Seabed seismometer retrieval system, vessel and corresponding method

Abstract

The invention relates to a recovery system for recovering a seabed seismometer (2), the recovery system (1) being intended to equip a ship (3). The recovery system (1) comprises a receiving device (11), preferably perforated, capable of receiving said seismometer (2); a guide barrier (121) capable of defining, with the hull of the ship (3), a guide zone of the seabed seismometer (2) towards the receiving device (11); and a movement mechanism (13) configured to move the receiving device (11) between a low position in which the receiving device (11) is at least partially submerged, and a high position allowing an operator or apparatus present on the ship (3) to recover the seabed seismometer (2) carried by the receiving device (11). The invention also relates to a ship and a corresponding method. Figure for abstract: Fig. 2

Description

Title of the invention: Seabed seismometer recovery system, vessel and corresponding method FIELD OF THE INVENTION

[0001] The present invention relates generally to the recovery of seabed seismometers in a marine environment. The present invention is particularly suitable for seismic surveys. PREVIOUS ART

[0002] In the field of prospecting for natural resources, and in particular hydrocarbons, the acquisition and processing of seismic data can be used to generate a profile, or image, of the geophysical structure of a subsoil. Although this profile does not provide a precise location of oil and gas reservoirs, it suggests, to persons experienced in this field, the potential presence or absence of such reservoirs.

[0003] Seismic data is obtained by sending artificially generated seismic or acoustic interrogation waves (vibration, impulsive shock, etc.) deep underground. Seismic sensors are used to measure the propagation as well as the reflections and refractions of the artificially generated seismic waves by the different layers of the subsoil.

[0004] In particular, sensors of this type can be placed directly on the ground at the seabed to carry out seabed seismic surveys. These small sensors are usually deployed and recovered via a cable which connects them, as for example described in application WO 03 / 096072, or by means of an underwater drone, as for example described in application WO 2006 / 024956.

[0005] At the same time, it is known to carry out monitoring of the seabed using larger caliber recorders (sensors), or seismometers (seismographs), which are dropped into the ocean, descend to rest on the bottom due to their own weight, to record the activity of the seabed over long periods. Once the monitoring campaign is finished, an external command is received by the recorder which triggers the release of a ballast associated with it, which allows the recorder to rise to the surface as described in application EP1217390.

[0006] The recorder is then recovered, by artisanal and manual means, as is for example illustrated in the video available at the following address https: / / www.youtube.com / watch?v=gJsKwd_iRVo.

[0007] In the context of seismic surveys, we are seeing a development in the use of so-called “free-fall” sensors / recorders for so-called seismic campaigns. sparse, in which ocean bottom seismometers or OBS (for Ocean Bottom Seismometer in English) are used, with the dropping of a large number of such sensors / recorders, according to a distribution density intermediate between that of classic seabed surveys with small dedicated sensors and that of classic seabed monitoring studies with larger caliber recorders.

[0008] During a sparse seismic campaign, the multiplication of the number of seabed seismometers deployed and the distance between them, make their recovery complicated. Existing methods, such as the use of a remotely operated underwater vehicle (ROV) or an unmanned surface vehicle (USV), which are used to recover small seismic sensors, distributed according to a high density, are not suitable in the case of sparse monitoring campaigns with seabed seismometers. Furthermore, the current method of seismometer recovery is long and not very appropriate.

[0009] The aim of the present invention is to propose a new system and a new method for recovering a seabed seismometer, making it possible to overcome all or part of the problems set out above. Summary of the invention

[0010] For this purpose, the invention relates to a recovery system for recovering a seabed seismometer, the recovery system being intended to equip a ship, characterized in that the recovery system comprises: - a receiving device, preferably openwork, capable of receiving said seismometer; - a guidance device comprising an elongated element, called a guidance barrier, which has one end capable of being coupled to the vessel, the guidance barrier being capable of defining, with the hull of the vessel, a guidance zone of the seabed seismometer towards the receiving device; and - a movement mechanism configured to move the receiving device between a low position in which the receiving device is at least partially submerged, and a high position allowing an operator or device present on the vessel to retrieve the seabed seismometer carried by the receiving device.

[0011] The recovery system is thus presented in the form of a reliable mechanical system with which a ship can be easily equipped, which allows the recovery of seismometers with optimized efficiency.

[0012] The recovery system allows for rapid and safe recovery of seabed seismometers without slowing down the vessel.

[0013] Such a design of the recovery system allows the recovery of seismometers in a secure manner, particularly under optimal 'offshore' standard security conditions.

[0014] The recovery system allows the seabed seismometer to be recovered easily and reliably from the surface, and brought up to the deck height of the ship, without stopping or slowing down the ship, which can move at a speed of around 5 to 6 knots.

[0015] The system allows the recovery of numerous seabed seismometers (seismic recorders) which, after their deployment, have been brought to the surface, preferably by a command to release a ballast associated with them.

[0016] According to embodiments, the recovery system is installable on different ships. The recovery system is transportable, and operable day and night, including in adverse weather conditions.

[0017] The system may also include one or more of the following features taken in any technically admissible combination.

[0018] According to an optional characteristic of the invention, the recovery system comprises a holding arm coupled to the guidance device, the holding arm being oriented in a transverse direction, or capable of taking a transverse position, preferably orthogonal, to the axis of the ship, to keep one end of the guidance barrier away from the hull of the ship.

[0019] According to an optional feature of the invention, the system comprises a cable connected to the vessel and to the holding arm to reinforce the holding arm.

[0020] According to an optional characteristic of the invention, the guide barrier comprises a first end provided with coupling means, making it possible to couple the guide barrier, directly or indirectly, to said receiving device, and a second opposite end, which is optionally provided with a float, the holding arm being coupled, directly or indirectly, to the float and / or to the guide barrier, at said second end of the guide barrier.

[0021] According to an optional characteristic of the invention, the length of the holding arm is adjustable, for example to adapt to the hull height of the ship.

[0022] According to an optional characteristic of the invention, the guide barrier is equipped with flotation means, and has a part which extends, below the flotation level, over a height preferably at least equal to 1 meter, for example 2 meters.

[0023] According to an optional characteristic of the invention, the receiving device is a cage having at least one, preferably at least two, open faces.

[0024] According to an optional characteristic of the invention, the receiving device is larger than the size of the seismometer to be recovered, the receiving device preferably being two to three times the size of the seismometer.

[0025] According to an optional characteristic of the invention, the guide barrier has a concave shape from a point of view from the bow of the ship.

[0026] According to an optional characteristic of the invention, the system is removable relative to the ship.

[0027] According to an optional characteristic of the invention, the guide barrier comprises - an inflatable tube associated with a net or a tarpaulin, preferably openwork, - a grid, rigid or flexible, mounted on an arc-shaped structure connecting a support arm to the receiving device, and / or - horizontal plastic rails mounted on a structure connecting a holding arm to the receiving device.

[0028] According to an optional characteristic of the invention, the angle formed between the longitudinal axis of the ship and the rope which connects the end of the guide barrier located on the side of the ship and the end of the opposite guide barrier away from the ship, is an acute angle preferably of the order of 30 to 60°.

[0029] According to an optional characteristic of the invention, the reception device comprises a plurality of recovery modules, and the movement mechanism is configured to allow said recovery modules to be successively raised to recover the seismometers collected in said recovery modules.

[0030] The invention also relates to a ship equipped on one side with a recovery system as proposed above.

[0031] The invention also relates to a method for recovering a seabed seismometer which is floating in the sea, using a recovery system, for example as proposed above, fitted to a ship, characterized in that the method comprises the following steps: - positioning a receiving device of the recovery system in the water in a semi-submerged manner, the receiving device being able to be lowered into this semi-submerged position immediately after the end of a previous recovery of a seismometer when a seismometer to be recovered is identified; - steer the vessel into the guidance corridor defined between the vessel's hull and a recovery system guidance device; - continue to move the vessel forward so that the seismometer is guided by the guidance device into the receiving device, and - reassemble the receiving device to allow an operator or device present on the ship to recover the seismometer.

[0032] According to one embodiment, a recovery system is proposed which comprises: - floating guide means extending between a first end provided of a floating body and a second end provided with means for coupling to the hull of a ship, - a securing arm for the first end, - a cage-type receiving device movable between a first position in which it is coupled to the second end of the guide means and a second position in which it is accessible on the deck of a ship. Brief description of the drawings

[0033] Other characteristics and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting and must be read in conjunction with the appended drawings, in which:

[0034] - [Fig.l] [Fig.l] is a schematic top view of a ship equipped with a seismometer recovery system according to one embodiment of the invention;

[0035] - [Fig.2] [Fig.2] is a schematic view in slight perspective and from the side of a ship equipped with a recovery system according to one embodiment of the invention, showing a seismometer which is present in the guidance corridor defined between the guidance device and the hull of the ship;

[0036] - [Fig.3] [Fig.3] is a schematic view showing the ship and the recovery system operation of [Fig.2], showing the seismometer being guided into the cage;

[0037] - [Fig.4] [Fig.4] is a schematic view showing the ship and the recovery system operation of [Fig.3], in the raised position of the recovery cage which contains the seismometer;

[0038] - [Fig.5] [Fig.5] is a block diagram showing several steps of a re recovery according to an embodiment in accordance with the invention. DETAILED DESCRIPTION

[0039] The inventive concept is described more fully below with reference to the accompanying drawings, in which embodiments of the inventive concept are shown. In the drawings, the size and relative sizes of elements may be exaggerated for clarity. Like numerals refer to like elements throughout the drawings. However, this inventive concept may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided so that this description is complete, and communicates the scope of the inventive concept to those skilled in the art.

[0040] A reference throughout the specification to "an embodiment" means that a particular functionality, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the occurrence of the expression "in an embodiment" at various locations throughout the specification does not necessarily refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0041] With reference to the figures, a recovery system 1 is proposed for recovering a seabed seismometer 2. The seabed seismometer 2 may be a "free-fall" type recorder, for example of the type of the device proposed under the reference MicrOBS by the company Sercel. The recovery system 1 equips a ship 3.

[0042] The recovery system 1 comprises a receiving device 11, preferably openwork, capable of receiving said seismometer 2. The receiving device 11 is adapted to limit the risk of the seismometer 2 involuntarily leaving said receiving device 11.

[0043] The system 1 also comprises a guidance device 12 which makes it possible to guide the seismometer 2 towards the receiving device 11 when the ship is moving forward and the seabed seismometer 2 is in contact with the guidance device 12. The movement of the seismometer 2 is then channelled by the guidance device 12 and possibly the hull of the ship, so that the seismometer ends up arriving in the receiving device 11.

[0044] In particular, the seismometer 2 is guided along the guidance device by the relative movement of the ship 3 equipped with the system with respect to the seismometer 2. The guidance device 12 forms a barrier with respect to the seabed seismometer 2 to constrain its movement towards the receiving device 11. The guidance device 12 has a part capable of being attached to the ship 3.

[0045] The receiving device 11 can be moved using a movement mechanism 13 between a low position in which the receiving device 11 remains on the surface while being partially submerged, for example over half its height, to allow the seismometer which is floating in the water to be collected, and a high position in which the receiving device 11 is out of the water and is located at a height which allows an operator or a device present on the ship 3, in particular its deck, to recover the seabed seismometer 2 carried by the receiving device 11.

[0046] In the low position, the receiving device 11 is capable of receiving at least one seismometer 2. The receiving device 11 is preferably arranged so as to follow the movements of the sea, while floating, while maintaining a semi-submerged position when it is in the low position.

[0047] Ship

[0048] The recovery system 1 equips one side of the ship. It can be provided that the opposite lateral side of the ship is also equipped with a recovery system 1. The system according to the invention is designed to be adaptable to existing ships of opportunity.

[0049] Receiving device

[0050] In the example illustrated in the figures, the receiving device 11 is a cage. The cage may have a single open face. It is also possible to provide for the cage to have several open faces, for example at least one open front entry face to allow the seismometer 2 to enter the cage in the lower position of the cage, and an open top face to easily remove it in the upper position of the cage.

[0051] Preferably, the receiving device 11 is larger than the size of the seismometer 2 to be recovered. The receiving device 11 is preferably two to three times the size of the seismometer 2. The width and height of the receiving device 11 can thus be equal to respectively twice the width and three times the height of the seismometer 2.

[0052] Guiding device

[0053] The guidance device 12 comprises an elongated element, called a guidance barrier 121, which is associated with flotation means 120 so as to remain on the surface. The flotation means 120 may extend along the elongated element, in the manner of a sausage, or be in a discrete form, in the manner of buoys distributed along the elongated element, or even be only punctual, with for example a single float at a chosen level of the guidance barrier 121.

[0054] The guide barrier 121 has, along its length, a portion which extends below the waterline, over a height preferably at least equal to 1 meter, for example 2 meters. This makes it possible to limit the risk of the seismometer 2 passing below the guide barrier 121, in particular in the event of rough seas.

[0055] The depth of the guide barrier is thus adapted to the guidance of seabed seismometers, in particular MicroOBS.

[0056] Advantageously, the guide barrier also has, along its length, a part which extends above the waterline to prevent the seismometer 2 from passing above the guide barrier 121.

[0057] According to one embodiment, a first end of the guide barrier 121 is provided with coupling means, making it possible to couple the guide barrier 121, directly or indirectly, to the ship 3. A second end of the guide barrier 121, opposite the first end, is coupled to a holding arm 14, possibly by means of a float 122. The holding arm 14 is coupled to the ship to keep the second end of the guide barrier 121 away from the hull of the ship 3.

[0058] The holding arm 14 is coupled, directly or indirectly, to the float 122 and / or to the guide barrier 121, preferably at said second end of the guide barrier 121.

[0059] Advantageously, the guide barrier 121 has a concave shape, preferably curved, according to a point of view from the bow of the ship. According to one embodiment, the float 122 is profiled parallel to the ship, over a length which can be 2 to 3 meters in this direction.

[0060] The guide barrier 121 can be produced in different ways. Thus the guide barrier 121 can comprise: - an inflatable sausage associated with a net or tarpaulin, preferably openwork, weighted; - a grid, rigid or flexible, mounted on an arc structure connecting the holding arm 14 to the receiving device 11; and / or - horizontal plastic rails mounted on a structure connecting the holding arm 14 to the receiving device 11.

[0061] According to one embodiment, the angle formed between the longitudinal axis A3 of the ship 3 and the chord which connects the end of the guide barrier 121 located on the side of the ship and the end of the opposite guide barrier 121 spaced from the ship 3, is an acute angle preferably of the order of 30 to 75° (or 30 to 60°), for example between 45° and 60°.

[0062] Moving mechanism

[0063] The movement mechanism 13 allows the receiving device 11 to move up and down relative to the waterline of the vessel, in order to have access to the seismometer 2.

[0064] It can be provided that the movement mechanism 13 comprises a chassis connected to the ship and a control system, for example by pulley and cable connected to the reception device 11 to control the raising and lowering of the reception device 11.

[0065] According to embodiments, the lowering and raising mechanism of the receiving device 11 may comprise a crane mechanism or a moving mechanism comprising a conveyor rail.

[0066] In particular, it may be provided that the receiving device 11 is a cage mounted on a mechanized vertical rail forming the movement mechanism.

[0067] Holding arm

[0068] As described above, the recovery system 1 comprises a holding arm 14 coupled to the guide device 12.

[0069] The holding arm is oriented in a transverse direction, preferably orthogonal or almost orthogonal, to the axis A3 of the ship, to keep one end of the guide barrier 121 away from the hull of the ship 3, in order to define between the hull of the ship 3 and the guide barrier 121 a guide zone, in the manner of a funnel, so that the seabed seismometer 2 is directed by the guide barrier and the movement of the ship, towards the receiving device 11. The holding arm 14 can be coupled to the guide barrier 121 and / or to the float 122. It is possible to provide that the holding arm 14 is movable between a stowed, folded position, and a deployed position.

[0070] The system 1 comprises a cable 15 for reinforcing said holding arm 14 in the manner of a stay, and possibly for moving said arm between its deployed and folded positions when the arm is articulated.

[0071] The holding arm 14 has, for example, a length of the order of 10 to 15 meters. The length of the holding arm 14 may be adjustable, for example to adapt to the hull height of the ship 3.

[0072] Preferably, the system 1 is removable relative to the ship 3. The system can be removed from the ship using a crane which is on board the ship, called a ship of opportunity.

[0073] Recovery method

[0074] The system described above makes it possible to recover floating seabed seismometers 2. An example of the method is presented below in connection with [Fig.5].

[0075] When a seabed seismometer recovery campaign 2 is initiated, the holding arm 14 is actuated, by articulation and / or telescopically, to deploy the guidance system 12 which makes it possible to catch the seismometers on the surface on one side of the ship and guide them towards a recovery cage.

[0076] In step 510, the receiving device 11 is positioned in the water in a semi-submerged manner; the receiving device can be lowered into this semi-submerged position immediately after the end of a previous recovery of a seismometer when a seismometer to be identified has been recovered and identified.

[0077] In step 520, the ship 3 is steered so as to bring the seismometer to be recovered into the guidance corridor or channel defined between the hull of the ship 3 and the guidance device 12 of the recovery system 1.

[0078] At step 530, the ship 3 continues to move forward so that the seismometer 2 is guided by the guidance device 12 into the receiving device 11.

[0079] Once the seismometer 2 has entered the receiving device 11, the latter can be mechanically reassembled, for example by command from an operator on the deck of the ship.

[0080] Thus in step 540, the receiving device 11 is raised to allow an operator or a device present on the ship 3 to recover the seismometer 2. The seismometer can then be recovered in the receiving device 11. Once the receiving device 11 is empty, it can be returned to be lowered back to the water level in order to collect the next seismometer.

[0081] The recovery system 1 according to the invention is particularly suitable for the recovery of seabed seismometers of the MicrOBS type, the use of which for seismic surveys separates them by a distance of a few hundred meters on the seabed, so that the recovery of two successive seismometers is of the order of a few minutes.

[0082] Alternatively, the ascent of the receiving device 11 can be actuated every two or three seismometers 2 recovered, if the size of the receiving device 11 is adapted relative to the seismometers 2.

[0083] Variant

[0084] According to an alternative embodiment not illustrated, the receiving device 11 comprises a plurality of recovery modules. The movement mechanism 13 can then be configured to allow said recovery modules to be raised successively to recover the seismometers 2 collected in said recovery modules. It is thus possible to set up several recovery cages which operate successively, for example in the manner of a conveyor.

[0085] The invention is not limited to the embodiments illustrated in the drawings.

[0086] Furthermore, the term "comprising" does not exclude other elements or steps. Furthermore, features or steps that have been described with reference to one of the embodiments set forth above may also be used in combination with other features or steps of other embodiments set forth above.

Claims

Claims

1. Vessel equipped with a lateral side of a recovery system (1) for recovering a seabed seismometer (2), characterized in that the recovery system (1) comprises: - a receiving device (11), preferably perforated, capable of receiving said seismometer (2); - a guiding device (12) comprising a guiding barrier (121), which has one end coupled to the vessel (3), the guiding barrier (121) being capable of defining, with the hull of the vessel (3), a guiding zone of the seabed seismometer (2) towards the receiving device (11); and - a movement mechanism (13) configured to move the receiving device (11) between a low position in which the receiving device (11) is at least partially submerged, and a high position allowing an operator or apparatus present on the vessel (3) to recover the seabed seismometer (2) carried by the receiving device (11).

2. A vessel according to claim 1, wherein the recovery system (1) comprises a holding arm (14) coupled to the guide device (12), the holding arm (14) being oriented in a transverse direction, or capable of taking a transverse position, preferably orthogonal, to the axis (A3) of the vessel, to keep one end of the guide barrier (121) away from the hull of the vessel (3).

3. A vessel according to claim 2, wherein the system (1) comprises a cable (15) connected to the vessel (3) and to the holding arm (14) to reinforce the holding arm.

4. A vessel according to any one of claims 2 or 3, wherein the guide barrier (121) comprises a first end provided with coupling means, allowing the guide barrier (121) to be coupled, directly or indirectly, to said receiving device (11), and a second opposite end, which is optionally provided with a float (122), the holding arm (14) being coupled, directly or indirectly, to the float (122) and / or to the guide barrier (121), at said second end of the guide barrier (121).

5. A vessel according to any one of claims 2 to 4, wherein the length of the holding arm (14) is adjustable, for example to suit the hull height of the vessel (3).

6. A vessel according to any preceding claim, wherein the guide barrier (121) is equipped with flotation means (120), and has a portion which extends, below the waterline, over a height preferably at least equal to 1 meter, for example 2 meters.

7. A vessel according to any preceding claim, wherein the receiving device (11) is a cage having at least one, preferably at least two, open faces.

8. A vessel according to any preceding claim, wherein the receiving device (11) is larger than the size of the seismometer (2) to be retrieved, the receiving device (11) preferably being two to three times the size of the seismometer (2).

9. A vessel according to any preceding claim, wherein the guide barrier (121) has a concave shape as viewed from the bow of the vessel.

10. A vessel according to any preceding claim, wherein the system (1) is removable from the vessel (3).

11. Ship according to any one of the preceding claims, in which the guide barrier (121) comprises: - an inflatable tube associated with a net or a tarpaulin, preferably openwork, - a grid, rigid or flexible, mounted on an arc-shaped structure connecting a holding arm (14) to the receiving device (11), and / or - horizontal plastic rails mounted on a structure connecting a holding arm (14) to the receiving device (11).

12. A vessel according to any preceding claim, wherein the angle formed between the longitudinal axis (A3) of the vessel (3) and the chord which connects the end of the guide barrier (121) located on the side of the vessel and the end of the opposite guide barrier (121) away from the vessel (3), is an acute angle preferably of the order of 30 to 60°.

13. A vessel according to any preceding claim, wherein the receiving device (11) comprises a plurality of recovery modules, and the moving mechanism (13) is configured to enable said recovery modules to be successively raised to recover the seismometers (2) collected in said recovery modules (11).

14. A method of recovering a seabed seismometer (2) floating in the sea, using a recovery system (1) fitted laterally raking a ship (3), characterized in that the method comprises the following steps: - positioning (510) a receiving device (11) of the recovery system (1) in the water in a semi-submerged manner, the receiving device being able to be lowered into this semi-submerged position as soon as a previous recovery of a seismometer has ended when a seismometer to be recovered is identified; - directing (520) the vessel (3) so as to cause the seismometer (2) to enter the guidance zone defined between the hull of the vessel (3) and a guidance device (12) of the recovery system (1); - continue (530) to advance the vessel (3) so that the seismometer (2) is guided by the guidance device (12) into the receiving device (11), and - raise (540) the receiving device (11) to allow an operator or device present on the ship (3) to recover the seismometer (2).

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