Method for extracting underground induced magnetic field of rescue well based on coordinate calibration and phase extraction

Abstract

The invention relates to the technical field of underground rescue, in particular to a method for extracting an underground induced magnetic field of a rescue well based on coordinate calibration and phase extraction, and the method comprises the steps: carrying out the current injection under the condition that a metal sleeve is not placed in an accident well, enabling a sensor to receive a background magnetic field signal, after a metal sleeve is placed in the accident well, current injection is carried out again, so that the sensor receives a total magnetic field signal; by taking the background field coordinate system as a reference, converting the total magnetic field signal to the background field coordinate system to obtain a calibrated total magnetic field signal; carrying out phase difference calculation based on the background magnetic field signal and the calibrated total magnetic field signal to obtain a phase relation between the two; and based on the background magnetic field signal and the calibrated total magnetic field signal, in combination with the phase relationship between the background magnetic field signal and the calibrated total magnetic field signal, carrying out induced magnetic field extraction to obtain an induced magnetic field signal generated by the metal sleeve. According to the method, the induced magnetic field signals can be reliably extracted, so that the efficiency and success rate of underground rescue are improved.

Description

Technical Field

[0001] The embodiments of this application relate to the field of downhole rescue technology, and in particular to a method for extracting the induced magnetic field of a rescue well based on coordinate calibration and phase extraction. Background Technology

[0002] Underground rescue refers to a series of emergency response activities, including locating, communicating, providing life support, and safely rescuing trapped personnel, following sudden accidents such as collapses, flooding, or fires in mines, tunnels, or other underground work sites. Due to the complex underground environment, limited space, and communication difficulties, as well as the potential presence of toxic and harmful gases and the risk of secondary collapses, quickly and accurately determining the location of trapped personnel and establishing effective communication are the key challenges in underground rescue operations.

[0003] Traditional underground personnel positioning methods primarily rely on wireless communication technologies such as RFID (Radio Frequency Identification), ZigBee, and UWB (Ultra Wide Band). However, these methods suffer from severe signal attenuation and difficulty penetrating obstacles in complex electromagnetic environments such as severely damaged tunnels, dense metal supports, or areas with significant water accumulation, leading to positioning failures. Therefore, research teams both domestically and internationally have begun exploring technologies that utilize the earth as a conductor for signal transmission. Among these, current injection is gradually emerging as a promising underground positioning and communication method.

[0004] The basic principle of the current injection method is to inject a low-frequency or power-frequency modulated current signal into the rock strata or the medium surrounding the tunnel at a specific location on the ground or underground. This current is conducted through the earth, forming a detectable potential distribution underground. The receiving device carried by the trapped personnel can measure the changes in the local electric field and demodulate the signal containing location information or command information, thereby achieving two-way communication and passive positioning. The current injection method utilizes the earth as a natural transmission medium, has strong penetration ability and resilience, and is particularly suitable for disaster scenarios where wireless communication is interrupted.

[0005] In the data acquisition process for locating accident wells using the current injection method, ideally, the data acquired by the sensor should be the induced magnetic field signal generated by the current converging on the metal casing. However, due to limitations of the field conditions, the magnetic field signal acquired by the sensor not only includes the induced magnetic field signal but also superimposed the magnetic field signal directly generated by the transmitting electrode (background magnetic field signal). This composite magnetic field signal (total magnetic field signal) will cause serious interference to the extraction and analysis of the induced magnetic field signal. Summary of the Invention

[0006] To address the aforementioned technical problems, embodiments of this application propose a method for extracting induced magnetic fields in rescue wells based on coordinate calibration and phase extraction. This method can reliably and accurately extract the induced magnetic field signal generated by the current converging on the metal casing, thereby improving the efficiency and success rate of downhole rescue.

[0007] To achieve the above objectives, embodiments of this application propose a method for extracting induced magnetic fields in rescue wells based on coordinate calibration and phase extraction. The method includes the following steps: In the absence of a metal casing in the accident well, current injection is performed, and the magnetic field signal received by the sensor is used as the background magnetic field signal. After placing the metal casing in the accident well, current injection is performed again, and the magnetic field signal received by the sensor is used as the total magnetic field signal. Using the background field coordinate system corresponding to the background magnetic field signal as a reference, the total magnetic field signal is transformed from the corresponding total field coordinate system to the background field coordinate system to obtain a calibrated total magnetic field signal. The phase difference between the background magnetic field signal and the calibrated total magnetic field signal is calculated to obtain the phase relationship between them. Based on the background magnetic field signal and the calibrated total magnetic field signal, and combined with the calculated phase relationship, the induced magnetic field is extracted to obtain the induced magnetic field signal generated by the metal casing.

[0008] To achieve the above objectives, embodiments of this application also propose a downhole induced magnetic field extraction device for rescue wells based on coordinate calibration and phase extraction. The device includes: a data acquisition module, a calibration module, a phase difference calculation module, and an induced magnetic field extraction module. The data acquisition module is used to inject current into the accident well without a metal casing, using the magnetic field signal received by the sensor as the background magnetic field signal. After placing the metal casing in the accident well, current injection is performed again, using the magnetic field signal received by the sensor as the total magnetic field signal. The calibration module is used to transform the total magnetic field signal from the corresponding total field coordinate system to the background field coordinate system, using the background field coordinate system corresponding to the background magnetic field signal as a reference, to obtain a calibrated total magnetic field signal. The phase difference calculation module is used to calculate the phase difference based on the background magnetic field signal and the calibrated total magnetic field signal, obtaining the phase relationship between the background magnetic field signal and the calibrated total magnetic field signal. The induced magnetic field extraction module is used to extract the induced magnetic field signal generated by the metal casing based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship.

[0009] To achieve the above objectives, embodiments of this application also propose an electronic device, including a processor and a memory, wherein the memory stores instructions executable by the processor, and the processor is configured to execute the instructions such that the electronic device can implement the above-described method for extracting downhole induced magnetic fields of a rescue well based on coordinate calibration and phase extraction.

[0010] To achieve the above objectives, embodiments of this application also propose a computer-readable storage medium storing a computer program that, when executed by a processor, enables the implementation of a method for extracting downhole induced magnetic fields of rescue wells based on coordinate calibration and phase extraction, as described above.

[0011] Optionally, the current injection uses a square wave current with an output frequency of 1.7Hz; In the absence of a metal casing in the accident well, the background magnetic field signals received by the sensor along the X, Y, and Z axes are respectively denoted as... , , The accelerations along the X, Y, and Z axes collected by the accelerometer are recorded as follows: , , , Indicates the sampling point; With a metal casing already installed in the accident well, the total magnetic field signals received by the sensor along the X, Y, and Z axes are denoted as follows: , , The accelerations along the X, Y, and Z axes collected by the accelerometer are recorded as follows: , , .

[0012] Optionally, when acquiring background magnetic field signals, the probe coordinate system is defined as the background field coordinate system, denoted as... , , , These are the X, Y, and Z axes of the background field coordinate system, respectively. The X-axis of the background field coordinate system points to the bottom of the metal casing, and the plane formed by the Y and Z axes is perpendicular to the X-axis. When acquiring the total magnetic field signal, the probe coordinate system is defined as the total field coordinate system, denoted as [X-axis]. , , , These are the X, Y, and Z axes of the total field coordinate system, respectively. The X-axis of the total field coordinate system points to the bottom of the metal casing, and the plane formed by the Y and Z axes is perpendicular to the X-axis. The probe coordinate system is the coordinate system corresponding to the metal casing. When the orientation of the metal sleeve changes, the rotation angle between the X-axis of the total field coordinate system and the X-axis of the background field coordinate system is denoted as... Let the rotation angle between the Y-axis of the total field coordinate system and the Y-axis of the background field coordinate system be denoted as... Let the rotation angle between the Z-axis of the total field coordinate system and the Z-axis of the background field coordinate system be denoted as... .

[0013] Optionally, the total magnetic field signal is transformed from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signal, including: To each , , Perform a Fast Fourier Transform (FFT). The DC component of the frequency domain signal after the FFT is used as the geomagnetic field information along the X, Y, and Z axes corresponding to the background magnetic field signal, denoted as follows: , , ; To each , , Perform a Fast Fourier Transform (FFT). The DC component of the frequency domain signal after the FFT is used as the geomagnetic field information along the X, Y, and Z axes corresponding to the total magnetic field signal, denoted as follows: , , ; based on , , , , , , , , , , , Calculated separately , , ; based on , , The rotation matrices for rotation around the X-axis are calculated respectively. Rotation matrix for rotation about the Y-axis Rotation matrix for rotation about the Z-axis Based on , , The total rotation matrix is ​​calculated. ; Using the following formula Will , , Transform to the background field coordinate system to obtain the calibrated total magnetic field signals along the X, Y, and Z axes. , , : .

[0014] Optionally, based on , , , , , , , , , , , Calculated separately , , This can be achieved through the following formula: ; , ; ; ; based on , , The rotation matrices for rotation around the X-axis are calculated respectively. Rotation matrix for rotation about the Y-axis Rotation matrix for rotation about the Z-axis This can be achieved through the following formula: , , ; based on , , The total rotation matrix is ​​calculated. This can be achieved through the following formula: .

[0015] Optionally, the phase difference between the background magnetic field signal and the calibrated total magnetic field signal is calculated to obtain the phase relationship between them, including: Will As a reference sequence; Calculate sequentially using the following formulas. , , , , and Cross-correlation function between , , , , : ; ; ; ; ; in, For time delay; Take respectively , , , , The maximum delay corresponds to the maximum value, and is denoted as follows: , , , , ; Based on the sampling frequency, the following formula is used. Main frequency The maximum delay corresponding to each cross-correlation function, respectively , , , , and Phase difference calculations are performed, and the following results are obtained sequentially. , , , , and Phase relationship between them: ; ; ; ; ; in, for and Phase relationship between for and Phase relationship between for and Phase relationship between for and Phase relationship between for and The phase relationship between them.

[0016] Optionally, based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship, the induced magnetic field signal generated by the metal sleeve is extracted, which is achieved through the following formula: ; in, , , These are the induced magnetic field signals for the X-axis, Y-axis, and Z-axis, respectively.

[0017] This application addresses the problem that the induced magnetic field cannot be accurately extracted in the location of accident wells using the current injection method due to interference from the direct field of the transmitting electrode, carrier rotation, and initial phase uncertainty. It creatively proposes a method for extracting the induced magnetic field in rescue wells based on coordinate calibration and phase extraction. The beneficial effects created by this method are mainly reflected in the following aspects.

[0018] First, it fundamentally improves the authenticity and accuracy of the induced magnetic field signal. This application directly addresses the two core technical challenges of "phase uncertainty" and "carrier rotation," overcoming the limitations of traditional differential methods in handling composite errors through precise phase correction and coordinate system calibration algorithms. This method transforms the extraction of the induced magnetic field from a simple signal estimation into a high-fidelity reconstruction of the target induced magnetic field. The extracted induced magnetic field signal can accurately reflect the physical field distribution generated by the current in the downhole metal casing, ensuring the accuracy and reliability of subsequent analysis from the data source.

[0019] Second, it significantly enhances the robustness and field adaptability of data acquisition. This application treats unavoidable errors in field operations (such as changes in the attitude of the metal casing) as solvable variables rather than noise. This means that the accuracy requirements for operation are reduced, and it has a stronger adaptability to complex downhole environments. Even if there are inconsistencies in attitude between two measurements, this application can still compensate through algorithms, greatly enhancing the stability of the entire measurement process and its reliability in practical engineering applications.

[0020] Third, it provides a highly stable data foundation for subsequent positioning algorithms. By providing clean and accurate induced magnetic field data, this application effectively avoids inputting "garbage data" into subsequent optimization algorithms, thereby directly improving the stability and final accuracy of positioning and orientation calculations. This application provides a solid and reliable data foundation for the entire accident well positioning process, and its role is global and crucial. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies of this application will be briefly introduced below. Obviously, the following drawings are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings described herein are only used to explain this application and are not intended to limit this application.

[0022] Figure 1 This is a flowchart of a method for extracting downhole induced magnetic fields of a rescue well based on coordinate calibration and phase extraction, provided in one embodiment of this application; Figure 2 This is a detailed schematic diagram of a method for extracting downhole induced magnetic fields of a rescue well based on coordinate calibration and phase extraction, provided in one embodiment of this application; Figure 3 This is a schematic diagram of the total field coordinate system and the background field coordinate system provided in one embodiment of this application; Figure 4 This is a schematic diagram of the connection of a simulation experiment system provided in one embodiment of this application; Figure 5 This is a schematic diagram of the structure of a downhole induction magnetic field extraction device for rescue wells based on coordinate calibration and phase extraction, provided in another embodiment of this application; Figure 6 This is a schematic diagram of the structure of an electronic device provided in another embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. Those skilled in the art will understand that many technical details have been presented in the embodiments of this application to facilitate better understanding. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this application. The following embodiments can be combined with and referenced by each other without contradiction.

[0024] One embodiment of this application proposes a method for extracting downhole induced magnetic fields in rescue wells based on coordinate calibration and phase extraction, applied to an electronic device. The electronic device can be a terminal or a server; this embodiment and subsequent embodiments will use a server as an example. The implementation details of the method for extracting downhole induced magnetic fields in rescue wells based on coordinate calibration and phase extraction proposed in this embodiment will be described below. The following implementation details are provided for ease of understanding and are not essential for implementing this solution.

[0025] The specific process of the rescue well downhole induced magnetic field extraction method based on coordinate calibration and phase extraction proposed in this embodiment can be described as follows: Figure 1 As shown, its specific details are as follows: Figure 2 As shown, the method includes: Step 11: Inject current into the accident well without placing a metal casing, and use the magnetic field signal received by the sensor as the background magnetic field signal. After placing a metal casing in the accident well, inject current again, and use the magnetic field signal received by the sensor as the total magnetic field signal.

[0026] In this specific implementation, this embodiment proposes a method to extract pure induced magnetic field signals by designing two different operating conditions and comparing two sets of experimental data. The two operating conditions are: no metal casing placed in the emergency well and metal casing placed in the emergency well. First, current injection is performed in the case where no metal casing is placed in the emergency well, and the magnetic field signal received by the sensor is collected. The magnetic field signal collected at this time is the background magnetic field signal. Then, a metal casing is placed in the emergency well, and current injection is performed again. The magnetic field signal received by the sensor is collected at this time. The magnetic field signal collected at this time is the superposition of the background magnetic field and the induced magnetic field, which is called the total magnetic field signal.

[0027] In one example, current injection uses a square wave current with an output frequency of 1.7 Hz, meaning the emitting electrode needs to output a square wave current with a frequency of 1.7 Hz to achieve current injection.

[0028] In one example, when no metal casing is placed in the accident well, that is, when collecting background magnetic field signals, the background magnetic field signals received (collected) by the sensor along the X, Y, and Z axes can be denoted as follows: , , The accelerations along the X, Y, and Z axes collected by the accelerometer are recorded as follows: , , ,in, This represents discrete sampling points.

[0029] In one example, where a metal casing has been placed in the accident well, that is, when collecting the total magnetic field signal, the total magnetic field signals received (collected) by the sensor along the X, Y, and Z axes can be denoted as follows: , , The accelerations along the X, Y, and Z axes collected by the accelerometer are recorded as follows: , , .

[0030] Step 12: Using the background field coordinate system corresponding to the background magnetic field signal as a reference, transform the total magnetic field signal from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signal.

[0031] In practical implementation, to compare and extract the differences between the presence and absence of metal casing in the accident well, it is necessary to calibrate the magnetic field signals collected in both sets to ensure the accuracy of data comparison and calculation. During data acquisition, the orientation of the probe (metal casing) in the rescue well may change, and the probe coordinate system will also change accordingly during the two sets of data acquisition. That is, the acquired total magnetic field signal and the background magnetic field signal must be calibrated to the same coordinate system to correctly extract the induced magnetic field signal. This embodiment selects the background field coordinate system corresponding to the background magnetic field signal as the reference, and transforms the total magnetic field signal from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signal. Of course, it is also feasible to use the total field coordinate system corresponding to the total magnetic field signal as the reference to transform the background magnetic field signal from the corresponding background field coordinate system to the total field coordinate system.

[0032] In such Figure 3 In the model shown, when acquiring background magnetic field signals, we can define the probe coordinate system as the background field coordinate system, denoted as [the model description would go here]. , , , These represent the X, Y, and Z axes of the background field coordinate system, respectively, and the X-axis of the background field coordinate system. Pointing to the bottom of the metal sleeve, Y-axis and Z-axis The plane formed by the X-axis Vertical. Similarly, when acquiring the total magnetic field signal, we can define the probe coordinate system as the total field coordinate system, denoted as [equation missing]. , , , These represent the X, Y, and Z axes of the total field coordinate system, respectively. Pointing to the bottom of the metal sleeve, Y-axis and Z-axis The plane formed by the X-axis Vertical. Here, the probe coordinate system is the same as the coordinate system corresponding to the metal casing. When the attitude of the metal casing changes (probe attitude change), we denote the rotation angle between the X-axis of the total field coordinate system and the X-axis of the background field coordinate system as [missing information]. Let the rotation angle between the Y-axis of the total field coordinate system and the Y-axis of the background field coordinate system be denoted as... Let the rotation angle between the Z-axis of the total field coordinate system and the Z-axis of the background field coordinate system be denoted as... .

[0033] When transforming the total magnetic field signal from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signal, it is necessary to perform a fast Fourier transform on the background magnetic field signal and the total magnetic field signal. Using a dynamic method based on dynamic dynamics, the tilt angle of the sensor in space in the probe is calculated through acceleration information, and the azimuth angle of the sensor is determined using geomagnetic field information, thereby determining the rotation angle and rotation matrix.

[0034] First, respectively , , Perform a Fast Fourier Transform (FFT). The DC component of the frequency domain signal after the FFT is used as the geomagnetic field information along the X, Y, and Z axes corresponding to the background magnetic field signal, denoted as follows: , , Subsequently, they respectively... , , Perform a Fast Fourier Transform (FFT). The DC component of the frequency domain signal after the FFT is used as the geomagnetic field information along the X, Y, and Z axes corresponding to the total magnetic field signal, denoted as follows: , , Next, based on , , , , , , , , , , , Calculated separately , , After that, based on , , The rotation matrices for rotation around the X-axis are calculated respectively. Rotation matrix for rotation about the Y-axis Rotation matrix for rotation about the Z-axis and based on , , The total rotation matrix is ​​calculated. Finally, using Will , , Transform to the background field coordinate system to obtain the calibrated total magnetic field signals along the X, Y, and Z axes. , , .

[0035] In one example, based on , , , , , , , , , , , Calculated separately , , This can be achieved through the following formula: ; , ; ; ; in, It is the arcsine function. It is the arctangent function.

[0036] In one example, based on , , The rotation matrices for rotation around the X-axis are calculated respectively. Rotation matrix for rotation about the Y-axis Rotation matrix for rotation about the Z-axis This can be achieved through the following formula: , , .

[0037] In one example, based on , , The total rotation matrix is ​​calculated. This can be achieved through the following formula: .

[0038] In one example, using Will , , Transform to the background field coordinate system to obtain the calibrated total magnetic field signals along the X, Y, and Z axes. , , This can be achieved through the following formula: .

[0039] Step 13: Calculate the phase difference based on the background magnetic field signal and the calibrated total magnetic field signal to obtain the phase relationship between the background magnetic field signal and the calibrated total magnetic field signal.

[0040] In practical implementation, after obtaining the calibrated total magnetic field signal, the phase difference can be calculated based on the background magnetic field signal and the calibrated total magnetic field signal to obtain the phase relationship between the background magnetic field signal and the calibrated total magnetic field signal. Cross-correlation of discrete sequences is a method used to measure the similarity between two sequences, especially their relative time delay (phase difference). The purpose of cross-correlation is to find the phase difference of one sequence relative to another.

[0041] Therefore, in this embodiment, a set of sequences is selected as the reference data set, and the remaining five sets of data are cross-correlated with it respectively. Here, we take... As an example, consider the reference sequence.

[0042] First, calculate sequentially using the following formula. , , , , and Cross-correlation function between , , , , : ; ; ; ; ; in, This is a time delay.

[0043] Next, take respectively , , , , The maximum delay corresponds to the maximum value, and is denoted as follows: , , , , .

[0044] by For example, The calculation formula is: .

[0045] Finally, we use the following formula, based on the sampling frequency Main frequency The maximum delay corresponding to each cross-correlation function, respectively , , , , and Phase difference calculation is performed to obtain the following results sequentially. , , , , and Phase relationship between them: ; ; ; ; ; in, for and Phase relationship between for and Phase relationship between for and Phase relationship between for and Phase relationship between for and The phase relationship between them, the dominant frequency That is, the frequency of the excitation signal output by the excitation source.

[0046] Step 14: Based on the background magnetic field signal and the calibrated total magnetic field signal, and combined with the calculated phase relationship, the induced magnetic field is extracted to obtain the induced magnetic field signal generated by the metal sleeve.

[0047] In practical implementation, after calculating the phase relationship, the induced magnetic field signal generated by the metal casing can be extracted based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship. Through calibration, the magnetic field signals acquired in the total field coordinate system and the background field coordinate system are completely transformed into the same coordinate system. By performing difference analysis on the calibrated magnetic field signal, the characteristics and differences of the induced magnetic field in the field can be well displayed. This method provides a solution for the correct recovery of system magnetic field data through probe calibration under various attitudes and provides a foundation for the extraction of induced magnetic field signals in accident wells with or without metal casing.

[0048] In one example, based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship, the induced magnetic field signal generated by the metal sleeve is extracted, which can be achieved by the following formula: ; in, , , These are the induced magnetic field signals for the X-axis, Y-axis, and Z-axis, respectively.

[0049] It is important to note that , , , , It refers to the phase relationship, not the traditional phase value (angle value). The phase relationship only... and Two possible values: if the calculated phase difference is 0 degrees, then the value is [value to be filled in]. If the calculated phase difference is 180 degrees, then the value is taken as... .

[0050] This embodiment addresses the problem that the current injection method cannot accurately extract the induced magnetic field in accident well positioning due to interference from the direct field of the transmitting electrode, carrier rotation, and initial phase uncertainty. It creatively proposes a method for extracting the induced magnetic field in rescue wells based on coordinate calibration and phase extraction. The beneficial effects created by this method are mainly reflected in the following aspects.

[0051] First, it fundamentally improves the authenticity and accuracy of the induced magnetic field signal. This embodiment directly addresses the two core technical challenges of "phase uncertainty" and "carrier rotation," overcoming the limitations of traditional differential methods in handling composite errors through precise phase correction and coordinate system calibration algorithms. This method transforms the extraction of the induced magnetic field from a simple signal estimation into a high-fidelity reconstruction of the target induced magnetic field. The extracted induced magnetic field signal can accurately reflect the physical field distribution generated by the current in the downhole metal casing, ensuring the accuracy and reliability of subsequent analysis from the data source.

[0052] Secondly, it significantly enhances the robustness and field adaptability of data acquisition. This embodiment treats unavoidable errors in field operations (such as changes in the attitude of the metal casing) as solvable variables rather than noise. This means that the accuracy requirements for operation are reduced, and it has a stronger adaptability to complex downhole environments. Even if there are inconsistencies in attitude between two measurements, this embodiment can still compensate through algorithms, greatly enhancing the stability of the entire measurement process and its reliability in practical engineering applications.

[0053] Third, it provides a highly stable data foundation for subsequent positioning algorithms. This embodiment effectively avoids inputting "garbage data" into subsequent optimization algorithms by providing clean and accurate induced magnetic field data, thereby directly improving the stability and final accuracy of positioning and orientation calculations. This embodiment provides a solid and reliable data foundation for the entire accident well positioning process, and its role is global and crucial.

[0054] The steps described above are merely for clarity in describing the technical solution. In actual implementation, they can be combined into one step, or certain steps can be broken down into multiple steps, as long as they involve the same logical relationship, they are all within the scope of protection of this application. Any insignificant modifications or designs added to the algorithm or process, as long as they do not change the core of the algorithm or process, are also within the scope of protection of this application.

[0055] In one embodiment, to verify the effectiveness of the proposed method for extracting downhole induced magnetic fields of rescue wells based on coordinate calibration and phase extraction (hereinafter referred to as "this method"), we conducted relevant simulation experiments and compared the results of this method with existing optimization data. The system connection of the simulation experiment can be described as follows: Figure 4 As shown in Table 1, the direction summary of the magnetic field data sets for each axis obtained using the relative processing method is presented.

[0056] Table 1: Summary of the directions of magnetic field data sets for each axis obtained using the relative processing method

[0057] Figure 4The magnetic field signal is acquired using a non-magnetic, watertight enclosure-enclosed magnetic field data acquisition container. The signal output from the signal generator is amplified and then connected to a radiation rod, the axis of which is aligned with the axis of the magnetic field data acquisition container. Inside the data acquisition container, two triaxial fluxgate sensors are installed on the axis, with each axis of these two sensors corresponding and aligned.

[0058] Under theoretical conditions, the phases of corresponding axes of the two sensors should be completely consistent. Using the X-axis of fluxgate sensor 1 as the reference data set and the other axes as the comparison data set, cross-correlation analysis was performed between each set and the reference data set. The initial phase of the reference data set was defined as 0 degrees (positive direction, marked "+") and 180 degrees (negative direction, marked "-"). The five sets of data were processed using this method, and the summaries of the magnetic field data for each axis of the two fluxgate sensors are shown in Table 1. For different data sets, when the sensor orientation changed, the phase relationships obtained through cross-correlation analysis were consistent with the theoretical expectations. This indicates that the correspondence between the axes of the two sensors remained unchanged throughout the experiment, and the acquired phase relationships met the theoretical requirements.

[0059] Another embodiment of this application proposes a downhole induced magnetic field extraction device for rescue wells based on coordinate calibration and phase extraction. The details of this device are described below. The following content is for illustrative purposes only and is not essential for implementing this solution. Figure 5 This is a schematic diagram of a downhole induction magnetic field extraction device for rescue wells based on coordinate calibration and phase extraction proposed in this embodiment, including: acquisition module 21, calibration module 22, phase difference calculation module 23 and induction magnetic field extraction module 24.

[0060] The acquisition module 21 is used to inject current in the accident well when no metal casing is placed, and use the magnetic field signal received by the sensor as the background magnetic field signal. After the metal casing is placed in the accident well, current is injected again and the magnetic field signal received by the sensor is used as the total magnetic field signal.

[0061] The calibration module 22 is used to transform the total magnetic field signal from the corresponding total field coordinate system to the background field coordinate system, based on the background field coordinate system corresponding to the background magnetic field signal, to obtain the calibrated total magnetic field signal.

[0062] The phase difference calculation module 23 is used to calculate the phase difference based on the background magnetic field signal and the calibrated total magnetic field signal, so as to obtain the phase relationship between the background magnetic field signal and the calibrated total magnetic field signal.

[0063] The induced magnetic field extraction module 24 is used to extract the induced magnetic field based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship, to obtain the induced magnetic field signal generated by the metal sleeve.

[0064] It is worth noting that all modules involved in this embodiment are logical modules. In practical applications, a logical module can be a physical module, a part of a physical module, or an organic combination of multiple physical modules. Furthermore, to highlight the innovative aspects of this application, this embodiment does not introduce modules that are not closely related to solving the technical problems proposed in this application. However, this does not mean that other modules are absent from this embodiment.

[0065] It is not difficult to see that this embodiment is a system embodiment corresponding to the above method embodiments, and this embodiment can be implemented in conjunction with the above method embodiments. The relevant technical details and technical effects mentioned in the above method embodiments are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the above method embodiments.

[0066] Another embodiment of this application provides an electronic device, such as Figure 6 As shown, it includes a processor 31 and a memory 32. The memory 32 stores instructions that the processor 31 can execute. When the processor 31 is configured to execute the instructions, the electronic device can realize a method for extracting the downhole induced magnetic field of a rescue well based on coordinate calibration and phase extraction as described in the above method embodiment.

[0067] The memory and processor are connected via a bus, which includes any number of interconnecting buses and bridges, connecting various circuits of one or more processors and the memory. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single component or multiple components, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0068] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0069] Another embodiment of this application proposes a computer-readable storage medium storing a computer program that, when executed by a processor, can implement a method for extracting downhole induced magnetic fields of a rescue well based on coordinate calibration and phase extraction as described in the above method embodiments.

[0070] That is, those skilled in the art will understand that all or part of the steps in the above method embodiments can be implemented by a program instructing related hardware. The program is stored in a storage medium and includes several instructions to cause a device (such as a microcontroller, chip, etc.) or processor to execute all or part of the steps of the method described in the method embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, random access memory, magnetic disks, or optical disks.

[0071] It will be understood by those skilled in the art that the above embodiments are specific implementations of this application, and various changes in form and detail can be made in practical applications without departing from the spirit and scope of this application. For those skilled in the art, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A method for extracting downhole induced magnetic fields in rescue wells based on coordinate calibration and phase extraction, characterized in that, The method includes: Current injection was performed in the accident well without a metal casing, and the magnetic field signal received by the sensor was used as the background magnetic field signal. After the metal casing was placed in the accident well, current injection was performed again, and the magnetic field signal received by the sensor was used as the total magnetic field signal. Using the background field coordinate system corresponding to the background magnetic field signal as a reference, the total magnetic field signal is transformed from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signal; The phase difference between the background magnetic field signal and the calibrated total magnetic field signal is calculated to obtain the phase relationship between them. Based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship, the induced magnetic field is extracted to obtain the induced magnetic field signal generated by the metal sleeve.

2. The method for extracting downhole induced magnetic field of a rescue well based on coordinate calibration and phase extraction according to claim 1, characterized in that, The current injection uses a square wave current with an output frequency of 1.7Hz; In the absence of a metal casing in the accident well, the background magnetic field signals received by the sensor along the X, Y, and Z axes are respectively denoted as... , , The accelerations along the X, Y, and Z axes collected by the accelerometer are recorded as follows: , , , Indicates the sampling point; With a metal casing already installed in the accident well, the total magnetic field signals received by the sensor along the X, Y, and Z axes are denoted as follows: , , The accelerations along the X, Y, and Z axes collected by the accelerometer are recorded as follows: , , .

3. The method for extracting downhole induced magnetic field of a rescue well based on coordinate calibration and phase extraction according to claim 2, characterized in that, When acquiring background magnetic field signals, the probe coordinate system is defined as the background field coordinate system, denoted as . , , , These are the X, Y, and Z axes of the background field coordinate system, respectively. The X-axis of the background field coordinate system points to the bottom of the metal casing, and the plane formed by the Y and Z axes is perpendicular to the X-axis. When acquiring the total magnetic field signal, the probe coordinate system is defined as the total field coordinate system, denoted as [X-axis]. , , , These are the X, Y, and Z axes of the total field coordinate system, respectively. The X-axis of the total field coordinate system points to the bottom of the metal casing, and the plane formed by the Y and Z axes is perpendicular to the X-axis. The probe coordinate system is the coordinate system corresponding to the metal casing. When the orientation of the metal sleeve changes, the rotation angle between the X-axis of the total field coordinate system and the X-axis of the background field coordinate system is denoted as... Let the rotation angle between the Y-axis of the total field coordinate system and the Y-axis of the background field coordinate system be denoted as... Let the rotation angle between the Z-axis of the total field coordinate system and the Z-axis of the background field coordinate system be denoted as... .

4. The method for extracting downhole induced magnetic field of a rescue well based on coordinate calibration and phase extraction according to claim 3, characterized in that, The total magnetic field signal is transformed from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signal, including: To each , , Perform a Fast Fourier Transform (FFT). The DC component of the frequency domain signal after the FFT is used as the geomagnetic field information along the X, Y, and Z axes corresponding to the background magnetic field signal, denoted as follows: , , ; To each , , Perform a Fast Fourier Transform (FFT). The DC component of the frequency domain signal after the FFT is used as the geomagnetic field information along the X, Y, and Z axes corresponding to the total magnetic field signal, denoted as follows: , , ; based on , , , , , , , , , , , Calculated separately , , ; based on , , The rotation matrices for rotation around the X-axis are calculated respectively. Rotation matrix for rotation about the Y-axis Rotation matrix for rotation about the Z-axis Based on , , The total rotation matrix is ​​calculated. ; Using the following formula Will , , Transform to the background field coordinate system to obtain the calibrated total magnetic field signals along the X, Y, and Z axes. , , : 。 5. The method for extracting downhole induced magnetic field of a rescue well based on coordinate calibration and phase extraction according to claim 4, characterized in that, based on , , , , , , , , , , , Calculated separately , , This can be achieved through the following formula: ； ， ； ； ； based on , , The rotation matrices for rotation around the X-axis are calculated respectively. Rotation matrix for rotation about the Y-axis Rotation matrix for rotation about the Z-axis This can be achieved through the following formula: ， ， ； based on , , The total rotation matrix is ​​calculated. This can be achieved through the following formula: 。 6. The method for extracting downhole induced magnetic field of a rescue well based on coordinate calibration and phase extraction according to claim 4, characterized in that, Phase difference calculations are performed based on the background magnetic field signal and the calibrated total magnetic field signal to obtain the phase relationship between the two signals, including: Will As a reference sequence; Calculate sequentially using the following formulas. , , , , and Cross-correlation function between , , , , : ； ； ； ； ； in, For time delay; Take respectively , , , , The maximum delay corresponds to the maximum value, and is denoted as follows: , , , , ; Based on the sampling frequency, the following formula is used. Main frequency The maximum delay corresponding to each cross-correlation function, respectively , , , , and Phase difference calculations are performed, and the following results are obtained sequentially. , , , , and Phase relationship between them: ； ； ； ； ； in, for and Phase relationship between for and Phase relationship between for and Phase relationship between for and Phase relationship between for and The phase relationship between them.

7. The method for extracting downhole induced magnetic field of a rescue well based on coordinate calibration and phase extraction according to claim 6, characterized in that, Based on the background magnetic field signal and the calibrated total magnetic field signal, and combined with the calculated phase relationship, the induced magnetic field signal generated by the metal sleeve is extracted, which is achieved through the following formula: ； in, , , These are the induced magnetic field signals for the X-axis, Y-axis, and Z-axis, respectively.

8. A device for extracting downhole induced magnetic fields in rescue wells based on coordinate calibration and phase extraction, characterized in that, The device includes: The acquisition module is used to inject current in the emergency well when no metal casing is placed, and use the magnetic field signal received by the sensor as the background magnetic field signal. After the metal casing is placed in the emergency well, current injection is performed again, and the magnetic field signal received by the sensor is used as the total magnetic field signal. The calibration module is used to transform the total magnetic field signal from the corresponding total field coordinate system to the background field coordinate system, based on the background field coordinate system corresponding to the background magnetic field signal, to obtain the calibrated total magnetic field signal. The phase difference calculation module is used to calculate the phase difference based on the background magnetic field signal and the calibrated total magnetic field signal, and obtain the phase relationship between the background magnetic field signal and the calibrated total magnetic field signal. The induced magnetic field extraction module is used to extract the induced magnetic field signal generated by the metal sleeve based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship.

9. An electronic device, characterized in that, include: The processor and memory, wherein the memory stores instructions that the processor can execute, and the processor is configured to, when executing the instructions, enable the electronic device to implement a method for extracting downhole induced magnetic fields of a rescue well based on coordinate calibration and phase extraction as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it can realize a method for extracting the downhole induced magnetic field of a rescue well based on coordinate calibration and phase extraction as described in any one of claims 1 to 7.

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