Ocean induced polarization and natural potential combined acquisition device and data processing method

Abstract

The invention discloses an ocean induced polarization and natural potential combined acquisition device and a data processing method, and solves the technical problem that the sulfide ore form cannot be accurately represented in the prior art. The system comprises a first underwater autonomous robot and a second underwater autonomous robot, the first underwater autonomous robot is provided with an induced polarization emission device, and the second underwater autonomous robot is provided with a natural potential acquisition device; the induced polarization emission device comprises an induced polarization control bin, a first watertight cable, an emission end positive pole and an emission end negative pole, and the natural potential acquisition equipment comprises a natural potential acquisition bin, a second watertight cable and a plurality of pairs of Ag / AgCl non-polarized electrodes. According to the method, the distribution characteristics of submarine sulfides can be more accurately explained, the multiplicity of solutions is reduced, and the exploration accuracy and reliability are improved.

Description

Technical Field

[0001] The present invention belongs to the field of marine geophysics, and particularly relates to a combined acquisition device and data processing method for marine induced polarization and spontaneous potential. Background Art

[0002] Submarine polymetallic sulfides are rich in metals such as copper, zinc, silver, and gold, and are considered to be one of the three potential marine mineral resources. Indoor rock electrical property measurement data shows that sulfides have a very strong induced polarization effect, which will distort the exploration data of the currently popular active-source electromagnetic method mainly based on resistivity, and the resistivity inverted cannot accurately characterize the morphology of sulfide ore. In addition, the inversion of spontaneous potential based on resistivity constraint will also result in incorrect interpretation results. Therefore, it is urgent to carry out marine induced polarization method exploration based on direct current resistivity. At the same time, developing joint inversion algorithms for multiple geophysical data can further reduce the non-uniqueness. The data of induced polarization method and spontaneous potential method are both obtained from the potential difference data between unpolarized electrodes, while the traditional towed measurement cannot ensure the stability of the electrodes. Therefore, the present invention proposes a combined acquisition device and data processing method for induced polarization and spontaneous potential data carried on an underwater autonomous robot. Summary of the Invention

[0003] The purpose of the present invention is to provide a combined acquisition device and data processing method for marine induced polarization and spontaneous potential, so as to solve the technical problem in the prior art that the morphology of sulfide ore cannot be accurately characterized.

[0004] To achieve the above purpose, the present invention provides the following technical solutions: In a first aspect, the present invention provides a combined acquisition device for marine induced polarization and spontaneous potential, including a first underwater autonomous robot and a second underwater autonomous robot. An induced polarization transmitting device is installed on the first underwater autonomous robot, and a spontaneous potential acquisition device is installed on the second underwater autonomous robot; The induced polarization transmitting device includes an induced polarization control chamber, a first watertight cable, a transmitting positive electrode and a transmitting negative electrode. The induced polarization control chamber is fixed on the outer shell of the first underwater autonomous robot. The first watertight cable is installed at the end of the first underwater autonomous robot. The transmitting positive electrode is installed at the tail of the first underwater autonomous robot. The transmitting negative electrode is fixed on the first watertight cable. An emission electric field is formed between the transmitting positive electrode and the transmitting negative electrode; The spontaneous potential acquisition device includes a spontaneous potential acquisition chamber, a second watertight cable, and several pairs of Ag / AgCl non-polarizable electrodes. The spontaneous potential acquisition chamber is fixed on the outer shell of the second underwater autonomous robot. The second watertight cable is installed at the end of the second underwater autonomous robot. The Ag / AgCl non-polarizable electrodes are distributed on the tail of the second underwater autonomous robot and the second watertight cable, and are used to collect the mixed data of induced polarization and spontaneous potential.

[0005] Further, it also includes several buoyancy balls. The buoyancy balls are slotted in the center and are distributed on the first watertight cable and the second watertight cable in sequence, maintaining an upward buoyancy to ensure the safe operation of the first underwater autonomous robot and the second underwater autonomous robot.

[0006] Further, it also includes a scientific research ship. An ultra-short baseline receiving device is installed on the scientific research ship, and an ultra-short baseline transmitting device is installed on the underwater autonomous robot. Through the cooperation of the transmitting and receiving devices, the position of the underwater robot and the distance between the underwater autonomous robots are located in real time.

[0007] Further, the distance between the first underwater autonomous robot and the second underwater autonomous robot is 100 meters. The distance between the positive pole and the negative pole of the transmitting end is 15 meters. The transmitting waveform is a bipolar square wave, and the transmitting period is 2S, and it is transmitted once every 10 seconds.

[0008] Further, the distance between two adjacent Ag / AgCl non-polarizable electrodes is 15 meters, and the receiving frequency of the Ag / AgCl non-polarizable electrode at the receiving end is set to 250Hz - 1000Hz.

[0009] Further, altimeters are installed at the bottom of the underwater autonomous robots to control the distance from the seabed. During the acquisition process, the underwater autonomous robots are controlled to be 15 meters away from the seabed, and the speed is controlled at 0.5 m / s.

[0010] In the second aspect, the present invention provides a data processing method for the joint acquisition of marine induced polarization and spontaneous potential, including: Collecting the mixed data of induced polarization and spontaneous potential through the equipment carried by the underwater autonomous robot; Obtaining the spontaneous potential data by resampling. The resampled spontaneous potential data is re-interpolated into the acquisition frequency, and then the original collected data is subtracted from the interpolated data to obtain the induced polarization data, realizing the preliminary separation of the two types of data; Performing denoising processing on the two types of data after preliminary separation to improve the data quality; Adopting a joint inversion method based on cross-gradient structure constraint to perform joint inversion on the denoised data to obtain a fine distribution image of submarine sulfide.

[0011] Furthermore, the objective functional of the joint inversion of the three-dimensional spontaneous potential and induced polarization method constrained by the cross-gradient structure is as follows:

[0012] where the superscripts sp and ip represent spontaneous potential and induced polarization data respectively, is the data weighting matrix, is the predicted data in the inversion, is the observed data after denoising, is the regularization factor used to control the weight of the model constraint term, is the model weighting matrix, is the model parameter obtained by inversion, is the reference model, is a constant coefficient used to control the weight of the cross-term in the joint inversion; The following iterative equations of the model change are obtained by using linearized least squares inversion:

[0013] where, , , , , , , .

[0014] Based on the above technical solutions, the embodiments of the present invention can at least produce the following technical effects: (1) For the joint acquisition device of marine induced polarization and spontaneous potential provided by the present invention, the present invention realizes two underwater autonomous vehicles (AUVs) carrying induced polarization and spontaneous potential devices, which can realize the simultaneous acquisition of two kinds of data. Moreover, due to the stable motion characteristics of the robots, the stability of the electrodes is ensured, thereby improving the accuracy of data acquisition. By optimizing the electrode mounting position and acquisition parameters, detection at different depths is realized, and the exploration efficiency is improved. The sulfides in the mid-ocean ridge are located under the seawater at a depth of about 1500 - 3000 meters, with complex terrain and large ocean currents. The underwater autonomous vehicles adopted by the present invention have strong environmental adaptability and can work stably in complex environments, ensuring the continuity and integrity of data acquisition.

[0015] (2) For the data processing method of the joint acquisition of marine induced polarization and spontaneous potential, by developing the separation and joint inversion algorithms for induced polarization data and spontaneous potential data, the present invention can more accurately interpret the distribution characteristics of submarine sulfides, reduce the non-uniqueness, and improve the accuracy and reliability of exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0017] Figure 1 is a schematic diagram of the induced polarization device and spontaneous potential device based on AUV of the present invention; Figure 2 is a schematic diagram of the structure of the first underwater autonomous robot of the present invention; Figure 3 is a schematic diagram of the structure of the second underwater autonomous robot of the present invention; Figure 4 Schematic diagram of the detection depth of the induced polarization equipment of the present invention; Figure 5 is a data processing flow chart of the present invention.

[0018] In the figure: 1. The first underwater autonomous robot; 2. The second underwater autonomous robot; 3. The induced polarization control cabin; 4. The first watertight cable; 5. The positive pole of the transmitter; 6. The negative pole of the transmitter; 7. The transmitting electric field; 8. The spontaneous potential acquisition cabin; 9. The second watertight cable; 10. The Ag / AgCl non-polarizable electrode; 11. The buoyancy ball; 12. The scientific research ship; 13. The seabed; 14. The main stern thruster; 15. The auxiliary bow thruster; 16. The bow horizontal rudder; 17. The stern horizontal rudder; 18. The forward-looking sonar; 19. The CTD sensor; 20. The vertical stabilizer; 21. The long baseline; 22. The acoustic communication transducer. Specific embodiments

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of the technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0020] This embodiment provides a combined acquisition device and data processing method for marine induced polarization and spontaneous potential. The following will be described in conjunction with the attached Figures 1-5 and described together.

[0021] Embodiment 1 Please refer toFigures 1-3 , a combined acquisition device for marine induced polarization and spontaneous potential, comprising a first underwater autonomous robot 1 and a second underwater autonomous robot 2. An induced polarization transmitting device is installed on the first underwater autonomous robot 1, and a spontaneous potential acquisition device is installed on the second underwater autonomous robot 2; The induced polarization transmitting device includes an induced polarization control chamber 3, a first watertight cable 4, a transmitting positive electrode 5 and a transmitting negative electrode 6. The induced polarization control chamber 3 is fixed on the outer shell of the first underwater autonomous robot 1. The first watertight cable 4 is installed at the end of the first underwater autonomous robot 1. The transmitting positive electrode 5 is installed at the tail of the first underwater autonomous robot 1. The transmitting negative electrode 6 is fixed on the first watertight cable 4. An emission electric field 7 is formed between the transmitting positive electrode 5 and the transmitting negative electrode 6; The spontaneous potential acquisition device includes a spontaneous potential acquisition chamber 8, a second watertight cable 9 and several pairs of Ag / AgCl non-polarizable electrodes 10. The spontaneous potential acquisition chamber 8 is fixed on the outer shell of the second underwater autonomous robot 2. The second watertight cable 9 is installed at the end of the second underwater autonomous robot 2. The Ag / AgCl non-polarizable electrodes 10 are distributed on the tail of the second underwater autonomous robot 2 and the second watertight cable 9, and are used for acquiring the mixed data of induced polarization and spontaneous potential.

[0022] In this embodiment, several buoyancy balls 11 are further included. The buoyancy balls 11 are provided with grooves at the centers and are sequentially distributed on the first watertight cable 4 and the second watertight cable 9 to maintain upward buoyancy and ensure the safe operation of the first underwater autonomous robot 1 and the second underwater autonomous robot 2.

[0023] In this embodiment, a scientific research ship 12 is further included. An ultra-short baseline receiving device is installed on the scientific research ship 12, and an ultra-short baseline transmitting device is installed on the underwater autonomous robot. Through the cooperation of the transmitting and receiving devices, the position of the underwater robot and the distance between the underwater autonomous robots are located in real time.

[0024] In this embodiment, both the first underwater autonomous robot 1 and the second underwater autonomous robot 2 include a robot outer shell spliced by buoyancy materials, a stern main propeller 14 and a bow auxiliary propeller 15 for driving the underwater autonomous robot to move forward, a bow horizontal rudder 16 and a stern horizontal rudder 17 for controlling the attitude and heading of the underwater autonomous robot, a forward-looking sonar 18 for detecting obstacles in front and underwater terrain, a thermosalinograph 19 arranged inside, a vertical stabilizer 20, a long baseline 21 for positioning and navigation, and a sound communication transducer 22 arranged on the upper part of the robot outer shell.

[0025] In order for the acquisition device to have higher stability and acquisition accuracy, the parameters of the underwater autonomous robot are adjusted in this embodiment. Please refer to Figure 4, the effective detection depth "o" of the induced polarization method is approximately equal to one-third of the distance between the midpoint "o" of the positive emitter 12 and the negative emitter 13 at the transmitting end and the midpoint "o'" of the Ag / AgCl non-polarizable electrode 16. After determining the distance L between the two AUVs, when the transmitting end of the induced polarization is excited once, data at three different depths (L / 3, L / 3 + 7.5, L / 3 + 15) can be obtained. Currently, the distribution of the mid-ocean ridge sulfide ore bodies under investigation is within 100 meters from the seabed. Therefore, the distance between the two AUVs needs to be maintained at 300 meters. Considering the attenuation of electromagnetic signals in seawater, it is advisable to keep the distance between the AUVs at 100 meters, and the maximum detection depth is approximately 50 meters. By reducing the distance L between the two AUVs, detection at different depths can be achieved.

[0026] The distance between the positive emitter 12 and the negative emitter 13 at the transmitting end of the induced polarization method is 15 meters. The transmitting waveform is a bipolar square wave, the transmitting period is 2S, and it is transmitted once every 10 seconds. The receiving frequency of the Ag / AgCl electrode at the receiving end is set to 250Hz - 1000Hz. During the acquisition process, the AUV is always controlled to be about 15 meters above the seabed, and the speed is controlled at 1 knot (0.5 m / s).

[0027] The induced polarization transmitting device includes an induced polarization control bin 3, a first watertight cable 4, a positive emitter 5 and a negative emitter 6 at the transmitting end. The induced polarization control bin 3 is fixed on the outer shell of the first underwater autonomous vehicle 1. The first watertight cable 4 is installed at the end of the first underwater autonomous vehicle 1. The positive emitter 5 is installed at the tail of the first underwater autonomous vehicle 1. The negative emitter 6 at the transmitting end is fixed on the first watertight cable 4, and an emission electric field 7 is formed between the positive emitter 5 and the negative emitter 6 at the transmitting end; The natural potential acquisition device includes a natural potential acquisition bin 8, a second watertight cable 9 and several pairs of Ag / AgCl non-polarizable electrodes 10. The natural potential acquisition bin 8 is fixed on the outer shell of the second underwater autonomous vehicle 2. The second watertight cable 9 is installed at the end of the second underwater autonomous vehicle 2. The Ag / AgCl non-polarizable electrodes 10 are distributed on the tail of the second underwater autonomous vehicle 2 and the second watertight cable 9, and are used to acquire the mixed data of induced polarization and natural potential.

[0028] Specifically, the induced polarization control bin is installed in the abdomen of the first underwater autonomous robot; the positive pole of the transmitter is installed at the tail of the first underwater autonomous robot, and the negative pole of the transmitter is installed on the first watertight cable 15 meters away from the positive pole of the transmitter. Buoyancy balls are installed on the first watertight cable between the positive and negative electrodes to ensure the safe operation of the first underwater autonomous robot. The natural potential acquisition bin is installed in the abdomen of the second underwater autonomous robot. The first pair of Ag / AgCl non-polarizable electrodes is installed at the tail of the second underwater autonomous robot, with a spacing of about 1.2 meters. The other two pairs of electrodes are installed on the second watertight cable, with a spacing of 15 meters. The interval between the electrode pairs can be appropriately increased, but too large a spacing will make the extension rod too long, affecting the safe operation of the AUV and introducing noise.

[0029] Embodiment 2 Please refer to Figure 5 , the data processing method for the combined acquisition of marine induced polarization and natural potential, including: Collect the mixed data of induced polarization and natural potential through the equipment carried by the underwater autonomous robot; Obtain the natural potential data by resampling. The resampled natural potential data is re-interpolated into the acquisition frequency, and then the original acquired data is subtracted from the interpolated data to obtain the induced polarization data, realizing the preliminary separation of the two kinds of data; Denoise the two kinds of data after preliminary separation respectively to improve the data quality; Adopt a joint inversion method based on cross-gradient structure constraint to perform joint inversion on the denoised data to obtain a fine distribution image of submarine sulfides.

[0030] Specifically, the Ag / AgCl non-polarizable electrodes collect the mixed data of induced polarization and natural potential. In Implementation 1, the acquisition frequency is set above 250 Hz. The bipolar square wave emission frequency is relatively low, and the induced secondary electric field only exists for a period of time near the rising edge and the falling edge. Therefore, the natural potential data is obtained by resampling. The resampled natural potential data is re-interpolated into the acquisition frequency, and then the original acquired data is subtracted from the interpolated data to obtain the induced polarization data. Subsequently, the two kinds of data are denoised respectively. The noise of the natural potential data mainly includes linear drift, temperature, etc. The induced polarization data is mainly to filter out the low-frequency interference of the natural potential. Perform cross-gradient-based joint inversion on the denoised induced polarization data and natural potential data to obtain the fine distribution of submarine sulfide ore.

[0031] Specifically, the objective functional of the joint inversion of three-dimensional natural potential and induced polarization method with cross-gradient structure constraint is as follows:

[0032] Among them, the superscripts sp and ip respectively represent natural potential and induced polarization data, is the data weighting matrix, is the predicted data in the inversion, is the observed data after denoising, is the regularization factor, used to control the weight of the model constraint term, is the model weighting matrix, is the model parameter obtained by inversion, is the reference model, is used to control the weight of the cross term in the joint inversion; The linearized least squares inversion is used to obtain the following iterative equations of the model change:

[0033] where, , , , , , , , are constant coefficients, used to control the weight of the cross-gradient constraint in the objective functional.

[0034] The present invention proposes a joint acquisition device and data processing method for induced polarization and spontaneous potential data carried on an underwater autonomous robot. Based on numerical simulation, the electrode mounting position is optimized to achieve high-precision acquisition of various electromagnetic data without affecting the normal operation of the AUV. The joint inversion obtains the fine structure of submarine sulfides, serving the precise exploration and resource evaluation of the sulfide contract area in the southwest Indian Ocean of China.

[0035] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. Marine induced polarization and spontaneous potential combined acquisition device, characterized in that, It includes a first underwater autonomous robot (1) and a second underwater autonomous robot (2). An induced polarization transmitting device is installed on the first underwater autonomous robot (1), and a spontaneous potential acquisition device is installed on the second underwater autonomous robot (2). The induced polarization transmitting device includes an induced polarization control bin (3), a first watertight cable (4), a transmitting positive electrode (5), and a transmitting negative electrode (6). The induced polarization control bin (3) is fixed on the outer shell of the first underwater autonomous robot (1). The first watertight cable (4) is installed at the end of the first underwater autonomous robot (1). The transmitting positive electrode (5) is installed at the tail of the first underwater autonomous robot (1). The transmitting negative electrode (6) is fixed on the first watertight cable (4). An emission electric field (7) is formed between the transmitting positive electrode (5) and the transmitting negative electrode (6). The spontaneous potential acquisition device includes a spontaneous potential acquisition bin (8), a second watertight cable (9), and several pairs of Ag / AgCl non-polarizable electrodes (10). The spontaneous potential acquisition bin (8) is fixed on the outer shell of the second underwater autonomous robot (2). The second watertight cable (9) is installed at the end of the second underwater autonomous robot (2). The Ag / AgCl non-polarizable electrodes (10) are distributed on the tail of the second underwater autonomous robot (2) and the second watertight cable (9) for acquiring the mixed data of induced polarization and spontaneous potential.

2. The marine induced polarization and spontaneous potential combined acquisition device according to claim 1, wherein It also includes several buoyancy balls (11). The buoyancy balls (11) are slotted at the center and are distributed on the first watertight cable (4) and the second watertight cable (9) in sequence to maintain upward buoyancy and ensure the safe operation of the first underwater autonomous robot (1) and the second underwater autonomous robot (2).

3. The joint acquisition device for marine induced polarization and spontaneous potential according to claim 1, wherein, It also includes a scientific research ship (12). An ultra-short baseline receiving device is installed on the scientific research ship (12), and an ultra-short baseline transmitting device is installed on the underwater autonomous robot. Through the cooperation of the transmitting and receiving devices, the position of the underwater robot and the distance between the underwater autonomous robots are located in real time.

4. The marine induced polarization and spontaneous potential combined acquisition device according to claim 1, characterized in that The distance between the first underwater autonomous robot (1) and the second underwater autonomous robot (2) is 100 meters. The distance between the transmitting positive electrode (5) and the transmitting negative electrode (6) is 15 meters. The transmitting waveform is a bipolar square wave. The transmitting period is 2S, and it is transmitted once every 10 seconds.

5. The marine induced polarization and spontaneous potential combined acquisition device according to claim 1, wherein, The distance between two adjacent Ag / AgCl non-polarizable electrodes (10) is 15 meters. The receiving frequency of the receiving end Ag / AgCl non-polarizable electrode (10) is set to 250Hz - 1000Hz.

6. The marine induced polarization and spontaneous potential combined acquisition device according to claim 1, wherein Altimeters are installed at the bottom of the underwater autonomous robots to control the distance from the seabed (13). During the acquisition process, the underwater autonomous robots are controlled to be 15 meters away from the seabed (13), and the speed is controlled at 0.5 m / s.

7. A data processing method for joint acquisition of marine induced polarization and spontaneous potential, which uses the marine induced polarization and spontaneous potential joint acquisition device described in any one of claims 1-6 to acquire data, and is characterized in that, It includes: Collecting the mixed data of induced polarization and spontaneous potential through the equipment carried by the underwater autonomous robot; Obtaining the spontaneous potential data by resampling. The resampled spontaneous potential data is re-interpolated into the acquisition frequency, and then the original acquired data is subtracted from the interpolated data to obtain the induced polarization data, realizing the preliminary separation of the two types of data. Denoise the two kinds of data after preliminary separation respectively to improve the data quality; Adopt a joint inversion method based on cross-gradient structure constraint to perform joint inversion on the denoised data and obtain a fine distribution image of submarine sulfide.

8. The data processing method for joint acquisition of marine induced polarization and spontaneous potential according to claim 7, characterized in that, The objective functional of the joint inversion of three-dimensional spontaneous potential and induced polarization method constrained by the cross-gradient structure is as follows: ； where the superscripts sp and ip represent spontaneous potential and induced polarization data respectively, is the data weighting matrix, is the predicted data in the inversion, is the observed data after denoising, is the regularization factor used to control the weight of the model constraint term, is the model weighting matrix, is the model parameter obtained by inversion, is the reference model, is a constant coefficient used to control the weight of the cross-term in the joint inversion; Use linearized least squares inversion to obtain the following iterative equations for model changes: ； Among them, , , , , , .

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