A device and method for detecting seabed resistivity

Abstract

The present invention discloses a device and method for detecting seabed resistivity, the device comprising: a main control module, a remote module and a near-pole module; the main control module is connected to the near-pole module and the remote module respectively, and is used to provide a positive excitation current signal for the near-pole module and a negative excitation current signal for the remote module; the remote module is connected to the main control module, and is used to transmit the negative excitation current signal in water; the near-pole module is connected to the main control module, and is used to transmit the positive excitation current signal in water, and is used to measure the potential of the electric field excited by the electric monopole formed around the near-pole module; the remote module is arranged away from the near-pole module to form an electric field excited by the electric monopole around the near-pole module. The present invention separates the remote module from the near-pole module by a large distance, so as to form an electric field similar to the electric monopole excitation near the near-pole module, thereby increasing the current entering below the seabed, increasing the amplitude of the abnormal field, and thus improving the detection depth.

Description

Technical Field

[0001] The present invention relates to the field of marine geophysical technology, and in particular to a device and method for detecting seabed resistivity. Background Art

[0002] The marine resistivity detection method is an extension of the ground resistivity method. Its principle is to send current in the water and lay out potential measuring electrodes to achieve resistivity detection of the seabed geological structure.

[0003] The existing resistivity detection methods and devices for the ocean (including lakes, rivers and other water bodies) are mainly taken from the ground electrical method, usually including static bottom-sinking or suspension type and dynamic cruise type or towing type. The static bottom-sinking or suspension type is to place the electrode array on the seabed or suspend it in the water (water surface) in imitation of the arrangement of the ground electrical method, and connect it to the main engine on the hull, and control the emission of current and the measurement of potential according to the required combination of current emission electrodes and potential measurement electrodes. The dynamic cruise type or towing type is to drag the electrode array to the hull, and emit current while measuring the potential to obtain detection data during the voyage. Through the above two measurement methods, when there is a geological body with a lower resistivity than the surrounding rock on the seabed, the potential difference (or electric field) measured near it will be weak, otherwise it will be strong. By quantitatively inverting the observation data of the marine resistivity method, the geological structure imaging below the seabed can be obtained, which can be used to find various geological structures with resistivity differences such as fault zones, boulders, cavities, and relics buried under the seabed. Since marine engineering surveys are difficult and costly, marine electrical methods have become a cheap and efficient geophysical survey technology.

[0004] However, whether it is static bottom-sinking or floating, or dynamic walking or dragging, the ocean resistivity detection method is similar to the observation of dipole-dipole device, that is, the distance between the positive and negative electrodes of the transmitting electrode is relatively close, so most of the current from the positive electrode flows back to the negative electrode through the seawater short circuit, resulting in relatively little current actually entering the seabed. In this way, the amplitude of the abnormal field generated by the structure below the seabed is very small, resulting in a shallow detection depth.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a seabed resistivity detection device and method to solve the problem that in the prior art ocean resistivity detection, the positive and negative poles of the transmitting electrode are relatively close to each other, so that most of the current from the positive pole is short-circuited through the seawater and flows back to the negative electrode, resulting in relatively little current actually entering the seabed, and the amplitude of the abnormal field generated by the structure below the seabed is very small, resulting in a shallow detection depth.

[0007] The technical solution of the present invention is as follows:

[0008] A seabed resistivity detection device comprises: a main control module, a far-pole module and a near-pole module; wherein:

[0009] The main control module is connected to the proximal module and the distal module respectively, and is used to provide a positive excitation current signal for the proximal module and a negative excitation current signal for the distal module;

[0010] The remote module is connected to the main control module, and the remote module is used to transmit the cathode excitation current signal in water;

[0011] The proximal module is connected to the main control module, and is used to transmit the positive pole excitation current signal in water and to measure the potential of the electric field excited by the electric monopole formed around the proximal module; wherein the distal module is arranged away from the proximal module to form an electric field excited by the electric monopole around the proximal module.

[0012] According to a further configuration of the present invention, the main control module comprises: a transmitting unit and a measuring unit;

[0013] The transmitting unit is connected to the distal module and the proximal module respectively, and is used to provide a negative excitation current signal to the distal module and a positive excitation current signal to the proximal module;

[0014] The measuring unit is connected to the proximal module, and is used for receiving and recording the potential measured by the proximal module.

[0015] According to a further configuration of the present invention, the remote module comprises: a remote, which is connected to the transmitting unit, and is used to transmit the negative pole excitation current signal emitted by the transmitting circuit in water.

[0016] In a further configuration of the present invention, the proximal electrode module comprises: a plurality of electrodes, wherein the plurality of electrodes comprises at least one proximal electrode, and the remaining electrodes are measuring electrodes;

[0017] The proximal pole is connected to the transmitting unit, and the proximal pole is used to transmit the positive pole excitation current signal emitted by the transmitting unit in water;

[0018] The measuring electrodes are connected to the measuring units respectively, wherein a potential difference is formed between two adjacent measuring electrodes.

[0019] According to a further configuration of the present invention, the remote module further includes: a first cable; the remote is connected to the transmitting unit via the first cable.

[0020] According to a further configuration of the present invention, the proximal electrode module further includes: a second cable; the proximal electrode and the measuring electrode are connected via the second cable, wherein the proximal electrode is respectively connected to the transmitting unit and the measuring unit via the second cable.

[0021] According to a further configuration of the present invention, in static measurement, any electrode in the proximal pole module can be used as a proximal pole; in dynamic measurement, the electrodes located at both ends of the second cable in the proximal pole module are used as proximal poles.

[0022] According to a further configuration of the present invention, a plurality of proximal modules are provided and are respectively connected to the main control module.

[0023] According to a further configuration of the present invention, the distal electrode and the proximal electrode are connected via a third cable, and the distal electrode and the proximal electrode are respectively connected to the transmitting unit via the third cable; the measuring electrodes are respectively connected to the measuring units via fourth cables; wherein the measuring electrodes are arranged close to the proximal electrode, and the distal electrode is arranged away from the proximal electrode.

[0024] Based on the same inventive concept, the present invention also provides a seabed resistivity detection method, which is applied to the seabed resistivity detection device described above, and comprises:

[0025] Transmitting a positive excitation current signal to the proximal module and a negative excitation current signal to the distal module through the main control module;

[0026] The positive excitation current signal and the negative excitation signal are respectively emitted in water through the proximal module and the distal module, and an electric field excited by electric monopole is formed around the proximal module;

[0027] The potential of the electric field excited by the electric monopole formed in the periphery is measured by the proximal module to obtain potential difference data;

[0028] Resistivity data is obtained based on the potential difference data.

[0029] The present invention provides a seabed resistivity detection device and method, the device comprising: a main control module, a remote module and a near-pole module; wherein the main control module is connected to the near-pole module and the remote module respectively, the main control module is used to provide a positive pole excitation current signal for the near-pole module, and to provide a negative pole excitation current signal for the remote module; the remote module is connected to the main control module, and the remote module is used to transmit the negative pole excitation current signal in water; the near-pole module is connected to the main control module, and the near-pole module is used to transmit the positive pole excitation current signal in water, and to measure the potential of the electric field excited by the electric monopole formed around the near-pole module; wherein the remote module is arranged away from the near-pole module to form an electric field excited by the electric monopole around the near-pole module. The present invention provides a positive excitation current signal to the near-pole module and a negative excitation current signal to the far-pole module through the main control module, and the far-pole module is arranged far away from the near-pole module. When the far-pole module transmits the negative excitation current signal in the water and the near-pole module transmits the positive excitation current signal in the water, an electric field excited by an electric monopole is formed around the near-pole module. The near-pole module measures the potential of the electric field excited by the electric monopole formed around the near-pole module to obtain potential difference data, and resistivity data can be obtained through the potential difference data. In this way, the present invention forms an electric field similar to that excited by an electric monopole near the near-pole module by separating the far-pole module from the near-pole module by a large distance, so that more current enters below the seabed, and the amplitude of the abnormal field generated below the seabed structure increases, thereby increasing the detection depth. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary personnel in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0031] Figure 1 It is a schematic diagram of static measurement of existing marine electrical exploration equipment.

[0032] Figure 2 It is a schematic diagram of the dynamic towing measurement of the existing marine electrical exploration equipment.

[0033] Figure 3 This is a schematic diagram of the seabed resistivity detection device of the present invention.

[0034] Figure 4 It is a schematic diagram of static measurement of the seabed resistivity detection device in the present invention.

[0035] Figure 5 It is a schematic diagram of dynamic measurement of the seabed resistivity detection device in the present invention.

[0036] Figure 6 It is a schematic diagram of a plurality of proximal modules sharing one distal module in the present invention.

[0037] Figure 7 It is a schematic diagram of an embodiment of the present invention in which the transmitting proximal pole and the transmitting distal pole share a cable.

[0038] Figure 8 It is a schematic flow chart of the seabed resistivity detection method of the present invention.

[0039] The marks in the accompanying drawings are: 100, main control module; 101, transmitting unit; 102, measuring unit; 200, far pole module; 201, far pole; 202, first cable; 300, near pole module; 301, near pole; 302, measuring electrode; 303, second cable; 400, third cable; 500, fourth cable; 600, hull. DETAILED DESCRIPTION

[0040] The present invention provides a device and method for detecting seabed resistivity. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] In the embodiments and the scope of the patent application, unless the text specifically defines the article, "a", "an", "the" and "the" may also include plural forms. If there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0042] It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there can also be intermediate elements. In addition, the "connection" or "coupling" used herein can include wireless connection or wireless coupling. The term "and / or" used herein includes all or any modules and all combinations of one or more associated listed items.

[0043] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0044] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] The inventors have found that the static sinking or suspended ocean resistivity detection method places the electrode array on the seabed or suspends it in the water (surface) in a manner similar to the arrangement of the ground electrical method. The electrodes are connected by a multi-core cable and connected to the main engine on the ship. The emission of current and the measurement of potential are controlled according to the required combination of current emission electrodes and potential measurement electrodes. Another type of dynamic walking or towing method is to tow the electrode array behind the ship with a tow cable, and obtain detection data while emitting current and measuring potential during navigation. Through the above two measurement methods, when there is a geological body with a lower resistivity than the surrounding rock on the seabed, the potential difference (or electric field) measured near it will be weak, otherwise it will be strong. By quantitatively inverting the observation data of the ocean resistivity method, the geological structure imaging below the seabed can be obtained, which can be used to find various geological structures with resistivity differences such as fault zones, boulders, cavities, and relics buried under the seabed. In addition, the static and dynamic ocean resistivity methods commonly used at present both use a single streamer cable, with taps at certain intervals on the streamer cable and electrodes arranged at the taps. In the static method, the electrodes and cables are in a static state, and various transmitting and receiving arrangements and combinations similar to the ground method can be used, such as Wenner, Schlumberger, dipole-dipole, etc. In the dynamic method, the electrodes and cables are in a moving state, and multiple electrode combinations cannot be used at one location, so the commonly used method is to first tow a pair of transmitting electrodes with the streamer cable, and then tow a number of receiving electrodes behind the transmitting electrodes, and then make observations similar to the dipole-dipole device.

[0046] However, no matter it is static bottom-sinking or floating, dynamic sailing or towing ocean resistivity detection method, the transmission and reception are on one cable, which is similar to the observation of dipole-dipole device, such as Figure 1 and Figure 2As shown, that is to say, the distance between the positive and negative electrodes of the transmitting electrode is relatively close, so most of the current from the positive electrode flows back to the negative electrode through the seawater short circuit (the shortest resistance path), resulting in relatively less current actually entering the seabed. In this way, the amplitude of the abnormal field generated by the structure below the seabed is very small, resulting in a shallow detection depth. If it is lower than the environmental background noise, detection cannot be performed, especially when the seawater layer is thick, the seawater short-circuit effect is obvious, and the detection effect of the structure below the seabed is even worse.

[0047] In view of the above technical problems, the present invention provides a seabed resistivity detection device and method, wherein the device comprises: a main control module, a remote module and a near-pole module; wherein the main control module is connected to the near-pole module and the remote module respectively, and the main control module is used to provide a positive excitation current signal for the near-pole module and a negative excitation current signal for the remote module; the remote module is connected to the main control module, and the remote module is used to transmit the negative excitation current signal in water; the near-pole module is connected to the main control module, and the near-pole module is used to transmit the positive excitation current signal in water, and is used to measure the potential of the electric field excited by the electric monopole formed around the near-pole module; wherein the remote module is arranged away from the near-pole module to form an electric field excited by the electric monopole around the near-pole module. The present invention provides a positive excitation current signal for the near-pole module and a negative excitation current signal for the far-pole module through the main control module, and the far-pole module is arranged far away from the near-pole module. When the far-pole module transmits the negative excitation current signal in the water and the near-pole module transmits the positive excitation current signal in the water, an electric field excited by an electric monopole is formed around the near-pole module, and the near-pole module measures the potential of the electric field excited by the electric monopole formed around the near-pole module to obtain potential difference data, and resistivity data can be obtained through the potential difference data. In this way, the present invention forms an electric field similar to that excited by an electric monopole near the near-pole module by separating the far-pole module from the near-pole module by a large distance, so that more current enters below the seabed, and the amplitude of the abnormal field generated below the seabed structure increases, thereby increasing the detection depth, and even when the thickness of the seawater layer is large, the detection effect of the structure below the seabed can be guaranteed.

[0048] Please also see Figures 3 to 7 , the present invention provides a preferred embodiment of a seabed resistivity detection device.

[0049] See also Figure 3The present invention provides a submarine resistivity detection device, which includes: a main control module 100, a remote module 200 and a near-pole module 300. The main control module 100 is connected to the near-pole module 300 and the remote module 200 respectively, and the main control module 100 is used to provide a positive excitation current signal for the near-pole module 300 and a negative excitation current signal for the remote module 200; the remote module 200 is connected to the main control module 100, and the remote module 200 is used to transmit the negative excitation current signal in water; the near-pole module 300 is connected to the main control module 100, and the near-pole module 300 is used to transmit the positive excitation current signal in water, and is used to measure the potential of the electric field excited by the electric monopole formed around the near-pole module 300; the remote module 200 is arranged away from the near-pole module 300 to form an electric field excited by the electric monopole around the near-pole module 300.

[0050] Specifically, the main control module 100 is usually arranged on the hull 600, and the main control module 100 is respectively connected to the remote module 200 and the near-pole module 300. The remote module 200 and the near-pole module 300 are both arranged in water, and the remote module 200 is arranged away from the near-pole module 300. Generally speaking, the remote module 200 is generally arranged on the water surface, and the near-pole module 300 can be arranged on the water surface, in the water or on the seabed. During the implementation process, the main control module 100 provides a positive excitation current signal for the proximal module 300 and a negative excitation current signal for the distal module 200. When the distal module 200 transmits the negative excitation current signal in the water and the proximal module 300 transmits the positive excitation current signal in the water, an electric field excited by an electric monopole is formed around the proximal module 300. The proximal module 300 measures the potential of the electric field excited by the electric monopole formed around the proximal module 300 to obtain potential difference data, and the resistivity data can be obtained through the potential difference data.

[0051] In the above technical solution, the present invention separates the far-pole module 200 and the near-pole module 300 by a large distance, thereby forming an electric field similar to electric monopole excitation near the near-pole module 300, reducing the short-circuit effect of the seawater layer. In this way, more current enters below the seabed, the amplitude of the abnormal field generated below the seabed structure is increased, and the measured abnormal signal is stronger, thereby being able to improve the detection depth and the response to weak targets.

[0052] Please continue reading Figure 3In a further implementation of an embodiment, the main control module 100 includes: a transmitting unit 101 and a measuring unit 102; the transmitting unit 101 is connected to the distal module 200 and the proximal module 300 respectively, and the transmitting unit 101 is used to provide a negative excitation current signal for the distal module 200, and to provide a positive excitation current signal for the proximal module 300; the measuring unit 102 is connected to the proximal module 300, and the measuring unit 102 is used to receive and record the potential measured by the proximal module 300.

[0053] Specifically, the transmitting unit 101 is connected to the distal module 200 and the proximal module 300 respectively, providing a positive excitation current signal for the proximal module 300 and a negative excitation current signal for the distal module 200. The measuring unit 102 is connected to the proximal module 300. When the distal module 200 transmits the negative excitation current signal in water and the proximal module 300 transmits the positive excitation current signal in water, an electric field excited by an electric monopole is formed around the proximal module 300. The proximal module 300 measures the potential of the electric field excited by the electric monopole formed around the proximal module 300. The measuring unit 102 collects the potential measured by the proximal module 300 to obtain potential difference data, and saves the collected potential difference data. Resistivity data can be obtained based on the potential difference data.

[0054] It should be noted that the transmitting unit 101 and the measuring unit 102 are both existing technologies, and thus will not be described in detail here.

[0055] Please continue reading Figures 3 to 5 In a further implementation of an embodiment, the distal module 200 includes: a distal electrode 201, the distal electrode 201 is connected to the transmitting unit 101, and the distal electrode 201 is used to transmit the negative pole excitation current signal emitted by the transmitting unit 101 in water. The proximal module 300 includes: a plurality of electrodes, wherein the plurality of electrodes include at least one proximal electrode 301, and the remaining electrodes are measuring electrodes 302; the proximal electrode 301 is connected to the transmitting unit 101, and the proximal electrode 301 is used to transmit the positive pole excitation current signal emitted by the transmitting unit 101 in water; the measuring electrodes 302 are respectively connected to the measuring units 102, wherein a potential difference is formed between two adjacent measuring electrodes 302, and the measuring unit 102 is used to receive the potential difference formed between two adjacent measuring electrodes 302.

[0056] Specifically, the distal module 200 further includes a first cable 202, the distal electrode 201 is connected to the transmitting unit 101 through the first cable 202, and the transmitting unit 101 sends the negative pole excitation current signal to the distal electrode 201 through the first cable 202. The proximal module 300 further includes a second cable 303, the second cable 303 is a multi-core cable, the proximal electrode 301 and the measuring electrode 302 are connected through the second cable 303, wherein the proximal electrode 301 is respectively connected to the transmitting unit 101 and the measuring unit 102 through the second cable 303, the transmitting unit 101 transmits the positive pole excitation current signal to the proximal electrode 301 through the second cable 303, and transmits the potential measured by the measuring electrode 302 to the measuring unit 102 through the second cable 303.

[0057] During static measurement, the second cable 303 is suspended on the water surface, in the water or sunk to the bottom of the water according to the measurement line requirements, and the distal electrode 201 maintains a certain distance from the proximal electrode 301 on the second cable 303 through the first cable 202 to ensure that an electric monopolar excitation electric field can be formed near the proximal electrode 301, and the positive and negative excitation current signals generated by the transmitting unit 101 are respectively introduced into the proximal electrode 301 and the distal electrode 201, wherein the positive and negative excitation current signals can be bipolar square wave signals. In static measurement, any of the electrodes on the second cable 303 can be used as the proximal electrode 301, that is, any of the electrodes in the proximal electrode module 300 can be used as the proximal electrode, and the other electrodes on the second cable 303 are used as the measuring electrodes 302, and a preset program and switch on the main control module 100 can be used to realize that a certain electrode on the second cable 303 is used as the proximal electrode 301 of the transmitting current. After the measuring electrode 302 measures the potential data, the measuring unit 102 collects and records the potential difference between the measuring electrodes 302 to obtain the observation data. For example, the measuring electrodes 302 are arranged in the order of 1, 2, 3, 4, and 5, and the measured potential difference data are 4 between 1-2, 2-3, 3-4, and 4-5. In some cases, if the electric field is weak, the electrode distance can be increased, such as measuring the three potential differences between 1-3, 2-4, and 3-5. The larger the electrode distance, the more reliable the measured signal strength, but the spatial resolution will be reduced to a certain extent. The size of the measuring electrode distance can be set according to the actual measurement results.

[0058] Because each electrode on the second cable 303 can be used as the near pole 301 during static measurement, the electrodes on the first cable 202 can take turns as the near pole 301 for transmitting current according to actual needs. In this way, by changing the position of the excitation point, the current can pass through the underground medium in different ways, thereby forming multiple sets of data excited at multiple positions, which can improve the measurement accuracy.

[0059] During dynamic measurement, i.e., dynamic drag measurement, the second cable 303 floats on the water surface, in the water, or drags on the bottom of the water according to the measurement line requirements, the first cable 202 and the electrodes on the second cable 303 are kept at a certain distance, and the positive and negative excitation current signals generated by the transmitting unit 101 are respectively introduced into the near pole 301 and the far pole 201. During dynamic measurement, the electrodes at both ends of the second cable 303 in the near pole module 300 are used as near poles, and the main control module 100 uses a preset program and switch to switch one of the electrodes at both ends of the second cable 303 as the near pole 301 of the transmitting current, and the other electrodes on the second cable 303 are used as measuring electrodes 302, so as to meet the farthest distance between the near pole 301 and the measuring electrode 302 during dynamic measurement, so as to maximize the detection depth, and the potential difference between the measuring electrodes 302 is recorded by the measuring unit 102 to obtain observation data.

[0060] Whether it is static measurement or dynamic measurement, during the observation process, if the second cable 303 floats on the water surface, the position of the electrode can be located using satellites or visual markers. If the second cable 303 sinks underwater, the position of each electrode on the second cable 303 can be determined using an ultra-short baseline hydroacoustic method. The distal pole 201 can generally float freely or sink to the bottom. The approximate position is determined based on the length of the first cable 202, and there is no need for precise positioning. The position information of the proximal pole 301, the measuring electrode 302, and the distal pole 201 can be used for data acquisition quality assessment and subsequent quantitative inversion imaging. In this way, the present invention only needs to locate the proximal pole 301 and the measuring electrode 302, but does not need to locate the distal pole 201. Compared with the traditional method in which the two emitters are very close to the measuring electrode 302, inaccurate positioning will cause a large error. The present invention reduces the positioning requirements of the electrodes in the water body, which is conducive to improving the reliability of the measurement data, thereby improving work efficiency and reducing costs. Furthermore, the distance between the transmitting electrodes (i.e., the distance between the proximal pole 301 and the distal pole 201) can be adjusted arbitrarily according to the water depth, sea conditions, cost, etc. to meet the requirements of different depths.

[0061] In addition, the location of the distal pole 201 can be flexibly selected according to needs. If the water depth is deep, the second cable 303 (near pole cable) needs to be as close to the seabed as possible, and the distal pole 201 can be laid on the water surface above the near pole 301 to save the length of the first cable 202 (distal pole cable), thereby reducing the difficulty of construction. If the water depth is shallow or the second cable 303 floats on the water surface, the distal pole 201 can be selected to be laid by a longer cable at a position farther horizontally. Figure 4 and Figure 5 As shown, the position of the distal pole 201 should be selected as position A1 to increase the distance between the distal pole 201 and the proximal pole 301, wherein, Figure 4In the figure: A1 represents the first position of the distal electrode 201, A2 represents the second position of the distal electrode 201, B1 represents the first position of the electrode to be measured, B2 represents the second position of the electrode 302 to be measured, Figure 5 In the figure: A1 represents the first position of the distal electrode 201 , A2 represents the second position of the distal electrode 201 , C1 represents the first position of the measuring electrode 302 , C2 represents the second position of the measuring electrode 302 , D1 represents the first position of the proximal electrode 301 , and D2 represents the second position of the proximal electrode 301 .

[0062] Furthermore, compared with the shortcomings of the existing single cable that penetrates less seabed current and the detection depth in deep water areas is insufficient, the present invention uses a single-stage device at sea to transmit current, that is, the proximal pole 301 of one of the transmitting electrodes and the measuring electrode 302 are on the same cable, while the distal pole 201 of the other transmitting electrode is spatially separated from the proximal pole 301 through another cable. This increases the distance between the positive and negative poles of the transmitting electrode, allowing more current to flow below the seabed, reducing the short-circuit effect of the seawater layer and increasing the detection depth.

[0063] See also Figure 6 In some embodiments, a plurality of proximal modules 300 are provided and are respectively connected to the main control module 100 .

[0064] Specifically, the seabed resistivity detection device can be equipped with multiple near-pole modules 300, that is, multiple near-pole modules 300 can share one far-pole module 200, wherein multiple second cables 303 are distributed or dragged in parallel according to a set interval. In this way, it is equivalent to completing the observation work of multiple survey lines at one time, which is conducive to improving the resolution perpendicular to the survey line direction, thereby facilitating three-dimensional exploration.

[0065] It should be noted that the measuring electrode 302 is used as an electrode for measuring potential data, and the potential data measurement can also be provided by an observation station, as long as the purpose of measuring potential data can be achieved.

[0066] See also Figure 7 In some embodiments, the distal pole 201 is connected to the proximal pole 301 via a third cable 400, and the distal pole 201 and the proximal pole 301 are respectively connected to the transmitting unit 101 via the third cable 400; the measuring electrode 302 is respectively connected to the measuring unit 102 via a fourth cable 500; wherein the measuring electrode 302 is arranged close to the proximal pole 301, and the distal pole 201 is arranged away from the proximal pole 301.

[0067] Specifically, the proximal pole 301 and the distal pole 201 are connected to the third cable 400, and the third cable 400 is connected to the transmitting unit 101, and the transmitting unit 101 provides an excitation current signal to the proximal pole 301 and the distal pole 201 through the third cable 400, wherein the length of the third cable 400 is long enough to form an electric field excited by an electric monopole near the proximal pole 301. The measuring electrode 302 is connected to the measuring unit 102 through the fourth cable 500, and the fourth cable 500 is close to the proximal pole 301, so as to measure the potential difference between the measuring electrodes 302.

[0068] In some embodiments, all electrodes can also be arranged on one cable, that is, the proximal pole 301, the distal pole 201 and the measuring electrode 302 are all arranged on one cable. It is sufficient to bring the proximal pole 301 and the measuring electrode 302 close to each other and keep a large distance between the distal pole 201 and the proximal pole 301, that is, an electric field that excites an electric monopole can be formed near the proximal pole 301.

[0069] In some embodiments, the hull 600 serves as a carrier of the main control module 100. If the hull 600 is a metal hull 600, the hull 600 can be used as an excitation electrode, and one end of the power supply can be connected to the hull 600. In this way, a distal electrode 201 or a proximal electrode 301 in the water can be omitted, thereby reducing the length of the cable in the water to reduce the difficulty and cost of the operation.

[0070] In some embodiments, all electrodes in the present invention, i.e., the proximal electrode 301, the distal electrode 201, and the measuring electrode 302, can be connected to the main control module 100 by independent underwater cables, and the relative positions between the electrodes can be controlled by the length of the cables. In this way, one cable is only responsible for one electrode, so that the resistance load carried by the cable is lighter, and the damage of a single cable does not affect the normal operation of the cables of other electrodes.

[0071] See also Figure 8 In some embodiments, the present invention further provides a seabed resistivity detection method, which is applied to the seabed resistivity detection device described above, and comprises the steps of:

[0072] S100, transmitting a positive excitation current signal to the proximal module and a negative excitation current signal to the distal module through a main control module;

[0073] S200, transmitting the positive excitation current signal and the negative excitation signal in water through the proximal module and the distal module respectively, and forming an electric field excited by electric monopole around the proximal module;

[0074] S300, measuring the potential of the electric field excited by the electric monopole formed in the periphery through the proximal module to obtain potential difference data;

[0075] S400, obtaining resistivity data according to the potential difference data. The seabed resistivity detection method is specifically as described in an embodiment of a seabed resistivity detection device, which will not be described in detail here.

[0076] In summary, the seabed resistivity detection device and method provided by the present invention have the following beneficial effects:

[0077] 1. By separating the far-pole module from the near-pole module by a large distance, an electric field similar to that excited by an electric monopole is formed near the near-pole module, so that more current enters below the seabed, and the amplitude of the abnormal field generated below the seabed structure increases, thereby increasing the detection depth. Even when the seawater layer is thick, the detection effect of the structure below the seabed can be guaranteed;

[0078] 2. By changing the position of the excitation point, the current can pass through the underground medium in different ways, thus forming multiple sets of data excited at multiple positions, which can improve the measurement accuracy;

[0079] 3. Compared with the traditional method where the two emitters and the measuring electrode are very close, inaccurate positioning will cause large errors. The present invention reduces the positioning requirements of the electrodes in the water body, which is conducive to improving the reliability of the measurement data, thereby improving work efficiency and reducing costs. In addition, the distance between the emitter electrodes can be adjusted arbitrarily according to the water depth, sea conditions, cost, etc. to meet the requirements of different depths;

[0080] 4. The location of the remote pole can be flexibly selected according to needs. If the water depth is deep, the second cable needs to be as close to the seabed as possible, and the remote pole can be laid on the water surface above the near pole to save the length of the first cable, thereby reducing the difficulty of construction.

[0081] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A seabed resistivity detection device, characterized in that: include: Main control module, distal module and proximal module; among them, The main control module is connected to the proximal module and the distal module respectively, and is used to provide a positive excitation current signal for the proximal module and a negative excitation current signal for the distal module; The remote module is connected to the main control module, and the remote module is used to transmit the cathode excitation current signal in water; The proximal module is connected to the main control module, and is used to transmit the positive pole excitation current signal in water and to measure the potential of the electric field excited by the electric monopole formed around the proximal module; wherein the distal module is arranged away from the proximal module to form an electric field excited by the electric monopole around the proximal module.

2. The seabed resistivity detection device according to claim 1, characterized in that: The main control module includes: a transmitting unit and a measuring unit; The transmitting unit is connected to the distal module and the proximal module respectively, and is used to provide a negative excitation current signal to the distal module and a positive excitation current signal to the proximal module; The measuring unit is connected to the proximal module, and is used for receiving and recording the potential measured by the proximal module.

3. The seabed resistivity detection device according to claim 2, characterized in that: The remote electrode module includes: a remote electrode, which is connected to the transmitting unit and is used to transmit the cathode excitation current signal emitted by the transmitting unit in water.

4. The seabed resistivity detection device according to claim 2, characterized in that: The near-pole module comprises: a plurality of electrodes, wherein the plurality of electrodes comprises at least one near-pole, and the remaining electrodes are measuring electrodes; The proximal pole is connected to the transmitting unit, and the proximal pole is used to transmit the positive pole excitation current signal emitted by the transmitting unit in water; The measuring electrodes are connected to the measuring units respectively, wherein a potential difference is formed between two adjacent measuring electrodes.

5. The seabed resistivity detection device according to claim 3, characterized in that: The remote module also includes: a first cable; the remote is connected to the transmitting unit via the first cable.

6. The seabed resistivity detection device according to claim 4, characterized in that: The proximal electrode module further includes: a second cable; the proximal electrode and the measuring electrode are connected via the second cable, wherein the proximal electrode is respectively connected to the transmitting unit and the measuring unit via the second cable.

7. The seabed resistivity detection device according to claim 6, characterized in that: During static measurement, any electrode in the proximal pole module can be used as a proximal pole; during dynamic measurement, the electrodes located at both ends of the second cable in the proximal pole module are used as proximal poles.

8. The seabed resistivity detection device according to claim 1, characterized in that: A plurality of proximal modules are provided and are respectively connected to the main control module.

9. The seabed resistivity detection device according to claim 4, characterized in that: The distal electrode is connected to the proximal electrode via a third cable, and the distal electrode and the proximal electrode are respectively connected to the transmitting unit via the third cable; the measuring electrodes are respectively connected to the measuring units via fourth cables; wherein the measuring electrodes are arranged close to the proximal electrode, and the distal electrode is arranged far away from the proximal electrode.

10. A method for detecting seabed resistivity, applied to the seabed resistivity detection device according to any one of claims 1 to 9, characterized in that: include: Transmitting a positive excitation current signal to the proximal module and a negative excitation current signal to the distal module through the main control module; The positive pole excitation current signal and the negative pole excitation current signal are respectively emitted in water through the proximal pole module and the distal pole module, and an electric field excited by electric monopole is formed around the proximal pole module; The potential of the electric field excited by the electric monopole formed in the periphery is measured by the proximal module to obtain potential difference data; Resistivity data is obtained based on the potential difference data.

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