Rescue well downhole inductive magnetic field extraction method based on coordinate calibration and phase extraction

Abstract

The application relates to the technical field of underground rescue, in particular to a rescue well underground induction magnetic field extraction method based on coordinate calibration and phase extraction, which comprises the following steps: current injection is carried out without placing a metal casing pipe in an accident well, so that a sensor receives a background magnetic field signal; current injection is carried out again after the metal casing pipe is placed in the accident well, so that the sensor receives a total magnetic field signal; taking a background field coordinate system as a reference, the total magnetic field signal is converted into the background field coordinate system, and a calibrated total magnetic field signal is obtained; phase difference calculation is carried out based on the background magnetic field signal and the calibrated total magnetic field signal, and a phase relationship between the two is obtained; induction magnetic field extraction is carried out based on the background magnetic field signal and the calibrated total magnetic field signal and in combination with the phase relationship between the two, and an induction magnetic field signal generated by the metal casing pipe is obtained. The method can reliably extract the induction magnetic field signal, thereby improving the efficiency and success rate of underground rescue.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of underground rescue, and in particular to a rescue well underground induction magnetic field extraction method based on coordinate calibration and phase extraction. BACKGROUND

[0002] Underground rescue refers to a series of emergency disposal activities including positioning, communication, life support and safety rescue for trapped personnel after a sudden accident such as collapse, water inrush, fire, etc. in a mine, tunnel or other underground work site. Due to the complex underground environment, limited space, communication difficulties, and the possible presence of toxic and harmful gases and the risk of secondary collapse, how to quickly and accurately determine the location of trapped personnel and establish effective communication is a key difficulty in underground rescue work.

[0003] Traditional underground personnel positioning methods are mainly based on RFID (Radio Frequency Identification), ZigBee, UWB (Ultra Wide Band) and other wireless communication technologies, but these methods have serious signal attenuation and are difficult to penetrate obstacles in complex electromagnetic environments such as severely damaged tunnels, dense metal supports or large amounts of water, resulting in positioning failure. Therefore, research teams at home and abroad have begun to explore the technical path of using the earth as a conductor for signal transmission, among which the current injection method has gradually become a promising underground positioning and communication means.

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

[0005] In the data acquisition process of accident well positioning using the current injection method, ideally, the data collected by the sensor should be the induction magnetic field signal generated by the current converging on the metal casing. However, due to the limitations of the site conditions, the magnetic field signal collected by the sensor not only contains the induction magnetic field signal, but also superimposes 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 induction magnetic field signal. SUMMARY

[0006] In order to solve the above technical problems, the embodiment of the present application proposes a rescue well downhole induction magnetic field extraction method based on coordinate calibration and phase extraction, which can reliably and accurately extract the induction magnetic field signal generated by the current gathered on the metal casing, thereby improving the efficiency and success rate of downhole rescue.

[0007] In order to achieve the above purpose, the embodiment of the present application proposes a rescue well downhole induction magnetic field extraction method based on coordinate calibration and phase extraction, which comprises the following steps: in the case that no metal casing is placed in the accident well, current injection is carried out, the magnetic field signal received by the sensor is taken as the background magnetic field signal, and after the metal casing is placed in the accident well, current injection is carried out again, the magnetic field signal received by the sensor is taken as the total magnetic field signal; taking the background field coordinate system corresponding to the background magnetic field signal as the reference, the total magnetic field signal is converted from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signal; based on the background magnetic field signal and the calibrated total magnetic field signal, the phase difference is calculated to obtain the phase relationship between the background magnetic field signal and the calibrated total magnetic field signal; based on the background magnetic field signal and the calibrated total magnetic field signal, the induction magnetic field extraction is carried out in combination with the calculated phase relationship to obtain the induction magnetic field signal generated by the metal casing.

[0008] In order to achieve the above purpose, the embodiment of the present application also proposes a rescue well downhole induction magnetic field extraction device based on coordinate calibration and phase extraction, which comprises: an acquisition module, a calibration module, a phase difference calculation module and an induction magnetic field extraction module; the acquisition module is used for current injection in the case that no metal casing is placed in the accident well, the magnetic field signal received by the sensor is taken as the background magnetic field signal, and after the metal casing is placed in the accident well, current injection is carried out again, the magnetic field signal received by the sensor is taken as the total magnetic field signal; the calibration module is used for taking the background field coordinate system corresponding to the background magnetic field signal as the reference, converting 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; the phase difference calculation module is used for calculating 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; the induction magnetic field extraction module is used for extracting the induction magnetic field based on the background magnetic field signal and the calibrated total magnetic field signal in combination with the calculated phase relationship to obtain the induction magnetic field signal generated by the metal casing.

[0009] In order to achieve the above purpose, the embodiment of the present application also proposes an electronic device, which comprises: a processor and a memory, the memory stores instructions executable by the processor, and the processor is configured to execute the instructions so that the electronic device can implement a rescue well downhole induction magnetic field extraction method based on coordinate calibration and phase extraction as described above.

[0010] To achieve the above object, the embodiment of the present application also provides a computer readable storage medium, which stores a computer program, and the computer program can realize the rescue well downhole induction magnetic field extraction method based on coordinate calibration and phase extraction when executed by a processor.

[0011] Optionally, the current injection adopts a square wave current with an output frequency of 1.7 Hz;

[0012] In the case that no metal casing pipe is placed in the accident well, the background magnetic field signals of the X-axis, the Y-axis and the Z-axis received by the sensor are respectively denoted as , , and the accelerations of the X-axis, the Y-axis and the Z-axis collected by the accelerometer are respectively denoted as , , , represents a sampling point;

[0013] In the case that a metal casing pipe is placed in the accident well, the total magnetic field signals of the X-axis, the Y-axis and the Z-axis received by the sensor are respectively denoted as , , and the accelerations of the X-axis, the Y-axis and the Z-axis collected by the accelerometer are respectively denoted as , , .

[0014] Optionally, when the background magnetic field signals are collected, the probe pipe coordinate system is defined as a background field coordinate system, denoted as , , , the X-axis, the Y-axis and the Z-axis of the background field coordinate system, the X-axis of the background field coordinate system points to the bottom of the metal casing pipe, and the plane composed of the Y-axis and the Z-axis is perpendicular to the X-axis, when the total magnetic field signals are collected, the probe pipe coordinate system is defined as a total field coordinate system, denoted as , , , the X-axis, the Y-axis and the Z-axis of the total field coordinate system, the X-axis of the total field coordinate system points to the bottom of the metal casing pipe, and the plane composed of the Y-axis and the Z-axis is perpendicular to the X-axis; wherein, the probe pipe coordinate system is the coordinate system corresponding to the metal casing pipe;

[0015] When the posture of the metal casing pipe 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 and the rotation angle between the Y-axis of the total field coordinate system and the Y-axis of the background field coordinate system is denoted as The rotation angle between the Z axis of the total field coordinate system and the Z axis of the background field coordinate system is denoted as .

[0016] Optionally, the total magnetic field signal is converted from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signal, including:

[0017] The fast Fourier transform is respectively performed on , , , and the direct current component of the frequency domain signal after the fast Fourier transform is taken as the geomagnetic field information corresponding to the X axis, the Y axis and the Z axis of the background magnetic field signal, respectively denoted as , , .

[0018] The fast Fourier transform is respectively performed on , , , and the direct current component of the frequency domain signal after the fast Fourier transform is taken as the geomagnetic field information corresponding to the X axis, the Y axis and the Z axis of the total magnetic field signal, respectively denoted as , , .

[0019] Based on , , , , , , , , , , , , the following are respectively calculated , , .

[0020] Based on , , , the following are respectively calculated: the rotation matrix rotating around the X axis, the rotation matrix rotating around the Y axis, and the rotation matrix rotating around the Z axis, and based on , , , the total rotation matrix is calculated.

[0021] By the following formula, the total magnetic field signal is obtained by using , , Transforming to the background field coordinate system, the calibrated total magnetic field signals of the X-axis, Y-axis and Z-axis are obtained 、 、 :

[0022] .

[0023] Optionally, based on 、 、 、 、 、 、 、 、 、 、 、 , the following are respectively calculated 、 、 , through the following formula:

[0024] ;

[0025] , ;

[0026] ;

[0027] ;

[0028] Based on 、 、 , the following are respectively calculated: the rotation matrix for rotation around the X-axis, the rotation matrix for rotation around the Y-axis, and the rotation matrix for rotation around the Z-axis, through the following formula:

[0029] , , ;

[0030] Based on 、 、 , the total rotation matrix is calculated, through the following formula:

[0031] .

[0032] Optionally, the phase difference calculation is performed based on the background magnetic field signal and the calibrated total magnetic field signal to obtain a phase relationship between the background magnetic field signal and the calibrated total magnetic field signal, including:

[0033] The background magnetic field signal is taken as a reference sequence;

[0034] The cross-correlation functions between , , , , and are calculated in sequence by the following formula:

[0035]

[0036]

[0037]

[0038]

[0039]

[0040] wherein, is a time delay;

[0041] The maximum delay corresponding to the maximum value of , , , , is taken as a maximum delay, and is sequentially recorded as , , , , ;

[0042] The phase difference calculation is performed based on the sampling frequency , the main frequency and the maximum delay corresponding to each cross-correlation function, respectively, on , , , , and to sequentially obtain , , , , and​​​​​​​​​​ Phase relationship between them:

[0043] ;

[0044] ;

[0045] ;

[0046] ;

[0047] ;

[0048] 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.

[0049] 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:

[0050] ;

[0051] in, , , These are the induced magnetic field signals for the X-axis, Y-axis, and Z-axis, respectively.

[0052] 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.

[0053] First, the authenticity and accuracy of the induced magnetic field signal are fundamentally improved. The present application directly faces the two core technical problems of "phase uncertainty" and "carrier rotation". Through accurate phase correction and coordinate system calibration algorithm, the limitations of traditional differential method that cannot handle composite errors are overcome. This method makes the extraction of the induced magnetic field no longer a simple signal estimation, but realizes the high-fidelity reconstruction of the target induced magnetic field. The extracted induced magnetic field signal can truly reflect the physical field distribution generated by the downhole metal casing current, ensuring the accuracy and reliability of subsequent analysis from the data source.

[0054] Second, the robustness and field adaptability of data acquisition are significantly enhanced. The inevitable errors in field operation, such as metal casing posture changes, are considered as solvable variables rather than noise. This means that the precision requirement of the operation is reduced, and the adaptability to complex downhole environments is stronger. Even if there is a posture inconsistency between the two measurements, the present application can still compensate through the algorithm, greatly enhancing the stability of the entire measurement process and the reliability in actual engineering applications.

[0055] Third, a high-stability data foundation is provided for subsequent positioning algorithms. By providing pure and accurate induced magnetic field data, the present application effectively avoids inputting "garbage data" into subsequent optimization algorithms, thereby directly improving the stability and final accuracy of positioning and orientation calculation. The present application provides a solid and reliable data cornerstone for the entire accident well positioning process, and its role is global and crucial. BRIEF DESCRIPTION OF DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings needed to be used in the embodiments of the present application or the related art description. Obviously, the following drawings are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings. The drawings described herein are only used to explain the present application and do not limit the present application.

[0057] Figure 1 is a flowchart of a rescue well downhole induced magnetic field extraction method based on coordinate calibration and phase extraction provided in an embodiment of the present application;

[0058] Figure 2 is a detailed schematic diagram of a rescue well downhole induced magnetic field extraction method based on coordinate calibration and phase extraction provided in an embodiment of the present application;

[0059] Figure 3 is a schematic diagram of the total field coordinate system and the background field coordinate system provided in an embodiment of the present application;

[0060] Figure 4 is a schematic diagram of a simulation experiment system connection provided in an embodiment of the present application;

[0061] Figure 5 is a structural schematic diagram of a downhole induced magnetic field extraction device based on coordinate calibration and phase extraction provided in an embodiment of the present application;

[0062] Figure 6 is a structural schematic diagram of an electronic device provided in another embodiment of the present application. DETAILED DESCRIPTION

[0063] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below with reference to the drawings. Those skilled in the art can understand that, in the embodiments of the present application, many technical details are proposed in order to make the readers better understand. However, the technical solutions claimed by the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The following embodiments are divided for the convenience of description, and should not constitute any limitation on the specific implementation of the present application. The following embodiments can be combined and referenced with each other without contradiction.

[0064] An embodiment of the present application proposes a downhole induced magnetic field extraction method based on coordinate calibration and phase extraction applied to an electronic device, wherein the electronic device can be a terminal or a server. The embodiments and the following embodiments are all described by taking the server as an example. The implementation details of the downhole induced magnetic field extraction method based on coordinate calibration and phase extraction proposed in the embodiment will be described in detail below. The following content only provides implementation details for the convenience of understanding, and is not necessary for implementing the present solution.

[0065] The specific process of the downhole induced magnetic field extraction method based on coordinate calibration and phase extraction proposed in the embodiment can be as shown in Figure 1 The specific details are as shown in Figure 2 The method comprises:

[0066] Step 11, in the case that no metal casing is placed in the accident well, current injection is performed, the magnetic field signal received by the sensor is taken as a background magnetic field signal, and after the metal casing is placed in the accident well, current injection is performed again, and the magnetic field signal received by the sensor is taken as a total magnetic field signal.

[0067] In a specific implementation, the embodiment proposes a method of extracting pure induced magnetic field signals by designing two different working conditions and comparing two sets of test data. The two working conditions are respectively that no metal casing is placed in the accident well and that a metal casing is placed in the accident well. First, current injection is performed without placing a metal casing in the accident well, and the magnetic field signals received by the sensor are collected. At this time, the collected magnetic field signals are background magnetic field signals. Then, a metal casing is placed in the accident well, and current injection is performed again, and the magnetic field signals received by the sensor are collected. At this time, the collected magnetic field signals are the superposition of the background magnetic field and the induced magnetic field, which are called total magnetic field signals.

[0068] In one example, the current injection adopts a square wave current with an output frequency of 1.7 Hz, that is, the transmitting electrode needs to output a square wave current with a frequency of 1.7 Hz to realize current injection.

[0069] In one example, in the case that no metal casing is placed in the accident well, that is, when collecting the background magnetic field signals, the background magnetic field signals received (collected) by the sensor on the X-axis, Y-axis and Z-axis can be respectively denoted as 、 、 , and the accelerations collected by the accelerometer on the X-axis, Y-axis and Z-axis can be respectively denoted as 、 、 , wherein represents a discrete sampling point.

[0070] In one example, in the case that a metal casing is placed in the accident well, that is, when collecting the total magnetic field signals, the total magnetic field signals received (collected) by the sensor on the X-axis, Y-axis and Z-axis can be respectively denoted as 、 、 , and the accelerations collected by the accelerometer on the X-axis, Y-axis and Z-axis can be respectively denoted as 、 、 .

[0071] Step 12, taking the background field coordinate system corresponding to the background magnetic field signals as the reference, the total magnetic field signals are converted from the corresponding total field coordinate system to the background field coordinate system to obtain the calibrated total magnetic field signals.

[0072] 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.

[0073] 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... .

[0074] When converting 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, the background magnetic field signal and the total magnetic field signal need to be fast Fourier transformed, the dynamic method based on dynamic power is used, the tilt angle of the sensor in the probe in space is calculated through acceleration information, and the azimuth angle of the sensor is determined through geomagnetic field information, so as to determine the rotation angle and the rotation matrix.

[0075] Firstly, the fast Fourier transform is performed on , , respectively, the direct current component of the frequency domain signal after the fast Fourier transform is taken as the geomagnetic field information of the X-axis, Y-axis and Z-axis corresponding to the background magnetic field signal, and is recorded as , , respectively. Subsequently, the fast Fourier transform is performed on , , respectively, the direct current component of the frequency domain signal after the fast Fourier transform is taken as the geomagnetic field information of the X-axis, Y-axis and Z-axis corresponding to the total magnetic field signal, and is recorded as , , respectively. Next, based on , , , , , , , , , , , , is calculated respectively , , . After that, based on , , , the rotation matrix rotating around the X-axis, the rotation matrix rotating around the Y-axis, and the rotation matrix rotating around the Z-axis are calculated respectively, and based on , , , the total rotation matrix is calculated. Finally, the total magnetic field signal is converted to the background field coordinate system by using , , to obtain the calibrated total magnetic field signal , , .

[0076] In one example, based on , , , , , , , , , , , , respectively, the following are calculated: , , , by the following formula:

[0077] ;

[0078] , ;

[0079] ;

[0080] ;

[0081] wherein, is the inverse sine function, is the inverse tangent function.

[0082] In one example, based on , , , respectively, the following are calculated: the rotation matrix for rotation around the X axis , the rotation matrix for rotation around the Y axis , the rotation matrix for rotation around the Z axis , by the following formula:

[0083] , , .

[0084] In one example, based on , , , the following is calculated: the total rotation matrix , by the following formula:

[0085] .

[0086] In one example, using , , , Transforming to the background field coordinate system, the X-axis, Y-axis, and Z-axis calibrated total magnetic field signals are obtained , , , which are realized by the following formula:

[0087] .

[0088] Step 13, based on the background magnetic field signal and the calibrated total magnetic field signal, phase difference calculation is performed to obtain the phase relationship between the background magnetic field signal and the calibrated total magnetic field signal.

[0089] In a specific implementation, after obtaining the calibrated total magnetic field signal, based on the background magnetic field signal and the calibrated total magnetic field signal, phase difference calculation is performed 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 for measuring the similarity between two sequences, especially their relative delay in time (phase difference), and the purpose of cross-correlation is to find the phase difference of one sequence relative to another sequence.

[0090] Therefore, this embodiment selects a group of sequences as a reference data group, and cross-correlates the remaining five groups of data with it respectively, taking as an example.

[0091] First, the cross-correlation functions between , , , , and are calculated in turn by the following formula , , , , :

[0092] ;

[0093] ;

[0094] ;

[0095] ;

[0096] ;

[0097] wherein, is the time delay.

[0098] Next, take , , , , , , , , , .

[0099] Take for example, , the calculation formula is: .

[0100] Finally, we calculate the phase difference between , and , , , , and based on the sampling frequency , , , , and , respectively, and the maximum delay corresponding to each cross-correlation function, so as to obtain the phase relationship between

[0101] ;

[0102] ;

[0103] ;

[0104] ;

[0105] ;

[0106] , wherein is the phase relationship between and , is the phase relationship between and , is the phase relationship between and , is the phase relationship between and , is the phase relationship between and , and the main frequency is the frequency of the excitation signal output by the excitation source.

[0107] Step 14, based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship, the induced magnetic field extraction is carried out, and the induced magnetic field signal generated by the metal sleeve is obtained.

[0108] In a specific implementation, after the phase relationship is calculated, the induced magnetic field extraction is carried out based on the background magnetic field signal and the calibrated total magnetic field signal, combined with the calculated phase relationship, and the induced magnetic field signal generated by the metal sleeve is obtained. Through correction, the magnetic field signals collected in the total field coordinate system and the background field coordinate system are completely converted into the same coordinate system. By analyzing the difference between the corrected magnetic field signals, the characteristics and differences of the induced magnetic field can be well displayed. This method provides a solution for the correct recovery of system magnetic field data under probe correction in multiple attitudes, and provides a basis for the extraction of induced magnetic field signals in the case of metal sleeve in accident wells.

[0109] 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 extraction is carried out, and the induced magnetic field signal generated by the metal sleeve is obtained, which can be realized by the following formula:

[0110] ;

[0111] Among them, 、 、 are the induced magnetic field signals of X-axis, Y-axis and Z-axis respectively.

[0112] It should be noted that, 、 、 、 、 is the phase relationship, not the traditional phase value (angle value). The phase relationship has only and two values. If the calculation result of the phase difference is 0 degree, the value is , and if the calculation result of the phase difference is 180 degrees, the value is .

[0113] The embodiment aims at the problem that the current injection method cannot accurately extract the induced magnetic field in the positioning of accident wells due to the direct field interference of the transmitting electrode, the carrier rotation and the initial phase uncertainty. A rescue well downhole induced magnetic field extraction method based on coordinate calibration and phase extraction is creatively proposed. The beneficial effects created by this method mainly reflect in the following aspects.

[0114] First, the authenticity and accuracy of the induced magnetic field signal are fundamentally improved. The embodiment directly faces the two core technical problems of "phase uncertainty" and "carrier rotation". Through accurate phase correction and coordinate system calibration algorithm, the limitations of traditional differential method that cannot handle composite errors are overcome. This method makes the extraction of the induced magnetic field no longer a simple signal estimation, but realizes the high-fidelity reconstruction of the target induced magnetic field. The extracted induced magnetic field signal can truly reflect the physical field distribution generated by the metal casing current underground, ensuring the accuracy and reliability of subsequent analysis from the data source.

[0115] Second, the robustness and field adaptability of data acquisition are significantly enhanced. In the embodiment, the inevitable errors in the field operation (such as changes in the attitude of the metal casing) are considered as solvable variables rather than noise. This means that the precision requirement of the operation is reduced, and the adaptability to complex underground environments is stronger. Even if there is an attitude inconsistency between the two measurements, the embodiment can still compensate through the algorithm, greatly enhancing the stability of the entire measurement process and the reliability in actual engineering applications.

[0116] Third, a high-stability data foundation is provided for subsequent positioning algorithms. By providing pure and accurate induced magnetic field data, the embodiment effectively avoids inputting "garbage data" into subsequent optimization algorithms, thereby directly improving the stability and final accuracy of positioning and orientation calculation. The embodiment provides a solid and reliable data cornerstone for the entire accident well positioning process, and its role is global and crucial.

[0117] The step division of the above methods is only to describe the technical solution clearly. In specific implementation, some steps can be combined into one step, or some steps can be divided into multiple steps, as long as the same logical relationship is included, and it is within the protection scope of the present application. Irrelevant modifications or irrelevant designs introduced in the algorithm or process are within the protection scope of the present application as long as the core of the algorithm and process is not changed.

[0118] In one embodiment, in order to verify the effectiveness of a rescue well induced magnetic field extraction method based on coordinate calibration and phase extraction (hereinafter referred to as the present method) proposed in the present application, we carried out relevant simulation experiments and compared the present method with existing optimization result data. The system connection situation of the simulation experiment can be shown as Figure 4 The direction summary of each axis magnetic field data set obtained by using the relative processing method is shown in Table 1.

[0119] Table 1: Direction summary of each axis magnetic field data set obtained by using the relative processing method

[0120]

[0121] Figure 4 The magnetic field data acquisition barrel packaged with a non-magnetic water-tight shell is used for magnetic field signal acquisition. The signal output by the signal generator is connected to the radiation rod after power amplification, and the axis of the radiation rod is consistent with the axis of the magnetic field data acquisition barrel. Two three-axis fluxgate sensors are installed inside the data acquisition barrel, and the axes of the two sensors are one-to-one corresponding and consistent.

[0122] Under the theoretical condition, the phases of the corresponding axes of the two sensors should be completely consistent. The X-axis of the fluxgate sensor 1 is used as the reference data set, and the other axes are used as the comparison data set. The initial phase of the reference data set is defined as 0 degrees (positive direction, marked as "+") and 180 degrees (negative direction, marked as "-"). Through this method, the five groups of collected data are processed, and the direction summary of the magnetic field data of each axis of the two fluxgate sensors is shown in Table 1. For different data sets, when the sensor direction changes, the phase relationship obtained by the cross-correlation analysis is consistent with the theoretical expectation. This shows that the corresponding relationship of the axes of the two sensors remains unchanged during the entire test process, and the collected phase relationship meets the theoretical requirements.

[0123] Another embodiment of the present application proposes a downhole induced magnetic field extraction device for a rescue well based on coordinate calibration and phase extraction. The details of the downhole induced magnetic field extraction device for a rescue well based on coordinate calibration and phase extraction proposed in this embodiment are described below. The following content is only provided for the implementation details for easy understanding, and is not necessary for implementing this solution, Figure 5 is a structural schematic diagram of the downhole induced magnetic field extraction device for a rescue well based on coordinate calibration and phase extraction proposed in this embodiment, which includes an acquisition module 21, a calibration module 22, a phase difference calculation module 23, and an induced magnetic field extraction module 24.

[0124] The acquisition module 21 is used for current injection in the case where no metal casing is placed in the accident well, and the magnetic field signal received by the sensor is used as the background magnetic field signal. After the metal casing is placed 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.

[0125] The calibration module 22 is used for converting 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.

[0126] The phase difference calculation module 23 is used for calculating 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.

[0127] The induced magnetic field extraction module 24 is configured to extract the induced magnetic field based on the background magnetic field signal and the calibrated total magnetic field signal, and in combination with the calculated phase relationship, to obtain an induced magnetic field signal generated by the metal sleeve.

[0128] It is worth mentioning that each module involved in the embodiment is a logical module. In actual application, one logical module can be one physical module, or a part of one physical module, or an organic combination of multiple physical modules. In addition, in order to highlight the innovative part of the present application, modules not closely related to solving the technical problems proposed in the present application are not introduced in the embodiment, but this does not mean that there are no other modules in the embodiment.

[0129] It can be found that the embodiment is a system embodiment corresponding to the above-mentioned method embodiment. The embodiment can be implemented in cooperation with the above-mentioned method embodiment. The related technical details and technical effects mentioned in the above-mentioned method embodiment are still valid in the embodiment. In order to reduce repetition, they will not be described here. Correspondingly, the related technical details mentioned in the embodiment can also be applied to the above-mentioned method embodiment.

[0130] Another embodiment of the present application provides an electronic device, as shown in the figure, comprising a processor 31 and a memory 32, wherein the memory 32 stores instructions executable by the processor 31, and the processor 31 is configured to execute the instructions, so that the electronic device can implement a rescue well downhole induced magnetic field extraction method based on coordinate calibration and phase extraction as described in the above-mentioned method embodiment. Figure 6

[0131] Wherein, the memory and the processor are connected in a bus mode, the bus includes any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors and memories together. The bus can also connect various other circuits such as peripheral devices, voltage stabilizers and power management circuits together, which are well known in the art, and therefore will not be further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements such as multiple receivers and transmitters, which provide units for communicating with various other devices on the transmission medium. The data processed by the processor is transmitted on the wireless medium through the antenna, and further, the antenna also receives data and transmits the data to the processor.

[0132] The processor is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interface, voltage regulation, power management and other control functions. And the memory can be used to store the data used by the processor in the execution operation.

[0133] ​Another embodiment of the present application provides a computer readable storage medium, wherein a computer program is stored in the computer readable storage medium, and the computer program, when executed by a processor, enables a method for extracting a downhole induced magnetic field of a relief well based on coordinate calibration and phase extraction to be implemented.

[0134] That is, a person skilled in the art can understand that all or part of the steps in the above method embodiments can be completed by programs instructing relevant hardware, the programs are stored in a storage medium, and the programs include a plurality of instructions for enabling a device (such as a single-chip microcomputer, a chip, etc.) or a processor to execute all or part of the steps of the method described in the method embodiments of the present application. The foregoing storage medium includes a U disk, a mobile hard disk, a read-only memory, a random access memory, a magnetic disk or an optical disk, and various media that can store program codes.

[0135] A person skilled in the art can understand that the above embodiments are specific embodiments of the present application, and in actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. For those skilled in the art, a number of improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements are also considered to be within the protection scope of the present application.

Claims

1. A method for extracting downhole induction magnetic field of a relief well based on coordinate calibration and phase extraction, characterized in that, The method comprises: In the case where no metal casing is placed in the accident well, current injection is performed, and the magnetic field signal received by the sensor is taken as a background magnetic field signal; and after the metal casing is placed in the accident well, current injection is performed again, and the magnetic field signal received by the sensor is taken as a total magnetic field signal; The total magnetic field signal is converted from a total field coordinate system corresponding to the total magnetic field signal to a background field coordinate system corresponding to the background magnetic field signal, to obtain a calibrated total magnetic field signal; Phase difference calculation is performed based on the background magnetic field signal and the calibrated total magnetic field signal, to obtain a phase relationship between the background magnetic field signal and the calibrated total magnetic field signal; Induced magnetic field extraction is performed based on the background magnetic field signal and the calibrated total magnetic field signal, in combination with the calculated phase relationship, to obtain an induced magnetic field signal generated by the metal casing.

2. The method of claim 1, wherein, The current injection adopts a square wave current with an output frequency of 1.7 Hz; 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; In the case of placing metal casing in the accident well, the total magnetic field signals of X-axis, Y-axis and Z-axis received by the sensor are respectively recorded as , , , and the accelerations of X-axis, Y-axis and Z-axis collected by the accelerometer are respectively recorded as , , .

3. The method of claim 2, wherein, 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. 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 The rotation angle between the Y axis of the total field coordinate system and the Y axis of the background field coordinate system is denoted as The rotation angle between the Z axis of the total field coordinate system and the Z axis of the background field coordinate system is denoted as .

4. The method of claim 3, wherein, The total magnetic field signal is converted from a total field coordinate system corresponding to the total magnetic field signal to a background field coordinate system corresponding to the background magnetic field signal, to obtain a calibrated total magnetic field signal, which comprises: 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: , , ; , , , , , ;​ Based on , , , , , , , , , , , , respectively, the following are calculated , , ; Based on , , , the rotation matrix of rotating around the X axis , the rotation matrix of rotating around the Y axis , the rotation matrix of rotating around the Z axis , based on , , , the total rotation matrix is calculated. By using the following formula will be converted to the background field coordinate system to obtain the calibrated total magnetic field signal of the X-axis, Y-axis, and Z-axis , , , , :​ 。 5. The method of claim 4, wherein, Based on , , , , , , , , , , , , respectively, are calculated , , , are achieved by the following formula: ； ， ； ； ； Based on , , , the rotation matrix for rotation around the X axis , the rotation matrix for rotation around the Y axis , the rotation matrix for rotation around the Z axis are calculated, respectively, by the following formula: ， ， ； Based on , , , the total rotation matrix is calculated by the following formula: 。 6. The method of claim 4, wherein, Phase difference calculation is performed based on the background magnetic field signal and the calibrated total magnetic field signal, to obtain a phase relationship between the background magnetic field signal and the calibrated total magnetic field signal, which comprises: Will As a reference sequence; The cross-correlation function between the signals and is calculated in turn by the following equations , , , , and , , , , :​ ； ； ； ； ； wherein is a time delay; Take respectively , , , , The maximum delay corresponds to the maximum value, and is denoted as follows: , , , , ; Based on the sampling frequency , the main frequency and the maximum delay corresponding to each cross-correlation function, the phase difference calculations are made between , , , , and , respectively, to obtain the phase relationship between , , , , and , in turn. ； ； ； ； ； wherein is the phase relationship between is the phase relationship between is the phase relationship between is the phase relationship between is the phase relationship between is the phase relationship between is the phase relationship between the phase relationship between 7. The method of claim 6, wherein, Induced magnetic field extraction is performed based on the background magnetic field signal and the calibrated total magnetic field signal, in combination with the calculated phase relationship, to obtain an induced magnetic field signal generated by the metal casing, which is realized through the following formula: ； wherein , , are the induced magnetic field signals of the X-axis, Y-axis, Z-axis, respectively.

8. A downhole inductive magnetic field extraction device for a relief well based on coordinate calibration and phase extraction, characterized in that, The device comprises: The acquisition module is configured to, in the case where no metal casing is placed in the accident well, perform current injection, and take the magnetic field signal received by the sensor as a background magnetic field signal; and after the metal casing is placed in the accident well, perform current injection again, and take the magnetic field signal received by the sensor as a total magnetic field signal; The calibration module is configured to, with a background field coordinate system corresponding to the background magnetic field signal as a reference, convert the total magnetic field signal from a total field coordinate system corresponding to the total magnetic field signal to the background field coordinate system, to obtain a calibrated total magnetic field signal; The phase difference calculation module is configured to perform phase difference calculation based on the background magnetic field signal and the calibrated total magnetic field signal, to obtain a phase relationship between the background magnetic field signal and the calibrated total magnetic field signal; The induced magnetic field extraction module is configured to perform induced magnetic field extraction based on the background magnetic field signal and the calibrated total magnetic field signal, in combination with the calculated phase relationship, to obtain an induced magnetic field signal generated by the metal casing.

9. An electronic device, comprising: The electronic device comprises: The computer program is executed by the processor, and can implement the method for extracting an induced magnetic field in a rescue well based on coordinate calibration and phase extraction according to any one of claims 1 to 7.

10. A computer readable storage medium storing a computer program, characterized in that, ​

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