Magnetotelluric detection interference suppression method and device, electronic equipment and storage medium

Abstract

The invention provides a magnetotelluric detection interference suppression method and device, electronic equipment and a storage medium, is applied to a magnetotelluric sounding system, and relates to the technical field of data processing. The method comprises the following steps: decoding original data of magnetotelluric sounding; wherein the decoded original data comprises electric field data and magnetic field data; performing noise reduction processing on the decoded original data; wherein the noise reduction processing comprises the steps of filtering power frequency interference, eliminating a direct current component, removing low-frequency trend interference and deducting equipment amplitude phase frequency response; carrying out the normalization processing of the original data after noise reduction, carrying out the impedance estimation, and determining the parameters corresponding to the original data of the magnetotelluric sounding; wherein the parameters at least comprise one of impedance tensor, apparent resistivity, impedance phase and tipper information; and through various noise reduction means, the amplitude and phase reliability of the signal at the natural electromagnetic field analysis frequency is improved, so that the impedance estimation precision is improved.

Description

Technical Field

[0001] The present invention relates to the field of data processing technology, and in particular to a method, device, electronic equipment and storage medium for suppressing interference in magnetotelluric detection. Background Art

[0002] When estimating impedance in magnetotelluric sounding, it is necessary to calculate the amplitude and phase of the electromagnetic field response at a series of frequency points in the acquired time domain data in segments, and obtain the apparent resistivity and impedance phase of each frequency point through least squares or robust estimation (ROBUST) and other methods. However, because natural electromagnetic field signals are non-periodic, random, broadband, and weak signals, they are easily affected by environmental and cultural electromagnetic fields, thus affecting the impedance estimation accuracy of observation data. In the spectrum analysis and processing of time series data, they are also easily affected by the low-frequency trend interference of the magnetotelluric field below the processing frequency and the low-frequency drift interference of the instrument itself, thereby reducing the amplitude and phase reliability of the signal at the natural electromagnetic field analysis frequency, and ultimately affecting the impedance estimation accuracy. Summary of the invention

[0003] The purpose of the present invention is to provide a method, device, electronic device and storage medium for suppressing interference in magnetotelluric detection, which improves the amplitude and phase reliability of signals at the natural electromagnetic field analysis frequency through multiple noise reduction means, thereby improving the impedance estimation accuracy.

[0004] In a first aspect, the present invention provides a method for suppressing interference in magnetotelluric detection, which is applied to a magnetotelluric sounding system, and the method comprises: Decoding and processing the raw data of magnetotelluric sounding; wherein the decoded raw data includes: electric field data and magnetic field data; The decoded raw data is subjected to noise reduction processing; the noise reduction processing includes: filtering out power frequency interference, eliminating DC components, removing low-frequency trend interference, and deducting the amplitude, phase, and frequency response of the equipment; After normalizing the raw data after noise reduction, impedance estimation is performed to determine the parameters corresponding to the raw data of magnetotelluric sounding; wherein the parameters include at least one of the following: impedance tensor, apparent resistivity, impedance phase and dipole information.

[0005] In some preferred embodiments of the present invention, the step of performing noise reduction processing on the decoded original data includes: The decoded original data is filtered to remove the power frequency interference wave of the preset frequency and the harmonics of the power frequency interference wave to obtain the first intermediate data.

[0006] In some preferred embodiments of the present invention, the step of performing noise reduction processing on the decoded original data further includes: Determine the DC component of the first intermediate data based on the arithmetic mean method; wherein, the DC component is constrained by the following formula: ; wherein, sp is the DC component, N t is the length of the first intermediate data, X 1 (i) is the time series of the original data; Eliminate the DC component from the first intermediate data to obtain the second intermediate data.

[0007] In some preferred embodiments of the present invention, the step of performing noise reduction processing on the decoded original data further includes: Perform cumulative moving average on the data samples in the second intermediate data to obtain low-frequency trend interference; wherein, the low-frequency trend interference is constrained by the following formula: ; wherein, f(j) is the low-frequency trend interference, N 1 is the length of the second intermediate data, N t is the length of the first intermediate data; Eliminate the low-frequency trend interference from the second intermediate data to obtain the third intermediate data.

[0008] In some preferred embodiments of the present invention, the step of performing noise reduction processing on the decoded original data further includes: Perform Fourier transform on the third intermediate data to obtain the third intermediate data in the frequency domain; Deduct the amplitude-phase-frequency response of the device from the third intermediate data in the frequency domain to obtain the noise-reduced original data; wherein, the device influence includes at least one of the following: the influence of the electromagnetic sensor, the amplitude influence of the receiver channel, and the phase-frequency response influence.

[0009] In some preferred embodiments of the present invention, after performing normalization processing on the noise-reduced original data, the steps of performing impedance estimation and determining the parameters corresponding to the original data of magnetotelluric sounding include: determining the impedance tensor by the following formula: ; ; wherein, Ex is the component of the electric field data on the x-axis, Ey is the component of the electric field data on the y-axis, H x is the component of the magnetic field data on the x-axis, H y is the component of the magnetic field data on the y-axis, Z xx is the first impedance tensor, Z xy is the second impedance tensor, Z yx is the third impedance tensor, Z yy is the fourth impedance tensor.

[0010] In some preferred embodiments of the present invention, after normalizing the original data after noise reduction, the steps of performing impedance estimation and determining the parameters corresponding to the original data of magnetotelluric sounding include: determining the tipper information through the following formula: ; where H x is the component of the magnetic field data on the x-axis, H y is the component of the magnetic field data on the y-axis, H z is the component of the magnetic field data on the z-axis, T zx is the first tipper information, and T zy is the second tipper information.

[0011] In a second aspect, the present invention provides a device for suppressing interference in magnetotelluric detection, which is applied to a magnetotelluric sounding system. The device includes: A data decoding module for decoding the original data of magnetotelluric sounding; wherein, the decoded original data includes: electric field data and magnetic field data; A data noise reduction module for performing noise reduction processing on the decoded original data; wherein, the noise reduction processing includes: filtering power frequency interference, eliminating DC components, removing low-frequency trend interference, and deducting the amplitude-phase-frequency response of the device; An impedance determination module for performing impedance estimation after normalizing the original data after noise reduction to determine the parameters corresponding to the original data of magnetotelluric sounding; wherein, the parameters include at least one of the following: impedance tensor, apparent resistivity, impedance phase, and tipper information.

[0012] In a third aspect, the present invention provides an electronic device, including a processor and a memory. The memory stores computer-executable instructions that can be executed by the processor, and the processor executes the computer-executable instructions to implement the method for suppressing interference in magnetotelluric detection provided in the first aspect above.

[0013] In a fourth aspect, the present invention provides a storage medium storing computer-executable instructions. When the computer-executable instructions are called and executed by the processor, the computer-executable instructions cause the processor to implement the method for suppressing interference in magnetotelluric detection provided in the first aspect above.

[0014] The present invention brings the following beneficial effects: The present invention provides a method, device, electronic device and storage medium for suppressing interference in magnetotelluric detection, which is applied to a magnetotelluric sounding system. The method includes: decoding the original data of magnetotelluric sounding; wherein, the decoded original data includes: electric field data and magnetic field data; performing noise reduction processing on the decoded original data; wherein, the noise reduction processing includes: filtering power frequency interference, eliminating DC components, removing low-frequency trend interference and deducting the amplitude-phase-frequency response of the device; after performing normalization processing on the noise-reduced original data, performing impedance estimation to determine the parameters corresponding to the original data of magnetotelluric sounding; wherein, the parameters include at least one of the following: impedance tensor, apparent resistivity, impedance phase and tipper information; by means of various noise reduction means, the amplitude and phase reliability of the signal at the natural electromagnetic field analysis frequency are improved, thereby improving the impedance estimation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a flowchart of a method for suppressing interference in magnetotelluric detection provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of an electric field data curve provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of an electric field data curve after filtering 50 Hz and its harmonic interference provided by an embodiment of the present invention; Figure 4 It is a schematic diagram of an electric field data curve after removing DC components provided by an embodiment of the present invention; Figure 5 It is a schematic diagram of a low-frequency trend electric field data curve with an analysis period greater than 2 seconds provided by an embodiment of the present invention; Figure 6 It is a schematic diagram of time series data after removing low-frequency trend interference provided by an embodiment of the present invention; Figure 7 It is a schematic diagram of an apparent resistivity curve and an impedance phase data curve of magnetotelluric sounding provided by an embodiment of the present invention; Figure 8 It is a schematic diagram of the structure of a device for suppressing interference in magnetotelluric detection provided by an embodiment of the present invention; Fig. 9 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention.

[0017] Icons: 310 - Data decoding module; 320 - Data noise reduction module; 330 - Impedance determination module; 400 - Memory; 401 - Processor; 402 - Bus; 403 - Communication interface. Detailed implementation

[0018] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0020] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0021] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0022] In addition, the terms "horizontal", "vertical", "hanging", etc. do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0023] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Magnetotelluric sounding is a method for deep detection of the electrical structure of the earth's interior that was proposed in the 1950s and gradually developed into maturity. It includes high-resolution electromagnetic field sensors, large dynamic range receivers, high-precision impedance estimation and forward and inversion interpretation technology. The field source of magnetotelluric sounding is an alternating electromagnetic field that exists naturally in the earth and is distributed regionally. It has a wide signal frequency band (n×10kHz-0.00001Hz) and a large penetration depth. It is an important geophysical method for detecting the electrical structure of the crust and upper mantle.

[0025] When estimating impedance in magnetotelluric sounding, it is necessary to calculate the amplitude and phase of the electromagnetic field response at a series of frequency points in the acquired time domain data in segments, and obtain the apparent resistivity and impedance phase of each frequency point through least squares or robust estimation (ROBUST) and other methods. However, because natural electromagnetic field signals are non-periodic, random, broadband, and weak signals, they are easily affected by environmental and cultural electromagnetic fields, thus affecting the impedance estimation accuracy of observation data. In the spectrum analysis and processing of time series data, they are also easily affected by the low-frequency trend interference of the magnetotelluric field below the processing frequency and the low-frequency drift interference of the instrument itself, thereby reducing the amplitude and phase reliability of the signal at the natural electromagnetic field analysis frequency, and even ultimately affecting the impedance estimation accuracy. At present, many experts and scholars have conducted research on the interference of environmental and cultural electromagnetic fields in magnetotelluric sounding and have achieved fruitful results. However, the influence of low-frequency trend interference of magnetotelluric fields and low-frequency drift interference of the instrument itself has not attracted enough attention, thereby reducing the impedance estimation accuracy of magnetotelluric observation data and affecting its actual application effect. It is a difficult problem that needs to be solved in the current magnetotelluric sounding data processing.

[0026] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0027] Embodiment 1 The present invention provides a method for suppressing interference in magnetotelluric detection, which is applied to magnetotelluric sounding system. Figure 1 The flowchart of a method for suppressing interference in magnetotelluric detection provided by an embodiment of the present invention is shown, and the method comprises: Step S102: Decode the original data of magnetotelluric sounding; among them, the decoded original data includes: electric field data and magnetic field data.

[0028] Specifically, let the sampling rate of a certain channel of the magnetotelluric sounding instrument for collecting data in a certain frequency band be , the sampling time series be , and the total acquisition time be ; let the longest period to be processed be , and the number of its sample points be , . is the period at the frequency to be analyzed.

[0029] Generally speaking, magnetotelluric sounding collects data in multiple frequency bands. For the time series data continuously collected in a certain frequency band, it needs to be processed in blocks during data processing. It is required that the time length of each block of data is at least 6 times the length of the processing period (the purpose is to reduce the influence of the spectrum analysis truncation effect). At the same time, at least 3 independent blocks of data are required for analysis and superposition processing to eliminate the influence of random interference. During actual data acquisition, the data length should be much greater than 18 times (6×3) the lowest analysis period of this frequency band.

[0030] Decode the original data of the observed magnetotelluric sounding. The original data of the magnetotelluric sounding observed in the field can include 4 components E x , E y , H x , H y or 5 components E x , E y , H x , H y , H z , and convert them into decimal electric field data (unit: mV) or magnetic field data (unit: mV); it should be emphasized that in the embodiment of the present invention, the x-axis is the identifier of a certain specified direction during measurement, the y-direction is perpendicular to the x-direction, and the z-direction is perpendicular to the xy plane; in some preferred embodiments of the present invention, the x-axis is the north-south direction.

[0031] Exemplarily, refer to Figure 2 A schematic diagram of an electric field data curve provided by an embodiment of the present invention shown. The figure shows a fragment of the electric field data curve of the magnetotelluric sounding observed at a certain place, and its sampling rate is 0.002 seconds.

[0032] Step S104: Denoise the decoded original data; among them, the denoising process includes: filtering power frequency interference, eliminating DC components, removing low-frequency trend interference, and deducting the amplitude-phase-frequency response of the equipment.

[0033] Specifically, in some preferred embodiments of the present invention, the step of performing noise reduction processing on the decoded original data includes: filtering out power frequency interference waves and harmonics of power frequency interference waves with a preset frequency from the decoded original data to obtain first intermediate data.

[0034] Specifically, for the decoded electric and magnetic field data, digital filtering and other methods are used to suppress the power frequency interference of 50 Hz and its harmonics. The power frequency interference of 50 Hz and its harmonics is a common man-made electromagnetic interference in magnetotelluric sounding (the frequency of the domestic power grid is 50 Hz, while that of the foreign power grid is mostly 60 Hz). This interference seriously affects the accuracy of the processing results and its influence needs to be eliminated in preprocessing.

[0035] Continue to refer to Figure 2 , the magnetotelluric fields collected in the field are strongly interfered by the power frequency of 50 Hz and its harmonics, and it is difficult to identify the effective signals from the curves. After digital filtering, refer to Figure 3 Figure

[0036] Further, in some preferred embodiments of the present invention, the step of performing noise reduction processing on the decoded original data further includes: determining the DC component of the first intermediate data based on the arithmetic mean method; wherein, the DC component is constrained by the following formula: . Wherein, sp is the DC component, N t is the length of the first intermediate data, X 1 (i) is the time series of the original data; eliminating the DC component from the first intermediate data to obtain the second intermediate data.

[0037] Specifically, for the filtered electric and magnetic field data, arithmetic mean and other methods are used to eliminate the DC component of the observed data, and the formed time series is ; the length of the original observed data is N. After suppressing the power frequency interference of 50 Hz and its harmonics by digital filtering, the remaining data length is , and its length is less than the length N of the original observed data. The DC component is constrained by the following formula: . ; wherein, sp is the DC component, N t is the length of the first intermediate data, X 1 (i) is the time series of the original data, and z(i) is the second intermediate data after removing the DC component. Refer to Figure 4 Figure

[0038] Further, in some preferred embodiments of the present invention, the step of performing noise reduction processing on the decoded original data further includes: performing cumulative moving average on the data samples in the second intermediate data to obtain low-frequency trend interference; wherein, the low-frequency trend interference is constrained by the following formula: . Wherein, f(j) is the low-frequency trend interference, N 1 is the length of the second intermediate data, N t is the length of the first intermediate data; the second intermediate data is eliminated of the low-frequency trend interference to obtain the third intermediate data.

[0039] Specifically, the magnetotelluric sounding time series observation data contains both broadband and random natural electromagnetic field signals, as well as various man-made electromagnetic interferences (such as power frequency interference mainly composed of 50 Hz and its harmonics, high-speed rail, photovoltaic, wind power, highway, communication, etc.), and the noise and drift of the measuring instrument itself. In data processing, in addition to suppressing the influence of various man-made electromagnetic interferences, it is also necessary to suppress the influence of the natural electromagnetic field trend signals below the processing period, as well as the drift interference of the instrument itself, so as to obtain more accurate natural electromagnetic field amplitude and phase at the processing period for use in the later magnetotelluric sounding impedance tensor estimation. Based on the fact that the natural electromagnetic field signal itself is broadband and random, the signal intensity at different frequencies (or periods) varies greatly (up to 120 dB), and the time series data collected in the field is of limited length. If the signals below the processing period are not suppressed, serious distortion will occur in the signal amplitude and phase at the processing period obtained during time-frequency conversion.

[0040] When processing the observation data of a certain frequency band and a certain area, when the required processing period is (or frequency , ), and its corresponding observation data length is , in order to suppress the influence of low-frequency trend interference with a period greater than the analysis period on the processed data, first perform cumulative moving average on data samples to form a new time series , that is: ; is the low-frequency trend interference with a period greater than in this block of data, that is to say, the low-frequency trend interference can be separated from the observation data through this method. Subtract from the time series to generate a new time series , that is: ; ; ; , That is, it is the time series data after removing the low-frequency trend interference.

[0041] Exemplarily, the sampling rate of the data in this frequency band is 0.002 seconds. Refer to Figure 5 the schematic diagram of the low-frequency trend electric field data curve with an analysis period greater than 2 seconds provided by the embodiment of the present invention shown in the figure. This curve is the low-frequency trend interference time series data separated by the above method; refer to Figure 6 the schematic diagram of the time series data after removing the low-frequency trend interference provided by the embodiment of the present invention shown in the figure. This curve is the electric field data curve with a period less than or equal to 2 seconds. In actual use, the data sampling rate , the data length N, and the analysis period (the corresponding data length ) are all variable and can be adjusted according to the actual observed data situation.

[0042] Furthermore, in some preferred embodiments of the present invention, the step of performing noise reduction processing on the decoded original data further includes: performing Fourier transform on the third intermediate data to obtain the third intermediate data in the frequency domain; subtracting the amplitude-phase-frequency response of the device from the third intermediate data in the frequency domain to obtain the noise-reduced original data; where the device influence includes at least one of the following: the influence of the electromagnetic sensor, the amplitude influence of the receiver channel, and the phase-frequency response influence.

[0043] Specifically, perform Fourier transform on the 4-component (E x 、E y 、H x 、H y ) or 5-component (E x 、E y 、H x 、H y 、H z ) data that have been respectively removed of the low-frequency trend interference through the above steps, convert from the time domain to the frequency domain, and subtract the amplitude, phase-frequency response of the electromagnetic sensor and the receiver channel.

[0044] Magnetic field sensors have different amplitude and phase responses at different frequencies. For example: for a certain magnetic field sensor at a frequency of 1000 Hz, its amplitude response is 100 mV / nT and its phase response is -20 degrees; but at 0.1 Hz, its amplitude response is 20 mV / nT and its phase response is 120 degrees; the same is true for the receiver channel, and the amplitude and phase responses at different frequencies are not exactly the same. At this time, it is necessary to subtract the amplitude-phase-frequency response base of themselves to obtain the true amplitude and phase magnitudes at a certain frequency of the natural electromagnetic field.

[0045] Step S106: After normalizing the denoised original data, impedance estimation is performed to determine the parameters corresponding to the original data of magnetotelluric sounding; wherein, the parameters include at least one of the following: impedance tensor, apparent resistivity, impedance phase, and tipper information.

[0046] Specifically, the original data after denoising through the above steps is further normalized for the electric field data (unit: mV / km) and the magnetic field data (unit: nT), and then conventional impedance estimation methods such as the least squares method, robust estimation method, etc. can be used to obtain the impedance tensor, apparent resistivity, impedance phase, tipper and other parameter information of magnetotelluric at different periods (or frequencies) that are basically logarithmically equally spaced.

[0047] Further, in some preferred embodiments of the present invention, the step of performing impedance estimation after normalizing the denoised original data to determine the parameters corresponding to the original data of magnetotelluric sounding includes: determining the impedance tensor through the following formula: ; ; where Ex is the component of the electric field data on the x-axis, Ey is the component of the electric field data on the y-axis, Hx is the component of the magnetic field data on the x-axis, Hy is the component of the magnetic field data on the y-axis, Zxx is the first impedance tensor, Zxy is the second impedance tensor, Zyx is the third impedance tensor, and Zyy is the fourth impedance tensor.

[0048] Further, in some preferred embodiments of the present invention, the step of performing impedance estimation after normalizing the denoised original data to determine the parameters corresponding to the original data of magnetotelluric sounding includes: determining the tipper information through the following formula: ; where H x is the component of the magnetic field data on the x-axis, H y is the component of the magnetic field data on the y-axis, H z is the component of the magnetic field data on the z-axis, Tzx is the first tipper information, and Tzy is the second tipper information.

[0049] Specifically, if only the 4-component E x , E y , H x , H y is observed in the field, only the impedance tensor information can be calculated, and the tipper information cannot be obtained; when the 5-component E x , E y , H x , H y , H z is observed, not only the impedance tensor information can be obtained, but also the tipper information can be obtained. The impedance tensor and tipper information are obtained by methods such as the least squares method, and they are all related to the frequency.

[0050] Exemplarily, refer to Figure 7 the schematic diagram of the apparent resistivity curve and impedance phase data curve of magnetotelluric sounding provided by the embodiment of the present invention shown in the figure. The magnetotelluric sounding apparent resistivity and impedance phase data obtained after the method provided by the embodiment of the present invention is processed have continuous and smooth data curves, which conform to the characteristics of magnetotelluric sounding data and can be directly used for inversion and interpretation, improving the ability of magnetotelluric sounding to solve complex geological problems.

[0051] The magnetotelluric detection interference suppression method provided by the present invention sequentially filters power frequency interference, eliminates DC components, removes low-frequency trend interference, and deducts the amplitude-phase-frequency response of the equipment, which can better separate and remove low-frequency trend interference and improve the calculation accuracy of magnetotelluric impedance estimation and parameters such as apparent resistivity and impedance phase.

[0052] The magnetotelluric detection interference suppression method provided by the present invention aims at the low-frequency trend interference in the aforementioned magnetotelluric sounding, which reduces the impedance estimation accuracy and affects its actual application effect. Based on the low-frequency trend drift characteristics of the magnetotelluric field and the instrument itself, starting from the observed discrete time series data, first, the low-frequency trend interference data is separated through moving average; then the low-frequency trend interference data is subtracted from the original observed data, and the remaining time series data is the magnetotelluric field data within the frequency range to be processed after removing the low-frequency trend interference. This method is original in the processing of magnetotelluric sounding data. Its advantages are simple and fast calculation method, less data loss, and small distortion. It can significantly suppress the influence of low-frequency trend interference in magnetotelluric sounding on the spectrum analysis accuracy, improve the impedance estimation accuracy, and enhance the application effect of magnetotelluric sounding in solving actual geological problems.

[0053] The present invention provides a magnetotelluric detection interference suppression method, which is applied to a magnetotelluric sounding system. The method includes: decoding the original data of magnetotelluric sounding; wherein, the decoded original data includes: electric field data and magnetic field data; performing noise reduction processing on the decoded original data; wherein, the noise reduction processing includes: filtering power frequency interference, eliminating DC components, removing low-frequency trend interference, and deducting the amplitude-phase-frequency response of the equipment; after performing normalization processing on the noise-reduced original data, performing impedance estimation to determine the parameters corresponding to the original data of magnetotelluric sounding; wherein, the parameters include at least one of the following: impedance tensor, apparent resistivity, impedance phase, and tipper information; through various noise reduction means, the amplitude and phase reliability of the signal at the natural electromagnetic field analysis frequency are improved, thereby improving the impedance estimation accuracy.

[0054] Embodiment 2 On the basis of the above embodiment, the embodiment of the present invention provides a magnetotelluric detection interference suppression device, which is applied to a magnetotelluric sounding system. Refer to Figure 8Schematic structural diagram of a magnetotelluric detection interference suppression device provided by an embodiment of the present invention. The device includes: A data decoding module 310, configured to decode the original data of magnetotelluric sounding; wherein, the decoded original data includes: electric field data and magnetic field data.

[0055] A data noise reduction module 320, configured to perform noise reduction processing on the decoded original data; wherein, the noise reduction processing includes: filtering power frequency interference, eliminating DC components, removing low-frequency trend interference, and deducting the amplitude-phase-frequency response of the device.

[0056] An impedance determination module 330, configured to perform normalization processing on the noise-reduced original data, then perform impedance estimation to determine the parameters corresponding to the original data of magnetotelluric sounding; wherein, the parameters include at least one of the following: impedance tensor, apparent resistivity, impedance phase, and tipper information.

[0057] Further, in some preferred embodiments of the present invention, the data noise reduction module 320 is configured to filter out power frequency interference waves and harmonics of power frequency interference waves with a preset frequency from the decoded original data to obtain first intermediate data.

[0058] Further, in some preferred embodiments of the present invention, the data noise reduction module 320 is further configured to determine the DC component of the first intermediate data based on the arithmetic mean method; wherein, the DC component is constrained by the following formula: ; where sp is the DC component, N t is the length of the first intermediate data, X 1 (i) is the time series of the original data; the DC component is eliminated from the first intermediate data to obtain second intermediate data.

[0059] Further, in some preferred embodiments of the present invention, the data noise reduction module 320 is further configured to perform cumulative moving average on the data samples in the second intermediate data to obtain low-frequency trend interference; wherein, the low-frequency trend interference is constrained by the following formula: ; where f(j) is the low-frequency trend interference, N 1 is the length of the second intermediate data, N t is the length of the first intermediate data; the low-frequency trend interference is eliminated from the second intermediate data to obtain third intermediate data.

[0060] Further, in some preferred embodiments of the present invention, the data noise reduction module 320 is further configured to perform Fourier transform on the third intermediate data to obtain the third intermediate data in the frequency domain; deduct the amplitude-phase-frequency response of the device from the third intermediate data in the frequency domain to obtain the noise-reduced original data; wherein, the device influence includes at least one of the following: the influence of the electromagnetic sensor, the amplitude influence of the receiver channel, and the phase-frequency response influence.

[0061] Further, in some preferred embodiments of the present invention, the impedance determination module 330 is configured to determine the impedance tensor through the following formula: ; ; where Ex is the component of the electric field data on the x-axis, Ey is the component of the electric field data on the y-axis, Hx is the component of the magnetic field data on the x-axis, Hy is the component of the magnetic field data on the y-axis, Zxx is the first impedance tensor, Zxy is the second impedance tensor, Zyx is the third impedance tensor, and Zyy is the fourth impedance tensor.

[0062] Further, in some preferred embodiments of the present invention, the tipper information is determined through the following formula: ; where H x is the component of the magnetic field data on the x-axis, H y is the component of the magnetic field data on the y-axis, H z is the component of the magnetic field data on the z-axis, T zx is the first tipper information, and T zy is the second tipper information.

[0063] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working process of the magnetotelluric detection interference suppression device described above can refer to the corresponding process in the embodiment of the magnetotelluric detection interference suppression method described above, and will not be elaborated here.

[0064] Embodiment III

[0065] The embodiment of the present invention also provides an electronic device for running the magnetotelluric detection interference suppression method; see Fig. 9 the structural schematic diagram of an electronic device provided by the embodiment of the present invention shown. The electronic device includes a memory 400 and a processor 401. Among them, the memory 400 is used to store one or more computer instructions, and the one or more computer instructions are executed by the processor 401 to implement the above-mentioned magnetotelluric detection interference suppression method.

[0066] Furthermore, Fig. 9 the electronic device shown also includes a bus 402 and a communication interface 403, and the processor 401, the communication interface 403, and the memory 400 are connected through the bus 402.

[0067] Among them, the memory 400 may include high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk memory. The communication connection between this system network element and at least one other network element is realized through at least one communication interface 403 (which can be wired or wireless), and the Internet, wide area network, local area network, metropolitan area network, etc. can be used. The bus 402 can be an ISA bus, a PCI bus, an EISA bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of representation, Fig. 9 only a bidirectional arrow is used in Fig. 9 , but it does not mean that there is only one bus or one type of bus.

[0068] The processor 401 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the integrated logic circuit in the hardware of the processor 401 or instructions in the form of software. The above-mentioned processor 401 can be a general-purpose processor, including a central processing unit (CPU for short), a network processor (NP for short), etc.; it can also be a digital signal processor (DSP for short), an application specific integrated circuit (ASIC for short), a field programmable gate array (FPGA for short), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiments of the present invention. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present invention can be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor. The software module can be located in a mature storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, register, etc. This storage medium is located in the memory 400, and the processor 401 reads the information in the memory 400 and combines its hardware to complete the steps of the method in the foregoing embodiments.

[0069] The embodiments of the present invention also provide a storage medium that stores computer-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions cause the processor to implement the above-mentioned magnetotelluric detection interference suppression method. For the specific implementation, reference can be made to the method embodiments, which will not be elaborated here.

[0070] The computer program product of the magnetotelluric detection interference suppression method, device and electronic device provided by the embodiments of the present invention includes a storage medium storing program codes. The instructions included in the program codes can be used to execute the methods in the foregoing method embodiments. For specific implementation, reference can be made to the method embodiments and will not be elaborated herein.

[0071] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described system and / or device can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0072] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection" and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0073] If the above functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs that can store program codes.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing interference in magnetotelluric detection, characterized in that: Applied to a magnetotelluric sounding system, the method comprises: Decoding the raw data of magnetotelluric sounding; wherein the decoded raw data includes: electric field data and magnetic field data; The decoded raw data is subjected to noise reduction processing; wherein the noise reduction processing includes: filtering out power frequency interference, eliminating DC components, removing low-frequency trend interference, and deducting the amplitude, phase, and frequency response of the equipment; wherein the decoded raw data is subjected to filtering out the power frequency interference to obtain the first intermediate data; the DC components are eliminated from the first intermediate data to obtain the second intermediate data; the data samples in the second intermediate data are subjected to cumulative moving average to obtain the low-frequency trend interference; After normalizing the raw data after noise reduction, impedance estimation is performed to determine parameters corresponding to the raw data of magnetotelluric sounding; wherein the parameters include at least one of the following: impedance tensor, apparent resistivity, impedance phase and dipole information.

2. The method for suppressing interference of magnetotelluric detection according to claim 1, characterized in that: The step of performing noise reduction processing on the decoded original data comprises: The decoded original data is filtered to remove the power frequency interference wave of a preset frequency and the harmonics of the power frequency interference wave to obtain the first intermediate data.

3. The method for suppressing interference of magnetotelluric detection according to claim 2, characterized in that: The step of performing noise reduction processing on the decoded original data also includes: The DC component of the first intermediate data is determined based on an arithmetic mean method; wherein the DC component is constrained by the following formula: ； Wherein, sp is the DC component, N t is the length of the first intermediate data, X1(i) is the time series of the original data; The DC component is eliminated from the first intermediate data to obtain second intermediate data.

4. The method for suppressing interference of magnetotelluric detection according to claim 3, characterized in that: The step of performing noise reduction processing on the decoded original data also includes: The low-frequency trend interference is constrained by the following formula: ； Wherein, f(j) is the low-frequency trend interference, N1 is the length of the second intermediate data, N t is the length of the first intermediate data; The low-frequency trend interference is eliminated from the second intermediate data to obtain third intermediate data.

5. The method for suppressing interference in magnetotelluric detection according to claim 4, characterized in that: The step of performing noise reduction processing on the decoded original data also includes: Performing Fourier transform on the third intermediate data to obtain the third intermediate data in the frequency domain; The third intermediate data in the frequency domain is deducted from the device influence to obtain the original data after noise reduction; wherein the device influence includes at least one of the following: the influence of the electromagnetic sensor, the amplitude influence of the receiver channel and the influence of the phase frequency response.

6. The method for suppressing interference in magnetotelluric detection according to claim 1, characterized in that: After normalizing the raw data after noise reduction, impedance estimation is performed to determine the parameters corresponding to the raw data of magnetotelluric sounding, including: determining the impedance tensor by the following formula: ； ； Among them, E x is the component of the electric field data on the x-axis, E y is the component of the electric field data on the y-axis, H x is the component of the magnetic field data on the x-axis, H y is the component of the magnetic field data on the y-axis, Z xx is the first impedance tensor, Z xy is the second impedance tensor, Z yx is the third impedance tensor, Z yy is the fourth impedance tensor.

7. The method for suppressing interference in magnetotelluric detection according to claim 6, characterized in that: After normalizing the raw data after noise reduction, performing impedance estimation to determine the parameters corresponding to the raw data of magnetotelluric sounding includes: determining the dipole information by the following formula: ； Among them, H x is the component of the magnetic field data on the x-axis, H y is the component of the magnetic field data on the y-axis, H z is the component of the magnetic field data on the z-axis, T zx is the first tilt information, T zy It is the second tilt information.

8. A device for suppressing interference of magnetotelluric detection, characterized in that: Applied to a magnetotelluric sounding system, the device comprises: A data decoding module is used to decode the raw data of magnetotelluric sounding; wherein the decoded raw data includes: electric field data and magnetic field data; A data noise reduction module is used to perform noise reduction processing on the decoded original data; wherein the noise reduction processing includes: filtering out power frequency interference, eliminating DC components, removing low-frequency trend interference and deducting the amplitude, phase and frequency response of the equipment; wherein the power frequency interference is filtered out from the decoded original data to obtain the first intermediate data; the DC component is eliminated from the first intermediate data to obtain the second intermediate data; the data samples in the second intermediate data are accumulated and moved averaged to obtain the low-frequency trend interference; The impedance determination module is used to perform impedance estimation after normalizing the raw data after noise reduction, and determine the parameters corresponding to the raw data of the magnetotelluric sounding; wherein the parameters include at least one of the following: impedance tensor, apparent resistivity, impedance phase and dipole information.

9. An electronic device, characterized in that: It comprises a processor and a memory, wherein the memory stores computer executable instructions that can be executed by the processor, and the processor executes the computer executable instructions to implement the method for suppressing interference in magnetotelluric detection as described in any one of claims 1 to 7.

10. A storage medium, characterized in that: The storage medium stores computer executable instructions. When the computer executable instructions are called and executed by the processor, the computer executable instructions prompt the processor to implement the method for suppressing interference in magnetotelluric detection as described in any one of claims 1 to 7.

Images