FR3026087A1 - OCEANOGRAPHIC SYSTEM AND CONTROL METHOD - Google Patents

Abstract

The invention relates to an oceanographic system comprising a heavy portion (1) for bringing the system to the bottom of the water, and a portion with variable positive buoyancy (2) for raising the system to the surface on order. The positive buoyant portion (2) comprises a reservoir (25) filled with pressurized fluid, a receptacle (26) initially filled with liquid, an actuator (27) adapted to switch between a closed state in which the fluid communication between the reservoir and the receptacle is prevented and an open state in which this communication is allowed. In the open state, the fluid in the reservoir flushes the liquid from the receptacle so as to raise the system to the surface. According to the invention, the actuator switches from the closed state to the open state when a mechanical force (F) created by releasing a floating device or a ballast is exerted on a pin (276) of the actuator.

Description

TECHNICAL FIELD The present invention relates to the field of exploration and monitoring of the seabed. It relates more particularly to an oceanographic system comprising particular surface-lift means. State of the art Exploration and exploitation of the oceans require certain intrusions into the environment. These studies are carried out using specific systems that are deposited at the bottom of the water to carry out the measurements related to the study and which, ideally, are then recovered. The system is lowered and maintained at the bottom of the water because of its weight through heavy elements used for ballast. In oceanography, it is still common practice to leave some of the equipment in the middle, for example the ballast at the end of the mission. There is no specific regulation in the field, but the scientific community wishes to promote and implement solutions that respect the environment, reduce the cases of abandonment of structures, cables, ballast or materials in the environment , and promote the use of non-polluting and biodegradable materials. At the same time, operators of oil and gas production sites must now demonstrate the safety of their facilities and plan their dismantling.

There is, therefore, a real need today to offer ocean exploration or exploitation systems that are environmentally friendly and can be fully recovered at the end of the mission. Various solutions currently exist to recover the oceanographic systems deposited at the bottom of the water. A first solution is to go up from a ship, the system by means of a carrying cable. For limited immersion depths of the system, the cable tie requires the intervention of a diver or, for greater immersion depths, the intervention of a submarine machine inhabited, expensive operation that requires heavy means. Another solution, described in particular in the document WO86 / 04873, consists in providing a system comprising, in addition to the measuring equipment and the ballast, a float and hooking means for connecting the float to the ballast via a cable reel ( classically called "rope canister" in the Anglo-Saxon literature). The attachment means are controlled remotely, for example by an acoustic signal. Thus, when the catch mechanism receives an acoustic signal emitted from a surface ship, the float is disengaged from the ballast and rises to the surface by unrolling the cable reel, the rest of the system being held on the seabed by the ballast. . The float can then be recovered on the surface by a ship. The rest of the system is then raised to the surface by pulling on the cable with traction means on board the ship. One of the negative points of this system is that in areas with strong ocean currents, the system is likely to rag the seabed. Indeed, when the float begins to rise or when it is on the surface, the forces related to the marine currents exerted on the cable and the float are important and the float can sink. The part of the system remained on the seabed, including the ballast can then be screened on the bottom and damage the marine site. The system can also be damaged. Finally, if the float is flowing, it can also be difficult to locate the system to recover it.

Another solution is to transfer a liquid or a gas from inside an enclosure to an outer flexible bag by means of a pump. A negative point of this solution is that it requires a pump and a source of energy to power this pump. Another solution, described in particular in GB2435856, consists in equipping the system with a flotation device comprising a tank containing liquefied gas (under pressure), a chamber initially filled with a liquid (for example, water). ) and a remotely controllable valve device adapted to switch between a closed state in which fluid communication between the tank and the chamber is prevented, and an open state in which fluid communication between the tank and the chamber is permitted. When the valve device is in an open state, the liquefied gas vaporizes and expels the liquid initially present in the chamber. The weight of the system decreases and it rises to the surface. One of the negative points of this solution is that, for depths greater than 1000 meters, it requires a large volume of gas. It also requires to provide in the system a sufficient amount of energy to power the valve device.

SUMMARY OF THE INVENTION An object of the invention is to propose an alternative solution to the solutions proposed above which is respectful of the environment and at least partially overcomes the aforementioned drawbacks. Another object of the invention is to provide a system that is simple to manufacture, compact and low energy consumption. Another object of the invention is to provide a system that is easily adaptable to existing systems. To this end, the invention relates to an oceanographic system comprising a heavy portion for bringing and maintaining the system at the bottom of the water, a portion with variable positive buoyancy to bring the system back to order on the surface, in which the portion variable positive buoyancy comprises at least one reservoir filled with fluid under pressure, a flexible or rigid receptacle initially empty or filled with a liquid, and an actuator able to switch between a closed state in which the fluid communication between the reservoir and the receptacle is prevented and an open state in which fluid communication between the reservoir and the receptacle is permitted, the reservoir fluid flushing the liquid from the receptacle or filling the receptacle when the actuator is in the open state so as to move the system up to the surface.

According to the invention, the actuator is a mechanical device capable of switching from the closed state to the open state when a mechanical force of an intensity greater than a predetermined intensity is exerted on an opening element of the actuator said force being created on command by dropping a floating device or a ballast. Thus, the system according to the invention requires no source of electrical energy to create the mechanical force used to trigger the opening of the actuator and raise the system. According to a preferred embodiment, the mechanical force is created by the release of the variable positive buoyant portion and the rise of the variable positive buoyant portion to a predetermined height. According to a particular embodiment, said positive buoyant portion comprises at least one permanent buoyancy float and a cable of predetermined length for connecting the opening element of the actuator to the heavy portion and a remotely controllable release device. to release on order the positive buoyant portion, the buoyancy of said at least one float being determined so that, after release of the positive buoyancy portion and reassembly thereof of a height equal to the length of the cable, the heavy portion exerts a mechanical force having a greater intensity than said predetermined intensity on the opening member of the actuator. Thus, when the positive floating portion is released, the latter rises, with the aid of the float, a first height substantially equal to the height of the cable, to create, once the cable tensioned, sufficient mechanical strength on the opening element of the actuator. The application of this force on said opening element then triggers the opening of the actuator. The opening of the actuator then causes the receptacle of the positive buoyant portion to be filled with the pressurized fluid contained in the reservoir, which has the consequence of increasing the buoyancy of the positive buoyant portion. The entire system (heavy portion and positive buoyancy portion) then rises to a second height until the positive float reaches the surface.

According to the invention, the rise of the system is therefore carried out in two stages and by two distinct means. Firstly, the positive buoyancy portion rises from a first height thanks to the buoyant float (s) (or buoyancy loaf) and, for a second time, the positive buoyancy portion and the heavy portion rise from a second height by filling the receptacle with pressurized fluid from the reservoir until the positive flotation portion reaches the surface.

Alternatively, one could consider creating the mechanical force triggering the opening of the actuator by releasing a ballast attached by a short cable to the opening element of the actuator. According to a particular embodiment, the release device comprises an acoustic width capable of receiving an acoustic order for dropping the positive floating portion. According to a particular embodiment, the opening element of the actuator is a pin, the mechanical force created being intended to move and / or remove the pin of the actuator. According to one embodiment, the receptacle is a pipe having an upper end connected to the reservoir via said actuator and a lower end open to the marine environment so that, when the actuator is in the open state, the fluid initially present in the tank fills the pipe. Advantageously, when the actuator is in the closed position, the receptacle is in fluid communication with the marine environment. In this embodiment, at the time of launching, the pipe having two ends in fluid communication with the marine environment, the pipe fills with seawater allowing the system to descend to the bottom of the water. At the time of raising the system, the actuator is in the open position. The upper end of the pipe is no longer in fluid communication with the marine environment. The water contained in the pipe is driven into the marine environment via the lower end of the open pipe on the middle and replaced by the reservoir fluid.

This embodiment has the advantage of being insensitive to the increase in the volume of fluid present in the pipe as the system rises (pressure decreases) since the fluid can escape through the end open hose.

Advantageously, the pipe is helically shaped to reduce its bulk. Alternatively, the lower end of the pipe is closed by a non-return valve and the liquid initially contained in the pipe is a heavier liquid than seawater, for example water brine. In this variant, when the actuator is in the open state, the liquid initially present in the pipe is driven into the marine environment by the open end of the pipe via the non-return valve.

According to one embodiment, the pressurized fluid contained in the reservoir comprises air and / or nitrogen and / or helium. The invention also relates to a control method of a system as defined above characterized in that the mechanical force having an intensity greater than the predetermined intensity is created by raising the positive buoyant portion on a first water level .

Other advantages may still appear to those skilled in the art on reading the examples below, illustrated by the appended figures, given for illustrative purposes. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 represents a perspective view from above of a system according to the invention; Figure 2 is a partial perspective view of the underside of the system of Figure 1; FIGS. 3A and 3B show sectional views of an actuator of the system of FIG. 1, said actuator being respectively in the closed state and in the open state; Figure 4 is an enlarged view of Figure 2 showing the release device of the system of Figure 1; FIG. 5 is a top view of the system of the invention in which certain elements of the system have been removed to show the release device; Figure 6 is a partial perspective view of the system of the invention for showing a portion of the release device, and Figures 7A-7C are views illustrating the ascent of the system of the invention in two stages.

DETAILED DESCRIPTION OF THE INVENTION With reference to FIGS. 1 and 2, the system of the invention mainly comprises a so-called heavy portion 1 and a so-called positive buoyancy portion 2. The positive buoyancy portion is positioned above the heavy portion and held in contact with the latter by means of a release device 3 which will be described in more detail below with reference to FIGS. 4 and 5. The heavy portion 1 essentially comprises a frame made of a heavy material. In the embodiment illustrated in Figures 1 and 2, it is shown schematically by a frame 10 of generally cylindrical shape. This frame can be weighed down by attaching extra heavy elements if necessary. The heavy portion is intended to bring and maintain the system at the bottom of the water. Since the system of the invention is intended for oceanographic exploration, oceanographic equipment (measuring equipment and the like) will be advantageously mounted on this heavy portion and will be counted in the weight of the heavy portion. Referring to Figures 1 and 2, the frame 10 comprises a circular ring, said lower ring 100, and a circular ring, said upper 101, which rings are spaced vertically and assembled to four uprights 102 so as to form a generally shaped structure cylindrical. The heavy portion rests by the lower ring 100 on the seabed. The positive buoyancy portion 2 also comprises a frame 20 which, in the exemplary embodiment illustrated, is of octagonal cross section. This frame comprises an octagonal ring, said lower ring 201, and an octagonal ring, said upper ring 202, which rings are spaced vertically and assembled by uprights 203 so as to form a cylinder open on all sides and octagonal section. The positive flotation portion 2 rests with its lower ring 201 on the upper ring 101 of the heavy portion 1. The diameter of the circle in which the octagonal ring 201 is circumscribed is therefore substantially greater than the diameter of the circular ring 101 of the heavy portion.

Positioning studs 23 are provided on the lower ring 201 to correctly position the frame 10 of the positive-floating portion relative to the frame 20 of the heavy portion. The frame 20 also comprises, in the upper part, crosspieces 204 connecting diametrically opposite portions of the ring 202 and, in the lower part, an additional circular ring 205 having its center substantially coincident with that of the ring 201 and diameter less than that of the ring 201. The ring 205 is attached to the ring 201 by two tabs 206 arranged symmetrically with respect to the center of the ring 205. As explained later in the description, the two tabs 206 are used by the release device 3 to maintain, before release, the positive buoyant portion 2 in contact with the heavy portion 1. The positive floating portion 2 further comprises floats or buoys 24 fixed to the frame 20, between the rings 201 and 202. In Figures 1 and 2, the positive-floating portion 2 comprises sixteen loaves of buoyancy 24 divided into four blocks of four float looses dis placed symmetrically with respect to the longitudinal axis of the frame 20 of the positive-floating portion. These buoyancy loaves are of parallelepipedal shape and have a constant and permanent positive buoyancy. These buoyancy bars are sized or their number is determined to be able to raise the positive flotation portion when the latter is no longer maintained in contact with the heavy portion by the release device and create a sufficient mechanical force F to trigger the opening of an actuator (presented later). The buoyancy bars are dimensioned to not be sufficient to raise the entire system, namely the positive flotation portion 2 and the heavy portion 1. The positive flotation portion 2 further comprises at least one fluid reservoir 25 under This reservoir is connected to a pipe 26 of helical (coil) shape via an actuator 27 adapted to switch between a closed state in which the fluid communication between the tank 25 and the pipe 26 is prevented and an open state in which the fluid communication between the tank 25 and the pipe 26 is allowed. The reservoir 25 is for example a bottle of gas under pressure. The pressurized gas contained in the reservoir advantageously comprises air and / or nitrogen and / or helium.

The pipe 26 is generally a receptacle for receiving the fluid from the tank 25. The actuator 27 is mounted on one of the cross members 204 of the frame 20. The upper end of the pipe 26 is sealingly connected to the actuator 27 and its lower end is open to the marine environment. The actuator 27 is in a closed state during the descent of the system to the bottom of the water. In this position (closed state), the actuator 27 puts the upper end of the pipe in fluid communication with the marine environment. As this descent, the seawater gradually replaces the air initially contained in the pipe 26 which escapes through the lower end of the pipe and the buoyancy of the system then decreases. When the system is at the bottom of the water, the pipe 26 is filled with seawater and the actuator 27 is in the closed state. When the actuator 27 is opened (transition from the closed state to the open state), the fluid communication between the upper end of the pipe and the marine environment is interrupted, the gas present in the tank 25 is propagated in the pipe , flushes the water present therein and increases the buoyancy of the positive buoyancy portion 2. The water present in the pipe 26 is discharged into the marine environment through the open lower end thereof and replaced by the gas of the reservoir 25. According to the invention, the actuator 27 is a mechanical device which is switched from the closed state to the open state by application of a mechanical force F on one of its elements, called element of opening. The force F is exerted by a cable 4 connected to the opening element by one of its ends and to the heavy portion 1 by the other of its ends. An example of an actuator 27 is shown in FIGS. 3A and 3B. Figure 3A shows the actuator in a closed state and Figure 3B shows the actuator in the open state. With reference to FIGS. 3A and 3B, the actuator 27 comprises a hollow body 270 comprising three consecutive coaxial chambers, namely an upper chamber 271A, a lower chamber 271C and an intermediate chamber 271B. It also comprises a piston 273 of generally cylindrical shape able to move in the chambers 271A, 271B and 241C.

The lower chamber 271C is generally cylindrical and has an open upper end opening into the intermediate chamber 271B and a lower end closed by a wall. This wall is provided with an orifice making it possible to put in fluid communication the lower chamber and the external medium when said orifice is not closed by a pin 276. The chamber 271C furthermore comprises a fluid inlet through which the fluid of the reservoir 25 enters the room.

Similarly, the upper chamber 271A is of generally cylindrical shape. It has an open bottom end opening into the intermediate chamber 271B and an upper end closed by a wall. This wall is provided with an orifice making it possible to put in fluid communication the upper chamber and the external medium when said orifice is not closed by a pin 277. The intermediate chamber 271B comprises a cylindrical upper portion adjacent to the upper chamber 271A. This upper portion is provided with outward openings 272A (i.e., the marine environment). The intermediate chamber also comprises, in its wider lower part, an opening 272B provided with a flange 272C on which is mounted sealingly the upper end of the pipe 26. The piston 273 is positioned to slide in the 3 chambers 271A, 271B and 271C. It comprises three collars each provided with a groove in which is housed a seal.

More specifically, it comprises at its lower end a first collar 274A provided with a groove in which is housed a seal 275A and above, at a distance of the order of one centimeter, a second collar 274B provided with a groove in which is housed a seal 275B. Whatever the position of the piston, the collar 274B is always above the fluid inlet 278 of the chamber 271C and the collar 274A is always below the fluid inlet 278.

The diameter of the flanges 274A and 275B is substantially equal to the inside diameter of the lower chamber 271C. In the closed state, the lower end of the piston is positioned against the bottom wall and the pin 276 closes the hole 279 of the lower end of the chamber 271C.

The piston 273 comprises a third collar 274C provided with a groove in which is housed a seal 275C. This collar is positioned to move in the intermediate chamber 271B. Its diameter is substantially equal to the inside diameter of the cylindrical upper portion of the chamber 271B. The piston 273 is also provided at its upper end with a groove in which is housed a seal 275D. The upper end of the piston 273 is intended to move in the upper chamber 271A. The diameter of the piston at its upper end is substantially equal to the inside diameter of the chamber 271A. The operation of the actuator 27 is as follows. Upon launching the system, the pin 277 is removed to adjust the pressure in the upper chamber 271A to the surface pressure. The pin 277 is then put back in place. When the system is lowered to the bottom of the water, the actuator is in the closed state (FIG. 3A). The collars 274A and 274B of the piston are positioned in the lower chamber 271C and the collar 274C is positioned in the intermediate chamber 271B. The water 25 is then gradually replace the air in the pipe 26 and the intermediate chamber 271C. The collar 274C not being engaged in the upper portion of the chamber 271C, the air can escape through the orifices 272A (arrow in broken lines). The fluid inlet 278 can supply fluid into the lower chamber 271C without displacing the piston 273 because its ends are in equipressure. To go from the closed state to the open state, the pin 276 is pulled down by means of the cable 4 as explained below. As the pressure on the lower end of the piston becomes greater than the pressure exerted on the upper end of the piston (pressure inside the chamber 271A), the piston 273 slides upwards until that the collar 274B enters the chamber 271B and that the collar 274C abuts against the upper wall of the chamber 271B. The fluidic communication between the intermediate chamber 271B and the orifices 272A is then stopped, the communication between the lower chamber 271C and the intermediate chamber 271B is established, and the fluid coming from the reservoir 25 (arrow in dashed lines in FIG. 3B) can flow towards the pipe 26 passing through the chambers 271C and 271B. The water in the pipe 26 is expelled by the fluid from the tank 25 and out of said pipe by its lower end open on the marine environment. The transition to the open state of the actuator 27 thus contributes to increasing the buoyancy of the positive buoyant portion 2. As indicated above, the system of the invention further comprises a release device 3 for controlling the release of the positive buoyancy portion 2. This release device is described in more detail with reference to FIGS. 4, 5 and 6.

The release device 3 comprises an acoustic width 31 adapted to receive an acoustic drop command and, in response, to control the lateral displacement of a C-piece 32 to release a lever arm 33 mounted on the heavy portion 1. lever arm 33, of substantially semicircular general shape, is able to pivot about a transverse axis of pivoting and provided at its ends with hooks 331. Before release, the C-piece 32 retains the lever arm so that the hooks 331 are engaged with the tabs 206 of the lower ring 201 of the variable buoyancy portion. When the acoustic width receives a release order, it moves laterally the C-piece 32 to release the lever arm 33 (see Figure 6). The lever arm, weighted or not, pivots, under the effect of its weight, around the pivot axis. The hooks 331 are then disengaged tabs 206, which has the effect of releasing the variable buoyant portion 2 of the system. This release device has the advantage of having only one release point release (at the C-piece) and two points of attachment (at the hooks 331) of the variable buoyancy portion 2 on the heavy portion 1.

Thus, according to the invention, the ascent of the system is operated in the following manner. This ascent is described with reference to FIGS. 7A to 7C. Note that in these figures, the system has been simplified compared to the system shown in Figures 1 to 6 but the operation remains the same.

Initially, the system is placed on the seabed (Figure 7A). An acoustic order is emitted from the surface to trigger the process of raising the system. This order is received by the acoustic width 31 to control the release of the positive buoyant portion. The acoustic width controls the lateral displacement of the C-piece 32. The lever arm 33 is then released and pivots about its pivot axis under the effect of its weight. The hooks 331 are then disengaged to release the positive buoyancy portion 2. With the buoyancy bars 24, the positive buoyancy portion 2 then begins to rise towards the surface on a first height H1 substantially equal to the length of the cable 4 (FIG. 7B). The cable 4 is stretched and, when fully stretched, it creates a pulling force F intended to dislodge the pin 276 of the actuator 27. The actuator 27 then passes into an open state and the gas from the reservoir 25 comes then flush the water and fill the pipe 26, then causing the rise of portions 1 and 2 of the system. These two portions are interconnected by the end 5. The upward phase of the system is completed when the portion 2 arrives at the surface (Figure 7C).

For the invention, it has been shown that 4 12-liter scuba tanks (tank 25) at a pressure of 200 bar can lift a load of 60 kilograms (total weight of the system in the water) from with a depth of about 900 m.

For the receptacle, a flexible PVC pipe 26 has been selected. To raise a load of 60 kilos, this pipe must have an interior volume of 60 liters. For example, a pipe having an internal diameter of 75 mm and a total length of about 13.6 m can be selected. As indicated above, the pipe 26 is open at one of its ends. This type of receptacle (one of whose ends is open to the marine environment) has the advantage of being insensitive to the increase in the volume of fluid present in the pipe as the system rises as the fluid can escape through the open end of the pipe. Other forms or types of receptacle are of course conceivable, for example a bladder or a balloon. This receptacle may be initially empty and then fill with the reservoir fluid during the upward movement of the positive buoyant portion of the system. This receptacle may be sized to receive the gas volume of the tank and support the expansion of this gas at the time of the rise of the system. Alternatively, it may have a lower end open to the marine environment or a valve system to allow gas to escape during the ascent. The embodiments described above have been given by way of example. It is obvious to those skilled in the art that they can be modified. Different modifications are possible. One could in particular consider simplifying the release device by building a device without lever arm but with only two parts at 30 C which cooperate with the cross members 206 of the portion 2.

One could also consider that, to open the actuator, the acoustic width 31 drops a ballast hooked to the pin of the actuator to remove it from the actuator.

According to another embodiment, it could be envisaged that the pipe 26 is flexible and initially folded back on itself, and thus initially empty. The pipe 26 would then deploy as it is filled with the fluid under pressure.

Claims (9)

CLAIMS1) Oceanographic system comprising a heavy portion (1) to bring the system to the bottom of the water, and a variable positive buoyancy portion (2) to bring the system up to the surface, in which the positive buoyancy portion variable (2) comprises - at least one reservoir (25) filled with fluid under pressure, - a receptacle (26) flexible or rigid initially empty or filled with a liquid, - an actuator (27) able to switch between a closed state wherein fluid communication between the reservoir and the receptacle is prevented and an open state in which fluid communication between the reservoir and the receptacle is permitted, the reservoir fluid flowing the liquid from the receptacle or filling the receptacle when the actuator is in the open state so as to raise the system to the surface, characterized in that the actuator (27) is a mechanical device capable of switching the state closed in the open state when a mechanical force of an intensity greater than a predetermined intensity (F) is exerted on an opening member (276) of the actuator, said mechanical force being created on command by release of a floating device or ballast. 2) System according to claim 1, characterized in that the mechanical force is created by a drop of the variable positive buoyancy portion (2) and a rise of the variable positive buoyant portion to a predetermined height (H1). 3) System according to claim 1, characterized in that the variable positive buoyant portion (2) comprises at least one permanent buoyancy float (24) and a cable (4) of predetermined length to connect the opening element ( 276) of the actuator at the heavy portion (1) and a remotely controllable release device (3) for jettisoning the positive buoyant portion (2) on order, the buoyancy of said at least one float being determined so that, after release of the positive buoyant portion (2) and raising of the positive buoyant portion by a height (H1) equal to the length of the cable (4), the heavy portion (1) exerts a mechanical force having a higher intensity at said predetermined intensity (F) on the opening member (276) of the actuator. 4) System according to claim 3, characterized in that the release device (3) comprises an acoustic width adapted to receive an acoustic order to release the portion with positive buoyancy. 5) System according to any one of the preceding claims, characterized in that the opening element of the actuator (27) is a pin (276), the mechanical force created being intended to move and / or remove the pin of the actuator. 6) System according to any one of the preceding claims, characterized in that the receptacle is a pipe (26) having an end, said upper, connected to the reservoir (25) via said actuator (27) and a lower end open on the marine environment so that when the actuator (27) is in the open state, the fluid initially present in the tank fills the pipe. 7) System according to claim 6, characterized in that the pipe (26) is helically shaped. 8) System according to any one of the preceding claims, characterized in that the pressurized fluid contained in the reservoir (25) comprises air and / or nitrogen and / or helium. 9) A method of controlling a system according to any one of claims 1 to 8, characterized in that the mechanical force having an intensity greater than the predetermined intensity (F) is created by raising the positive buoyant portion on a first water level (H1).