Wave signal acquisition device, preferably a seismic acquisition device

Abstract

The invention relates to a wave signal acquisition device, preferably a seismic acquisition device, comprising a housing (1); a wave sensor system housed inside the housing (1) and coupled to the bottom wall of the housing. The housing (1) is provided with an acoustic black hole (2) made of polymer, preferably flexible, so as to absorb parasitic wave frequencies below 500 Hz, preferably below 400 Hz. Figure for the abstract: Fig. 5

Description

Title of the invention: Wave signal acquisition device, preferably a seismic acquisition device. FIELD OF THE INVENTION

[0001] The present invention relates generally to vibro-acoustic wave acquisition devices, particularly for seismic applications, especially for use in geoscience or geophysical exploration.

[0002] The invention relates in particular to a seismic acquisition device comprising in particular a wave signal sensor and an acoustic black hole. EARLIER ART

[0003] The acquisition and processing of seismic data generate a profile (image) of a geophysical structure beneath the ground surface, known as the subsurface, for example, for natural resource exploration. In particular, although this profile does not provide a precise location of oil and gas reservoirs, it suggests, to those trained in the field, the presence or absence of such reservoirs. Thus, providing a high-resolution image of the subsurface is important, for example, for those who need to determine where oil and gas reservoirs are located or, conversely, areas where carbon can be stored.

[0004] Reflection seismology is a geophysical exploration method that relies on the use of a controlled energy source that sends energy into the ground. By measuring the time it takes for reflections to return to several receivers, it is possible to assess the depth of the ground features causing these reflections. These features may be associated with underground hydrocarbon deposits or other subsurface configurations, such as cavities forming under railway lines.

[0005] A seismic acquisition system for recording the reflections of seismic waves, caused by geological structures present in the subsoil, uses seismic acquisition devices, also called seismic nodes.

[0006] 11 It is of course desirable that the seismic acquisition device has a limited size (bulk) and weight, especially since some research campaigns use several thousand devices in hard-to-reach places.

[0007] An autonomous seismic node is described, for example, in the application WO2021 / 048629. Although this seismic node provides reliable results, it appears that the external environment generates vibrational and acoustic disturbances towards the enclosure, i.e., noise. Some of these disturbances have a frequency that includes in, or close to, the frequency band useful for the source data, for example frequencies below 400Hz.

[0008] The problem of interference from noise from the external environment, as well as the need for a small size and limited weight, also arise for a wave acquisition device in the context of applications other than seismic, for example for monitoring the condition of an infrastructure such as a bridge.

[0009] It is known in the prior art to use an acoustic black hole to dampen acoustic energy in the field of sound insulation.

[0010] However, the activation frequencies of acoustic black holes used in the field of sound insulation (specific frequencies from which acoustic black holes begin to work effectively to absorb waves) are high and therefore do not allow the absorption of acoustic waves generated by the environment in which the housing is located, in particular in the frequency band 0 - 400 or 0 - 500 Hz which corresponds to the frequency band of use of seismic sensors.

[0011] The present invention aims to provide a new device that addresses, at least partially, one or more of the problems described above. Summary of the invention

[0012] For this purpose, the invention relates to a wave signal acquisition device, preferably a seismic acquisition device, comprising: - a housing; - a wave sensor system, preferably a seismic sensor system, housed inside the casing and coupled to the bottom wall of the casing; characterized in that the case is equipped with an acoustic black hole, the acoustic black hole being made of polymer, preferably flexible, so as to absorb parasitic wave frequencies below 500Hz, preferably below 400Hz.

[0013] Such a design of the acquisition device makes it possible to filter the mechanical, or vibro-acoustic, waves of a noisy external environment which propagate through the peripheral and possibly upper wall of the housing, so as to remove or attenuate the acoustic disturbances, and to be able to acquire the signal transmitted by the ground without interference in the frequency band of interest of the vibratory waves acquired by the sensor system.

[0014] Indeed, the implementation of an acoustic black hole made of polymer, preferably flexible, makes it possible to cut off the low frequencies of parasitic waves emitted by the environment that the housing receives, which makes it possible to improve the quality of the signals, preferably Seismic data is acquired by the sensor, preferably a seismic sensor, coupled to the housing. The device's acoustic black hole allows for the suppression of parasitic frequencies within a given frequency band, preferably between 0 and 500 Hz, for example between 0 and 400 Hz.

[0015] Thus, the acquisition by the sensor system of the frequencies of interest in the intended application, in particular the frequencies below 400 Hz, preferably below 150 Hz, of seismic waves, is not disturbed by external noise whose frequency band corresponding to the frequency band of interest of the signals acquired by the sensor system has been filtered by the acoustic black hole.

[0016] The use of a polymer to make the acoustic black hole with which the case is equipped makes it possible to cut the vibration frequencies of the case for a frequency of use below kHz.

[0017] The acoustic black hole thus makes it possible to isolate the device housing from external noise on the frequency band of interest in order to improve the signal, efficiently and while maintaining a device of limited size and weight.

[0018] The device's housing is adapted to capture waves from the ground, while being robust enough to withstand the stresses of the working environment. In particular, the housing exhibits greater rigidity than the acoustic black hole.

[0019] The housing of the device thus retains sufficient solidity (hardness) to allow the transmission of vibrations from the ground to the sensor system, and allows the acquisition device to be sufficiently resistant to tolerate environmental constraints, both due to their long-term use in demanding outdoor conditions and the conditions of installation.

[0020] The device may also include one or more of the following features taken in any technically feasible combination.

[0021] According to one embodiment, the polymer in which the acoustic black hole is made has a Young's modulus less than or equal to 10 MPa, preferably less than or equal to 5 MPa.

[0022] According to one embodiment, the polymer in which the acoustic black hole is made is an elastomer, for example silicone, a butadiene-acrylonitrile copolymer (NBR) or rubber, or a thermoplastic elastomer (TPE).

[0023] According to one embodiment, the acoustic black hole is housed, preferably by overmolding, in a wall of the housing by presenting an active surface, preferably concave, directed towards the inside or outside of the housing.

[0024] According to one embodiment, the acoustic black hole is added as an element attached to an external surface or to an internal surface of the housing.

[0025] According to one embodiment, an air pocket is maintained between the acoustic black hole and the housing.

[0026] According to one embodiment, the acoustic black hole comprises a main surface which has an active area of ​​generally concave shape, preferably of parabolic shape.

[0027] According to one embodiment, the acoustic black hole has a main surface of variable thickness with a thinning in the central part.

[0028] According to one embodiment, the housing is made of polymer material.

[0029] According to one embodiment, the peripheral contour of the acoustic black hole is round shape.

[0030] The invention also relates to the use of the wave signal acquisition device, preferably a seismic acquisition device, according to any of the preceding embodiments, in the field of geoscience or for the monitoring of structures or monuments, in particular for terrestrial seismic use. Brief description of the drawings

[0031] Other features and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting and should be read in conjunction with the accompanying drawings, on which:

[0032] - [Fig. 1] [Fig. 1] is a cross-sectional view of a seismic acquisition device according to the invention;

[0033] - [Fig.2] [Fig.2] is a perspective view of the acoustic black hole of the device seismic acquisition of the [Fig.l];

[0034] - [Fig.3] [Fig.3] is a cross-sectional view of the acoustic black hole of [Fig.2] according to the cutting zone III;

[0035] - [Fig.4] [Fig.4] is a perspective view of a variant of the device seismic acquisition according to another embodiment of the invention;

[0036] - [Fig. 5] [Fig. 5] is a perspective view of a variant of the device seismic acquisition according to another embodiment of the invention;

[0037] - [Fig.6] [Fig.6] is a cross-sectional view of [Fig.5] along section area VI. DETAILED DESCRIPTION

[0038] Embodiments are described below with reference to the accompanying drawings. Similar numbers refer to similar features in all drawings. However, the invention can be implemented in many different forms and should not be construed as being limited to the embodiments shown here. The scope of the invention is defined by the accompanying claims.

[0039] A reference throughout the specification to "an embodiment" means that a particular functionality, structure, or feature described in relation to an embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the expression "in an embodiment" in various Locations throughout the specification do not necessarily refer to the same embodiment. Furthermore, functionalities, structures, or particular characteristics may be combined in any suitable way in one or more embodiments.

[0040] With reference to the figures, a seismic acquisition device 10 is shown. The description is also applicable to vibro-acoustic signal acquisition devices for applications other than seismic surveying, in particular for applications other than geophysical exploration. Vibro-acoustic signals may also be referred to as vibrational and / or acoustic signals, or wave signals, for the remainder of this description. Other applications may include the monitoring of infrastructure such as bridges by acquiring vibrational signals transmitted to the device by the structure, or any geophysical study aimed, for example, at decarbonization.

[0041] The terms "lower" and "upper", as well as "below", "above" or other similar relative term, are defined by reference to the ground-positioned state of the enclosure with the bottom wall of the enclosure in contact with the ground.

[0042] As detailed below, the seismic acquisition device includes an acoustic black hole 2 adapted to filter the low frequencies of interest in the intended application, which in the following description is seismic.

[0043] The seismic acquisition device 10 comprises a housing 1 in which is housed a seismic sensor system 3 and which is equipped with the acoustic black hole 2. The seismic acquisition device 10 can be used in the field of geoscience and for monitoring the condition of structures or monuments, such as bridges, in particular for terrestrial seismic use.

[0044] In the case of a two-dimensional configuration, an acoustic black hole is thus generally presented in the form of a body of decreasing thickness, preferably from an outer peripheral edge towards the center of the body, so as to form a concave active surface, which can dampen acoustic waves in at least one direction of wave movement.

[0045] In the example of [Fig.1], the housing 1 has an upper wall 11, a lower wall 12 and at least one side wall 13 (peripheral wall) connecting the upper wall 11 and lower wall 12.

[0046] The lower wall 12 can be provided with a base, or even with a spike 14 configured to be planted in a soil S and thus allow the device 10 to be held in place.

[0047] The sensor system 3 is preferably positioned on an inner surface 121 of the lower wall 12.

[0048] The seismic sensor system 3 is coupled with the lower wall 12 of the housing 1, which is intended to be in contact with the ground S subjected to the waves and / or vibrations of which We wish to be able to acquire the corresponding signals. By "coupled," we mean "acoustic" coupling, that is, an arrangement of the seismic sensor system 3 with the lower wall 12 of the housing 1 such that a wave incident on the lower wall 12 of the housing 1 is transmitted through the lower wall 12 of the housing 1 to the seismic sensor system 3. The seismic sensor system 3 can thus be in direct or indirect contact with the lower wall 12 of the housing 1.

[0049] Thus, when the lower wall 12 of the housing 1 is in contact with the ground, the seismic acquisition device 10 allows the acquisition with the sensor system 3 of signals corresponding to waves coming from the ground and transmitted by the lower wall 12 of the housing 1 to the sensor system 3.

[0050] The sensor system 3 may comprise one or more sensors, for example a triaxial seismic sensor. The seismic sensor system is preferably a micro-electromechanical system (MEMS).

[0051] The sensor system 3 is connected to a processing unit which allows the acquired signals to be processed to generate seismic data which can be recorded in a memory housed in the casing and / or transmitted by radio link to a remote receiver, using a radio communication module of the processing unit.

[0052] At least the bottom wall of the housing has a rigidity suitable for transmitting waves from the ground to the sensor system. The housing is, for example, made of polyurethane or polyamide type plastic.

[0053] The housing, or seismic sensor system, used may be a housing, or seismic sensor system, of the type described in application WO2021 / 048629.

[0054] As illustrated in particular in the view of [Fig.2], in the state not yet applied to the housing 1, the acoustic black hole 2 has a main surface 15 of generally concave shape, preferably of parabolic shape.

[0055] The peripheral contour 16 of the acoustic black hole 2 is preferably round. Other shapes are possible. The shape of the acoustic black hole 2 is suitable for integration on or in a wall of the device housing 1.

[0056] According to one embodiment, the acoustic black hole 2 is made of a flexible polymer material to have very low operating frequencies between 0 and 400 Hz. For example, the acoustic black hole 2 is made of silicone or TPE and has a Young's modulus of less than or equal to 1 MPa, preferably less than or equal to 5 MPa.

[0057] In a preferred embodiment, the housing 1 is also made of polymer material. The acoustic black hole 2 can thus be attached to the housing 1 by Various suitable methods exist for bonding plastics. Other solutions are possible, regarding the choice of materials and the bonding process.

[0058] The housing can be made of a material, in particular a polymer, having a Young's modulus greater than or equal to 3000 MPa, better greater than or equal to 5000 MPa, better still greater than or equal to 8000 MPa.

[0059] The use of the acoustic black hole 2 makes it possible to filter out parasitic waves, preferably between 0 and 500 Hz, for example between 0 and 400 Hz. By absorbing or attenuating the low frequencies of the waves to which the peripheral wall and / or the upper wall of the housing is exposed, the acoustic black hole 2 allows the sensor system 3 to acquire the signals corresponding to the waves transmitted by the ground through the bottom wall 12, without interference from the low frequencies of the noise waves of the surrounding medium, which are distinct from the waves transmitted by the ground useful for the seismic application.

[0060] In the illustrated example, the acoustic black hole 2 has a diameter D of 45 mm and a maximum thickness emax of 3 mm.

[0061] As illustrated in the view of [Fig.3], the main surface 15 of the acoustic black hole 2 has a variable thickness e, preferably, in cross-sectional view, a thinning from the outside to the inside of the acoustic black hole 2.

[0062] This variation in thickness allows the formation of an active zone 17 on the acoustic black hole 2, enabling the absorption of unwanted acoustic waves. To be functional, the active zone 17 must retain a sufficient degree of freedom. Thus, the active zone 17 is preferably kept away from any rigid element of the housing 1 to allow it to vibrate and absorb unwanted acoustic waves. In other words, the active zone 17, which in this example includes the center 18 of the acoustic black hole 2, is free from deformation.

[0063] In the example illustrated in the view of [Fig.1], the acoustic black hole 2 is positioned on an internal surface 1II of the upper wall 11. The acoustic black hole 2 is, for example, added as a patch (add-on part) in the housing 1, for example an existing housing, thus improving the performance of existing or installed housings.

[0064] According to another embodiment illustrated in the view of [Fig.4], the acoustic black hole 2 is added as a patch to a housing 1 on the outer surface 13E of the side wall 13, in particular for existing housings.

[0065] The acoustic black hole 2, when brought in patch form, can thus be mounted on the housing 1 or inside the housing 1.

[0066] In the embodiments of figures 1 and 4, the acoustic black hole 2 includes a peripheral rim 21 (forming in top view of the acoustic black hole a peripheral ring) itself fixed to the housing 1.

[0067] The peripheral border 21 has a thickness ea greater than or equal to the maximum thickness emax of the acoustic black hole 2.

[0068] In the embodiments of figures 1 and 4, an air pocket 20 is preferably formed between the active zone 17 and the housing 1. This air pocket 20 thus allows the free deformation of the active zone 17 to allow it to vibrate in order to absorb the parasitic waves.

[0069] In this example, the air pocket 20 has a maximum thickness ep at least equal to, and in particular greater than, the maximum thickness emax of the acoustic black hole 2, which allows the acoustic black hole 2 to vibrate and thus be effective.

[0070] The concavity of the acoustic black hole 2 is oriented towards the housing 1 so that the air pocket 20 is formed between the main concave surface 15 of the acoustic black hole 2 and the surface of the wall of the housing 1 on which the acoustic black hole 2 is applied.

[0071] According to another embodiment, illustrated in the views of figures 5 and 6, the acoustic black hole 2 is overmolded to the housing 1 in a wall of the housing, in this example on the upper wall 11, in a housing 25 which opens onto the outside of the housing 1.

[0072] The housing 25 thus forms a reserved space in the housing 1 to house the acoustic black hole 2. In particular, the peripheral edge 21 is attached to the inner peripheral face 27 of the housing 25. The acoustic black hole 2 is then visible from outside the housing.

[0073] The processing unit (not shown) is, for example, in the form of a processor and a data memory in which computer instructions executable by said processor are stored, or in the form of a microcontroller.

[0074] The invention is not limited to the embodiments illustrated in the drawings.

[0075] Furthermore, the term "including" does not exclude other elements or steps. In addition, 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 from other embodiments set forth above.

[0076] It can also be expected that the device will have irregular shapes.

[0077] The use of several acoustic black holes, particularly those of different sizes, shapes, and / or materials, can provide different cutoff frequency ranges. This allows for a wider operating range. The acoustic black hole can also be reinforced.

Claims

Demands

1. A wave signal acquisition device (10), preferably a seismic acquisition device, comprising: a housing (1); a wave sensor system (3), preferably a seismic sensor system, housed inside the housing (1) and coupled to the bottom wall (12) of the housing; characterized in that the housing (1) is provided with an acoustic black hole (2), the acoustic black hole (2) being made of polymer, preferably flexible, so as to absorb parasitic wave frequencies below 500Hz, preferably below 400Hz.

2. Device (10) according to claim 1, wherein the polymer in which the acoustic black hole is made has a Young's modulus less than or equal to 10 MPa, preferably less than or equal to 5 MPa.

3. Device (10) according to claim 1 or 2, wherein the polymer in which the acoustic black hole is made is an elastomer, for example silicone, a butadiene-acrylonitrile copolymer (NBR) or rubber, or a thermoplastic elastomer (TPE).

4. Device (10) according to any one of the preceding claims, wherein the acoustic black hole (2) is housed, preferably by overmolding, in a wall (11) of the housing (1) having an active surface, preferably concave, directed towards the inside or outside of the housing.

5. Device (10) according to any one of claims 1 to 3, wherein the acoustic black hole (2) is added as an element attached to an external surface (13E) or to an internal surface (111) of the housing.

6. Device (10) according to claim 5, in which an air pocket (20) is maintained between the acoustic black hole (2) and the housing (1).

7. Device (10) according to any one of the preceding claims, wherein the acoustic black hole (2) comprises a main surface (15) which has an active area (17) of generally concave shape, preferably of parabolic shape.

8. Device (10) according to any one of the preceding claims, wherein the acoustic black hole (2) has a main surface (15) of variable thickness (e) with a thinning in the central part.

9. Device (10) according to any one of the preceding claims, wherein the housing is made of polymer material.

10. Device (10) according to any one of the preceding claims, wherein the peripheral contour (16) of the acoustic black hole (2) is round in shape.

11. Use of the device (10) according to any of the preceding claims, in the field of geoscience or for the monitoring of structure or monument, in particular for terrestrial seismic use.