CN-114629467-B - Interference filtering device and method for receiving underground electromagnetic wave signals of oil-gas well on ground

Abstract

The invention provides an interference filtering device and method for underground electromagnetic wave signals of a ground receiving oil-gas well, wherein the filtering device comprises a signal receiving and frequency domain conversion module, an interference component estimation module, an interference component reconstruction module and an interference filtering judgment module, wherein the signal receiving and frequency domain conversion module is configured to receive electromagnetic wave signals and conduct frequency domain conversion, the interference component estimation module is configured to estimate harmonic parameters of interference components in the signals converted by the signal receiving and frequency domain conversion module, the interference reconstruction module is configured to reconstruct the harmonic parameters of the interference components estimated by the interference component estimation module to obtain power frequency harmonic signals, and the interference filtering judgment module is configured to subtract the power frequency harmonic signals from the received electromagnetic wave signals to obtain effective signals and judge whether interference in the effective signals is filtered. The invention has the advantages of estimating the power frequency fundamental frequency, reconstructing interference signals, removing power frequency interference, guaranteeing effective identification of signals and the like.

Inventors

• LI ZHILIN
• HE CHAO
• YANG XIAOFENG
• LI WEICHENG
• BU CHENGZHONG
• HAN XIONG
• PANG DONGXIAO
• YUE MING
• ZHANG TENG
• WANG ZHIMIN
• LU QI
• HUANG CHONGJUN

Assignees

• 中国石油天然气集团有限公司
• 中国石油集团川庆钻探工程有限公司

Dates

Publication Date

20260508

Application Date

20211231

Claims (8)

1. 1. The interference filtering method for receiving the underground electromagnetic wave signals of the oil-gas well on the ground is characterized by comprising the following steps: carrying out frequency domain transformation on the electromagnetic wave signals received by the ground, and estimating harmonic parameters for primarily filtering interference components; reconstructing a power frequency interference signal according to the harmonic parameters of the interference components, and subtracting the power frequency interference signal components from the received electromagnetic wave signals to obtain effective signals; Judging whether the power frequency interference signal in the effective signal is filtered to be qualified or not, if so, demodulating and restoring the effective signal into the underground electromagnetic wave signal, and if not, carrying out the next interference filtering operation again until the effective signal is filtered to be qualified; The harmonic parameters for filtering the interference components comprise the frequency, amplitude and phase of the interference components, and the harmonic parameters are obtained through the following steps: Sampling a received signal, determining an expression of the received signal, performing DFT (discrete Fourier transform) on the expression, and solving the amplitude and the phase in the expression by using a direct solution or a differential solution; The mathematical expression of the interference component is as follows: ,n=0,1,...,N-1 (1) Wherein x (N) represents a sinusoidal sampling sequence with a length of N, f is frequency, s -1 ;f s is sampling rate, s -1 , A is amplitude, unit is consistent with the measurement signal, θ is phase, rad; And (3) recording: 0≤DELTA. <1, and K is an integer, formula (1) being rewritten as: (2) the DFT conversion includes the steps of: Performing DFT conversion on the formula (2) to obtain the following components: (3) And (3) recording: (4) (5) Then (6) (7) By using Representation of , Representation of Substituting the formulas (4) and (5) into the formula (3), and expanding by the number of stages: Obtaining: (8) expanding the exponential form, the real and imaginary parts of X (k) are written as follows: (9) (10)。
2. 2. the method for filtering out interference for receiving electromagnetic wave signals in oil and gas well underground according to claim 1, wherein the step of filtering out is qualified comprises the steps of: judging whether the proportion of the energy of the effective signal in the energy of the received signal is more than 50%, if so, indicating that the intensity of the effective signal is greater than the intensity of the interference signal, and enabling the effective signal to enter a demodulation module for demodulation.
3. 3. The method of interference filtering for receiving electromagnetic wave signals downhole in an oil and gas well according to claim 1, wherein said method further comprises the steps of: And (3) recording: (11) (12) wherein the signal parameter term Is a constant independent of the spectral line position k, and is obtained by eliminating by a proportional method: (13) the method is deduced according to a triangular formula: (14) Substituting formula (14) into formula (13): (15) Only k+Δ is an unknown term in equation (15), so K and Δ are solved by equation (15).
4. 4. A method of interference filtering a downhole electromagnetic wave signal for a surface receiving well according to claim 3, the method further comprising the steps of: And (3) recording: ; (16) ; (17) (18) Substituting into (15) to obtain: (19) Since 0≤Δ <1, solution: (20) (21) Wherein the symbol [ (i) indicates a downward rounding; Substituting the formulas (20), (21) into the formulas (9) and (10) to obtain: (22) (23) The amplitude A and the phase θ are obtained by combining the expression (22) and the expression (23).
5. 5. The method of interference filtering for receiving electromagnetic wave signals downhole in an oil and gas well according to claim 4, wherein said method further comprises the steps of: Converting formulae (9) and (10) to a differential form: (24) (25) the method is obtained according to a triangular formula: (26) the first term of the denominator in equation (26) is a function of k, and the same equation (17) is denoted as g (k), and the following differential proportional form is obtained according to equation (23): (27) obtaining a quadratic equation: (28) Wherein, the (29) Solving for K and delta by substituting X in the solution of formula (28) into formulas (20) and (21); substituting the values of K and delta into the differential formulas (23) and (24) to obtain: (30) (31) and (3) combining the two (30) and (31) to obtain A and theta.
6. 6. An interference filtering device for receiving electromagnetic wave signals underground in an oil-gas well on the ground, which is characterized in that the device is used for realizing the interference filtering method for receiving electromagnetic wave signals underground in the oil-gas well on the ground according to any one of claims 1-5, wherein: The filtering device comprises a signal receiving and frequency domain transforming module, an interference component estimating module, an interference component reconstructing module and an interference filtering judging module, The signal receiving and frequency domain transforming module is configured to receive electromagnetic wave signals and perform frequency domain transformation; the interference component estimation module is configured to estimate harmonic parameters of interference components in the signals transformed by the signal receiving and frequency domain transforming module; the interference component reconstruction module is configured to reconstruct the harmonic parameters of the interference components estimated by the interference component estimation module to obtain power frequency harmonic signals; the interference filtering judging module is configured to subtract the power frequency harmonic signal from the received electromagnetic wave signal to obtain an effective signal, and judge whether the interference in the effective signal is filtered.
7. 7. The interference filtering device for receiving electromagnetic wave signals under oil and gas well on the ground according to claim 6, wherein, the interference filtering device further comprises a demodulation module, and the demodulation module is configured to demodulate the effective signal after interference filtering.
8. 8. The device for filtering out interference for receiving electromagnetic wave signals in oil and gas well underground according to claim 6, wherein the interference components are distributed near the power frequency and the frequency multiplication thereof, and the electromagnetic wave signals in oil and gas well underground are selected to have a frequency below 10 Hz.

Description

Interference filtering device and method for receiving underground electromagnetic wave signals of oil-gas well on ground Technical Field The invention relates to the technical field of oil and gas well information and control engineering, in particular to an interference filtering device and method for receiving electromagnetic wave signals in an oil and gas well on the ground. Background The underground communication of oil and gas is a key technology for establishing a digital oil field in the future, and a method for establishing underground communication with the ground is basically established at present, but the electromagnetic noise on the ground, especially the power frequency interference of a well site (namely the electromagnetic field, leakage current and the like generated when equipment on the ground of the well site is powered on) has serious influence on signal reception, the power frequency interference is mainly distributed at 50Hz and the vicinity of frequency multiplication thereof, because the power consumption of the well site is mainly a 50Hz power supply, the frequency multiplication is greatly changed at different well sites and different times, and the interference is very chaotic. The lower the signal carrier frequency of the electromagnetic signal is, the farther the signal transmission is, and the electromagnetic signal can be applied to deeper wells, so that the electromagnetic signal carrier frequency below 10Hz is generally selected as the frequency of underground and ground signal transmission. Because the signal transmitted underground is smaller, the amplitude of the power frequency is 3 orders of magnitude larger than that of the effective signal, so that the signal is completely submerged by noise, and the effective signal cannot be directly observed from a spectrogram. Therefore, in order to be able to receive the effective signal, it is necessary to suppress the power frequency extremely harmonic interference signal. For such narrowband interference, engineering is typically filtered out using a trap, but the traps are typically implemented using Infinite Impulse Response (IIR) filters. Since the phase response of the IIR filter is not linear, a large distortion is caused to the normal communication signal. Moreover, the frequency of the power frequency interference cannot be changed along with different well sites, so that the trap cannot be suitable for the scene. In order to ensure that the filter does not interfere with the effective signal, it must be ensured that the phase shift of the filter for different frequencies is linear, so we can only use Finite Impulse Response (FIR) filters. However, the low-pass filter has attenuation of about 2dB for signals below 10Hz, and the frequency components are slightly different, so that the filter may distort the effective signal. Considering that the main energy of the frequency component of the power frequency interference signal on the well site is often concentrated on the power frequency fundamental frequency and each subharmonic of the power frequency, if the power frequency fundamental frequency and each subharmonic parameter thereof can be estimated, the interference signal can be reconstructed, and the interference signal is directly subtracted from the received signal. Therefore, the power frequency interference is eliminated, and meanwhile, the distortion brought to effective signals is reduced as much as possible. Disclosure of Invention The present invention is directed to solving one or more of the problems of the prior art, including the shortcomings of the prior art. For example, one of the purposes of the present invention is to provide an interference filtering method for effectively identifying the electromagnetic wave signal under the ground receiving oil and gas well, which can estimate the fundamental frequency of the power frequency and the harmonic parameters thereof, reconstruct the interference signal, remove the power frequency interference from the received signal, and ensure the signal. For another example, another object of the present invention is to provide an interference filtering method for effectively identifying electromagnetic wave signals in the underground oil and gas well by estimating the fundamental frequency of the power frequency and its various subharmonic parameters, reconstructing the interference signal, removing the power frequency interference from the received signal, and guaranteeing the signal. In order to achieve the above object, according to an aspect of the present invention, there is provided an interference filtering device for receiving electromagnetic wave signals downhole in an oil-gas well on the ground, the filtering device comprising a signal receiving and frequency domain transforming module, an interference component estimating module, an interference component reconstructing module and an interference filtering judging module, wherein, The signal receiving