CN108345033B - A kind of microseism signal time-frequency domain first arrival detection method - Google Patents

A kind of microseism signal time-frequency domain first arrival detection method Download PDF

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CN108345033B
CN108345033B CN201810076278.5A CN201810076278A CN108345033B CN 108345033 B CN108345033 B CN 108345033B CN 201810076278 A CN201810076278 A CN 201810076278A CN 108345033 B CN108345033 B CN 108345033B
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imf
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dfa
denoising
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CN108345033A (en
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唐杰
温雷
张文征
孙成禹
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China University of Petroleum East China
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/28Processing seismic data, e.g. for interpretation or for event detection
    • G01V1/288Event detection in seismic signals, e.g. microseismics
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/28Processing seismic data, e.g. for interpretation or for event detection
    • G01V1/36Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy
    • G01V1/364Seismic filtering
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V2210/00Details of seismic processing or analysis
    • G01V2210/30Noise handling
    • G01V2210/32Noise reduction
    • G01V2210/324Filtering

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  • Remote Sensing (AREA)
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Abstract

The present invention provides a kind of microseism signal time-frequency domain first arrival detection method, when carrying out data processing using ICEEMDAN, using microseism signal as primary data, a specific white noise is added in each stage of decomposition, and a unique residual error is calculated to obtain each IMF, one sophisticated signal adaptively can be decomposed into a series of IMF components by ICEEMDAN, and IMF component meets from high frequency to low frequency Sequence distribution;Using IMF component as input, the mode of noise dominant is directly removed, DFA denoising is carried out to other mode, residual noise is removed by interval hard -threshold;Result after different scale is denoised carries out the earthquake record after fusion reconstruct is denoised, as useful signal;Pass through the first break information for the useful signal that high-precision time frequency analysis detects.For the present invention compared with empirical mode decomposition result, modal overlap phenomenon has more apparent reduction, is capable of providing the Accurate Reconstruction of original signal, has better convergence.

Description

A kind of microseism signal time-frequency domain first arrival detection method
Technical field
The present invention relates to exploration geophysics fields, especially relate to one of seism processing and are based on overall put down Equal empirical mode decomposition ICEEMDAN and remove the united microseism signal detecting method of trend wave theory approach (DFA).
Background technique
The usual energy of micro-seismic event signal is weaker, and there are energy losses in communication process in addition, this results in ground to connect The seismic data useful signal of receipts haves the shortcomings that energy is weak, signal-to-noise ratio is low, therefore the signal-to-noise ratio for improving microseism data is micro- The top priority of seismic data process and explanation.With the increasing for improving positioning accuracy and the full Moment tensor inversion demand of focal mechanism Add, the requirement to noise-removed technology also steps up.The method of tradition compacting random noise has very much, can be divided into spatial domain and transformation The method in domain, the former mainly includes mean filter, median filtering and anisotropic diffusion filtering etc., and the latter mainly includes Fourier Transform domain filtering method, Threshold Denoising Method based on wavelet transformation, warp wavelet etc. etc..Ground micro-seismic data, which has, makes an uproar by force The characteristics of sound, weak useful signal, conventional denoising method are often difficult to obtain preferable denoising effect, thus study specifically for The denoising method of ground micro-seismic data is highly important.For empirical mode decomposition (EMD) method it is unstable and generate mould State aliasing (Huang, 1998), overall experience mode decomposition (EEMD) utilize the equally distributed statistics of white Gaussian noise frequency spectrum Different white noises is added into original signal for characteristic, so that signal has continuity, but this method meter on different scale Inefficient (Wu, 2009);Complete overall experience mode decomposition method (CEEMD) is made an uproar by the way that positive and negative pairs of auxiliary is added Sound form, can effectively eliminate the remaining aid in noise in reconstruction signal, and computational efficiency can also be improved (Yeh, 2009) precision can be lacking when, but reconstructing;Torres (2011,2014) is using improved complete overall experience mode point Solution method (ICEEMDAN) can Accurate Reconstruction original signal, effectively reduce the noise in false mode and mode, calculate simultaneously Cost also decreases.
But the above method can not yet effectively remove noise, achieve the purpose that accurately to detect microseism signal.
Summary of the invention
The object of the present invention is to provide one kind to be detected based on the united microseism signal time-frequency domain first arrival of ICEEMDAN and DFA Method, to effectively remove noise, to make up the deficiencies in the prior art.
Contain noise in the IMF component decomposed due to ICEEMDAN, by eliminating fluctuation tendency analysis method (DFA) separation Useful signal and noise out, to achieve the purpose that eliminate noise.Therefore the purpose of the present invention can by following technical measures come It realizes:
One kind is based on ICEEMDAN and the united microseism signal time-frequency domain first arrival detection method of DFA, comprising the following steps:
(1) when carrying out data processing using ICEEMDAN, using microseism signal as primary data, in each of decomposition Stage adds a specific white noise, and calculates a unique residual error to obtain each IMF, and ICEEMDAN can be adaptively by one A sophisticated signal is decomposed into a series of intrinsic mode functions (IMF) component, and IMF component satisfaction is divided from high frequency to low frequency series Cloth;
(2) a series of intrinsic mode functions (IMF) component for obtaining (1) processing is as input, to the mould of noise dominant State directly removes, and carries out DFA denoising to other mode;
(3) data reconstruction after denoising is obtained to the result after joint denoising: after different scale denoising in step (2) As a result the earthquake record after fusion reconstruct is denoised, as useful signal are carried out;
(4) first break information of the useful signal obtained by high-precision time frequency analysis detecting step (3).
Further, in the step (1), the step of ICEEDAN, is described below:
101: the calculating x of signal after different noises are added is realized by EMDi=x+ ε0E1i), it is residual that level-one is obtained later Difference
102: calculating first IMF component IMF1=x-r1
103:EMD realizes r11E2i), it is residual to calculate second level
104: the K to k=3 ..., calculate k rank residual error
105: calculating k-th of IMF component IMFk=rk-1-rk
106: repeating step 104,105 until residual error cannot be decomposed;
Wherein: defining operator Ej() is to acquire j-th of mode by EMD to Setting signal;ωiZero for unit variance is equal It is worth white Gaussian noise, i=1,2 ... .I, xi=x+ ωiFor the signal after different noises is added;εkAllow to select to believe in each stage It makes an uproar ratio;M () indicates local mean value operator, E in EMD1=x-M (x).
Further, in the step (2), DFA denoising method specifically:
I-th of IMF component signal IMF of the microseism signal given for onei(t), its accumulated deviation y is calculatedi(t), The average value of the sequence has been filtered off first, sequence reconstruct is then carried out, to yi(t) isometric segmentation is carried out respectively, will be grown with length k Degree is n sequences segmentation into m nonoverlapping sections, wherein m=[n/k] (round numbers);Since sequence length is not always increment k Integral multiple, therefore, sequence tail end is it sometimes appear that the data information of fraction fails to be utilized;In order to make full use of data, The reverse sequence of sequence is similarly operated, the section of an equal length is obtained;Then to each section, least square is used The k number that method is included to each section respectively is according to carrying out first-order linear fitting;It is square after calculating each section elimination trend Difference, by sequence, formula is calculated respectively with backward herein;It averages and evolution to all equal length sections, DFA is calculated Wave function.
Further, in the step (2), the DFA wave function is white to reduce by threshold range removal IMF component Noise, threshold range are defined as α=φ ± 0.5.
The advantages of the present invention:
Population mean empirical mode decomposition and the united microseism signal time-frequency domain first arrival detection side DFA in the present invention Method, population mean empirical mode decomposition, which is utilized, has the characteristics that good multiple dimensioned and DFA validity, can suppress micro- Stronger random noise in seismic signal.Population mean empirical mode decomposition and the united microseism signal of DFA in the present invention It is combined with improved DFA method, is further increased on the basis of population mean empirical mode decomposition by detection method The detection effect of microseism signal.The present invention utilizes population mean empirical mode decomposition and DFA, has obtained the micro- of high s/n ratio For seismic processing as a result, being conducive to subsequent microseism data positioning and mechanism analysis etc., this method is that the inverting of microseism positions Etc. laying a good foundation.
For the present invention compared with empirical mode decomposition result, modal overlap phenomenon has more apparent reduction, is capable of providing The Accurate Reconstruction of original signal has better convergence.Trend wave theory approach (DFA) is gone to be able to detect noise-containing micro- It is noise which accumulates mode in seismic signal in, and it is purified signal which accumulates mode in, and then is retaining microseism signal physics Under the premise of meaning, noise contained in microseism is removed, the signal-to-noise ratio of seismic signal is improved.
Detailed description of the invention
Fig. 1 is specific flow chart of the invention;
Fig. 2 is the waveform recording figure of microseism signal in embodiment;
Fig. 3 is the result figure that microseism signal passes through ICEEMADAN high-precision time frequency analysis in Fig. 2;
Fig. 4 is that microseism signal passes through the intrinsic modal graph that ICEEMADAN is decomposited in Fig. 2;
Fig. 5 is the microseismograms after denoising in embodiment and the result figure by ICEEMADAN high-precision time frequency analysis.
Specific embodiment
To enable above and other objects, features and advantages of the invention to be clearer and more comprehensible, preferably implementation is cited below particularly out Example, and cooperate institute's accompanying drawings, it is described in detail below.
Embodiment 1: the microseism data in somewhere are selected.
As shown in Figure 1, a kind of be based on ICEEMDAN and the united microseism signal time-frequency domain first arrival detection method of DFA, packet Include following steps:
(1) when carrying out data processing using ICEEMDAN, using microseism signal as primary data, in each of decomposition Stage adds a specific white noise, and calculates a unique residual error to obtain each IMF, and ICEEMDAN can be adaptively by one A sophisticated signal is decomposed into a series of intrinsic mode functions (IMF) component, and IMF component satisfaction is divided from high frequency to low frequency series Cloth;
(2) a series of intrinsic mode functions (IMF) component for obtaining (1) processing is as input, to the mould of noise dominant State directly removes, and carries out DFA denoising to other mode;
(3) data reconstruction after denoising is obtained after joint denoises as a result, by after different scale denoising in step (2) As a result the earthquake record after fusion reconstruct is denoised, as useful signal are carried out;
(4) first break information of the useful signal obtained by high-precision time frequency analysis detecting step (3).
The above method specifically:
(1) the microseism waveform recording for needing to carry out noise compacting is selected, as shown in Figure 2.It is carried out using ICEEMDAN When data processing, regard microseism signal as primary data, ICEEMDAN decomposition is carried out to original signal, the IMF decomposited divides Amount meets the Sequence distribution from high frequency to low frequency, and Fig. 3 gives the preceding important time-frequency distributions of denoising.Define operator Ej(.) To acquire j-th of mode by EMD to Setting signal;ωiFor the zero mean Gaussian white noise of unit variance, i=1,2 ... .I, xi =x+ ωiFor the signal after different noises is added;εkAllow to select signal-to-noise ratio in each stage;M () indicates local mean value operator, E in EMD1The step of=x-M (x), ICEEDAN, is described below:
101: the calculating x of signal after different noises are added is realized by EMDi=x+ ε0E1i), it is residual that level-one is obtained later Difference
102: calculating first IMF component IMF1=x-r1
103:EMD realizes r11E2i), calculate second level residual error
104: the K to k=3 ..., calculate k rank residual error
105: calculating k-th of IMF component IMFk=rk-1-rk
106: repeating step 104,105 until residual error cannot be decomposed;
Process enters step (2);
(2) microseismograms after the decomposition for obtaining step (1) processing, as shown in figure 4, as input, to noise master The mode led can be removed directly, carry out DFA denoising to other mode, and eliminating fluctuation tendency analysis method is identification containing noise A kind of new method of IMF component:
I-th of IMF component signal IMFi (t) of the microseism signal given for one, calculates its accumulated deviation yi (t), the average value of the sequence has been filtered off first, is then carried out sequence reconstruct, isometric segmentation is carried out respectively to yi (t), with length k It is n sequences segmentation into m nonoverlapping sections, wherein m=[n/k] (round numbers) by length;Since sequence length is not always The integral multiple of increment k, therefore, sequence tail end is it sometimes appear that the data information of fraction fails to be utilized.In order to make full use of Data similarly operate the reverse sequence of sequence, and the section of an equal length is obtained.Then to each section, with most The k number that small square law is included to each section respectively is according to carrying out first-order linear fitting.After calculating each section elimination trend Mean square deviation (herein by sequence formula calculates respectively with backward).It averages and evolution, calculates to all equal length sections Obtain DFA wave function;
Change window size, minimum 5 sampling periods, maximum is no more than a quarter of time series sample number amount. Draw the log-log graph of the root mean square fluctuation of corresponding time window length, straight slopeFor scaling exponent;Scaling exponent can be used as The index of roughness;Value is bigger, and signal is more steady;In brief,It is worth the more rapid fluctuation of smaller expression signal.Utilize DFA Slope realizes the Denoising Algorithm based on ICEEMD, threshold valueThe IMF component containing noise can be distinguished;Generally speaking threshold valueModel It encloses for α=φ ± 0.25;The purpose of this method first stage ICCEMDAN is white to reduce by threshold range removal IMF component Noise, therefore, threshold range are defined as α=φ ± 0.5;After processing if the IMF component there is also residual noises, can use Interval hard thresholding method carries out post-processing removal residual noise;Process enters step (3) later;
(3) result after different scale denoising in step (2) is subjected to the earthquake record after fusion reconstruct is denoised, i.e., For joint denoising method obtain as a result, as shown in Figure 5;
(4) microseismograms after denoising will be subjected to the high-resolution time frequency analysis based on ICEEMDAN in step (3), The time-frequency distributions of signal are analyzed, for the first break information for detecting useful signal.
Wherein, Fig. 3 is the result that microseism signal passes through ICEEMADAN high-precision time frequency analysis;Due to microseism data In include a large amount of noise, effective first break information is difficult to effectively pick up;Fig. 4 is that microseism signal passes through ICEEMADAN in Fig. 2 The intrinsic mode decomposited;Fig. 5 be denoising after microseismograms and by ICEEMADAN high-precision time frequency analysis as a result, The first arrival for the pickup microseism data that can be convenient from Fig. 5, as shown in phantom in Figure 5;It can be seen that and be based on from Fig. 2 to Fig. 5 ICEEMADAN decomposes the good application effect with the joint denoising method of DFA for theoretical model, and noise has obtained effective pressure System.Joint denoising method provided by the invention can effectively suppress the random noise in section, highlight effective microseism letter Number, it is good to practical microseismograms progress noise pressing result with the joint denoising method of DFA by being decomposed based on CEEMADAN, Signal-to-noise ratio is significantly improved.This method is that inverting positioning of microseism etc. is laid a good foundation.

Claims (3)

1. one kind is based on ICEEMDAN and the united microseism signal time-frequency domain first arrival detection method of DFA, which is characterized in that including Following steps:
(1) when carrying out data processing using ICEEMDAN, using microseism signal as primary data, in each stage of decomposition A specific white noise is added, and calculates a unique residual error to obtain each IMF, ICEEMDAN can be adaptively multiple by one Miscellaneous signal decomposition is a series of IMF components, and IMF component meets from high frequency to low frequency Sequence distribution;
(2) a series of IMF components for obtaining (1) processing directly remove the mode of noise dominant, as input to others Mode carries out DFA denoising, the DFA denoising method specifically:
I-th of IMF component signal IMF of the microseism signal given for onei(t), its accumulated deviation y is calculatedi(t), first The average value of the component signal is filtered off, sequence reconstruct is then carried out, to yi(t) isometric segmentation is carried out respectively, with length k by length For n sequences segmentation at the nonoverlapping sections m, wherein m=[n/k], m round numbers;Since sequence length is not always increment k Integral multiple, therefore, sequence tail end is it sometimes appear that the data information of fraction fails to be utilized;In order to make full use of data, The reverse sequence of sequence is similarly operated, the section of m equal length is obtained;Then to each section, least square is used The k number that method is included to each section respectively is according to carrying out first-order linear fitting;It is square after calculating each section elimination trend Difference, by sequence, formula is calculated respectively with backward herein;It averages and evolution to all equal length sections, DFA is calculated Wave function;
(3) data reconstruction after denoising is obtained to the result after joint denoising: by the result after different scale denoising in step (2) Carry out the earthquake record after fusion reconstruct is denoised, as useful signal;
(4) first break information of the useful signal obtained by high-precision time frequency analysis detecting step (3).
2. detection method as described in claim 1, which is characterized in that in the step (1), the step of ICEEDAN is as follows:
101: the calculating x of signal after different noises are added is realized by EMDi=x+ ε0E1i), level-one residual error is obtained later
102: calculating first IMF component IMF1=x-r1
103:EMD realizes r11E2i), calculate second level residual error
104: the K to k=3 ..., calculate k rank residual error
105: calculating k-th of IMF component IMFk=rk-1-rk
106: repeating step 104,105 until residual error cannot be decomposed;
Wherein: defining operator Ej() is to acquire j-th of mode by EMD to Setting signal;ωiIt is high for the zero-mean of unit variance This white noise, i=1,2 ... .I, xi=x+ ωiFor the signal after different noises is added;εkAllow to select noise in each stage Than;M () indicates local mean value operator, E in EMD1=x-M (x).
3. detection method as described in claim 1, which is characterized in that in the step (2), the DFA wave function passes through Threshold range removes IMF component to reduce white noise, and threshold range is defined as α=φ ± 0.5.
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CN110702103A (en) * 2019-09-19 2020-01-17 天津大学 EEMD-DFA inertial sensor data noise reduction method for PDR system
CN110659621A (en) * 2019-09-27 2020-01-07 山东科技大学 Combined noise reduction method based on variational modal decomposition and permutation entropy
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CN111538082B (en) * 2020-06-05 2021-12-07 吉林大学 Automatic first arrival picking method for seismic wave time-frequency domain
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