An Underwater Buoy Installation System and Kit, a Method for Assembling It, Use Thereof, and a Method for Installing a Buoy

Abstract

A system with an underwater vehicle for installation and de-installation of buoys (9) under sea level (6). The vehicle (10) comprises a buoyancy adjustment system (19) for continuously adjusting the buoyancy of the vehicle (10) during underwater operation. A gripper (24) is connected to the vehicle frame (10) by an orientation adjustment mechanism (29, 30, 31) for adjusting the gripper (24) orientation when installing a buoy (9) onto a flexible underwater line or for deinstalling the buoy (9) therefrom. The vehicle (10) further comprises a controller for manoeuvring and operation.

Claims

1. A method of installing a buoy (9) onto an underwater construction (1), the method comprising, providing an underwater vehicle (10) configured for underwater operation and transport of buoys (9) under sea level (6); wherein the vehicle (10) comprises a propulsion and steering system for manoeuvring the vehicle (10) and a buoyancy adjustment system (19) for adjusting the buoyancy of the vehicle (10) during underwater operation; wherein the vehicle (10) comprises a vehicle frame (10) and a gripper system (18) extending from the frame (10); the gripper system (18) comprising a gripper (24) for gripping and releasing a buoy (9), the gripper system (18) further comprising an adjustment mechanism (29, 30, 31) for adjusting the gripper (24) orientation relatively to the vehicle frame (10) for installing a buoy (9) in controlled orientation onto a construction or for de-installing the buoy (9) therefrom, wherein the method further comprises: providing a buoy (9) in the gripper (24); navigating the vehicle (10) with the buoy (9) to the underwater construction (1), determining a location on the underwater construction (1) for installing the buoy (9); determining a specific necessary orientation and position of the buoy (9) for installing; adjusting the gripper (24) relatively to the vehicle frame (10) in order for the actual orientation of the buoy (9) in the gripper (24) to match the specific necessary orientation of the buoy; navigating the vehicle (10) with the buoy (9) in the gripper (24) to match the specific necessary position of the buoy (9); and installing the buoy (9) at the construction in the specific necessary orientation and position.

2. A method according to claim 1, where in the underwater construction (1) is located at least partly under a ship (5) or under a stationary surface installation, and wherein the method comprises navigating the vehicle (10) under the ship (5) or the stationary surface installation to the construction (1) and installing a buoy (9) onto the construction (1) at a location under the ship (5) or stationary surface installation.

3. A method according to claim 2, wherein the underwater construction is a flexible underwater line (1, 2) extending from a seabed (4) to the ship (5) or other surface installation.

4. A method according to claim 1, wherein the method comprises providing the vehicle (10) with a buoyancy adjustment system (19) on the gripper system (18) remotely from the frame (10); the method further comprising, after installation of the buoy (9) on the construction (1) and before releasing of the buoy (9) from the gripper (24), increasing the buoyance of the buoyancy adjustment system (18) to a level corresponding to the buoyancy of the buoy (9) and then releasing the buoy (9) from the gripper (24).

5. A method according to claim 1, wherein the method comprises providing the gripper (24) with two hinged jaws (25a, 25b) for gripping the buoy (9), wherein each jaw (25a, 25b) comprises a holding mechanism (40) for engaging with one half (9a, 9b) of a buoy (9) and for pulling two halves (9a, 9b) of the buoy (9) apart by opening the jaws (25a, 25b); the method further comprising activating the holding mechanism (40) and engaging each one of the two jaws (25a, 25b) with one of the two halves (9a, 9b) of the buoy (9) and pulling the two halves (9a, 9b) of the buoy (9) apart by opening the jaws (25a, 25b), navigating the vehicle (10) to the specific necessary installation position of the buoy (9) and by closing the two jaws (25a, 25b) bringing the two halves (9a, 9b) of the buoy (9) together around a part of the construction for thereby fixing the buoy (9) to the construction; disengaging the holding mechanism (40) from the buoy (9) and opening the gripper (24) without pulling the two halves (9a, 9b) of the buoy (9) apart and thereby releasing the buoy (9) from the gripper (24).

6. An underwater buoy installation and de-installation system (10), the system comprising an underwater vehicle (10) configured for underwater operation and transport of buoys (9) under sea level (6); wherein the vehicle (10) comprises a propulsion and steering system for manoeuvring the vehicle and a buoyancy adjustment system (19) for adjusting the buoyancy of the vehicle (10) during underwater operation; wherein the vehicle (10) comprises a vehicle frame (10) and a gripper system (18) extending from the frame (10); the gripper system (18) comprising a gripper (24) for gripping and releasing a buoy (9), the gripper system (18) further comprising an adjustment mechanism (29, 30, 31) for adjusting the gripper (24) orientation relatively to the vehicle frame (10) for installing a buoy (9) in controlled orientation and position onto an underwater construction or for de-installing the buoy (9) therefrom.

7. A system according to claim 6, further comprising a surface control vessel (13) and an umbilical (14) that is connecting the control vessel (13) with the vehicle (10); wherein a control centre (15) is provided on the control vessel (13) for remotely controlling manoeuvring and operation of the vehicle (10); wherein the vehicle (10) further comprises a controller system (17) functionally connected to the propulsion and steering system and to the adjustment mechanism (29, 30, 31), the controller system (17) being configured for receiving operational commands from the control centre (15) for propulsion and steering and for adjusting the orientation of the gripper (24) and for gripping and releasing a buoy (9); wherein the umbilical (14) comprises a signal transmission line from the control centre (15) to the controller (17) for transmission of the operational commands.

8. A system according to claim 6, wherein the buoyancy adjustment system (19) comprises a plurality of water tanks (29), wherein each water tank (20) is divided into a first compartment (20a) for water and a second compartment (20b) for gas, the two compartments (20a, 20b) being mutually separated by a flexible membrane (21) and configured for filling of pressurised gas into the second compartment (20b) to exert pressure on the membrane and thereby pressing water out of the first compartment (24a) in order to increase buoyancy of the vehicle (10).

9. A system according to claim 8, wherein the flexible membrane (21) is an inflatable bladder inside the tank (20).

10. A system according to claim 8, wherein the plurality of tanks (20) are attached to the gripper (24) remotely from the frame (10).

11. A system according to claim 8, wherein the system comprises a gas system (32, 33) for providing pressurised gas to the tanks (20) and a pressure meter (44) with a pressure display for displaying the actual gas pressure in the gas system (32, 33); the system further comprising a surface control vessel (13) and an umbilical (14) that is connecting the control vessel (13) with the vehicle (10); wherein a control centre (15) is provided on the control vessel (13) for remotely controlling manoeuvring and operation of the vehicle (10); wherein the vehicle (10) further comprises a controller system (17) functionally connected to the propulsion and steering system and to the adjustment mechanism (29, 30, 31), the controller system (17) being configured for receiving operational commands from the control centre (15) for propulsion and steering and for adjusting the orientation of the gripper (24) and for gripping and releasing a buoy (9); wherein the umbilical (14) comprises a signal transmission line from the control centre (15) to the controller (17) for transmission of the operational commands; wherein a camera system is configured for imaging the pressure display and for transmission of the corresponding digital image data via the umbilical to the control centre (15) on the control vessel (13) for display thereof.

12. A system according to claim 6, wherein the gripper (24) comprises two hinged jaws (25a, 25b) for gripping a buoy (9), wherein each jaw (25a, 25b) comprises a holding mechanism for engaging with one half (9a, 9b) of a buoy (9) and for pulling two halves (9a, 9b) of the buoy (9) apart by opening the jaws (25a, 25b) for thereby releasing the buoy (9) from the flexible underwater line or for attaching the buoy.

13. A system according to claim 12, wherein the holding mechanism comprises a movable pin (40) that is movable towards and away from the buoy (9) when the buoy (9) is abutting the jaws (25a, 25b) for engaging with a cooperating receiver element in the buoy (9).

14. A system according to claim 6, wherein the orientation adjustment mechanism (29, 30, 31) comprises a coupling (37) between the frame (10) and the gripper (24), the coupling (37) comprising a tilt hinge (30) and a tilt actuator for tilting the gripper (24) relatively to the frame (10) about the tilt hinge (30), the coupling (37) further comprising a rotation axle (31) normal to a rotational direction of the hinge (30) for rotation of the gripper (24) relatively to the frame (10).

15. A method for assembling a system comprising an underwater vehicle (10) configured for underwater operation and transport of buoys (9) under sea level (6); wherein the vehicle (10) comprises a propulsion and steering system for manoeuvring the vehicle and a buoyancy adjustment system (19) for adjusting the buoyancy of the vehicle (10) during underwater operation; wherein the vehicle (10) comprises a vehicle frame (10) and a gripper system (18) extending from the frame (10); the gripper system (18) comprising a gripper (24) for gripping and releasing a buoy (9), the gripper system (18) further comprising an adjustment mechanism (29, 30, 31) for adjusting the gripper (24) orientation relatively to the vehicle frame (10) for installing a buoy (9) in controlled orientation and position onto an underwater construction or for de-installing the buoy (9) therefrom; the method comprising, providing a gripper-free underwater vehicle with a propulsion and steering system for manoeuvring the vehicle but without a gripper system (18) and submerging the gripper-free vehicle (10) under sea level (6); providing a gripper system (18) separately from the gripper-free vehicle and submerging the gripper system (18) under sea level adjacent to the gripper-free vehicle; adjusting the buoyancy of the gripper system (18) to largely neutral buoyancy of the gripper system (18); mounting the gripper system (18) onto the gripper-free vehicle while submerged in water.

16. An assembly kit for an underwater buoy installation and de-installation system, the assembly kit comprising a gripper-free underwater vehicle with a propulsion and steering system for manoeuvring the vehicle but without a gripper system (18); a gripper system (18) separately from the gripper-free vehicle, the gripper system comprising a gripper (24) and a connector for connecting of the gripper to the gripper-free underwater vehicle; and the gripper system comprising an adjustment mechanism (29, 30, 31) between the connector and the gripper for adjusting the gripper (24) orientation relatively to the connector.

17. An assembly kit according to claim 16, the gripper system further comprising a buoyancy adjustment system (18) for adjusting the buoyancy of the gripper (24).

18. A system according to claim 6, wherein the buoyancy adjustment system (19) comprises at least one tank (24) attached to the buoy gripper (24) remotely from the frame (10) for specific buoyancy adjustment of the gripper (24).

Description

SHORT DESCRIPTION OF THE DRAWINGS

[0029] The invention will be explained in more detail with reference to the drawing, where

[0030] FIG. 1 shows a ship connected by a riser line to a subsea station;

[0031] FIG. 2 illustrates operation of a ROV underneath the ship;

[0032] FIG. 3 illustrates an underwater vehicle in a) side view, b) end view, c) top view, and d) perspective view;

[0033] FIG. 4 is a drawing of a buoyancy tank when a) increasingly inflated and b) deflated

[0034] FIG. 5 is a schematic drawing of the tank system;

[0035] FIG. 6 shows a coupling between the frame and the gripper;

[0036] FIG. 7 illustrates a holding mechanism for the buoys;

[0037] FIG. 8 illustrates the vehicle in the process of detaching a buoy from a riser in a) a first perspective, b) second perspective and c) in an enlarged view.

DETAILED DESCRIPTION/PREFERRED EMBODIMENT

[0038] FIG. 1 illustrates a riser 1 with a flow line 2 between a station 3 at the sea bed 4 and a ship 5 at the surface 6 of the sea. A riser flow line 2 extends relatively steeply from an anchoring point 7 at the sea bed 4 up to a floating part 8 of the riser 1. The floating part 8 comprises a plurality of buoys 9 attached to the flow line 2. As an alternative to the ship 5, the riser 1 could also extend to a stationary surface construction, for example a platform.

[0039] FIG. 2 illustrates a system for removal and attachment of buoys 9 to the flow line 2. The system comprises an underwater operating vehicle 10 for transportation of buoys 9 under sea level and for removal and attachments of the buoys 9 to the flow line 2. The underwater vehicle 10 in operation when gripping buoys is seen in greater detail in FIG. 8b. With reference to FIG. 2, the vehicle 10 comprises a propulsion system, for example propellers or jet thrusters, as well as a steering system for in cooperation moving the vehicle 10 safely controlled under water. The vehicle 10 is unmanned and steered by remote control by operational control signals transmitted to the remotely operated vehicle (ROV) from a control vessel 13 through an umbilical 14 connecting a control centre 15 on the control vessel 13 with the vehicle 10.

[0040] With reference to FIG. 2 and FIG. 3d, to vehicle 10 comprises an illumination system 43 and a video camera system 16 that is capturing the surroundings of the vehicle 10 in order for the control centre 15 to follow the operation of the vehicle 10 and to give corresponding operational control commands to the vehicle 10 via the umbilical 14 in order to accomplish the mission at the flow line 2 at the floating part 8 of the riser 1 under the ship 5. As illustrated, the vehicle 10 is capable of manoeuvring under the ship 5 and approach the flow line 2 with the plurality of buoys 9, even where the flow line 2 is underneath the ship 5 and, therefore, difficult accessible from above.

[0041] Alternatively, the vehicle 10 is operating autonomously and not connected to the control vessel 13. In this case, a computer of the vehicle 10 is programmed to steer the vehicle 10 to a certain underwater location and perform the necessary operation in accordance with the programming and supported by evaluation of the video recording taken continuously by the camera system of the vehicle 10.

[0042] In the following, the operation of the vehicle 10 is explained with respect to control signals received by the vehicle through the umbilical 14, but it is understood that a similar operation could be performed autonomously by the computer on board of the vehicle 10 instead of the control centre 15 on the control vessel 13, where human control, command, and intervention typically takes place.

[0043] FIG. 3 shows the vehicle 10 in greater detail in a) side view, b) end view, c) top view, and d) perspective view. The vehicle 10 comprises a gripper system 18 dimensioned and configured for gripping buoys 9 of the size and shape as used on deep sea risers.

[0044] As best seen in FIG. 3a and FIG. 3d, a buoy is placed between the open jaws 25a, 25b of the gripper 24. The jaws 25a, 25b are opened and closed by a linear actuator 27 causing the two jaws 25a, 25b to mutually rotate about the hinge 26. As shown in FIG. 3 a and in greater detail in the partial drawing in FIG. 6, the gripper 24 can be tilted up and down by the combination of a tilt hinge 30 and linear tilt actuator 29. Rotation of the gripper 24 is accomplished about rotation axle 31.

[0045] Such buoys 9 have buoyancy in the order of 500-1500 kg, which implies that the vehicle 10 must comprise a correspondingly heavy underwater weight in order to perform a controlled take up and delivery of such buoys 9. On the other hand, manoeuvring of the vehicle 10 under water without a buoy 9 in the gripper 24 should not be hampered due to an unnecessarily overheavy vehicle 10. For this reason, the vehicle 10 is equipped with a buoyancy adjustment system 19 where a plurality of tanks 20 are controllably filled with an amount of water and gas in varying volume ratios, dependent on the desired buoyancy. The tanks 20 are provided on the gripper 24 in order to adjust the buoyancy of the gripper 24 in dependent on a buoy 9 with weight or buoyancy being held in the gripper 24.

[0046] The system as illustrated in FIG. 3 is suitable for an assembly kit in which a gripper system 18 is mounted onto a gripper-free vehicle part 47, for example multi-purpose standard gripper-free underwater vehicle, such as AUV (autonomous underwater vehicle) or ROV (remotely operated vehicle), as part of customization. The gripper-free vehicle part 47 comprises an upper frame part 46a. To this upper frame part 46a, there is attached a lower frame part 46b. This lower frame part 46b carries the gripper system 18. Together, the upper frame part 46a and the lower frame part 46b constitute a frame 10 of the underwater vehicle 10. In a kit comprising a gripper system 18 for a multi-purpose standard gripper-free underwater vehicle, the lower frame part 46b can be part of such kit. In this case, the lower frame part 46b is mounted onto the gripper free vehicle as a first step. In order for the lower frame part to be floating under water, it is equipped with a buoyancy system. As the weight of the lower frame part 46b is not changing, the buoyancy system for the lower frame part 46b can be non-adjustable, for example provided with foam-filled containers.

[0047] FIGS. 4a and 4b illustrates an exemplary embodiment. Each of the tanks 20 is divided into two compartments, a first compartment 20a for water and a second compartment 20b for gas, wherein the two compartments 20a, 20b are mutually separated by a flexible membrane 21, for example, as illustrated, a resilient inflatable bladder. The tank 20 has a water inlet/outlet 22a to the first compartment 20a and a gas inlet/outlet 22b to the second compartment 20b. Pumping gas into the second compartment 20b presses water out of the first compartment 20a, increasing the buoyancy 42 of the tank 20, which is illustrated in FIG. 4a as compared to FIG. 4b where the second compartment 20b is smaller. Release of gas from the second compartment 20b allows more water to flow into the first compartment 20a. The gas for the tank 20 is provided from a container that contains the gas under pressurised conditions in order for the gas to be able to press out the water from the first compartment 20a.

[0048] FIG. 5 illustrates components of the buoyancy adjustment system 19. Two sets of tanks 20 are filled independently of each other with pressurised gas from gas reservoirs 33 through two manifolds 32. A first hydraulically operated valve 36a is used for filling pressurised gas into the manifolds, a second hydraulically operated valve 36b is used for releasing the gas from the tanks 20, and a third hydraulically operated valve 36c is used for the water flow in and out of the tanks 20 in dependence on the volume left in the first compartment 20a of the respective tanks 20 after filling pressurised gas in the second compartment 20b on one side of the membrane 21. Instead of hydraulically controlling the valves 36a, 36b, 36c, they could be controlled pneumatically. A water meter 43 and a pressure meter 44 are viewable in a panel 39 by a camera. For example, the two gas reservoirs 33 have a volume of 45 litre and are filled with gas at a pressure of 300 bars. With correspondingly dimensioned tanks 20, the vehicle may empty the tanks from water twice at a depth of 150 m.

[0049] FIG. 6 illustrates the coupling 37 between the vehicle frame 10 and the gripper system 18 in greater detail with the tilt actuator 29, the tilt hinge 30 and the rotation axle 31. The vehicle comprises a latch system 38 hydraulic flow connectors for quick connection, and the gripper system 18 comprises a cooperating panel 39. The panel 39 also comprises various meters, including the water meter 43 for the ballast water and the air pressure meter 44, and potentially further meters, such as hydraulic pressure meters. These meters are video captured by the camera system, the signal of which is transmitted to the control centre 15 on the control vessel via the umbilical 14. This results in a very simple and reliable data transfer system with minimized risk for failure.

[0050] FIG. 7 shows the jaws 25a, 25b in greater detail. The jaws 25a, 25b are provided with a holding mechanism for holding the buoys. For the holding the buoy, the jaws 25a, 25b are provided with pins 40 for cooperating with the buoys 9. As indicated in FIG. 3a and FIG. 3d, the buoy 9 consists of two halves 9a, 9b in order for the buoy 9 to be placed around the flow line 2. FIGS. 8a, 8b, and 8c show the vehicle 10 in the process of holding the gripper 24 around a buoy 9, where the two halves 9a, 9b of the buoy 9 are enclosing the flow line 2 on a riser 1. For attachment and detachment, the two buoy halves 9a, 9b have to be separated a distance sufficient for the flow line 2 to fit into the central hollow part of the buoy 9. By engaging the pins 40 with either buoy half 9a, 9b, the two halves are secured to either jaw 25a, 25b, and the opening action of the jaws, once engagement has been made with the buoy 9 by the gripper, the jaws can be used to force the two buoy halves 9a, 9b apart for release from the flow line 2 or for attachment thereto. In order to provide a secure holding, the pins 40 can be moved hydraulically towards and away from the buoy, which is indicated by double arrow 41 in FIG. 7. Typically, the buoys would be provided with pin receivers for cooperating with the pins when the buoys are to be installed. However, the pins can also be used for de-installation of types of buoys without pin receivers, in which case the pins are used for puncturing the skin of the buoys.

NUMBERING

[0051] 1 riser [0052] 2 flow line [0053] 3 station at sea bed 4 [0054] 4 sea bed [0055] 5 ship [0056] 6 surface [0057] 7 anchoring point [0058] 8 floating part [0059] 9 buoys [0060] 9a, 9b First and second half of buoy 9 [0061] 10 vehicle [0062] 10 vehicle frame with upper vehicle frame part 46a and lower vehicle frame part 46b [0063] 11 propulsion system [0064] 12 steering system [0065] 13 control vessel [0066] 14 umbilical [0067] 15 control centre on control vessel [0068] 16 camera system [0069] 17 controller on vehicle 10 [0070] 18 gripper system [0071] 19 buoyancy adjustment system [0072] 20 water fillable tanks of buoyancy adjustment system 19 [0073] 20a, 20b, first and second compartment in tank 20 separated by membrane 21 [0074] 21 membrane in compartment [0075] 22a water inlet/outlet of first compartment 20a [0076] 22b water inlet/outlet of second compartment 20b [0077] 23 container with pressurised gas [0078] 24 gripper in gripper system 18 [0079] 25a, b jaws of gripper 24 [0080] 26 hinge between jaws [0081] 27 actuator for opening and closing jaws 25a, b [0082] 28 rotational axle for gripper 24 [0083] 29 tilt actuator [0084] 30 tilt hinge [0085] 31 rotation axle [0086] 32 manifolds for filling tanks 20 [0087] 33 pressurised gas reservoirs [0088] 34 water inlet and outlet [0089] 35 gas outlet [0090] 36a, 36b, 36c hydraulically operated valves for gas filling and release and water flow [0091] 37 coupling between vehicle 10 and gripper system 18 [0092] 38 latch system with hydraulic flow connectors [0093] 39 panel on gripper system 18 cooperating with hydraulic flow connectors 38 [0094] 40 longitudinally movable pins in jaws [0095] 41 double arrow illustrating direction of motion of pins 40 [0096] 42 buoyancy [0097] 43 water meter [0098] 44 pressure meter [0099] 45 illumination system [0100] 46 vehicle frame [0101] 46a upper vehicle frame part [0102] 46b lower vehicle frame part [0103] 47 gripper-free vehicle part