines will be placed in the carrier. Alternatively, the nodes may be loaded into the magazines while the magazines are in the carrier, by means of the pushers as described above. After retrieving the nodes, i.e.

[0049] after the nodes have been picked up from the sea floor and placed in the magazines and the ROV with the carrier has been moved to the sea surface and lifted aboard the vessel, or possibly on shore, the magazines will be removed from the carrier, and the nodes will be unloaded from the magazines. Alternatively, the nodes may be unloaded from the magazines while the magazines are in the carrier, by means of the pushers as described above.

[0050] The carrier 5 and the structural parts of the magazines 25 may be made from steel, which is favourable due to strength and material cost.