Primary Field Weak Coupling Receiving Device and Method for Electromagnetic Exploration

A receiving device and electromagnetic method technology, applied in the field of electromagnetic method exploration, can solve problems such as small secondary field amplitude, adverse effects of received signals, and large number of coil turns

Active Publication Date: 2019-04-19
CHONGQING CUILU DETECTION TECH CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] (1) There is a mutual inductance between the sending coil and the receiving coil. The signal induced by the receiving coil not only includes the secondary field signal collected by the receiver, but also aliases the excitation primary field generated by the electromagnetic transmitter. There are primary field and secondary field aliasing problem;
[0005] (2) Due to the large amplitude of the primary field signal and the small amplitude of the secondary field, it is very difficult to distinguish the secondary field from the background of the primary field, and the receiving signal has a large fluctuation range, making it difficult to receive the secondary field signal;
[0006] (3) The number of turns of the sending and receiving coils of the conventional small wire frame same point device is large, the mutual inductance influence is strong, the reliability of the conventional small wire frame same point device is poor, and it is difficult to be practically applied;
[0007] (4) Sending and receiving are two relatively independent systems. The relative position is uncertain during exploration, the mutual inductance changes greatly, and the distortion of the signal is uncertain, resulting in large errors in the detection data and inconvenient use.
[0008] For example, the "transient electromagnetic instrument" with the patent authorization number ZL200720151836.7 can eliminate the influence of the primary field during the power supply period and in a short time after it is turned off, but after the switch is switched, the mutual inductance still exists, and there is still signal confusion. In addition, four switches are used, the structure is complicated, and the switching of the switch will have a bad influence on the received signal
[0009] (5) The patent authorization number 2010101145349 "a method and device for integrating transmission and reception of electromagnetic survey" can realize the elimination of the primary field by adjusting the number of turns arranged in the inner and outer receiving coils of the transmitting coil, but this adjustment The method depends on the cooperation of the number of turns, and non-integer turns are prone to occur, resulting in low accuracy of primary field elimination, and this centralized winding receiving coil has a large self-inductance, which is likely to cause distortion of the received signal

Method used

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  • Primary Field Weak Coupling Receiving Device and Method for Electromagnetic Exploration
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  • Primary Field Weak Coupling Receiving Device and Method for Electromagnetic Exploration

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0150] Embodiment 1, applied to the time-domain electromagnetic method, is carried out in the following order:

[0151] according to Figure 7 As shown, the central point O is selected on the plane, and the transmitting coil 2 is designed to be a 20-turn plane spiral coil, and each coil is approximately a circle; the radius of the innermost coil is 400mm, the radius of the outermost coil is 460mm, and the line width is 2.5mm. The distance between them is 0.5mm;

[0152] Design each sub-receiving coil as a 300-turn helical coil, and each turn of the coil is approximately a circle; the radius of the innermost coil is 100.5mm, the radius of the outermost coil is 120.5mm, the line width is 0.5mm, and the distance between lines is 0.5.

[0153] 2. Calculate the magnetic flux ψ passing through the sub-receiving coil m under the action of the primary field m1 (m=1, 2, 3, ... 7)

[0154]

[0155] Get: ψ m1 ≈1.5149×10 -9 i(t)(Wb)

[0156] 3. Start the transmitter, send as Fi...

Embodiment 2

[0164] Embodiment 2, applied to the frequency domain electromagnetic method, is carried out according to the following sequential steps;

[0165] 1, adopt the sending coil of embodiment 1 design, receiving coil group, get by the 2nd step of embodiment 1

[0166] ψ m1 ≈1.5149×10 -9 i(t)(Wb)

[0167] 2. Start the transmitter, send such as Figure 11 The sinusoidal current shown in the Figure 11 Middle: the horizontal axis is time t, each division is 0.02ms; the vertical axis is current, each division is 1A;

[0168] The signal is the sending current in Example 2. The frequency of the sending current is 10000 Hz. The sending current is measured by a current sensor. The conversion ratio of the current sensor is 100 mV / A, so the peak value of the sending current is 5.8 A. The sinusoidal current expression can be approximated: i(t)=5.5×cos(20000πt)(A);

[0169] 3. Calculate the primary field induced voltage of the inner receiving coil

[0170]

[0171] have to:

[01...

Embodiment 3

[0176] Embodiment 3, applied to the time-domain electromagnetic method, is carried out in the following order:

[0177] 1. Design of sending coil and receiving coil:

[0178] according to Figure 14 As shown, the central point O is selected on the plane, and the transmitting coil 2 is designed to be a 20-turn square solenoid; the side length of the square is 300mm, the line width is 2mm, and the distance between lines is 3mm;

[0179] The sub-receiving coil is designed as a 300-turn square solenoid; the side length of the square is 110mm, the line width is 2mm, and the distance between lines is 1.8mm;

[0180] 2. Calculate the magnetic flux ψ passing through the inner receiving coil 1 under the action of the primary field m1 :

[0181]

[0182] Get: ψ m1 ≈2.3149×10 -9 i(t)(Wb)

[0183] Among them: l 1 : The side length of each turn of the sub-receiving coil;

[0184] x: the x-coordinate of a point on the i-th coil plane of the sub-receiving coil;

[0185] y: the y ...

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Abstract

An electromagnetic method prospected primary field loose coupling receiving device and method. The device comprises: a transmitter (1), a transmit coil (2), a signal conditioning module (4), and a receiver (5). Two transmit output ends of the transmitter (1) are connected to both ends of the transmit coil (2). The device further comprises n receive coils. The n receive coils constitute a receive coil module (3). The receive coil module (3) is connected to the signal conditioning module (4). The output end group of the signal conditioning module (4) is connected to the receiver (5). The receive coil module (3) is disposed at an edge of the transmit coil (2). The receive coil module (3) partially intersects the transmit coil (2). Part of the orthographic projection of the transmit coil (2) overlaps part of the orthographic projection of the receive coil module (3). Aliasing of a primary field and second field of a conventional receive coil is eliminated; the dynamic range of a receive signal is reduced, and the problem of being difficult to receive a signals of a weak second field is resolved; the application range is wide; an integrated system and convenient use are achieved; easy operation and accurate and reliable conditioning effect are achieved.

Description

technical field [0001] The invention relates to the technical field of electromagnetic prospecting, in particular to a primary field weak coupling receiving device and method for electromagnetic prospecting. Background technique [0002] Electromagnetic exploration has been widely used in mineral exploration, engineering geological exploration, groundwater resources, underground pipelines and environmental geological exploration and other fields. Among them, frequency domain electromagnetic method and time domain electromagnetic method are commonly used. Electromagnetic transmitters are used to generate excitation primary fields. The secondary field induced by the geological body is collected by the receiver, and the structure of the geological body is detected by analyzing the secondary field. [0003] However, in the prior art, electromagnetic prospecting still has the following deficiencies: [0004] (1) There is a mutual inductance between the sending coil and the recei...

Claims

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Application Information

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Patent Type & AuthorityPatents(China)
IPC IPC(8): G01V3/10
CPCG01V3/104
Inventor付志红王浩文李军强王耀陈景明朱学贵王唯邱婧竹魏秋生
OwnerCHONGQING CUILU DETECTION TECH CO LTD