Transducer for emitting seismic waves, system and method for performing seismic surveys from a bed of a body of water

Abstract

A transducer for emitting seismic waves configured to be installed on a bed (2) of a body of water (3) has a main body (14), which comprises a perimeter wall ( 15), which has a free edge (16) and is configured to bound together with bed (2) of body of water (3) a closed chamber (17) containing water; and a hydraulic connector (18) configured to connect main body (14) to an alternating flow source (5) so as to generate pressure waves within closed chamber (17) that propagate from bed (2) of body of water (3) in the form of seismic waves.

Description

[0001] "TRANSDUCER FOR EMITTING SEISMIC WAVES , SYSTEM AND METHOD FOR PERFORMING SEISMIC SURVEYS FROM A BED OF A BODY OF

[0002] WATER"

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This Patent Appl ication claims priority from Italian Patent Application No . 102023000022530 filed on October 26 , 2023 , the entire disclosure of which is incorporated herein by reference .

[0005] TECHNICAL SECTOR

[0006] The present invention concerns a transducer for emitting seismic waves from a bed of a body of water .

[0007] Furthermore , the present invention concerns a system and method for performing seismic surveys from a bed of a body of water .

[0008] BACKGROUND OF THE INVENTION

[0009] In order to investigate the characteristics of the subsoil , seismic survey techniques are notoriously employed, which are used, for example , in exploration and prospecting operations of hydrocarbon deposits and to monitor their evolution during the di f ferent phases of production .

[0010] In addition, the known seismic survey techniques are used for monitoring carbon dioxide storage operations at underground storage sites , in order to veri fy the structural conditions of said storage sites during the inj ection phases , as well as to control any migrations of carbon dioxide over time . In particular, the monitoring of hydrocarbon deposits and carbon dioxide storage sites requires that seismic surveys be repeated periodically in order to detect any static or dynamic changes in the deposit / storage site and in the portion of the subsoil that overlies said deposit / storage site . Said repeated seismic surveys over time are known as " 4D seismic" or " time-lapse seismic" .

[0011] The monitoring o f hydrocarbon deposits during their productive li fe allows optimi zing the exploitation plans of said deposits . In the case of carbon dioxide storage sites , said monitoring is continued beyond the end of the storage operations , in order to veri fy the containment capacity of the storage site itsel f and monitor any migration o f carbon dioxide in the subsoil and outside the storage site .

[0012] Typically, seismic survey methods involve generating, via a generator, seismic waves that propagate in the subsoil . Said waves , by crossing masses with di f ferent acoustic impedance , are reflected or refracted and can be detected by sensors appropriately placed based on the obj ectives of the seismic survey . The seismic signals acquired are subsequently processed in order to allow the creation of an acoustic map of the subsoil and then obtain detailed information on the geological characteristics of the subsoil .

[0013] In particular, such seismic survey techniques may also be employed to detect the composition and / or conformation of the subsoil from a bed of a body of water . Typically, a service vessel towing an acoustic source and one or more parallel arrays of seismic detectors (hydrophones ) are employed to perform said surveys . The activation of the acoustic source results in the propagation of waves in the water and through the bed of the body of water, in the subsoil in the form of seismic waves . Said waves are reflected and refracted in the subsoil and through the bed of the body of water they propagate again in the water until they are then detected by the hydrophones placed on the surface .

[0014] In some circumstances , it may be convenient to install the seismic detectors directly on the bed of the body of water, through nodes or through acquisition cables ( respectively "ocean bottom nodes" and "ocean bottom cables" ) . This approach brings several advantages , including the possibility of obtaining a better quality of the detected seismic signal , the ability to detect shear waves that cannot be acquired through hydrophones and an improvement in the monitoring capabilities of the deposits over time .

[0015] Commonly used acoustic sources exploit the implosion of air bubbles in the body of water, generating acoustic pulses of relatively short duration and characteri zed by a relatively broad frequency spectrum . In particular, several devices are known, each of which produces characteristic acoustic footprints . By way of example , compressed air mechanical systems or " air guns" are commonly used, or, alternatively, said air bubbles can be created by the heat generated by an electric discharge in water ( " sparkers" ) or by the cavitation caused by the rapid movement of plates ( "boomers " ) .

[0016] In the seismic surveys conducted in a body of water, the electrical signal useful for generating a signi ficant seismic impulse requires a considerable amount of energy, such as to counteract the energy dispersions and di ssipations that are required when crossing the body of water itsel f . In the case of acoustic sources , especially i f close to the surface of the body of water, i . e . far from the bed of the body of water, the energy ef ficiency is very low due to the dissipations and dispersions in the body of water itsel f .

[0017] For this reason, the energy released by the acoustic sources placed near the surface of the body of water is necessarily high and causes strong noise pollution, negatively impacting the lives of numerous underwater organisms .

[0018] In addition, the high costs associated with the use of service vessels , in addition to the problems related to the safety of the personnel employed on said vessels , lead to limiting the number of seismic survey campaigns , to the detriment of the opportunities to frequently monitor the deposits .

[0019] To overcome the drawbacks highlighted above , the technique of using sources of vibratory seismic waves carried by underwater vehicles and placed near the bed of the body of water is known . However, this technique has poor repeatability and the seismic signal detected is often disturbed .

[0020] A further known technique consists in placing seismic wave sources within extraction or inj ection wells of underground deposits . However, the number and the arrangement of the seismic wave sources depends on the availability of said wells . This factor may limit the development of a matrix of seismic wave sources that allows performing seismic surveys of the deposit in its entirety . In addition, in the case of some sites for the storage of carbon dioxide , such as saline aqui fer sites , the presence of wells is typically very scarce . OBJECT OF THE PATENT

[0021] An aim of the present invention is to provide a transducer for emitting seismic waves from a bed of a body of water that is able to overcome the drawbacks of the prior art .

[0022] In particular, the main obj ects of the present invention are to limit the environmental impact due to noise pollution, to improve the repeatability of the seismic surveys , and to reduce the costs of the periodic campaigns .

[0023] In accordance with the present invention there is provided a transducer for emitting seismic waves , the transducer being configured to be installed on a bed of a body of water and comprising a main body, which comprises : a perimeter wall , which has a free edge and is configured to delimit together with the bed of the body of water a closed chamber containing water ; and

[0024] - a hydraulic connector configured to connect the main body to an alternating flow source so as to generate pressure waves within the closed chamber that propagate from the bed of the body of water in the form of seismic waves .

[0025] Thanks to the present invention, it is possible to emit seismic waves from a bed of a body of water in a simple , economical , reliable and low environmental impact manner .

[0026] Since the transducer is installable directly on the bed of the body of water, it is possible to emit seismic waves from the bed of the body of water releasing a limited energy and consequently reducing the noise pollution of the body of water .

[0027] Furthermore , it is possible to install each transducer in a desired position on the bed o f the body of water so as to allow a high repeatability of the collection of seismic data and facilitate the continuous monitoring of the deposits .

[0028] In particular, the transducer is configured to emit seismic waves within a wide frequency band, for example ranging from 5 Hz to 100 Hz , of modulable amplitude .

[0029] In particular, the perimeter wall is configured to penetrate at least partially into the bed of the body of water .

[0030] In this way, it is possible to insert the transducer into the bed of the body of water .

[0031] In particular, the main body comprises an upper wall connected to the perimeter wall , and a lower opening, which is opposite to the upper wall and is bounded by the free edge of the perimeter wall .

[0032] In practice , the main body assumes the configuration of a bell partially fitted to the bed of the body of water .

[0033] In particular, the perimeter wall is substantially cylindrical in shape .

[0034] In particular, the hydraulic connector has a connecting opening configured to hydraulically connect the closed chamber to the alternating flow source so as to generate pressure waves within the closed chamber that propagate from the bed of the body of water in the form of seismic waves .

[0035] In particular, the pressure waves are generated solely by the volume changes in the closed chamber determined by the alternating flow source , without the need to provide vibrating masses that transmit vibrations to the bed of the body of water .

[0036] In other words , the alternating flow source is configured to determine cyclic volume changes within the closed chamber, so as to propagate from the bed of the body of water longitudinal seismic waves having a direction predominantly perpendicular to the surface of the bed of the body of water .

[0037] In particular, the main body is devoid of moving components .

[0038] In this way, the simplicity and reliability of the transducer can be increased . In accordance with a further embodiment , the transducer comprises a flexible pouch, which is arranged within the closed chamber, i s configured to contain water under pressure and is in hydraulic communication with the hydraulic connector such that , in use , the alternating flow source controls an expansion and a contraction of the flexible pouch .

[0039] In this way, it is possible to emit seismic waves in a simple and economical way even on a bed of a body of water having soil with high permeability .

[0040] In other words , at a bed of the body of water with high permeability, it is possible to prevent the volume changes induced in the closed chamber from causing permeations in the bed of the body of water, reducing the energy e f ficiency of the transducer and possibly causing soil erosion phenomena .

[0041] A further obj ect of the present invention is to provide a seismic source for performing seismic surveys from a bed of a body of water that allows to overcome or at least mitigate the described drawbacks .

[0042] In accordance with the present invention there is provided a seismic source for emitting seismic waves from a bed of a body of water, the seismic source comprising :

[0043] - the transducer as previously described; and

[0044] - an alternating flow source , which is connected to the main body of the transducer via the hydraulic connector and is configured to generate pressure waves within the closed chamber that propagate from the bed of the body of water in the form of seismic waves .

[0045] In particular, the alternating flow source comprises at least one volumetric machine , which is hydraulically connected to the hydraulic connector and is configured to generate alternating volume changes within the closed chamber .

[0046] A further obj ect of the present invention is to provide a system for performing seismic surveys from a bed of a body of water that allows to overcome or at least mitigate the described drawbacks .

[0047] In accordance with the present invention there is provided a system for performing seismic surveys from a bed of a body of water, the system comprising :

[0048] - a seismic source as previously described; an energy source , which is configured to supply electrical energy to the alternating flow source ; and

[0049] - a control device , which is configured to control the alternating flow source .

[0050] In particular, the system comprises an unmanned underwater vehicle configured to control the energy source that supplies energy to the alternating flow source .

[0051] In accordance with one embodiment , the alternating flow source is integral with the main body and is preferably coupled to the main body outside the closed chamber .

[0052] In accordance with an alternative embodiment , the alternating flow source is coupled to the unmanned underwater vehicle .

[0053] In this way, the underwater vehicle can transport the alternating flow source into the body of water and, i f necessary, can connect the alternating flow source to the transducer .

[0054] A further obj ect of the present invention is to provide a method for performing seismic surveys from a bed of a body of water that allows to overcome or at least mitigate the described drawbacks .

[0055] In accordance with the present invention, a method for performing seismic surveys from a bed of a body of water is reali zed, the method comprising the steps of :

[0056] - installing a main body of a transducer to emit seismic waves on the bed of the water body so as to delimit a closed chamber containing water between the main body and the bed of the body of water ; connecting the main body to an alternating flow source ; and

[0057] - feeding and controlling the alternating flow source so as to generate volume changes within the closed chamber that propagate from the bed of the body of water in the form of seismic waves .

[0058] BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Further features and advantages of the present invention will become clear from the following description of a non-limiting embodiment example , with reference to the accompanying Figures , wherein :

[0060] Figure 1 is a side elevational view, with parts removed for clarity' s sake and parts schemati zed, of a system for performing seismic surveys from a bed of a body of water reali zed in accordance with the present invention;

[0061] Figure 2 is a side elevational view, with parts removed for clarity ' s sake , parts schemati zed and parts in section, of a detail of the system of Figure 1 ;

[0062] - Figures 3-5 are side elevational views , with parts removed for clarity ' s sake , parts schemati zed and parts in section, of the detail of Figure 2 reali zed in accordance with respective variants of the present invention;

[0063] - Figure 6 is a sectional view, with parts removed for clarity ' s sake , of a transducer of the system of Figure 1 ;

[0064] - Figure 7 is a sectional view, with parts removed for clarity ' s sake , of the transducer of Figure 5 realized in accordance with a variant of the present invention; and

[0065] - Figure 8 is a schematic view of a dynamic behaviour of the transducer of Figure 5 .

[0066] DETAILED DESCRIPTION OF THE FIGURES

[0067] With reference to Figure 1 , number 1 denotes as a whole a system for performing seismic surveys from a bed 2 of a body of water 3 comprising a seismic source 13 conf igured to emit seismic waves from bed 2 of body of water 3 .

[0068] In particular, seismic source 13 comprises a transducer 4 for emitting seismic waves and an alternating flow source 5 . System 1 further comprises an unmanned underwater vehicle 6 , which is configured to control and / or transport and / or supply alternating flow source 5 .

[0069] In the case described and shown herein, underwater vehicle 6 is an ROV and system 1 comprises a support vessel 7 and a connection group 8 for electrically connecting and exchanging signals of underwater vehicle 6 to support vessel 7 .

[0070] Within the scope of this description, the term "ROV" means a Remote Operated Vehicle .

[0071] In particular, connection group 8 comprises a cable management system 9 , which is configured to be arranged in body of water 3 ; a connection cable 10 for electrically connecting and for data exchange o f underwater vehicle 6 to cable management system 9 ; and an umbilical cable 11 for electrically connecting and for data exchange cable management system 9 to support vessel 7 .

[0072] In accordance with an alternative embodiment , not shown in the attached figures , underwater vehicle 6 can be an "Autonomous Underwater Vehicle" (AUV) or an underwater vehicle of any other type .

[0073] Furthermore , system 1 comprises at least one detector 12 , which is configured to detect seismic waves reflected from bed 2 of body of water 3 .

[0074] In the case described and shown herein, not limiting the present invention, system 1 comprises a plurality of transducers 4 and a plurality of detectors 12 , which are in communication with each other and are installed on bed 2 of body of water 3 .

[0075] In practice , each detector 12 is configured to detect the seismic waves generated by transducer 4 .

[0076] With reference to Figure 2 , transducer 4 comprises a main body 14 , which comprises a perimeter wall 15 , which has a free edge 16 and is configured to delimit together with bed 2 of body of water 3 a closed chamber 17 containing water ; and a hydraulic connector 18 configured to connect main body 14 to alternating flow source 5 so as to generate pressure waves within closed chamber 17 that propagate from bed 2 of body of water 3 in the form of seismic waves .

[0077] In the case shown in Figure 2 , alternating flow source

[0078] 5 comprises a volumetric machine , such as a volumetric pump . Hydraulic connector 18 hydraulical ly connects closed chamber 17 to alternating flow source 5 .

[0079] In accordance with a non-limiting embodiment of the present invention, alternating flow source 5 is configured to emit , through the transducer, seismic waves at a frequency ranging from 6 Hz to 60 Hz .

[0080] In particular, alternating flow source 5 is integral with underwater vehicle 6 . In particular, underwater vehicle

[0081] 6 comprises a module 19 provided with alternating flow source 5 and a connection element 20 , and a manipulator 21 configured to connect connection element 20 to hydraulic connector 18 of transducer 4 .

[0082] In the case described and shown herein, connection element 20 comprises a hydraulic connection tube .

[0083] In accordance with an embodiment not shown in the attached Figures , connection element 20 comprises a hydraulic hose and / or electrical cables configured to supply sensors and / or integrated control devices in communication with alternating flow source 5 .

[0084] In addition, system 1 comprises an energy source 30 , such as an electric battery, which is configured to supply electrical energy to alternating flow source 5 ; and a control device 31 , which is configured to control alternating flow source 5 , in particular to control the operating frequency of alternating flow source 5 .

[0085] In the case described and shown herein, not limiting the present invention, energy source 30 and control device 31 are connected to underwater vehicle 6 . In such a configuration, energy source 30 is configured to transmit energy to alternating flow source 5 through underwater vehicle 6 and control device 31 is configured to transmit a control signal to alternating flow source 5 through underwater vehicle 6 so as to control a volume change within closed chamber 17 .

[0086] In practice , underwater vehicle 6 is configured to transmit electric power to energy source 30 and alternating flow source 5 and to transport alternating flow source 5 into body of water 3 and, i f neces sary, connect alternating flow source 5 to transducer 4 via connection element 20 .

[0087] With reference to Figure 3 , system 1 reali zed in accordance with a variant of the present invention is shown .

[0088] In the case shown in Figure 3 , alternating flow source 5 is integral with main body 14 and is coupled to main body 14 outside closed chamber 17 . Hydraulic connector 18 hydraulically and / or mechanically connects alternating flow source 5 to transducer 4 .

[0089] In practice , alternating flow source 5 is removed from underwater vehicle 6 and is installed on main body 14 of transducer 4 .

[0090] In accordance with this embodiment , energy source 30 and control device 31 are connected to underwater vehicle 6 , which is configured to transport energy source 30 and control device 31 in body of water 3 .

[0091] With reference to Figure 4 , system 1 reali zed in accordance with a further variant of the present invention is shown .

[0092] In the case shown in Figure 4 , alternating flow source

[0093] 5 and energy source 30 are integral with main body 14 and are coupled to main body 14 outside closed chamber 17 . In practice , energy source 30 is removed from underwater vehicle

[0094] 6 and is installed on main body 14 of transducer 4 .

[0095] In accordance with this embodiment , control device 31 is connected to underwater vehicle 6 , which is configured to transport control device 31 in body of water 3 .

[0096] With reference to Figure 5 , system 1 reali zed in accordance with a further variant of the present invention is shown . In the case shown in Figure 5 , alternating flow source 5 , energy source 30 and control device 31 are integral with main body 14 and are coupled to main body 14 outside closed chamber 17 . In practice , control device 31 is removed from underwater vehicle 6 and is installed on main body 14 of transducer 4 .

[0097] With reference to Figure 6 , main body 14 comprises an upper wall 24 connected to perimeter wall 15 , and a lower opening 25 , which is opposite to upper wall 24 and is bounded by free edge 16 of perimeter wall 15 .

[0098] In practice , upper wall 24 and perimeter wall 15 define a shell 26 , which is provided with lower opening 25 and encloses closed chamber 17 together with bed 2 of body of water 3 . In other words , main body 14 is shaped as an upturned cup .

[0099] In particular, perimeter wall 15 is configured to penetrate at least partially into bed 2 of body of water 3 . In more detail , free edge 16 has a chisel-like end 27 configured to facilitate the penetration of perimeter wall 15 into bed 2 of body of water 3 .

[0100] In accordance with a non-limiting embodiment of the present invention, perimeter wall 15 is substantially cylindrical in shape and extends around a longitudinal axis Al .

[0101] In accordance with a non-limiting embodiment of the present invention, upper wall 24 comprises a substantially flat plate 28 and houses hydraulic connector 18 . In particular, hydraulic connector 18 is provided with a connection opening 29 passing through plate 28 . In more detail , hydraulic connector 18 is of the "hot stab" type .

[0102] In practice , in the case described and shown herein, main body 14 is devoid of moving components .

[0103] Referring to Figure 7 , a transducer 32 reali zed in accordance with a further embodiment of the present invention is shown .

[0104] Transducer 32 comprises a flexible pouch 33 , which is disposed within closed chamber 17 , is configured to contain water and is in hydraulic communication with hydraulic connector 18 such that , in use , alternating flow source 5 controls an expansion and a contraction of flexible pouch 33 .

[0105] In accordance with one embodiment , flexible pouch 33 has a bellows shape and is configured to expand and contract in a direction substantially parallel to the longitudinal axis Al .

[0106] In use and with reference to Figure 2 , underwater vehicle 6 transports transducer 4 in body of water 3 and places transducer 4 in a certain position on bed 2 of body of water 3 .

[0107] When it is necessary to emit seismic waves from bed 2 of body of water 3 , underwater vehicle 6 connects connecting element 20 to hydraulic connector 18 so as to hydraulically connect alternating flow source 5 to closed chamber 17 .

[0108] At this point , control device 31 commands the activation of alternating flow source 5 , which substantially causes a volume change within closed chamber 17 . The volume change of closed chamber 17 corresponds to the vibratory motion induced to bed 2 of body of water 3 by means of transducer 4 . In particular, alternating flow source 5 generates , through the transducer, seismic waves at a frequency ranging from 6 Hz to 60 Hz .

[0109] Referring to Figure 8 , seismic waves are generated by applying a force F to the surface of bed 2 of body of water 3 .

[0110] The force F is proportional to the pressure P within closed chamber 17 which corresponds to an equal and opposite reaction that is attributable to the mass m of transducer 4 and to the interaction between transducer 4 and bed 2 of body of water 3 .

[0111] In other words :

[0112] F = P A = mx + rx + kx wherein the parameter A represents the area of bed 2 of body of water 3 comprised within closed chamber 17 , the parameter r represents the damping coef ficient of bed 2 of body of water 3 , the parameter k represents the elastic coe f ficient of bed 2 of body of water 3 , and the variable x represents the displacement of transducer 4 in a substantially vertical direction .

[0113] Finally, it is evident that variations can be made to the present invention without however leaving the scope of protection of the appended claims .

Claims

CLAIMS1. A transducer for emitting seismic waves, the transducer (4; 32) being configured to be installed on a bed (2) of a body of water (3) and comprising a main body (14) , which comprises:- a perimeter wall (15) , which has a free edge (16) and is configured to delimit together with the bed (2) of the water body (3) a closed chamber (17) containing water; and- a hydraulic connector (18) configured to connect the main body (14) to an alternating flow source (5) so as to generate pressure waves within the closed chamber (17) that propagate from the bed (2) of the body of water (3) in the form of seismic waves.

2. The transducer as claimed in Claim 1, wherein the perimeter wall (15) is configured to penetrate at least partially into the bed (2) of the body of water (3) .

3. The transducer as claimed in Claim 1 or 2, wherein the perimeter wall (15) is substantially cylindrical in shape .

4. The transducer as claimed in any one of the foregoing Claims, wherein the main body (14) comprises an upper wall (24) connected to the perimeter wall (15) , and a lower opening (25) , which is opposite to the upper wall (24) and is bounded by the free edge (16) of the perimeter wall (15) .

5. The transducer as claimed in Claim 4, wherein the upper wall (24) comprises a plate (28) and houses thehydraulic connector (18) .

6. The transducer as claimed in any one of the foregoing Claims, wherein the main body (14) is shaped as an upturned cup.

7. The transducer as claimed in any one of the foregoing Claims, wherein the hydraulic connector (18) has a connecting opening (29) configured to hydraulically connect the closed chamber (17) to the alternating flow source (5) so as to generate pressure waves within the closed chamber (17) that propagate from the bed (2) of the body of water (3) in the form of seismic waves.

8. The transducer as claimed in any one of the foregoing Claims, wherein the transducer (4; 32) has no moving components.

9. The transducer as claimed in any one of Claims 1 to 7, and comprising a flexible pouch (33) , which is disposed within the closed chamber (17) , is configured to contain water, and is in hydraulic communication with the hydraulic connector (18) such that, in use, the alternating flow source (5) controls an expansion and a contraction of the flexible pouch (33) .

10. A se ismic source for emitting seismic waves from a bed of a body of water, the seismic source (13) comprising:- the transducer (4; 32) as claimed in any one of the foregoing Claims; and- an alternating flow source (5) , which is connected to the main body (14) of the transducer (4; 32) via thehydraulic connector (18) and is configured to generate pressure waves within the closed chamber (17) that propagate from the bed (2) of the body of water (3) in the form of seismic waves.

11. The seismic source as claimed in Claim 10, wherein the alternating flow source (5) comprises at least one volumetric machine, which is hydraulically connected to the hydraulic connector (18) and is configured to generate alternating volume changes within the closed chamber (17) .

12. A system for performing seismic surveys from a bed of a body of water, the system (1) comprising:- a seismic source (13) as claimed in Claim 10 or 11;- an energy source (30) , which is configured to supply electrical energy to the alternating flow source (5) ; and- a control device (31) , which is configured to control the alternating flow source (5) .

13. The system as claimed in Claim 12, and comprising an unmanned underwater vehicle (6) configured to control the energy source (30) that supplies energy to the alternating flow source (5) .

14. The system as claimed in Claim 13, wherein the alternating flow source (5) is coupled to the underwater vehicle (6) and is configured to be transported in the body of water (3) by the underwater vehicle (6) .

15. The system as claimed in Claim 13 or 14, wherein the energy source (30) and / or the control device (31) are coupled to the underwater vehicle (6) .

16. The system as claimed in Claim 12 or 13, wherein the alternating flow source (5) is integral with the main body (14) and is preferably coupled to the main body (14) outside the closed chamber (17) .

17. The system as claimed in Claim 16, wherein the energy source (30) and / or the control device (31) are integrally coupled to the main body (14) .

18. The system as claimed in any one of Claims 12 to 17, and comprising at least one detector (12) , which is configured to detect seismic waves and preferably to be installed on the bed (2) of the body of water (3) .

19. A method for performing seismic surveys from a bed of a body of water, the method comprising the steps of:- installing a main body (14) of a transducer (4) to emit seismic waves on the bed (2) of the water body (3) so as to delimit a closed chamber (17) containing water between the main body (14) and the bed (2) of the body of water (3) ;- connecting the main body (14) to an alternating flow source ( 5 ) ; and- feeding and controlling the alternating flow source (5) so as to generate volume changes within the closed chamber (17) that propagate from the bed (2) of the body of water (3) in the form of seismic waves.

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