Transient electromagnetic combined device and detection method thereof

Abstract

The invention provides a transient electromagnetic combination device and a detection method thereof. The transient electromagnetic combination device comprises a transmitting coil, a receiver, N compensation coils, M magnetic sensors and P transmitters, the transmitting coil and the compensating coil are connected with corresponding transmitters; the magnetic sensor is connected with a receiver; the vertical projections of the compensation coil and the magnetic sensor in the plane where the transmitting coil is located are located in the transmitting coil, and the vertical projection of the magnetic sensor is outside the vertical projection of the compensation coil; the transmitting coil and the compensating coil are same in winding direction and current direction; the sum of the magnetic induction intensities generated by all the transmitting coils and all the compensating coils in the same magnetic sensor is equal, and the directions are opposite. The transient electromagnetic early signal information is richer, the exploration blind area is reduced, and the observed transient electromagnetic signal conforms to the actual rule; a field source signal is enhanced, so that a higher signal-to-noise ratio and higher exploration depth are achieved; and exploration requirements of different depths can be met.

Description

Technical Field

[0001] The invention relates to the field of magnetic detection, and in particular to a transient electromagnetic combination device and a detection method thereof. Background Art

[0002] Transient Electromagnetic Methods (TEM) is a geophysical exploration method based on the principle of electromagnetic induction, that is, based on the difference in electrical and magnetic properties of underground media, using an ungrounded return line or a grounded line source to emit a primary magnetic field underground. When the primary magnetic field passes through various underground media with electrical and magnetic differences, it will induce weak eddy currents, which will generate a secondary magnetic field in the opposite direction of the primary electromagnetic field. This method is mainly used in archaeological surveys, unexploded ordnance detection, tunnel advance prediction and other fields.

[0003] Conventional transient electromagnetic devices often use overlapping loop devices or loop devices with reverse coils to detect shallow areas. The overlapping loop devices are seriously affected by the interference of the primary field and the mutual inductance between the transmitting and receiving coil devices, which seriously affects the early data, resulting in inaccurate shallow detection and the actual use effect is inconsistent with the actual geological conditions. At present, a compensation method with a reverse coil is often used to solve this problem. However, although the loop device with a reverse coil solves the interference problem of the primary field and improves the shallow exploration effect, it weakens the field source signal, resulting in a reduction in the exploration depth.

[0004] Therefore, how to improve detection accuracy and deepen exploration depth has become one of the problems that technical personnel in this field need to solve urgently.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a transient electromagnetic combination device and a detection method thereof, so as to solve the problems of poor detection accuracy and small exploration depth in the prior art.

[0007] To achieve the above-mentioned and other related purposes, the present invention provides a transient electromagnetic combination device, which at least comprises:

[0008] A transmitting coil, a receiver, N compensation coils, M magnetic sensors and P transmitters, where N and M are natural numbers greater than or equal to 1, and P is a natural number greater than or equal to 1 and less than or equal to N+1;

[0009] The transmitting coil and the compensating coil are connected to the output end of the corresponding transmitter, and the magnetic sensor is connected to the receiver; the vertical projections of the compensating coil and the magnetic sensor in the plane where the transmitting coil is located are located inside the transmitting coil, and the vertical projection of the magnetic sensor is outside the vertical projection of the compensating coil; when N is greater than or equal to 2, the compensating coils are arranged at intervals; when M is greater than or equal to 2, the magnetic sensors are arranged at intervals;

[0010] The transmitting coil and the compensating coil have the same winding direction and the same current direction; the total magnetic induction intensity generated by all transmitting coils and all compensating coils in the same magnetic sensor is equal in magnitude and opposite in direction.

[0011] Optionally, when at least two coils are connected to the same transmitter, each coil is connected in series to an output end of the corresponding transmitter.

[0012] Optionally, the transmitting coil, the compensation coil and the magnetic sensor are located in the same plane.

[0013] Optionally, the transmitting coil, the compensation coil and the magnetic sensor are not all located in the same plane.

[0014] Optionally, when N is greater than or equal to 2, the magnetic sensor is located in a central area of ​​the transmitting coil.

[0015] Optionally, the shape of each coil is configured as a circle, an ellipse or a polygon.

[0016] Optionally, at least one coil is implemented using a stretch bracket.

[0017] More optionally, when N is greater than or equal to 2, the compensation coils are arranged in an array.

[0018] More optionally, when M is greater than or equal to 2, the magnetic sensors are arranged in an array.

[0019] To achieve the above-mentioned purpose and other related purposes, the present invention also provides a transient electromagnetic detection method, which comprises:

[0020] Providing the above transient electromagnetic combination device, adjusting the circumference, number of turns or shape of each coil to ensure that the total magnetic induction intensity generated by all transmitting coils and all compensating coils in the same magnetic sensor is equal in magnitude and opposite in direction;

[0021] Based on the transient electromagnetic combination device, a primary magnetic field is emitted underground, and the primary magnetic field passes through the object to be detected to generate a secondary magnetic field. The secondary magnetic field is acquired and the object to be detected is detected based on the change pattern of the secondary magnetic field over time.

[0022] As described above, the transient electromagnetic combination device and detection method of the present invention have the following beneficial effects:

[0023] In the transient electromagnetic combined device and detection method of the present invention, the total magnetic induction intensity generated by the transmitting coil and all the compensation coils in each magnetic sensor is zero, which can eliminate the aliasing phenomenon of the primary field and the secondary field of the conventional receiving coil, reduce the influence of mutual inductance, make the transient electromagnetic early signal information richer, reduce the exploration blind area, and make the observed transient electromagnetic signal conform to the actual law. In addition, compared with other transient electromagnetic devices using positive and negative transmitting coils with compensation effects, the field source signal strength of the present invention is not weakened, but enhanced. Therefore, compared with the detection device of the above-mentioned compensation coil, the present invention has a higher signal-to-noise ratio and a higher exploration depth.

[0024] The transmitting coil and all the compensation coils of the present invention have adjustable circumferences, adjustable shapes, and adjustable numbers of turns, and can meet the exploration requirements of different depths. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Shown is a structural schematic diagram of the transient electromagnetic combination device of the present invention.

[0026] Figure 2 It is a schematic diagram of an exploded structure of the transient electromagnetic combination device of the present invention.

[0027] Figure 3 Display as Figure 2 Schematic diagram of the top view of the transient electromagnetic combination device.

[0028] Component number description

[0029] 1 Transient electromagnetic combination device

[0030] 11 Transmitter Coil

[0031] 12 Compensation coil

[0032] 13 Magnetic sensor

[0033] 14 Transmitter

[0034] 15 Receiver DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] See also Figure 1 to Figure 3 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0037] In order to solve the above problems, the present invention provides an array type transmitting and receiving compensation transient electromagnetic combination device, the transient electromagnetic combination device comprising:

[0038] A transmitting coil, a receiver, N compensation coils, M magnetic sensors and P transmitters, where N and M are natural numbers greater than or equal to 1, and P is a natural number greater than or equal to 1 and less than or equal to N+1 (the number of transmitters is not greater than the sum of the number of transmitting coils and compensation coils).

[0039] The transmitting coil and the compensation coil are connected to the output end of the corresponding transmitter, and the magnetic sensor is connected to the receiver; the vertical projections of the compensation coil and the magnetic sensor in the plane where the transmitting coil is located are located inside the transmitting coil, and the vertical projection of the magnetic sensor is outside the vertical projection of the compensation coil; when N is greater than or equal to 2, the compensation coils are arranged at intervals; when M is greater than or equal to 2, the magnetic sensors are arranged at intervals; the transmitting coil and the compensation coil have the same winding direction and the same current direction; the total magnetic induction intensity generated by all transmitting coils and all compensation coils in the same magnetic sensor is equal in magnitude and opposite in direction.

[0040] The transient electromagnetic combined device 1 of the present invention can eliminate the primary magnetic field in the received signal, avoid the overlap of the primary magnetic field signal and the secondary magnetic field signal, reduce the mutual inductance between the transceiver, make the observed transient electromagnetic signal conform to the actual electromagnetic law, and strengthen the field source signal, thereby improving the exploration depth. The transient electromagnetic combined device 1 of the present invention is described in detail below based on a specific example.

[0041] Embodiment 1

[0042] like Figure 1 As shown, this embodiment provides a transient electromagnetic combination device 1, including a transmitting coil 11, two compensation coils 12, two magnetic sensors 13, a transmitter 14 and a receiver 15; wherein the transmitting coil 11, the compensation coil 12 and the magnetic sensor 13 are located in the same plane.

[0043] like Figure 1 As shown, the compensation coil 12 and the magnetic sensor 13 are arranged inside the transmitting coil 11 , and the magnetic sensor 13 is arranged outside the compensation coil 12 .

[0044] Specifically, the two compensation coils 12 are spaced apart in an array, that is, there is a certain distance between the two compensation coils 12 and they do not overlap; similarly, the two magnetic sensors 13 are also spaced apart in an array. In this example, the two compensation coils 12 are arranged in a first direction, and the two magnetic sensors 13 are also arranged in the first direction; in actual use, the arrangement directions of the compensation coils 12 and the magnetic sensors 13 may be consistent or inconsistent, and are not limited to this embodiment.

[0045] Specifically, in this example, the two magnetic sensors 13 are located between the two compensation coils 12, that is, located near the center of the transmitting coil 11, so as to achieve a better detection effect. In actual use, the magnetic sensor 13 can be located at any position in the transmitting coil 11 (outside the compensation coil 12) to achieve detection, and is not limited to this embodiment.

[0046] Specifically, in this embodiment, the transmitting coil 11 and the compensating coil 12 are both set to be circular; in actual use, the transmitting coil 11 and the compensating coil 12 can be set to any closed shape as needed, including but not limited to a circle, an ellipse or a polygon.

[0047] like Figure 1 As shown, in this embodiment, a transmitter 14 provides current to multiple coils (transmitting coils and compensation coils), and the transmitting coil 11 and the compensation coil 12 are connected in series to the output end of the transmitter 14. The winding directions of the transmitting coil 11 and the compensation coils 12 are the same, and the direction and magnitude of the current flowing through the transmitting coil 11 and the compensation coils 12 are also the same. The direction of the magnetic field inside the transmitting coil 11 is the same as the direction of the magnetic field inside all the compensation coils 12, and the direction of the magnetic field inside the transmitting coil 11 is opposite to the direction of the magnetic field outside all the compensation coils 12.

[0048] Furthermore, at least one of the transmitting coil 11 and the compensating coil 12 of the present invention is adjustable, and the adjustable parameters include but are not limited to any one or more of the circumference, number of turns and shape of the coil, so as to adjust the magnetic induction intensity generated by it, so that the magnetic induction intensity generated by the transmitting coil 11 in each magnetic sensor 13 is equal to the magnetic induction intensity generated by the two compensating coils 12 in the same magnetic sensor 13. Among them, at least one coil is implemented by a stretching bracket, so that the circumference of the coil can be adjusted; at this time, the shape of the coil is preferably a rectangle, a square or other regular polygon.

[0049] According to the Biot-Savart law, the magnetic induction intensity at any point inside or outside the coil satisfies:

[0050]

[0051] Among them, n is the number of turns of the coil, μ0 is the magnetic permeability of vacuum, C is a constant, I is the current in the coil, dl is the line element vector on the coil, and r is the vector distance between any point inside or outside the coil and the coil line element vector.

[0052] Then, in this embodiment, the magnetic induction intensity generated by the transmitting coil 11 in the kth magnetic sensor 13 satisfies:

[0053]

[0054] Among them, n 0 is the number of turns of the transmitting coil 11; C 0 I is the circumference of the transmitting coil 11; 0 is the current in the transmitting coil 11; dl 0 is the line element vector on the transmitting coil 11; r 0k is the vector distance between the line element vector from the kth magnetic sensor 13 to the transmitting coil 11; k∈[1, ..., M], that is, k=1, 2 in this example.

[0055] The magnetic induction intensity generated by the i-th compensation coil 12 in the k-th magnetic sensor 13 satisfies:

[0056]

[0057] Among them, n i is the number of turns of the i-th compensation coil 12; C i is the circumference of the i-th compensation coil 12; i is the current in the i-th compensation coil 12 (in this example, I 0 =I 1 =I 2 );dl i is the line element vector on the i-th compensation coil 12; r ik is the vector distance between the line element vectors from the kth magnetic sensor 13 to the ith compensation coil 12; i∈[1,...,N], ie, i=1, 2 in this example.

[0058] The total magnetic induction intensity generated by the N compensation coils 12 in the kth magnetic sensor 13 satisfies:

[0059]

[0060] The primary field induced voltage collected by the receiver 15 satisfies:

[0061]

[0062] Among them, S k is the sensitivity of the kth magnetic sensor 13 .

[0063] In order to make the primary field induced voltage U collected by the receiver 15 1 is approximately 0, it is necessary to ensure that the magnetic induction intensity generated by the transmitting coil 11 in each magnetic sensor 13 is equal in magnitude and opposite in direction to the magnetic induction intensity generated by all the compensation coils 12 in each magnetic sensor 13, that is, B 0k =-B Bk (6) Therefore, the present invention can adjust at least one of the current magnitude, number of turns, circumference, and shape of the transmitting coil 11 and each compensation coil 12 to achieve the purpose of making the primary field induced voltage collected by the receiver equal to 0 or approximately equal to 0.

[0064] The present invention can achieve the cancellation of the primary field by adjusting the area, number of turns and current of the transmitting coil 11 and / or each compensation coil 12, eliminate the phenomenon of the primary field and the secondary field aliasing of the conventional receiving coil, reduce the influence of the mutual inductance between the transceiver, make the transient electromagnetic early signal information richer, reduce the exploration blind area, and the observed transient electromagnetic signal is more in line with the actual law; and the dynamic range of the received signal is reduced, solving the problem of difficulty in receiving weak secondary signals; in addition, compared with other transient electromagnetic devices using positive and negative transmitting coils with compensation effects, the field source signal strength of the present invention is not weakened, but enhanced, so the present invention has a higher signal-to-noise ratio and a higher exploration depth. At the same time, the overall working device of the present invention is smaller in size and easy to use; after using the fixed bracket, no adjustment is required, and the measurement effect is accurate and reliable.

[0065] It should be noted that the equality of the sum of the magnetic induction intensities generated by all transmitting coils and all compensating coils in the same magnetic sensor described in the present invention does not mean that they are completely equal, but that the error is within a preset range, which can reduce the primary field induced voltage collected by the receiver, thereby achieving the purpose of improving detection accuracy and deepening exploration depth.

[0066] Embodiment 2

[0067] like Figure 2 and Figure 3 As shown, this embodiment provides a transient electromagnetic combination device 1, which is different from the first embodiment in that the number of compensation coils 12 is set to four, and the number of magnetic sensors 13 is set to four; the transmitting coil 11, the compensation coil 12 and the magnetic sensor 13 are not located in the same plane.

[0068] Specifically, Figure 2As shown, in this example, the transmitting coil 11 is located in a first plane, the four compensation coils 12 are located in a second plane, and the four magnetic sensors 13 are located in a third plane. The planes may be parallel or non-parallel (non-perpendicular to each other), and the vertical projection of each compensation coil in the plane where the transmitting coil 11 is located is located in the transmitting coil 11, and the vertical projection of each magnetic sensor 13 in the plane where the transmitting coil 11 is located is located in the transmitting coil 11, and the vertical projection of the magnetic sensor 13 is outside the vertical projection of the compensation coil 12. See the top view. Figure 3 The four compensation coils 12 are arranged in an array at intervals, and the four magnetic sensors 13 are also arranged in an array at intervals; in this example, the compensation coils 12 are arranged in a first direction and a second direction in groups of two, and the first direction and the second direction intersect, so that the four compensation coils 12 are arranged in a two-dimensional array; the four magnetic sensors 13 are also arranged in a two-dimensional array, and the arrangement direction is consistent; in actual use, the number of compensation coils and the number of magnetic sensors may not be the same, and the arrangement direction may also be inconsistent, which will not be described one by one here.

[0069] Specifically, in this example, the vertical projection of the magnetic sensor 13 is located inside the vertical projection of each compensation coil 12 , that is, the vertical projection of each compensation coil 12 forms an encirclement, and the vertical projection of the magnetic sensor 13 is located within the encirclement, so that the magnetic sensor 13 is located in the central area of ​​the transmitting coil 11 .

[0070] It should be noted that in actual use, more or fewer planes can be set, each compensation coil 12 can be located in a different plane, each magnetic sensor 13 can be located in a different plane, the transmitting coil, part of the compensation coil or part of the magnetic sensor 13 can be located in the same plane, which will not be described one by one here.

[0071] Embodiment 3

[0072] This embodiment provides a transient electromagnetic combination device 1, which is different from the first and second embodiments in that two transmitters 14 are provided; the same transmitter 14 provides one current, and the corresponding transmitting coil 11 and compensation coil 12 can be connected to the output end of the transmitter as needed.

[0073] Taking the first embodiment as an example, as an example, the output end of the first transmitter is connected to the transmitting coil, and the output end of the second transmitter is connected to two compensation coils; as another example, the output end of the first transmitter is connected to a transmitting coil and a compensation coil, and the output end of the second transmitter is connected to another compensation coil. In actual use, the number of transmitters 14 can be set as needed. When at least two coils are connected to the same transmitter, each coil is connected in series to the output end of the corresponding transmitter. The number and corresponding connection relationship of transmitters, transmitting coils and compensation coils can be configured according to actual needs, and are not limited to this embodiment.

[0074] The present invention also provides a transient electromagnetic detection method, which is implemented based on the transient electromagnetic combination device 1 of the present invention. The method includes:

[0075] The transient electromagnetic combination device 1 of the present invention is provided to adjust the circumference, number of turns or shape of each coil to ensure that the total magnetic induction intensity generated by all transmitting coils 11 and all compensation coils 12 in the same magnetic sensor 13 is equal in magnitude and opposite in direction, satisfying the relationship (6).

[0076] The transmitter 14 based on the transient electromagnetic combination device 1 transmits a primary magnetic field underground. The primary magnetic field passes through the object to be detected to generate a secondary magnetic field. The secondary magnetic field is detected by the magnetic sensor in the transient electromagnetic combination device 1 and provided to the receiver 15 to obtain the secondary magnetic field and detect the object to be detected based on the change pattern of the secondary magnetic field over time.

[0077] Among them, since the total magnetic induction intensity generated by the transmitting coil 11 and all the compensation coils 12 in each magnetic sensor 13 is zero, the phenomenon of aliasing of the primary magnetic field and the secondary magnetic field in the magnetic sensor is eliminated, the mutual inductance effect is reduced, the field source signal is enhanced, and it is suitable for exploration needs at different depths.

[0078] In summary, the present invention provides a transient electromagnetic combined device and a detection method thereof, comprising: a transmitting coil, a receiver, N compensation coils, M magnetic sensors and P transmitters, N and M are natural numbers greater than or equal to 1, and P is a natural number greater than or equal to 1 and less than or equal to N+1; the transmitting coil and the compensation coil are connected to the output end of the corresponding transmitter, and the magnetic sensor is connected to the receiver; the vertical projections of the compensation coil and the magnetic sensor in the plane where the transmitting coil is located are located inside the transmitting coil, and the vertical projection of the magnetic sensor is outside the vertical projection of the compensation coil; when N is greater than or equal to 2, each compensation coil is arranged at intervals; when M is greater than or equal to 2, each magnetic sensor is arranged at intervals; the transmitting coil and the compensation coil have the same winding direction and the same current direction; the sum of the magnetic induction intensities generated by all the transmitting coils and all the compensation coils in the same magnetic sensor is equal in magnitude and opposite in direction. The transient electromagnetic early signal information of the transient electromagnetic combined device and the detection method thereof of the present invention is richer, the exploration blind area is reduced, and the observed transient electromagnetic signal conforms to the actual law; the field source signal is enhanced, has a higher signal-to-noise ratio, and a higher exploration depth; and can adapt to the exploration needs of different depths. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0079] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A transient electromagnetic combination device, characterized in that: The transient electromagnetic combination device at least comprises: A transmitting coil, a receiver, N compensation coils, M magnetic sensors and P transmitters, where N and M are natural numbers greater than or equal to 1, and P is a natural number greater than or equal to 1 and less than or equal to N+1; The transmitting coil and the compensating coil are connected to the output end of the corresponding transmitter, and the magnetic sensor is connected to the receiver; The vertical projections of the compensation coil and the magnetic sensor in the plane where the transmitting coil is located are located inside the transmitting coil, and the vertical projection of the magnetic sensor is outside the vertical projection of the compensation coil; when N is greater than or equal to 2, the compensation coils are arranged at intervals; when M is greater than or equal to 2, the magnetic sensors are arranged at intervals; The transmitting coil and the compensating coil have the same winding direction and the same current direction; the total magnetic induction intensity generated by all transmitting coils and all compensating coils in the same magnetic sensor is equal in magnitude and opposite in direction.

2. The transient electromagnetic combination device according to claim 1, characterized in that: When at least two coils are connected to the same transmitter, each coil is connected in series to the output end of the corresponding transmitter.

3. The transient electromagnetic combination device according to claim 1, characterized in that: The transmitting coil, the compensation coil and the magnetic sensor are located in the same plane.

4. The transient electromagnetic combination device according to claim 1, characterized in that: The transmitting coil, the compensation coil and the magnetic sensor are not all located in the same plane.

5. The transient electromagnetic combination device according to claim 1, characterized in that: When N is greater than or equal to 2, the magnetic sensor is located in the central area of ​​the transmitting coil.

6. The transient electromagnetic combination device according to claim 1, characterized in that: The shape of each coil is respectively configured as a circle, an ellipse or a polygon.

7. The transient electromagnetic combination device according to claim 1, characterized in that: At least one coil is implemented using a stretched support.

8. The transient electromagnetic combination device according to any one of claims 1 to 7, characterized in that: When N is greater than or equal to 2, the compensation coils are arranged in an array.

9. The transient electromagnetic combination device according to any one of claims 1 to 7, characterized in that: When M is greater than or equal to 2, the magnetic sensors are arranged in an array.

10. A transient electromagnetic detection method, characterized in that: The transient electromagnetic detection method comprises: Providing a transient electromagnetic combination device as claimed in any one of claims 1 to 9, adjusting the circumference, number of turns or shape of each coil to ensure that the sum of magnetic induction intensities generated by all transmitting coils and all compensating coils in the same magnetic sensor is equal in magnitude and opposite in direction; Based on the transient electromagnetic combination device, a primary magnetic field is emitted underground, and the primary magnetic field passes through the object to be detected to generate a secondary magnetic field. The secondary magnetic field is acquired and the object to be detected is detected based on the change pattern of the secondary magnetic field over time.

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