Underwater Electromagnetic Imaging

Abstract

Underwater Electro-Imager: A long-range, covert underwater detection instrument comprising two pairs of probes arranged in two orthogonal directions within an underwater enclosure. Each direction constitutes a detection unit. Utilizing the principle of micro-resistivity electro-imaging, it continuously probes the micro-resistivity of current lines in various directions around the enclosure, rotating layer by layer from near to far. The presence of interference sources inevitably causes changes in the micro-resistivity of the probe current lines. The location of the interference source is determined by the intersection of the two orthogonal probe current lines, achieving long-range covert detection. This invention has the following characteristics: 1. The probe current is closed, imperceptible to external instruments, providing extremely high concealment. 2. The instrument has no moving parts, ensuring high reliability. 3. The instrument is made from common materials and manufactured using common methods, resulting in low cost and good economic efficiency. 4. Detection relies on current, resulting in minimal delay. 5. Detection only measures the resistivity of the probe lines, minimizing the impact of water flow fluctuations. Applications include submarine, ship, and coastal detection, marine search and rescue, and geological exploration.

Description

(I) Technical Field

[0001] This invention relates to underwater detection instruments for submarines and ships, and in particular to an underwater electrical imaging instrument that utilizes microresistivity for electrical imaging detection. (II) Background Technology

[0002] In the field of underwater detection for submarines and ships, sonar is currently mainly used for long-range underwater detection. In the field of oil exploration, micro-resistivity imaging instruments are frequently used to detect underground geological formations.

[0003] Sonar can be classified into active sonar and passive sonar according to its working method; and into surface ship sonar, submarine sonar, airborne sonar, portable sonar, and coastal sonar according to the equipment target.

[0004] External conditions have a significant impact on sonar performance. Propagation attenuation, multipath effects, reverberation interference, ocean noise, self-noise, target reflection characteristics, and radiated noise intensity all have a significant impact on sonar.

[0005] Because sonar has been used for underwater detection for a very long time, various techniques for circumventing interference with sonar detection have emerged. Therefore, it is necessary to develop a completely new, effective, and covert underwater detection instrument.

[0006] The basic structure of a micro-resistivity scanning imager consists of an array of electrodes mounted on four mutually perpendicular plates, pushed against the well wall. During measurement, a pusher pushes the plates against the well wall, and an alternating current is emitted from the pusher plates. This current flows through the drilling fluid column and formation within the wellbore, returning to the loop electrode at the top of the instrument. The array electrode in the center of the plates emits current towards the well wall. To ensure that the emitted current enters the well wall perpendicularly, a potential of the same phase is applied to the pusher and the metal components of the plates, forcing the array electrode current to be focused and emitted. In a homogeneous medium, the ratio of each electrode current to the total current is constant and independent of the medium's resistivity. Inside the wellbore, the difference in drilling fluid resistivity and formation resistivity alters the current line distribution of the focused current and electrode currents, and the ratio of electrode current to total current also changes. The instrument uses this information to determine the downhole formation conditions.

[0007] The following are some of the patents related to underwater exploration in recent years:

[0008] The patent, titled "UNDERWATER DETECTOR, AND DEVICE AND METHOD FOR MEASURING FLOW VELOCITY AND FLOW DIRECTION OF GROUNDWATER," has the following features: 1-Infrared sensing module; 2-Electronic compass; 3-Indicator; 4-Light source; 5-Sealed glass; 6-Power assembly; 7-Processor module; 8-Metal counterweight; 9-Main shaft; 10-Sealed housing; 11-Cable; 12-Windlock; 13-Operation panel. (Patent number: CN:2020073542:W)

[0009] This patent uses infrared light for detection, and it is obvious that this detection method cannot be used for long-distance covert detection.

[0010] The patent, CN202011031971.4, is titled "An Underwater Multi-Band Crossed Linear Array Laser Three-Dimensional Scanning System." This patent relates to an underwater multi-band crossed linear array laser three-dimensional scanning system, comprising: a carrier for controlling the system to scan target objects underwater and acquire real-time inertial navigation data; an underwater laser emitting unit mounted on the carrier, comprising multiple linear lasers of different wavelengths, the laser lines emitted by each linear laser intersecting in pairs to form a multi-band crossed linear array with the surface of the target object; an underwater imager mounted on the carrier for acquiring image sequences of the target object whose surface is covered by the crossed linear array; and a control unit for receiving the inertial navigation data and the image sequences, extracting the crossed linear array coordinate data from the image sequences, calculating the relative coordinates of each point on the crossed linear array of the target object with respect to the underwater imager based on the triangulation distance principle, and combining the inertial navigation data with the relative coordinates to obtain the spatial coordinates of the crossed linear array on the surface of the target object.

[0011] This patent uses a laser array for detection, but it obviously cannot perform long-distance covert detection. (III) Summary of the Invention

[0012] To develop a novel, effective, and covert underwater long-range detection instrument, two pairs of detection rods are arranged in two orthogonal directions around an underwater enclosure. Each direction constitutes a detection unit. Utilizing the principle of micro-resistivity electro-imaging, the micro-resistivity of the current lines around the enclosure is continuously detected layer by layer from near to far. The presence of interference sources inevitably causes changes in the micro-resistivity of the detection current lines. The location of the interference source is determined by the intersection of the two orthogonal detection current lines, thus achieving long-range covert detection.

[0013] The objective of this invention is achieved as follows:

[0014] Two pairs of probes are arranged in two orthogonal directions within the underwater tank. Each probe consists of 24 control electrodes and 12 detection electrodes evenly arranged on an isolation tube, with a special detection electrode positioned at the center of its end. Each detection electrode comprises a transmitting electrode and a cluster sleeve, with the cluster sleeve constraining the current of the transmitting electrode into a thin line. Each electrode is insulated and sealed from the tank.

[0015] The present invention has three detection modes:

[0016] Mode 1: Routine Detection Mode

[0017] The 24 control electrode pairs are charged with the same voltage, cycling from low to high and then back to low. The 12 detection electrode pairs are also charged with the same voltage, and the control circuit detects the current between these 12 pairs of electrodes. When the current in a particular detection electrode pair deviates, it indicates the presence of an interference source in that circuit. The distance to the interference source is determined based on the voltage levels of the control electrode pairs; the location of the interference source is determined by the detection results of two pairs of orthogonal probe rods 1 and 2, and probe rods 3 and 4.

[0018] Mode 2: Precise Positioning Mode

[0019] Of the 24 control electrode pairs, 21 have the same voltage. Among the 12 detection electrode pairs, the voltage of one detection electrode's corresponding control electrode pair and its adjacent electrode pairs is lower than the voltages of the other electrode pairs. Furthermore, the voltage magnitudes of these two adjacent electrode pairs change continuously, resulting in a continuous change in the voltage distribution around the detection rod. This process is sequentially applied to the 12 detection electrodes, causing the detection current to continuously rotate along the detection rod axis, thus enabling detection around the enclosure without blind spots. Referring to Mode 1, the distance to the interference source is determined based on the voltage levels of each control electrode pair; the location of the interference source is accurately determined by the detection results of two orthogonal detection rods.

[0020] Mode 3: Remote Positioning Mode

[0021] The operating mode of the 24 control electrode pairs is the same as in Mode 2. In this mode, the 12 evenly distributed detection electrodes also function as control electrodes, participating in the precise control of the 13th detection electrode at the center of the detection rod. The operation is similar to Mode 2, but the 13th detection electrode at the center of the detection rod can perform long-distance detection around the enclosure without blind spots. Referring to Mode 1, the distance to the interference source is determined based on the voltage levels of each control electrode pair; the location of the remote interference source is precisely determined by the detection results of the two orthogonal detection rods. (iv) Description of the attached drawings

[0022] The specific structure of the present invention is given by the following embodiments and accompanying drawings:

[0023] Appendix Figure 1 This is a cross-sectional view of the underwater electro-imaging device of the present invention.

[0024] Appendix Figure 2 This is a cross-sectional view of the detection rod of the underwater electro-imaging instrument of the present invention.

[0025] Appendix Figure 3 This is an enlarged view of the cross-sectional view of the detection rod of the underwater electro-imaging instrument of the present invention.

[0026] Appendix Figure 4 This is a cross-sectional view of the detection electrode of the underwater electro-imaging instrument of the present invention.

[0027] Appendix Figure 5 This is an isometric view of the detection rod of the underwater electro-imaging instrument of the present invention.

[0028] Appendix Figure 6 This is an axonometric view of the detection electrode of the underwater electro-imaging instrument of the present invention.

[0029] Appendix Figure 7 This is a left view of the detection rod of the underwater electro-imaging instrument of the present invention.

[0030] Appendix Figure 8 This is a schematic diagram illustrating the working principle of the underwater electro-imaging device of this invention.

[0031] Appendix Figure 9 This is an isometric view of the underwater electro-imager of the present invention.

[0032] Among them, (1) housing, (2) detection rod 1, (3) detection rod 2, (4) control box, (5) current 1, (6) current 2, (7) current 3, (8) current 4, (9) current 5, (10) detection rod 3, (11) detection rod 4, (101) flange, (201) isolation tube, (202) detection electrode, (203) control electrode, (204) cable, (205) bolt, (206) sealing ring 1, (20201) transmitting electrode, (20202) isolation sleeve, (20203) cluster sleeve, (202 04) Sealing ring 2, (20205) Sealing ring 3, (20206) Bundled sleeve wire, (2021) Detection electrode 1, (2022) Detection electrode 2, (2023) Detection electrode 3, (2024) Detection electrode 4, (2026) Detection electrode 6, (2020) Detection electrode 0, (20211) Detection electrode 11, (20212) Detection electrode 12, (2031) Control electrode 1, (2032) Control electrode 2, (20312) Control electrode 12, (20324) Control electrode 24.

[0033] See attached document Figure 1The box (1) is equipped with detection rods 1 (2) and 2 (3) at the front and back. The box (1) contains a control box (4). The electro-imager (2) and the electro-imager (3) are connected to the control box (4) via a cable (204). The internal structures of detection rods 1 (2), 2 (3), 3 (10), and 4 (11) are the same.

[0034] See attached document Figure 2 Appendix Figure 3 Appendix Figure 5 The detection rod 1 (2) is fixed to the flange (101) by bolts (205); the detection rod 1 (2) has an isolation tube (201) on which 24 control electrodes (203) and 13 detection electrodes (202) are inlaid, and each electrode is connected to the control box (4) by a cable (204); the sealing ring 1 (206) is used to seal the connection between the detection rod 1 and the flange (101).

[0035] See attached document Figure 4 Appendix Figure 6 The detection electrode (202) has an emitter (20201) inside the isolation tube (20202) and a bundle tube (20203) outside; the isolation tube (20202) and the emitter (20201) are sealed by a sealing ring 3 (20205) and the bundle tube (20203) is connected to the control box (4) through the bundle tube wire (20206); the seal between the detection electrode (202) and the isolation tube (201) is a sealing ring 2 (20204).

[0036] See attached document Figure 7 : 24 control electrodes (203) are evenly arranged outside the isolation tube (201) of the detection rod 1 (2), namely: control electrode 1 (2031), control electrode 2 (2032), control electrode 12 (20312)... control electrode 24 (20324); 12 detection electrodes (202) are evenly arranged at a 45-degree angle at its end, namely: detection electrode 1 (2021), detection electrode 2 (2022), detection electrode 3 (2023), detection electrode 4 (2024)... detection electrode 6 (2026),... detection electrode 11 (20211), detection electrode 12 (20212); and detection electrode 0 (2020) is located at the center of the end.

[0037] See attached document Figure 8 Detection rod 1 (2) is connected to a positive potential, and detection rod 2 (3) is connected to a negative potential. The two detection rods (2) and (3) are connected by seawater current.

[0038] The external current line between the control electrodes (2031) of the two detection rods (2) and (3) is current 1 (5), and the external current line between the control electrodes (20312) of the two detection rods (2) and (3) is current 5 (9).

[0039] The external current line between the detection electrodes 1 (2021) of the two detection rods (2) and (3) is current 2 (6), the external current line between the detection electrodes 1 (2026) of the two detection rods (2) and (3) is current 4 (8), and the external current line between the detection electrodes 1 (2020) of the two detection rods (2) and (3) is current 3 (7).

[0040] The above figures are for ease of description only. There are 24 control electrodes (203) evenly arranged outside the isolation tube (201) of the detection rod 1 (2). In fact, this number can be arbitrarily arranged according to requirements. Correspondingly, 12 detection electrodes (202) are evenly arranged at a 45-degree angle at its end; this number is also arbitrary. Furthermore, the number of detection rod pairs is arbitrary, and the positive and negative potentials connected to the two detection rods 1 (2) and 2 (3) are also arbitrary. The detection current and control voltage are not limited to direct current; they can also be pulse current or alternating current.

[0041] See attached document Figure 9 Detection rods 3 (10) and 4 (11) are arranged in the orthogonal direction of detection rods 1 (2) and 2 (3) on the outside of the box. The above description of detection rods 1 (2) and 2 (3) also applies to detection rods 3 (10) and 4 (11).

[0042] This invention is not limited to applications in submarines, ships, coastal exploration, and marine search and rescue, but can also be applied in the field of geological exploration. (V) Detailed Implementation

[0043] According to the appendix Figure 4 Install sealing ring 3 (20205) and bundle tube wire (20206) on the emitter (20201). Install sealing ring 2 (20204) on the isolation sleeve (20202), put the bundle tube (20203) on, and connect the bundle tube wire (20206) to the bundle tube (20203). Insert the emitter (20201) into the isolation sleeve (20202). Its isometric view is attached. Figure 6 .

[0044] Install the above-mentioned detection electrode (202) according to the attached... Figure 2 Appendix Figure 3 As shown, it is installed on the isolation tube (201). A control electrode (203) and a sealing ring 1 (206) are then installed on it, and a cable (204) is connected. This process is the installation process for detection rod 1 (2), detection rod 2 (2), detection rod 3 (10), and detection rod 4 (11). (See attached diagram) Figure 5 The image shows the isometric view of detection rod 1 (2), detection rod 2 (2), detection rod 3 (10), and detection rod 4 (11).

[0045] According to the appendix Figure 9 Installation: Box (1), Detection rod 1 (2), Detection rod 2 (3), Control box (4), Detection rod 3 (10), Detection rod 4 (11).

[0046] The working process of this invention is as follows:

[0047] Mode 1:

[0048] 1. Detection rod 1 (2) is connected to a positive potential, detection rod 2 (3) is connected to a negative potential, and the external current between detection rod 1 (2) and detection rod 2 (3) and between detection rod 3 (10) and detection rod 4 (11) is conducted through seawater.

[0049] 2. When the same potential difference is applied between each corresponding electrode pair, if the medium around the enclosure (1) is uniform, and the control electrode (203) is connected to a DC current and a sinusoidal signal to synthesize a signal voltage, and the voltages between each corresponding electrode pair are equal, then the corresponding current signals are also equal. This indicates that there are no interference sources around the enclosure (1).

[0050] 3. When there are interference sources around the box (1), if the current of a certain circuit of the detection electrode (202) is not equal to the current of other circuits under the above conditions, then there are interference sources in this circuit.

[0051] 4. Based on the combined detection results between detection rod 1 (2) and detection rod 2 (3), and between detection rod 3 (10) and detection rod 4 (11), determine the location of the interference source.

[0052] 5. The angle and distance of the interference source between detection rod 1 (2) and detection rod 2 (3) are detected by detection rod 1 (2) and detection rod 2 (3). The angle and distance of the interference source between detection rod 3 (10) and detection rod 4 (11) are detected by detection rod 3 (10) and detection rod 4 (11).

[0053] 6. Based on the above calculations, determine the actual location and shape of the interference source, and use a computer program to display the location and shape information of the interference source on the monitor.

[0054] Mode 2:

[0055] 1. In mode 1, an abnormal current is detected in a pair of detection electrodes (202). Assuming it is detection electrode (2021), control electrode 24 (20324), control electrode 1 (2031), and control electrode 2 (2032) are connected to a combined voltage of sinusoidal voltage and DC voltage, so that the electric field distribution between the three control electrodes is in a scanning mode, so that the detection current of detection electrode 1 (2021) is continuously scanned and detected in this interval, that is, between control electrode 24 (20324) and control electrode 2 (2032).

[0056] 2. Similar to Mode 1, the location of the interference source is determined by combining the detection results between detection rod 1 (2) and detection rod 2 (3), and between detection rod 3 (10) and detection rod 4 (11).

[0057] 3. The angle and distance of the interference source between detection rod 1 (2) and detection rod 2 (3) are detected by detection rod 1 (2) and detection rod 2 (3). The angle and distance of the interference source between detection rod 3 (10) and detection rod 4 (11) are detected by detection rod 3 (10) and detection rod 4 (11).

[0058] 4. Based on the above calculations, determine the actual location and shape of the interference source, and use a computer program to display the precise location and shape information of the interference source on the monitor.

[0059] Mode 3:

[0060] 1. To perform long-distance detection, enable detection electrode 0 (2020).

[0061] 2. Use detection electrodes 1 (2021) to 12 (20212) as control electrodes.

[0062] 3. Similar to mode 2, firstly, control electrode 24 (20324), control electrode 1 (2031), and control electrode 2 (2032) are connected to a combined voltage of sinusoidal voltage and DC voltage, so that the electric field distribution between the three control electrodes is in a scanning mode, so that the detection current of detection electrode 1 (2021) is continuously scanned and detected in this interval, i.e., between control electrode 24 (20324) and control electrode 2 (2032).

[0063] 4. Simultaneously detect electrode 12 (20212), detection electrode 1 (2021), and detection electrode 2 (2022), as in step 3, so that the detection current of detection electrode 2020 is continuously scanned and detected in this interval, i.e., between detection electrode 12 (20212) and detection electrode 2 (2022).

[0064] 5. Similar to Mode 1, combine the detection results between detection rod 1 (2) and detection rod 2 (3), and between detection rod 3 (10) and detection rod (11) 4 to determine the location of the interference source.

[0065] 6. The angle and distance of the interference source between detection rod 1 (2) and detection rod 2 (3) are detected by detection rod 1 (2) and detection rod 2 (3). The angle and distance of the interference source between detection rod 3 (10) and detection rod 4 (11) are detected by detection rod 3 (10) and detection rod 4 (11).

[0066] 7. Based on the above calculations, determine the actual location and shape of the interference source, and use a computer program to display the remote location and shape information of the interference source on the monitor.

[0067] 8. The schematic diagram of this detection process is shown in the attached figure. Figure 8 As shown.

[0068] This invention has the following characteristics:

[0069] 1. The detection current is closed, and cannot be detected by external instruments, making it extremely concealed.

[0070] 2. The instrument has no moving parts, making it highly reliable.

[0071] 3. The instrument is made of common materials and processed in a common way, so it is low in cost and economical.

[0072] 4. The detection is performed using electric current, resulting in minimal delay.

[0073] 5. The detector only measures the resistivity of the detection line, and is minimally affected by water flow fluctuations.

Claims

1. An underwater detection device, an underwater electrical imaging device, characterized in that: This underwater electro-optical imaging device has the following features: Box (1), detection rod 1 (2), detection rod 2 (3), control box (4), detection rod 3 (10), detection rod 4 (11); The internal structures of detection rod 1(2), detection rod 2(3), detection rod 3(10), and detection rod 4(11) are the same; Detection rod 1 (2), detection rod 2 (3), detection rod 3 (10), and detection rod 4 (11) are fixed to the flange (101) by bolts (205); The detection rod 1 (2) includes: an isolation tube (201), a detection electrode (202), a control electrode (203), a cable (204), and a sealing ring 1 (206); The box body (1) is equipped with detection rods 1 (2) and 2 (3) at the front and back, and detection rods 3 (10) and 4 (11) on the left and right sides; Detection rods 1(2), 2(3), 3(10), and 4(11) are arranged orthogonally; Twelve detection electrodes (202) are evenly arranged at a 45-degree angle at the end of the detection rod 1 (2), namely: detection electrode 1 (2021), detection electrode 2 (2022), detection electrode 3 (2023), detection electrode 4 (2024)... detection electrode 12 (20212), and detection electrode 0 (2020) is located at the center of the end. 24 control electrodes (203) are evenly arranged outside the isolation tube (201) of the detection rod 1 (2), namely: control electrode 1 (2031), control electrode 2 (2032), control electrode 3 (2033)... control electrode 24 (20324).

2. The underwater electro-optical imaging device according to claim 1, characterized in that: The front and rear of the housing (1) are equipped with detection rods 1 (2) and 2 (3), and the housing (1) contains a control box (4); the detection rods 1 (2) and 2 (3) are connected to the control box (4) by cables (204).

3. The underwater electro-optical imaging device according to claim 1, characterized in that: The detection rod 1 (2) has an isolation tube (201) on which 24 control electrodes (203) and 13 detection electrodes (202) are inlaid. Each electrode is connected to the control box (4) through a cable (204).

4. The underwater electro-optical imaging device according to claim 1, characterized in that: The sealing ring 1 (206) is used to seal the connection between the detection rod 1 (2) and the flange (101).

5. The underwater electro-optical imaging device according to claim 1, characterized in that: The detection electrode (202) has an emitter (20201) inside the isolation tube (20202) and a bundle tube (20203) outside; the isolation tube (20202) and the emitter (20201) are sealed by a sealing ring 3 (20205) and the bundle tube (20203) is connected to the control box (4) through the bundle tube wire (20206).

6. The underwater electro-optical imaging device according to claim 1, characterized in that: The seal between the detection electrode (202) and the isolation tube (201) is a sealing ring 2 (20204).

7. The underwater electro-optical imaging device according to claim 1, characterized in that: The control electrode (203) is connected to a DC power supply and a sinusoidal signal to synthesize a signal voltage, and the voltages between corresponding electrode pairs are equal.

8. The underwater electro-optical imaging device according to claim 1, characterized in that: The control electrodes 24 (20324), 1 (2031), and 2 (2032) are connected to a combined voltage of a sinusoidal voltage and a DC voltage, so that the electric field distribution between the three control electrodes is in a scanning mode, and the detection current of the detection electrode 1 (2021) is continuously scanned and detected in this interval, i.e., between the control electrodes 24 (20324) and 2 (2032).

9. The underwater electro-optical imaging device according to claim 1, characterized in that: The positive and negative potentials connected to detection rod 1 (2) and detection rod 2 (3) are arbitrary, and the detection current and control voltage are one of direct current, pulse current and alternating current.

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