JP2017058334A - Subsea exploration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a subsea exploration apparatus capable of accurately exploring for metallic mineral resources under seabed.SOLUTION: A subsea exploration apparatus 1 includes a transmission coil 10, a transmission current source 20 that supplies transmission current I1 to the transmission coil 10, a compensation coil 30 disposed to surround a metal element 100 exposed to a magnetic field from the transmission coil 10, and a compensation current source 40 that supplies compensation current I2 to the compensation coil 30 to reduce the magnetic field at the metal element 100.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a seafloor exploration device.

  Exploration of metal mineral resources (for example, submarine hydrothermal deposits, etc.) existing under the seabed is actively conducted. For example, Patent Document 1 discloses a seafloor exploration apparatus that performs electromagnetic exploration below the seabed by arranging potential measurement electrodes around a transmission loop.

JP 2014-98669 A

  When searching for metal mineral resources under the seabed by electromagnetic exploration, unlike on land, low resistivity seawater exists as a medium. Therefore, extremely low resistivity metal elements (submersibles (remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs)) that must be placed close to the transmitter coil Etc.) and a magnetic field caused by an induced current generated in a pressure vessel, etc.) has been a problem.

  The present invention has been made in view of the above problems, and according to some aspects of the present invention, it is possible to provide a seafloor exploration device that can accurately search for metal mineral resources under the seabed. .

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
The seafloor exploration device according to this application example
A transmission coil;
A transmission current supply source for supplying a transmission current to the transmission coil;
A compensation coil for generating a magnetic field such that the magnetic field in the metal element receiving the magnetic field from the transmission coil is reduced;
A compensation current supply source for supplying a compensation current to the compensation coil;
Is a seafloor exploration device.

  According to this application example, the magnetic field generated by the compensation coil can reduce the magnetic field in the metal element, so that the induced current generated in the metal element can be reduced. Therefore, since the influence caused by the induced current of the metal element can be reduced, it is possible to realize a seafloor exploration device that can accurately search for metal mineral resources under the seabed.

[Application Example 2]
In the above-mentioned seafloor exploration device,
The compensation coil may be provided so as to surround the metal element in a plan view.

According to this application example, the magnetic field can be reduced over almost the entire metal element with a simple configuration. Therefore, since the influence caused by the induced current of the metal element can be reduced, it is possible to realize a seafloor exploration device that can accurately search for metal mineral resources under the seabed.

[Application Example 3]
In the above-mentioned seafloor exploration device,
The compensation coil may be smaller than the metal element in plan view.

  According to this application example, the magnetic field can be reduced with respect to at least a part of the metal element with a small compensation coil. Therefore, since the influence caused by the induced current of the metal element can be reduced, it is possible to realize a seafloor exploration device that can accurately search for metal mineral resources under the seabed.

[Application Example 3]
In the above-mentioned seafloor exploration device,
The compensation current supply source may cut off the compensation current in conjunction with a timing at which the transmission current supply source cuts off the transmission current.

  According to this application example, the primary induced current generated in the metal element can be reduced with a simple configuration. Therefore, since the influence caused by the induced current of the metal element can be reduced, it is possible to realize a seafloor exploration device that can accurately search for metal mineral resources under the seabed.

[Application Example 4]
In the above-mentioned seafloor exploration device,
Further comprising a compensating magnetic field sensor attached to the metal element;
The compensation current supply source may supply the compensation current to the compensation coil so that a magnetic field detected by the compensation magnetic field sensor approaches zero.

  According to this application example, the induced current (primary induced current and secondary induced current) generated in the metal element can be effectively reduced. Therefore, since the influence caused by the induced current of the metal element can be reduced, it is possible to realize a seafloor exploration device that can accurately search for metal mineral resources under the seabed.

[Application Example 5]
In the above-mentioned seafloor exploration device,
A receiving coil;
In a plan view, the transmission coil may be disposed so as to surround the metal element, and the reception coil may be disposed so as to overlap with the transmission coil or surround the transmission coil.

  Of the magnetic flux lines resulting from the induced current of the metal element, the magnetic flux lines entering and exiting inside the receiving coil are not detected by the receiving coil and therefore do not become noise. According to this application example, since the receiving coil is larger than the metal element in plan view, it is possible to reduce the influence caused by the induced current of the metal element. Accordingly, it is possible to realize a seafloor exploration device that can accurately search for metal mineral resources under the seabed.

FIG. 1A and FIG. 1B are schematic diagrams for explaining a conventional seabed survey apparatus. It is a functional block diagram of submarine exploration device 1 concerning a 1st embodiment. FIG. 3A is a side view schematically showing the arrangement of the seabed exploration device 1 according to the first embodiment, and FIG. 3B schematically shows the arrangement of the seabed exploration device 1 according to the first embodiment. FIG. FIG. 4A is a side view schematically showing the arrangement of the seabed exploration device 1a according to the modification of the first embodiment, and FIG. 4B is the seabed exploration device 1a according to the modification of the first embodiment. It is a top view which shows typically arrangement | positioning. It is a flowchart which shows an example of the seabed search method using the seabed search apparatus 1 which concerns on 1st Embodiment. 6A is a timing chart of the transmission current I1, FIG. 6B is a timing chart of the compensation current I2, FIG. 6C is a timing chart of the counter electromotive force P generated in the transmission coil 10, and FIG. (D) is a timing chart of the magnetic field H generated by the transmission coil 10. It is a schematic diagram for demonstrating the induced current which the transmission coil 10 generates. 5 is a graph showing an example of a response of a magnetic field detected by a reception magnetic field sensor 52. It is a functional block diagram of the seabed exploration device 2 according to the second embodiment. FIG. 10A is a side view schematically showing the arrangement of the seabed exploration device 2 according to the second embodiment, and FIG. 10B schematically shows the arrangement of the seabed exploration device 2 according to the second embodiment. FIG. It is a flowchart which shows an example of the seabed exploration method using the seabed exploration apparatus 2 which concerns on 2nd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The drawings used are for convenience of explanation. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

  FIG. 1A and FIG. 1B are schematic diagrams for explaining a conventional seabed survey apparatus. FIG. 1 (A) shows an installation-type submarine exploration device in which a submarine exploration device is installed on the seabed and measured away from a remotely operated vehicle (ROV). FIG. 1 (B) shows a mobile submarine exploration device that performs measurement while being mounted on a remotely operated vehicle (ROV).

  In the example shown in FIG. 1A, a metal pressure vessel is arranged above the transmission coil. The pressure vessel contains a power supply and circuit for supplying a transmission current to the transmission coil, a magnetic field sensor for receiving a magnetic field, a measurement circuit for performing measurement based on an output from the magnetic field sensor, and the like.

  In the example shown in FIG. 1B, a metal pressure vessel and a metal remote control unmanned explorer are disposed above the transmission coil.

  In both FIG. 1 (A) and FIG. 1 (B), an extremely low resistivity metal element (submersible (remotely operated vehicle; ROV ) And autonomous underwater vehicles (AUV), pressure vessels, etc.) to search for metal mineral resources (eg, submarine hydrothermal deposits) that exist beneath the seabed. Is a large noise source.

1. First Embodiment FIG. 2 is a functional block diagram of a seabed exploration device 1 according to a first embodiment. FIG. 3A is a side view schematically showing the arrangement of the seabed exploration device 1 according to the first embodiment, and FIG. 3B schematically shows the arrangement of the seabed exploration device 1 according to the first embodiment. FIG. In FIG. 3A and FIG. 3B, members that indicate each configuration are omitted.

  The seafloor exploration apparatus 1 according to this embodiment includes a transmission coil 10, a transmission current supply source 20, a compensation coil 30, a compensation current supply source 40, a reception unit 50, a measurement unit 60, an analysis unit 70, It is comprised including.

  The transmission coil 10 is configured as a coil through which the transmission current I1 output from the transmission current supply source 20 flows. The cable constituting the transmission coil 10 may be covered with an insulating film. As a result, it is possible to cause an induced current to flow under the seabed with the transmission coil 10 and seawater insulated. In the example shown in FIG. 3B, the number of turns of the transmission coil 10 is one, but the number of turns may be plural.

  In the present embodiment, the coil surface of the transmission coil 10 may be disposed to face the seabed. The arrangement where the coil surface and the seabed face each other is such that the seabed exists in the normal direction of the coil surface.

  In the example shown in FIG. 3A, the transmission coil 10 is disposed on the lower side of the metal element 100 (the side closer to the seabed to be searched).

  The metal element 100 is a metal device such as a diving machine (remotely operated vehicle (ROV), autonomous underwater vehicle (AUV), etc.) or a pressure vessel. In the present embodiment, the transmission current supply source 20, the compensation current supply source 40, the measurement unit 60, and the analysis unit 70 are accommodated in a pressure resistant container as the metal element 100.

  According to the present embodiment, since the induced current generated by the transmission coil 10 spreads in the depth direction below the seabed, the electrical property at a deep position below the seabed can be probed.

  The transmission current supply source 20 supplies a transmission current to the transmission coil 10. In the present embodiment, the transmission current supply source 20 repeats a state in which the transmission current I1 is supplied to the transmission coil 10 and a state in which the transmission current I1 is cut off. By supplying the transmission current I1 to the transmission coil 10 and then cutting off the transmission current I1, an induced current is generated around the transmission coil 10. The transmission current I1 output from the transmission current supply source 20 may be, for example, about several tens of amperes depending on the purpose of exploration.

  The compensation coil 30 generates a magnetic field so that the magnetic field in the metal element 100 that receives the magnetic field from the transmission coil 10 becomes small. For example, the compensation coil 30 may generate a magnetic field substantially opposite to the magnetic field generated by the transmission coil 10.

  The compensation current supply source 40 supplies a compensation current I2 to the compensation coil 30. For example, in the present embodiment, the compensation current supply source 40 supplies a compensation current I2 having a direction opposite to the transmission current I1. As described above, in the present embodiment, the transmission current supply source 20 repeats the state in which the transmission current I1 is supplied to the transmission coil 10 and the state in which the transmission current I1 is cut off. The compensation current supply source 40 also repeats the state of supplying the compensation current I2 to the compensation coil 30 and the state of cutting off the compensation current I2.

  According to the present embodiment, since the magnetic field generated by the compensation coil 30 can reduce the magnetic field in the metal element 100, the induced current generated in the metal element 100 can be reduced. Therefore, since the influence resulting from the induced current of the metal element 100 can be reduced, it is possible to realize the seafloor exploration device 1 that can accurately search for metal mineral resources under the seabed.

The compensation coil 30 may be provided so as to surround the metal element 100 that receives the magnetic field from the transmission coil 10 in plan view. In the example shown in FIG. 3, the compensation coil 30 is provided so as to surround the metal element 100 that receives the magnetic field from the transmission coil 10, but may be provided above or below the metal element 100. The compensation coil 30 is configured as a coil through which the compensation current I2 output from the compensation current supply source 40 flows. The cable constituting the compensation coil 30 may be covered with an insulating film. In the example shown in FIG. 3B, the number of turns of the compensation coil 30 is one, but the number of turns may be plural. Further, the compensation coil 30 may be plural. In the present embodiment, the compensation coil 30 is provided so that the coil surface of the compensation coil 30 and the coil surface of the transmission coil 10 are parallel to each other.

  According to the present embodiment, the magnetic field can be reduced over almost the entire metal element 100 with a simple configuration. Therefore, since the influence resulting from the induced current of the metal element 100 can be reduced, it is possible to realize the seafloor exploration device 1 that can accurately search for metal mineral resources under the seabed.

  FIG. 4A is a side view schematically showing the arrangement of the seabed exploration device 1a according to the modification of the first embodiment, and FIG. 4B is the seabed exploration device 1a according to the modification of the first embodiment. It is a top view which shows typically arrangement | positioning. The compensation coil 30 is not limited to the configuration shown in FIG. 3, and may be smaller than the metal element 100 in plan view, for example. For example, the area of the coil surface of the compensation coil 30 may be smaller than the area when the metal element 100 is viewed in plan. In the example shown in FIG. 4, the compensation coil 30 is provided above the metal element 100, but may be provided below the metal element 100.

  According to the present embodiment, the magnetic field can be reduced with respect to at least a part of the metal element 100 with the small compensation coil 30. Therefore, since the influence resulting from the induced current of the metal element 100 can be reduced, it is possible to realize the seafloor exploration device 1 that can accurately search for metal mineral resources under the seabed.

  In the present embodiment, the compensation current supply source 40 may cut off the compensation current I2 in conjunction with the timing at which the transmission current supply source 20 cuts off the transmission current I1. For example, the compensation current supply source 40 may cut off the compensation current I2 at the same time as the transmission current supply source 20 cuts off the transmission current I1.

  According to this embodiment, the primary induced current generated in the metal element 100 can be reduced with a simple configuration. Therefore, since the influence resulting from the induced current of the metal element 100 can be reduced, it is possible to realize the seafloor exploration device 1 that can accurately search for metal mineral resources under the seabed.

  The receiving unit 50 detects the amount of change (time differentiation) of the magnetic field or the magnitude of the magnetic field itself. In the present embodiment, the receiving unit 50 includes a receiving coil 51 that detects the amount of change (time differentiation) of the magnetic field. In the present embodiment, the reception coil 51 is provided so that the coil surface of the reception coil 51 and the coil surface of the transmission coil 10 are parallel to each other. In the example shown in FIG. 3B, the number of turns of the receiving coil 51 is one, but the number of turns may be plural. The receiving unit 50 may include a receiving magnetic field sensor 52 that detects the magnitude of the magnetic field itself. In the example shown in FIG. 3, the reception magnetic field sensor 52 is provided in the vicinity of the center of the coil surface of the reception coil 51.

  As shown in FIG. 3B, in this embodiment, the transmission coil 10 is disposed so as to surround the metal element 100 and the reception coil 51 is disposed so as to surround the transmission coil 10 in plan view. . Note that the reception coil 51 may be disposed so as to overlap the transmission coil 10.

Of the magnetic flux lines resulting from the induced current of the metal element 100, the magnetic flux lines entering and exiting inside the receiving coil 51 are not detected by the receiving coil 51 and therefore do not cause noise. According to this embodiment, since the receiving coil 51 is larger than the metal element 100 in plan view, the influence caused by the induced current of the metal element 100 can be reduced. Therefore, it is possible to realize the seafloor exploration apparatus 1 that can accurately search for metal mineral resources under the seabed.

  The measurement unit 60 measures a transient response after the transmission current I1 is interrupted, which is included in the change over time of the magnetic field detected by the reception coil 51. In particular, it is preferable to measure the change in the magnetic field over time immediately after the transmission current supply source 20 switches from the state in which the transmission current I1 is supplied to the transmission coil 10 to the state in which the transmission current I1 is cut off.

  According to the present embodiment, since the induced current generated by the transmission coil 10 flows below the seabed, the transient response after the interruption of the transmission current I1 included in the change over time of the magnetic field detected by the reception coil 51 is measured. By doing so, you can explore the electrical properties under the seabed. That is, according to the present embodiment, time domain electromagnetic exploration on the sea floor can be performed. The seabed exploration device 1 can also be applied when performing electromagnetic survey in the frequency domain on the seabed.

  The analysis unit 70 calculates the specific resistance under the seabed based on the transient response after the interruption of the transmission current I1 included in the change of the magnetic field detected by the reception coil 51 with time. As will be described later, the smaller the specific resistance under the seabed, the more slowly the induced current decays, so the magnetic field caused by the induced current also slowly decays. Therefore, according to the present embodiment, the specific resistance under the seabed can be calculated based on the transient response after the interruption of the transmission current I1 included in the temporal change of the magnetic field detected by the receiving coil 51.

  The control unit 90 controls the transmission current supply source 20, the compensation current supply source 40, and the measurement unit 60. For example, the control unit 90 controls the timing at which the transmission current I1 is cut off, or controls the operation of the compensation current supply source 40 and the measurement unit 60 in accordance with the timing at which the transmission current I1 is cut off.

  FIG. 5 is a flowchart showing an example of a seabed exploration method using the seabed exploration apparatus 1 according to the first embodiment.

  In the example shown in FIG. 5, first, after the transmission current supply source 20 supplies the transmission current I1 to the transmission coil 10 and the compensation current supply source 40 supplies the compensation current I2 to the compensation coil 30, the transmission current I1 and the compensation current are supplied. The current I2 is cut off (step S100).

  In step S <b> 100, an induced current is generated around the transmission coil 10 by cutting off the transmission current I <b> 1 after supplying the transmission current I <b> 1 to the transmission coil 10.

  6A is a timing chart of the transmission current I1, FIG. 6B is a timing chart of the compensation current I2, FIG. 6C is a timing chart of the counter electromotive force P generated in the transmission coil 10, and FIG. (D) is a timing chart of the magnetic field H generated by the transmission coil 10. FIG. 7 is a schematic diagram for explaining the induced current generated by the transmission coil 10. In FIG. 7, when the transmission current I1 is positive, the current flows through the transmission coil 10 in the direction of the arrow.

First, as shown in FIG. 6A, a positive transmission current I1 is output from the transmission current supply source 20 to the transmission coil 10. Next, the transmission current I1 is suddenly cut off. As a result, as shown in FIG. 6C, an electromotive force E is generated to maintain the same magnetic field before the interruption by the law of electromagnetic induction, and an induced current is generated on the sea bottom. Thereafter, a negative transmission current I1 is output from the transmission current supply source 20 to the transmission coil 10. Next, the transmission current I1 is suddenly cut off. Such an operation is repeated at a period T.

  The induced current at the bottom of the sea is attenuated in accordance with the specific resistance below the sea floor, but a new induced current is generated in the ground to prevent the change of the current. This process is repeated, and a phenomenon occurs as if the induced current 500 propagates to the induced current 501 and the induced current 502 to the deep part under the seabed.

  These induced currents attenuate according to the specific resistance of the current path formation. For this reason, it is possible to detect the attenuation of the induced current as a time change of the magnetic field as shown in FIG. 6D by using the receiving coil 51 arranged in the vicinity of the seabed and know the specific resistance under the seabed. For example, when the underground has a high resistivity, the induced current decays rapidly, but when the underground has a low resistivity, it slowly decays.

  Returning to FIG. 5, after step S100, the transient response of the magnetic field after the transmission current I1 is cut off is measured (step S102). This enables exploration of electrical properties beneath the seabed.

  After step S102, the specific resistance under the seabed is calculated based on the transient response of the magnetic field after the transmission current I1 is cut off (step S104). As described above, the smaller the specific resistance under the seabed, the slower the induced current decays, so the magnetic field caused by the induced current also slowly decays. Therefore, the specific resistance under the seabed can be calculated based on the transient response of the magnetic field after the transmission current I1 is cut off.

  Although the induced current under the seabed has been described with reference to FIG. 7, induced current is also generated in the seawater and the metal element 100 based on the same principle. Since the metal element 100 has a small specific resistance, it similarly becomes a large noise when searching for a metal mineral resource under the seabed having a small specific resistance.

  As shown in FIG. 6B, in this embodiment, a compensation current I2 having a direction opposite to the transmission current I1 is supplied to the compensation coil 30. This reduces the magnetic field in the metal element. Therefore, since the influence resulting from the induced current of the metal element 100 can be reduced, it is possible to realize the seafloor exploration device 1 that can accurately search for metal mineral resources under the seabed.

  FIG. 8 is a graph showing an example of a magnetic field response detected by the reception magnetic field sensor 52. The horizontal axis in FIG. 8 represents the elapsed time after the transmission current I1 is cut off (linear scale), and the vertical axis represents the magnetic field response (logarithmic scale).

  In FIG. 8, data 1001 is a simulation result in the case of seawater only (when the metal element 100 and the compensation coil 30 are not present), and data 1002 is a simulation result when the metal element 100 is present and the compensation coil 30 is not present. The data 1003 shows the simulation result when the metal element 100 and the compensation coil 30 exist.

  As shown in FIG. 8, the data 1002 has the magnetic field attenuated more slowly than the data 1001. This is because an induced current is generated in the metal element 100. On the other hand, in the data 1003, the influence of the induced current generated in the metal element 100 is reduced and approaches the data 1001.

  In this way, by providing the submarine exploration device 1 with the compensation coil 30, it is possible to reduce the influence caused by the induced current generated in the metal element 100, and to realize the submarine exploration device 1 that can accurately search for metal mineral resources under the seabed. Became clear.

2. Second Embodiment FIG. 9 is a functional block diagram of a seafloor exploration device 2 according to a second embodiment. FIG. 10A is a side view schematically showing the arrangement of the seabed exploration device 2 according to the second embodiment, and FIG. 10B schematically shows the arrangement of the seabed exploration device 2 according to the second embodiment. FIG. In FIG. 10A and FIG. 10B, members that indicate each configuration are omitted. Moreover, the same code | symbol is attached | subjected to the structure similar to the seabed exploration apparatus 1 which concerns on 1st Embodiment, and detailed description is abbreviate | omitted.

  The seafloor exploration device 2 according to the present embodiment includes a compensation magnetic field sensor 80. The compensation magnetic field sensor 80 is attached in the vicinity of the metal element 100. In the example shown in FIGS. 10A and 10B, the compensation magnetic field sensor 80 is attached to the center of the metal element 100. The compensation magnetic field sensor 80 is attached near the center of the coil surface of the transmission coil 10 in plan view.

  The compensation current supply source 40 supplies the compensation current I2 to the compensation coil 30 so that the magnetic field detected by the compensation magnetic field sensor 80 approaches zero. In the present embodiment, the compensation current supply source 40 sets the magnetic field detected by the compensation magnetic field sensor 80 to 0 regardless of whether or not the transmission current supply source 20 supplies the transmission coil I1 with the transmission current I1. A compensation current I2 is supplied to the compensation coil 30 so as to approach.

  In the metal element 100, not only the induced current (primary induced current) directly caused by the transmission current I1 flowing through the transmission coil 10, but also the induced current 500 caused by the induced current 500 is smaller than the primary induced current. A current (secondary induced current) also flows. According to this embodiment, the induced current (primary induced current and secondary induced current) generated in the metal element 100 can be effectively reduced. Therefore, since the influence resulting from the induced current of the metal element 100 can be reduced, it is possible to realize the seafloor exploration device 2 that can accurately search for the metal mineral resources under the seabed.

  FIG. 11 is a flowchart showing an example of a seabed exploration method using the seabed exploration device 2 according to the second embodiment. Steps similar to those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the example shown in FIG. 11, first, the transmission current supply source 20 supplies the transmission coil I1 with the transmission current I1, the compensation current supply source 40 supplies the compensation coil 30 with the compensation current I2, and then the transmission current I1 is cut off. (Step S200). In step S200, the compensation current I2 is not specifically controlled to be cut off. Through the subsequent steps, the compensation current supply source 40 allows the magnetic field detected by the compensation magnetic field sensor 80 to approach zero. A compensation current I2 is supplied to the compensation coil 30.

  In step S <b> 200, an induction current is generated around the transmission coil 10 by cutting off the transmission current I <b> 1 after supplying the transmission current I <b> 1 to the transmission coil 10. The generation principle of the induced current is as described with reference to FIG.

  After step S200, the transient response of the magnetic field after the transmission current I1 is cut off is measured (step S102). This enables exploration of electrical properties beneath the seabed.

  After step S102, the specific resistance under the seabed is calculated based on the transient response of the magnetic field after the transmission current I1 is cut off (step S104). As described above, the smaller the specific resistance under the seabed, the slower the induced current decays, so the magnetic field caused by the induced current also slowly decays. Therefore, the specific resistance under the seabed can be calculated based on the transient response of the magnetic field after the transmission current I1 is cut off.

The seabed exploration device 2 according to the present embodiment has the same effect for the same reason as the seabed exploration device 1 according to the first embodiment, in addition to the above-described effects.

  As mentioned above, although this embodiment or the modification was demonstrated, this invention is not limited to these this embodiment or a modification, It is possible to implement in a various aspect in the range which does not deviate from the summary.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1, 1a, 2 ... Submarine exploration device, 10 ... Transmission coil, 20 ... Transmission current supply source, 30 ... Compensation coil, 40 ... Compensation current supply source, 50 ... Reception part, 51 ... Reception coil, 52 ... Reception magnetic field sensor, 60 ... Measurement unit, 70 ... Analysis unit, 80 ... Compensation magnetic field sensor, 90 ... Control unit, 100 ... Metal element, 500,501,502 ... Inductive current, 1001,1002,1003 ... Data

Claims (6)

A transmission coil;
A transmission current supply source for supplying a transmission current to the transmission coil;
A compensation coil for generating a magnetic field such that the magnetic field in the metal element receiving the magnetic field from the transmission coil is reduced;
A compensation current supply source for supplying a compensation current to the compensation coil;
Submarine exploration equipment including In the seafloor exploration device according to claim 1,
The compensation coil is a seafloor exploration device provided to surround the metal element in plan view. In the seafloor exploration device according to claim 1,
The compensation coil is smaller than the metal element in plan view. In the seafloor exploration device according to any one of claims 1 to 3,
The submarine exploration device, wherein the compensation current supply source cuts off the compensation current in conjunction with a timing at which the transmission current supply source cuts off the transmission current. In the seafloor exploration device according to any one of claims 1 to 3,
Further comprising a compensating magnetic field sensor attached to the metal element;
The compensation current supply source supplies the compensation current to the compensation coil so that the magnetic field detected by the compensation magnetic field sensor approaches zero. In the seabed exploration device according to any one of claims 1 to 5,
A receiving coil;
The seafloor exploration device, wherein the transmission coil is disposed so as to surround the metal element in a plan view and overlaps with the transmission coil, or the reception coil is disposed so as to surround the transmission coil.

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