CN106443787B - Prestack seismic gather presses method for de-noising and its device - Google Patents
Prestack seismic gather presses method for de-noising and its device Download PDFInfo
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Abstract
The present invention provides a kind of prestack seismic gathers to press method for de-noising and its device, the method includes：Derivative Type synchronous compression is carried out to each trace record of prestack seismic gather and converts DSST, generates the DSST time-frequency spectrums of the prestack seismic gather；The vector parallel with useful signal concentrated according to pre-stack seismic road described in the DSST time-frequencies spectrum estimation；Parameter of making an uproar is pressed according to prestack seismic gather setting one；It pressure is carried out to the prestack seismic gather makes an uproar processing according to the DSST time-frequency spectrums, the vector and the pressure parameter of making an uproar, generate the DSST time-frequency spectrums pressed after making an uproar；DSST time-frequency spectrums after being made an uproar according to the pressure reconstruct to obtain the prestack seismic gather after pressure is made an uproar.The DSST time-frequency spectrums that the method and its device of the present invention generates have higher time frequency resolution, and pressure makes an uproar parameter and the vector parallel with useful signal makes Noise Elimination parameter adaptive adjust and protect useful signal, to better SNR estimation and compensation effect.
Description
Technical Field
The invention relates to the field of oil-gas seismic exploration, in particular to a prestack seismic trace gather noise suppression method and a prestack seismic trace gather noise suppression device.
Background
In the field of oil and gas exploration, the processing of three-high (high resolution, high signal-to-noise ratio and high fidelity) of seismic data is always a difficult point and a hot point in scientific research and production, and particularly under the condition that a seismic exploration target gradually turns to a concealed complex oil and gas reservoir, the description and development of the oil reservoir impose higher requirements on the processing quality of the seismic data. The signal-to-noise ratio level of the seismic data greatly restricts the improvement of the resolution, because the broadening of high-frequency components is accompanied with the reduction of the integral signal-to-noise ratio of the data, and if a reasonable noise suppression means is not provided, the data processed by high resolution often cannot provide effective information for actual production because the signal-to-noise ratio is too low. Therefore, the research of the noise suppression technology has important scientific research significance and practical value in the seismic data processing.
The existing denoising methods are various at present, different applicable conditions are provided for different types of noise, the basic idea of most methods is to decompose the noise-containing records through mathematical transformation, the signals and the noise have better separation degree in a transformation domain, the noise can be suppressed based on certain characteristics, and then the noise-suppressed records are obtained through mathematical inverse transformation. Because seismic records have non-stationary characteristics, time-frequency transformation can be used as a powerful tool for analyzing and processing non-stationary signals, and therefore, signal-noise separation in the time-frequency domain becomes a common method in seismic data noise suppression processing. For example, a threshold function is used in a wavelet transform domain or a curvelet transform domain to implement a suppression process of random noise or surface waves.
However, for seismic recording of non-stationary signals, the common time-frequency transformation method has a poor processing effect. SST (synchronous compressive transformation) has good theoretical support and mathematical properties, so that SST is increasingly applied to the field of non-stationary signal processing analysis, wherein noise filtering in the SST time-frequency domain is possible due to good time-frequency resolution, noise robustness and reconfigurability. SST is actually a wavelet transform-based time-frequency analysis method similar to EMD (Empirical Mode Decomposition), and the main idea is to refocus the divergently blurred wavelet coefficients obtained by wavelet transform, so that the time-frequency spectrum has higher frequency resolution.
However, the processing and interpretation of seismic data for increasingly complex reservoirs places greater demands on the quality of the seismic data.
Disclosure of Invention
The invention provides a prestack seismic channel gather noise suppression method and a prestack seismic channel gather noise suppression device, which are used for solving one or more defects in the prior art.
The invention provides a prestack seismic channel gather noise suppression method, which comprises the following steps: step 1: performing derivative synchronous compression transform (DSST) on each record of the pre-stack seismic gather to generate a DSST time frequency spectrum of the pre-stack seismic gather; step 2: estimating vectors in the pre-stack seismic trace set parallel to the effective signals according to the DSST time spectrum; and step 3: setting a noise suppression parameter according to the pre-stack seismic gather; and 4, step 4: performing noise suppression processing on the pre-stack seismic gather according to the DSST time spectrum, the vector and the noise suppression parameter to generate a denoised DSST time spectrum; and 5: and reconstructing according to the DSST time spectrum after noise suppression to obtain the pre-stack seismic gather after noise suppression.
In one embodiment, setting a noise suppression parameter according to the prestack seismic gather includes: performing quality analysis on the pre-stack seismic gather, and estimating to obtain the signal-to-noise ratio of the pre-stack seismic gather; and calculating the noise suppression parameter according to the signal-to-noise ratio.
In one embodiment, after step 5, the method comprises: calculating residual data of the pre-stack seismic channel sets before and after noise suppression according to the difference value of the pre-stack seismic channel set and the pre-stack seismic channel set after noise suppression; and performing amplitude preservation analysis on the pre-stack seismic gather subjected to noise suppression according to the residual data, and if the effective signal is damaged, repeatedly executing the step 3 to the step 5.
In one embodiment, performing amplitude preservation analysis on the denoised pre-stack seismic gather according to the residual data includes: and combining well information, and performing amplitude preservation analysis on the pre-stack seismic gather subjected to noise suppression according to the residual data.
In one embodiment, the DSST time spectrum is complex; the method comprises the following steps: respectively executing the steps 2 to 4 on the real part and the imaginary part of the DSST time frequency spectrum to obtain the real part and the imaginary part of the denoised DSST time frequency spectrum; and combining the real part and the imaginary part of the denoised DSST time spectrum to generate the denoised DSST time spectrum.
In one embodiment, the expression of the DSST time spectrum is:
wherein, ω islIs the l-th discrete angular frequency, Δ ω is the discrete interval of the discrete angular frequency, Ws(akAnd b) is the wavelet coefficient of the prestack seismic gather signal, akIs the kth discrete scale, b is time, ωs(akAnd b) is the angular frequency of the prestack seismic gather signal, (Δ a)k＝ak+1-akP-2, k-1, 2, …, N are discrete numbers.
In one embodiment, the expression of the vector is:
wherein,is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,
n＝1,2,…,N1，N1is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2Is the total number of time samples, fmDenotes the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples.
In one embodiment, the expression of the noise suppression parameter is:
wherein the parameter lambda1(n,tj) For suppressing noise in pre-stack seismic trace concentration, parameter lambda1(n,tj) Has a value range of [ lambda ]D,λU]Parameter λ2(n,tj) For protecting effective signals, lambda, in prestack seismic trace gathersDAnd λUIs a setting parameter, SNR (n, t)j) Is the signal-to-noise ratio of the pre-stack seismic gather,is the SNR (n, t) of all signal-to-noise ratiosj) Maximum value of (1), 2, …, N1，N1Is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2is the total number of time samples, α0It is to set the coefficients of the coefficients,
in one embodiment, the expression of the denoised DSST time spectrum is as follows:
wherein,is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,is the vector, λ (N, j) is the squelch parameter, N is 1,2, …, N1，N1Is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2Is the total number of time samples, fmDenotes the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples is,is the denoised DSST time spectrum.
In one embodiment, the expression of the denoised prestack seismic gather is:
where s (0) is an integration constant, Δ ω is a discrete interval of discrete angular frequencies,
is constant coefficientThe inverse number of (c) is,is the conjugate function of the fourier spectrum of the mother wavelet ψ, b and t are time, t > 0.
The invention also provides a pre-stack seismic channel gather noise suppression device, which comprises: a DSST time frequency spectrum generating unit, configured to perform derivative synchronous compression transform DSST on each record of the pre-stack seismic gather, and generate a DSST time frequency spectrum of the pre-stack seismic gather; a vector generation unit, configured to estimate a vector parallel to the effective signal in the pre-stack seismic trace set according to the DSST time spectrum; the noise suppression parameter setting unit is used for setting a noise suppression parameter according to the pre-stack seismic gather; a post-denoising DSST time spectrum generating unit, configured to perform denoising processing on the pre-stack seismic gather according to the DSST time spectrum, the vector, and the denoising parameter, and generate a denoised DSST time spectrum; and the pre-stack seismic gather reconstruction unit is used for reconstructing the post-noise-suppression DSST time spectrum to obtain the post-noise-suppression pre-stack seismic gather.
In one embodiment, the noise suppression parameter setting unit includes: the signal-to-noise ratio generation module is used for carrying out quality analysis on the pre-stack seismic gather and estimating the signal-to-noise ratio of the pre-stack seismic gather; and the noise suppression parameter generating module is used for calculating the noise suppression parameter according to the signal-to-noise ratio.
In one embodiment, the apparatus comprises: a residual data generating unit, configured to calculate residual data of the pre-stack seismic trace sets before and after noise suppression according to a difference between the pre-stack seismic trace set and the post-noise-suppression pre-stack seismic trace set; and the noise suppression control unit is used for carrying out amplitude preservation analysis on the pre-stack seismic gather subjected to noise suppression according to the residual data, and if the effective signal is damaged, the noise suppression parameter setting unit, the post-noise suppression DSST time-frequency spectrum generating unit and the pre-stack seismic gather reconstruction unit are repeatedly operated.
In one embodiment, the re-coring control unit includes: and the amplitude preservation analysis module is used for carrying out amplitude preservation analysis on the pre-stack seismic gather after noise suppression according to information on a well.
In one embodiment, the apparatus comprises: the time spectrum real part and imaginary part splitting unit is used for respectively processing the real part and the imaginary part of the DSST time spectrum through the vector generating unit, the noise suppression parameter setting unit and the post-noise-suppression DSST time spectrum generating unit to obtain the real part and the imaginary part of the post-noise-suppression DSST time spectrum; and the time-frequency spectrum real part and imaginary part combination unit is used for combining the real part and the imaginary part of the denoised DSST time spectrum to generate the denoised DSST time spectrum.
The prestack seismic channel gather noise suppression method and the prestack seismic channel gather noise suppression device of the embodiment of the invention realize prestack seismic channel gather noise suppression processing based on derivative type synchronous compression transformation DSST, have higher time-frequency resolution than the time-frequency spectrum of the conventional synchronous compression transformation SST, focus more time-frequency energy clusters, and are favorable for signal-noise separation; and separating the effective signal from random noise on a frequency spectrum in DSST by using a vector parallel to the effective signal and a noise suppression parameter and vector space projection, and setting a plurality of adjustable parameters to respectively realize noise self-adaptive suppression and effective signal protection. High quality data is provided for subsequent processing and interpretation of seismic data, particularly lithological inversion.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts. In the drawings:
FIG. 1 is a schematic flow chart of a pre-stack seismic trace gather noise suppression method according to an embodiment of the invention;
FIG. 2 is a flow chart illustrating a method for setting a noise suppression parameter according to an embodiment of the present invention;
FIG. 3 is a schematic flow chart of a pre-stack seismic trace gather denoising method according to an embodiment of the invention;
FIG. 4 is a schematic illustration of an original pre-stack seismic gather signal according to an embodiment of the present invention;
FIG. 5 is a graph of the SST spectrum of the signal shown in FIG. 4;
FIG. 6 is a diagram of a DSST spectrum of the signal shown in FIG. 4;
FIG. 7 is a schematic representation of pre-stack seismic gather signals after reconstruction of the DSST spectrum of FIG. 6;
FIG. 8 is a graphical representation of the relative error percentages of the original pre-stack seismic signals of FIG. 4 and the reconstructed post-stack seismic gather signals of FIG. 7;
FIG. 9 is a schematic illustration of a noise-free pre-stack seismic gather signal according to another embodiment of the present invention;
FIG. 10 is a schematic illustration of the pre-stack seismic gather signal of FIG. 9 after noise;
FIG. 11 is a graphical illustration of the signal-to-noise ratio of the noisy pre-stack seismic gather shown in FIG. 10;
FIG. 12 is a schematic illustration of the seismic gather signals of FIG. 10 after the noisy seismic gather signals have been suppressed by a suppression method according to an embodiment of the invention;
FIG. 13 is a schematic illustration of the noise signals of the noisy seismic gather signal of FIG. 10 filtered by a noise suppression method according to an embodiment of the present invention;
FIGS. 14-16 are DSST time frequency spectrum diagrams of signals of traces 3, 9, and 15, respectively, of the noise-free pre-stack seismic gather of FIG. 9;
FIGS. 17-19 are DSST time frequency spectrum diagrams of signals of traces 3, 9, and 15, respectively, of the noisy pre-stack seismic gather of FIG. 10;
FIG. 20 is a graphical illustration of spectral trends in the active signals generated from the noisy pre-stack seismic gather of FIG. 10;
FIGS. 21 to 23 are DSST time frequency spectrums of the DSST time frequency spectrums shown in FIGS. 17 to 19 after being subjected to noise suppression by the noise suppression method according to the embodiment of the present invention, respectively;
FIG. 24 is a schematic illustration of an original pre-stack seismic gather in an embodiment of the invention;
FIG. 25 is a schematic illustration of the original pre-stack seismic gather shown in FIG. 24 after it has been noise suppressed by a noise suppression method according to an embodiment of the present invention;
FIG. 26 is a schematic illustration of the original prestack seismic gather of FIG. 24 with noise traces filtered out by a noise compression method according to an embodiment of the invention;
FIGS. 27 and 28 are schematic diagrams of signal-to-noise ratios of the pre-stack seismic gathers shown in FIGS. 24 and 25, respectively;
FIGS. 29 and 30 are schematic diagrams of the destination layer amplitude of the prestack seismic gathers shown in FIGS. 24 and 25, respectively;
FIG. 31 is a schematic structural diagram of a pre-stack seismic trace gather denoising apparatus according to an embodiment of the present invention;
fig. 32 is a schematic structural diagram of a noise suppression parameter setting unit according to an embodiment of the present invention;
FIG. 33 is a schematic structural diagram of a pre-stack seismic trace gather denoising apparatus according to an embodiment of the present invention;
FIG. 34 is a schematic structural diagram of a pre-stack seismic trace gather noise suppression device according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.
FIG. 1 is a schematic flow chart of a prestack seismic trace gather denoising method according to an embodiment of the invention. As shown in fig. 1, the prestack seismic trace gather denoising method according to the embodiment of the present invention includes the steps of:
s101: carrying out derivative type synchronous compression transform (DSST) on each record of the pre-stack seismic channel set to generate a DSST time frequency spectrum of the pre-stack seismic channel set;
s102: estimating vectors in the pre-stack seismic trace set parallel to the effective signals according to the DSST time spectrum;
s103: setting a noise suppression parameter according to the pre-stack seismic gather;
s104: performing noise suppression processing on the pre-stack seismic gather according to the DSST time spectrum, the vector and the noise suppression parameter to generate a denoised DSST time spectrum;
s105: and reconstructing according to the DSST time spectrum after noise suppression to obtain the pre-stack seismic gather after noise suppression.
According to the pre-stack seismic trace gather noise suppression method provided by the embodiment of the invention, in the vector space projection noise suppression process, noise is suppressed through the noise suppression parameters, the effective signals are protected through the vectors parallel to the effective signals, and the noise suppression parameters and the effective signal protection parameters are combined, so that the selection of each parameter has clear purpose and physical significance, and noise suppression and effective signal protection are facilitated.
Fig. 2 is a flowchart illustrating a method for setting a noise suppression parameter according to an embodiment of the present invention. As shown in fig. 2, in step S103 of the prestack seismic gather denoising method shown in fig. 1, the method for setting a denoising parameter according to the prestack seismic gather may include the steps of:
s201: performing quality analysis on the pre-stack seismic gather, and estimating to obtain the signal-to-noise ratio of the pre-stack seismic gather;
s202: and calculating the noise suppression parameter according to the signal-to-noise ratio.
In the embodiment of the invention, the noise suppression parameter is set according to the signal-to-noise ratio, so that the noise suppression of the pre-stack seismic gather is more targeted and the noise suppression effect is better.
In one embodiment, it is assumed that the prestack seismic trace gather in step S201 is denoted as a (t, X), where t is a time sample, X is 1,2, …, and X is a trace number. The prestack seismic gather a (t, x) is composed of an effective signal component s (t, x) and a noise component n (t, x), and the energy of the effective signal component s (t, x) and the noise component n (t, x) are respectively Es(t, x) and En(t, x), the signal-to-noise ratio is defined as follows:
the effective signal component s (t, x) in equation (1) can be estimated as follows:
wherein m and n are positive integers.
The noise component n (t, x) in equation (1) can be expressed as:
n(t,x)＝a(t,x)-s(t,x)。 (3)
substituting the formula (2) and the formula (3) into the formula (1) can estimate the signal-to-noise ratio of the prestack seismic channel set, wherein each sampling point in the prestack seismic channel set can estimate a signal-to-noise ratio value.
FIG. 3 is a flow chart of a pre-stack seismic trace gather denoising method according to an embodiment of the invention. As shown in fig. 3, after step S105 of the prestack seismic trace gather denoising method shown in fig. 1, the method may further include the steps of:
s106: calculating residual data of the pre-stack seismic channel sets before and after noise suppression according to the difference value of the pre-stack seismic channel set and the pre-stack seismic channel set after noise suppression;
s107: and performing amplitude preservation analysis on the denoised pre-stack seismic gather according to the residual data, and if the effective signal is damaged, repeatedly executing the steps S103 to S105.
In step S107, when the residual data exceeds a certain range, it indicates that the valid signal is damaged.
In the embodiment of the invention, the amplitude preservation analysis is carried out on the pre-stack seismic gather after noise suppression, and the noise suppression parameter can be adaptively adjusted according to the actual signal-to-noise ratio level of the pre-stack seismic gather data, so that the noise suppression effect is improved and effective signals are protected.
In one embodiment, in step S107 of the pre-stack seismic gather denoising method shown in fig. 3, if the well information exists, the amplitude preservation analysis may be performed on the denoised pre-stack seismic gather according to the residual data by combining the well information. The uphole information may include destination reservoir information from which AVO (amplitude versus offset) amplitude curves may be derived.
In the embodiment of the invention, whether the effective signals concentrated by the prestack seismic channels after noise pressing are damaged or not can be judged more easily by combining the standard amplitude of the well information.
In one embodiment, the DSST time spectrum is a complex number, and the real part and the imaginary part of the DSST time spectrum obtained in the step S101 are respectively executed in the step S102.
In one embodiment, the real part and the imaginary part of the DSST time spectrum obtained in the above step S101 are respectively performed in step S103.
In one embodiment, step S104 is performed on the real part and the imaginary part of the DSST time frequency spectrum obtained in step S101, respectively, to obtain the real part and the imaginary part of the noisy DSST time frequency spectrum; then, the real part and the imaginary part of the denoised DSST time spectrum are combined to generate the denoised DSST time spectrum in step S105.
In the embodiment of the invention, the steps S102 to S104 are respectively carried out according to the real part and the imaginary part of the time spectrum, so that the calculation complexity in the process of noise suppression of the pre-stack seismic channel gather is favorably reduced.
Conventional synchronous compression transformation SST focuses on a divergent wavelet coefficient on the basis of wavelet transformation to obtain a spectrum with high time-frequency resolution characteristics.
The continuous wavelet transform of the signal s (t) is defined as follows:
in the formula (4), inIn, phi*(t) is mother wavelet ψ (t), scale a and time b are the scaling and translation factors of the mother wavelet, W, respectivelysAnd (a, b) are wavelet coefficients.
For arbitrary Ws(a, b) ≠ 0, and the instantaneous frequency can be approximately defined by:
synchronous compression is to compress data (W) on a time-scale planes(a, b)) data mapped onto the time-frequency plane (denoted as time spectrum T)s(ωlB)), while converting the coordinate point (b, a) into (b, ω)s(a, b)), so that a time-frequency distribution based on a continuous wavelet transform can be obtained. The data mapping rules are as follows:
in the formula (6), akIs the kth discrete scale, satisfies | ωs(ak,b)-ωlI ≦ Δ ω/2, k ≦ 1,2, …, N is a discrete number, (Δ a)k＝ak+1-ak，ωlIs the ith discrete angular frequency and Δ ω is the angular frequency discrete interval. The significance of the formula (6) is to compress the fuzzy range in the wavelet transformation scale direction to a concentrated region, thereby improving the readability of time-frequency distribution.
Synchronous compression transformation SST has reversible transformation and can pass through Ts(ωlB) reconstructed signal s (t):
in the formula (7), constant coefficientF representing psioutput spectrum (Fourier spectrum is also expressed by ^ in other embodiments), Re [. cndot. ]]Indicating the real part operation.
In one embodiment, the mapping equation (6) is modified as follows:
in the formula (8), P is a variable parameter.
In the embodiment of the invention, according to Parseval's theorem, the following can be obtained:
for equation (9), it is written as:
when P is-1, equation (8) deteriorates to equation (6).
When P ═ 2, equation (11) can change to:
if the signal s (t) (i.e., s (b)) has a derivative s ' (t) (i.e., s ' (b)), according to Fourier's derivation theorem, there are:
then, the signal s (t) can be reconstructed by means of derivative integration:
equation (14) shows that when P ═ 2, the signal can be reconstructed indirectly through its derivative.
In the embodiment of the present invention, equation (8) (in the case where P is-2) is referred to as derivative synchronous compressed DSST, and equation (14) is an inverse transform of the derivative synchronous compressed DSST.
In one embodiment, in step S101 of the prestack seismic trace gather denoising method shown in fig. 1, using the above formula (8), P is taken as-2, derivative synchronous compression transform DSST is performed, and an expression of a frequency spectrum at the time of the DSST is obtained by calculation:
in the formula (15), ωlIs the l-th discrete angular frequency, Δ ω is the discrete interval of the discrete angular frequency, Ws(akAnd b) is the wavelet coefficient of the prestack seismic gather signal, akIs the kth discrete scale, b is time, ωs(akAnd b) is the angular frequency of the prestack seismic gather signal, (Δ a)k＝ak+1-akP-2, k-1, 2, …, N are discrete numbers.
In the embodiment of the invention, the time frequency spectrum based on the derivative type synchronous compression transform DSST has higher time frequency resolution than that of the conventional synchronous compression transform SST, and the time frequency energy cluster is more focused, thereby being beneficial to signal-noise separation.
In the embodiment of the invention, the noise-containing prestack seismic gather is recorded as s (n, t)j) Assuming that the noise type is random noise (the same applies below), the track number N is 1,2, …, N1，N1Is the total number of tracks, tjIs the jth time sample, j is 1,2, …, N2，N2The total number of time samples. Each channel is processed by derivative type synchronous compression transform DSST, three-dimensional time-frequency spectrum data can be obtained and recorded as SF (n, t)j,fm)，fmFor the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples.
In one embodiment, the denoising process can be implemented by vector space projection by using the idea of vector decomposition method.
First, the concept of the vector space is explained. From three-dimensional time-frequency spectral data SF (n, t)j,fm) One-dimensional data, such as all frequency sample data corresponding to the 1 st time sample of the 1 st channel, i.e. SF (1, t)1,fm). From the perspective of the spatially resolved geometry, this data can also be viewed as N3A dimensional space vector.
For simplicity, the label SF (1, t)1,fm) Has a real part of(the imaginary part is processed similarly).
Real part vectorWhich contains two approximately perpendicular components, namely a valid signal vector and a noise vector. Assume that a vector parallel to the effective signal vector isDue to the vector of the real partContains noise, thereforeAndare not parallel but have a certain included angleand the stronger the noise, the larger the angle alpha.
The inventors then consider that the idea of suppressing noise is to find a vector parallel to the effective signalVector of real partIn a vector parallel to the effective signalIs decomposed into vectors parallel to the spaceComponent (b) ofAnd perpendicular to the vectorComponent (b) ofThen, the vertical component is suppressed by using a noise suppression parameter lambdaParallel and parallel componentsRecombining noisy vectorsThe specific mathematical expression is as follows:
in the formula (16), the noise suppression parameter λ may range from 0 to 1, and when λ takes 0, the vertical component is completely suppressed, and when λ takes 1, the vertical component is not suppressed.
In practical application, due to vectorsThere is often some error in the estimation of (a), and some of the effective signal may be decomposed in the vertical component, so it is not desirable to completely suppress the vertical component, and λ is preferably chosen to be a reasonable intermediate value.
How to estimate the vector parallel to the effective signal, as described aboveAnd selecting a proper noise suppression parameter lambda, which is the key in the noise suppression step.
The inventors contemplate a prestack seismic gather s (n, t)j) With lateral continuity, i.e. the amplitudes of the different tracks at the same instant are uniformly graduated, and correspondingly the temporal spectra SF (n, t) of the different tracks at the same instantj,fm) Also has better correlation, and these transient spectrums are recorded as vectorsThe directions of these instantaneous spectral vectors are substantially identical, but due to factors such as noise, the vector direction deviates to some extent from the effective signal vector direction.
In one embodiment, the vector parallel to the effective signal is estimated by summing unit vectorsThe vector parallel to the effective signal in step S102 of the prestack seismic trace gather denoising method shown in fig. 1Can be expressed as：
In the formula (17), the reaction mixture,representing a time tjThe temporal spectrum of each channel corresponds to a vector parallel to the effective signal. Wherein,is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,n＝1,2,…,N1，N1is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2Is the total number of time samples, fmDenotes the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples.
In the embodiment of the invention, the effective signals concentrated in the pre-stack seismic channel can be effectively protected from being damaged less in the noise pressing process through the vector parallel to the effective signals.
The inventors consider that the noise suppression parameter λ (n, t)j) Is two-dimensional data, i.e. different channels correspond to different noise suppression parameter values at different times, and the noise suppression parameter lambda (n, t) can be obtainedj) Divided into two parts lambda1(n,tj) And λ2(n,tj)，λ1(n,tj) Has the effect of suppressing the noise, lambda2(n,tj) The function of (1) is to protect valid signals.
In an embodiment, according to the signal-to-noise ratio estimated in fig. 2, in step S103 of the prestack seismic gather noise suppression method shown in fig. 1, the expression of the noise suppression parameter may be:
in the formula (18), the parameter λ1(n,tj) For suppressing noise in pre-stack seismic trace concentration, parameter lambda1(n,tj) Has a value range of [ lambda ]D,λU]Parameter λ2(n,tj) For protecting effective signals, lambda, in prestack seismic trace gathersDAnd λUIs a setting parameter, SNR (n, t)j) For the above signal-to-noise ratio (effective signal energy/noise energy),is the SNR (n, t) of all signal-to-noise ratiosj) Maximum value in (two-dimensional data), N ═ 1,2, …, N1，N1Is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2is the total number of time samples, α0Is to set the coefficients (in radians),
parameter lambda1(n,tj) Can be adaptive, i.e. the signal-to-noise ratio SNR (n, t)j) The higher, λ1(n,tj) The larger the suppression of the vertical component. Due to vectorCertain errors are inevitable, although most of the useful signal information is distributed in and vectorsOn the parallel component, but still with a small part of the useful signal information distributed on the perpendicular component, the parameter lambda2(n,tj) protect the included angle at alpha0The inner vertical component.
In the embodiment of the invention, the noise suppression parameter can adaptively suppress noise and can effectively protect effective signals, so that the pre-stack seismic channel gather noise suppression method has a better noise suppression effect.
In one embodiment, in combination with the above equation (16) and equation (18), in step S104 of the pre-stack seismic gather denoising method shown in fig. 1 according to the above snr, the expression of the denoised DSST-time spectrum may be:
in the formula (19), in the following formula,is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,is a vector parallel to the effective signal, λ (N, j) is the noise suppression parameter, N is 1,2, …, N1，N1Is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2Is the total number of time samples, fmDenotes the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples is,is the denoised DSST time spectrum.
In one embodiment, in step S105 of the method for denoising a prestack seismic gather shown in fig. 1, the expression of the denoised prestack seismic gather may be:
where s (0) is an integration constant, Δ ω is a discrete interval of discrete angular frequencies,
is constant coefficientThe inverse number of (c) is,is the conjugate function of the fourier spectrum of the mother wavelet ψ, b and t are time, t > 0.
To illustrate the effectiveness of the pre-stack seismic trace gather noise suppression method according to the embodiment of the present invention, the effect of the present invention will be described in an embodiment, but the present invention is not limited to the scope of the present invention.
Fig. 4 is a schematic diagram of an original pre-stack seismic gather signal, fig. 5 is a schematic diagram of an SST spectrum of the signal shown in fig. 4, fig. 6 is a schematic diagram of a DSST spectrum of the signal shown in fig. 4, fig. 7 is a schematic diagram of a pre-stack seismic gather signal after reconstruction of the DSST spectrum shown in fig. 6, and fig. 8 is a schematic diagram of a relative error percentage of the original pre-stack seismic gather signal shown in fig. 4 and the reconstructed pre-stack seismic gather signal shown in fig. 7, according to an embodiment of the present invention.
As shown in FIG. 4, the original pre-stack seismic gather signal generated by simulation consists of two frequency-converted harmonics, the dominant frequency of the first sine wave oscillates at 40Hz or above, and the dominant frequency of the second sine wave oscillates at 90Hz or above. As shown in fig. 5, the time spectrum is obtained by performing conventional synchronous compression transformation SST on the original simulated prestack seismic gather signals, and it can be clearly seen that the main frequencies of the two components change with time in a sine wave manner. As shown in FIG. 6, the time spectrum is obtained by performing a derivative synchronous compression transform DSST on the original simulated prestack seismic gather signal. Comparing fig. 5 and fig. 6, it is found that the time-frequency trends of the two time-frequency spectrums are basically consistent, the local time-frequency characteristics in the signal can be clearly reflected, and both have higher time-frequency resolution; however, the two spectra have a certain difference, and the time-frequency focusing property of the SST spectrum is weaker than that of the DSST spectrum in the vicinity of 400ms and 1000 ms. This shows that, under the condition that the main frequency of the signal changes rapidly, the time-frequency resolution effect of the DSST spectrum is superior to that of the SST spectrum, i.e., the DSST is more beneficial to describing the local time-frequency characteristics of the signal. As shown in fig. 7, the signal is reconstructed from the DSST spectrum and substantially coincides with the amplitude of the original signal. As shown in fig. 8, the original signal and the DSST spectrum are reconstructed to obtain a relative error percentage curve of both signals, and the relative error is controlled within 10%, which indicates that the signal reconstructed from the DSST spectrum has better reliability.
Fig. 9 is a schematic diagram of a noise-free pre-stack seismic gather signal according to another embodiment of the present invention, fig. 10 is a schematic diagram of the pre-stack seismic gather signal shown in fig. 9 after being noisy, fig. 11 is a schematic diagram of a signal-to-noise ratio of the noisy pre-stack seismic gather shown in fig. 10, fig. 12 is a schematic diagram of a seismic gather signal of the noisy seismic gather signal shown in fig. 10 after being subjected to noise suppression by a noise suppression method according to an embodiment of the present invention, and fig. 13 is a schematic diagram of a noise signal of the noisy seismic gather signal shown in fig. 10 after being subjected to noise suppression by a noise suppression method according to an embodiment of the present invention.
As shown in fig. 9, the synthesized prestack seismic gather model has different variation trends in the transverse Amplitude, and simulates the AVO (Amplitude Versus Offset) characteristics of the reservoir in actual production, for example, the recorded Amplitude gradually increases at 300ms, which reflects the AVO characteristics of class II, and the recorded Amplitude gradually decreases at 350ms, which reflects the AVO characteristics of class I. As shown in FIG. 10, random noise is added to the noise-free pre-stack seismic gather shown in FIG. 9, where the maximum amplitude of the random noise is 20% of the effective recording maximum, resulting in a noisy pre-stack seismic gather. As shown in fig. 11, the snr (effective signal energy/noise energy) is estimated from the noisy prestack seismic gather shown in fig. 10, and each trace has a signal-to-noise ratio at each time point, where the maximum signal-to-noise ratio is 7.39, it can be seen that the snr levels at different times of different gathers are different, which also requires different snr parameters to be applied at different points for the snr processing. As shown in fig. 12, after the noise-containing prestack seismic gather shown in fig. 10 is subjected to noise suppression by the prestack seismic gather noise suppression method of the present invention, random noise is better filtered, and the continuity of the transverse amplitude is enhanced. As shown in fig. 13, from the filtered noise profile, it can be seen that most of the filtered noise is random noise, and the damage to the effective signal is small.
Fig. 14-16 are DSST time-frequency spectrum diagrams of the signals of traces 3, 9, and 15, respectively, of the noise-free pre-stack seismic gather of fig. 9. As shown in fig. 14 to 16, the distribution of the spectral energy boluses at the DSST of different channels has a similar regularity, the trend trends are substantially consistent, and there is a certain difference in detail, reflecting the change of the amplitude of each channel.
Fig. 17-19 are DSST time-frequency spectra of signals from traces 3, 9, and 15 of the noisy pre-stack seismic gather of fig. 10, respectively, and fig. 20 is a plot of the time-frequency spectrum of an active signal generated from the noisy pre-stack seismic gather of fig. 10. As shown in fig. 17 to 19, compared with the three graphs of fig. 14 to 16, some new energy clusters appear on the time frequency spectrum, and the consistency and regularity of the time frequency spectrum of each channel are damaged to some extent. As shown in fig. 20, the time-frequency spectrum does not represent the time-frequency spectrum of a single channel, but represents the energy distribution trend of the effective signal in each channel of the time-frequency spectrum, i.e. represents the vector parallel to the effective signal
Fig. 21 to 23 are DSST time frequency spectrums of the DSST time frequency spectrums shown in fig. 17 to 19 respectively after being subjected to noise suppression by the noise suppression method according to the embodiment of the present invention. As shown in fig. 21 to 23, the noise suppression parameter λ is selectedDIs 0.1, lambdaUis 0.8, α0Is pi/200. Compared with fig. 17 to 19, irregular energy masses in the frequency spectrum are effectively suppressed after noise suppression; compared with fig. 14 to 16, the main energy cluster distribution of the spectrum after noise suppression is substantially consistent with the spectrum without noise. Of course, the results of fig. 21 to 23 are slightly reduced in time-frequency energy focusing, but are enough to reflect the time-frequency energy distribution trend of the effective signal. The comparison results of the trace sets before and after noise suppression in fig. 9 to 13 show that the noise suppression method of the present invention can better filter out random noise and protect effective signals.
Fig. 24 is a schematic diagram of an original pre-stack seismic gather according to an embodiment of the present invention, fig. 25 is a schematic diagram of a pre-stack seismic gather after the original pre-stack seismic gather shown in fig. 24 is subjected to noise suppression by a noise suppression method according to an embodiment of the present invention, and fig. 26 is a schematic diagram of a noise gather of the original pre-stack seismic gather shown in fig. 24, which is filtered by the noise suppression method according to the embodiment of the present invention. As shown in fig. 24 to fig. 26, comparing the original trace set with the noise-suppressed trace set, it is found that the in-phase axes of the noise-suppressed trace set are clear and continuous, and the wave group characteristics are obvious. As shown in fig. 26, random noise is filtered in the noise-pressing process, which indicates that the effective signal is less damaged in the noise-pressing process.
FIGS. 27 and 28 are schematic diagrams of signal-to-noise ratios of the prestack seismic gathers shown in FIGS. 24 and 25, respectively. FIG. 27 shows the signal-to-noise ratio of the pre-squelch gather and FIG. 28 shows the signal-to-noise ratio of the post-squelch gather. As shown in fig. 27 and 28, the average snr of the pre-squelch gather is 0.52 and the average snr of the post-squelch gather is 1.50, indicating that the squelch processing greatly improves the snr level of the data.
FIGS. 29 and 30 are schematic diagrams of the destination layer amplitude of the prestack seismic gathers shown in FIGS. 24 and 25, respectively. The lateral amplitude (scatter) of the destination layer (at about 1400 ms) is picked up on the pre-compressed gather as shown in fig. 29, and on the post-compressed gather as shown in fig. 30. In fig. 29 and 30, the solid line is an AVO amplitude curve which is forward based on the destination reservoir information on the well, the horizontal axis is the track number, and the vertical axis is the amplitude value. As shown in fig. 29 and 30, the amplitude curve of the pre-squelch gather oscillates seriously, the attenuation trend is not obvious, and the AVO amplitude change characteristic cannot be reflected well; the trend of the amplitude curve of the gather after noise suppression is basically consistent with the AVO forward curve, and the AVO characteristics are well reflected. According to the prestack gather processed by the method, prestack AVO inversion is carried out, and the coincidence rate of inversion results and well information is improved from 70.5% to 85.6% (totally counting 180 wells), and is improved by 15.1%.
The prestack seismic channel gather noise suppression method provided by the embodiment of the invention is used for realizing prestack seismic channel gather noise suppression processing based on derivative synchronous compression transformation DSST and providing high signal-to-noise ratio seismic data for subsequent AVO inversion. According to the pre-stack seismic channel gather noise suppression method, the pre-stack seismic channel gather is subjected to time-frequency decomposition from derivative synchronous compression transform (DSST), energy cluster distribution on a time-frequency spectrum has good focusing performance, and local time-frequency resolution is high; separating effective signals from random noise on a frequency spectrum during DSST by using a vector space projection mode, and setting a plurality of adjustable parameters to respectively realize noise adaptive suppression and effective signal protection; and reconstructing a signal according to the filtered DSST time spectrum to obtain a denoised prestack gather. The prestack noise suppression technology based on the DSST can well suppress random noise, protect effective signals, enhance the transverse continuity of a gather and highlight the characteristic of a same-phase axial wave group.
Based on the same inventive concept as the prestack seismic trace gather denoising method shown in fig. 1, the embodiment of the invention also provides a prestack seismic trace gather denoising device, as described in the following embodiments. The principle of solving the problems of the prestack seismic channel gather noise suppression device is similar to that of the prestack seismic channel gather noise suppression method, so the implementation of the prestack seismic channel gather noise suppression device can refer to the implementation of the prestack seismic channel gather noise suppression method, and repeated parts are not described again.
Fig. 31 is a schematic structural diagram of a prestack seismic trace gather noise suppression device according to an embodiment of the present invention. As shown in fig. 31, the pre-stack seismic gather denoising device according to the embodiment of the present invention includes a DSST time-frequency spectrum generating unit 3110, a vector generating unit 3120, a denoising parameter setting unit 3130, a post-denoising DSST time-frequency spectrum generating unit 3140, and a pre-stack seismic gather reconstructing unit 3150. The units are connected in sequence.
The DSST time-frequency spectrum generating unit 3110 is configured to perform derivative synchronous compression transform DSST on each record of the prestack seismic gather, and generate a DSST time-frequency spectrum of the prestack seismic gather.
The vector generating unit 3120 is configured to estimate a vector parallel to the effective signal in the set of pre-stack seismic traces according to the DSST time spectrum.
The noise suppression parameter setting unit 3130 is configured to set a noise suppression parameter according to the prestack seismic gather.
And the post-denoising DSST time frequency spectrum generating unit 3140 is configured to perform denoising processing on the pre-stack seismic gather according to the DSST time frequency spectrum, the vector, and the denoising parameter, and generate a denoised DSST time frequency spectrum.
The prestack seismic gather reconstructing unit 3150 is configured to obtain the prestack seismic gather after noise suppression according to the post-noise-suppression DSST time spectrum reconstruction.
According to the pre-stack seismic channel gather noise suppression device disclosed by the embodiment of the invention, in the vector space projection noise suppression process, the noise suppression parameter setting unit is used for setting the noise suppression, the vector generation unit is used for generating the vector protection effective signal parallel to the effective signal, and the noise suppression parameter and the effective signal protection parameter are combined to enable the selection of each parameter to have clear purpose and physical significance, so that the noise suppression and the effective signal protection are facilitated.
Fig. 32 is a schematic structural diagram of a noise suppression parameter setting unit according to an embodiment of the present invention. As shown in fig. 32, the noise-pressing parameter setting unit 3130 may include an snr generating module 3131 and a noise-pressing parameter generating module 3132.
The signal-to-noise ratio generation module 3131 is configured to perform quality analysis on the prestack seismic gather, and estimate a signal-to-noise ratio of the prestack seismic gather.
The noise suppression parameter generating module 3132 is configured to calculate the noise suppression parameter according to the signal-to-noise ratio.
In the embodiment of the invention, the noise suppression parameter generation module sets the noise suppression parameter according to the signal-to-noise ratio generated by the signal-to-noise ratio generation module, so that the noise suppression of the pre-stack seismic gather is more targeted and the noise suppression effect is better.
Fig. 33 is a schematic structural diagram of a prestack seismic trace gather denoising device according to an embodiment of the present invention. As shown in fig. 33, the pre-stack seismic trace gather denoising device shown in fig. 31 may further include a residual data generation unit 3160 and a re-denoising control unit 3170.
The residual data generating unit 3160 is configured to calculate residual data of the pre-stack seismic trace sets before and after denoising according to a difference between the pre-stack seismic trace set and the post-denoising pre-stack seismic trace set.
The re-denoising control unit 3170 is configured to perform amplitude preservation analysis on the denoised pre-stack seismic gather according to the residual data, and if the effective signal is damaged, repeatedly operate the denoising parameter setting unit, the post-denoising DSST time-frequency spectrum generating unit, and the pre-stack seismic gather reconstructing unit.
In the embodiment of the invention, the amplitude preservation analysis is carried out on the pre-stack seismic gather after noise suppression through the re-noise suppression control unit, and the noise suppression parameter can be adaptively adjusted according to the actual signal-to-noise ratio level of the pre-stack seismic gather data, so that the noise suppression effect is improved and effective signals are protected.
In one embodiment, in the pre-stack seismic trace gather noise suppression device shown in fig. 33, the re-noise suppression control unit 3170 may include an amplitude preservation analysis module 3171.
The amplitude preservation analysis module 3171 is configured to perform amplitude preservation analysis on the noise suppressed prestack seismic gather according to information on a well. The uphole information may include destination reservoir information from which AVO amplitude curves may be developed.
In the embodiment of the invention, the amplitude preservation analysis module is combined with the standard spectrum of the information on the well, so that whether the effective signals concentrated by the prestack seismic traces after noise pressing are damaged or not can be analyzed more easily.
FIG. 34 is a schematic structural diagram of a pre-stack seismic trace gather noise suppression device according to an embodiment of the invention. As shown in fig. 34, the DSST time frequency spectrum generated by the DSST time frequency spectrum generating unit 3110 is a complex number, and the pre-stack seismic channel gather noise suppression apparatus according to the embodiment of the present invention may include a time frequency spectrum real part and imaginary part splitting unit 3180 and a time frequency spectrum real part and imaginary part combining unit 3190.
The time-frequency spectrum real part and imaginary part splitting unit 3180 may be connected between the DSST time-frequency spectrum generating unit 3110 and the vector generating unit 3120, and the time-frequency spectrum real part and imaginary part combining unit 3190 may be connected between the post-noise-pressing DSST time-frequency spectrum generating unit 3140 and the pre-stack seismic gather reconstructing unit 3150.
The time spectrum real part and imaginary part splitting unit 3180 is configured to process the real part of the DSST time spectrum and the imaginary part of the DSST time spectrum through the vector generating unit 3120, the noise suppression parameter setting unit 3130, and the post-noise-suppression DSST time spectrum generating unit 3140, respectively, to obtain the real part and the imaginary part of the post-noise-suppression DSST time spectrum;
the real part and imaginary part combination unit 3190 of the time-frequency spectrum is configured to combine the real part and the imaginary part of the denoised DSST time frequency spectrum to generate the denoised DSST time frequency spectrum.
In the embodiment of the invention, the time frequency spectrum is respectively processed according to the real part and the imaginary part of the time frequency spectrum by the time frequency spectrum real part and imaginary part splitting unit, which is favorable for reducing the calculation complexity in the pre-stack seismic channel set noise suppression process.
In an embodiment, the expression of the DSST time spectrum generated by the DSST time spectrum generating unit 3110 is as follows:
wherein, ω islIs the l-th discrete angular frequency, Δ ω is the discrete interval of the discrete angular frequency, Ws(akAnd b) is the wavelet coefficient of the prestack seismic gather signal, akIs the kth discrete scale, b is time, ωs(akAnd b) is the angular frequency of the prestack seismic gather signal, (Δ a)k＝ak+1-akP-2, k-1, 2, …, N are discrete numbers.
In the embodiment of the invention, the DSST time spectrum generating unit has higher time-frequency resolution than that of the conventional SST based on derivative synchronous compression transformation DSST, and the time-frequency energy clusters are more focused, thereby being beneficial to signal-noise separation.
In one embodiment, the vector generated by the vector generation unit 3120 has the following expression:
wherein,is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,
n＝1,2,…,N1，N1is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2Is the total number of time samples, fmDenotes the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples.
In the embodiment of the invention, the vector generation unit can effectively protect the effective signals concentrated by the pre-stack seismic channels from being damaged in the noise pressing process through the vector parallel to the effective signals.
In one embodiment, the expression of the noise pressing parameter set by the noise pressing parameter setting unit 3130 is:
wherein the parameter lambda1(n,tj) For suppressing noise in pre-stack seismic trace concentration, parameter lambda1(n,tj) Has a value range of [ lambda ]D,λU]Parameter λ2(n,tj) For protecting effective signals, lambda, in prestack seismic trace gathersDAnd λUIs a setting parameter, SNR (n, t)j) In order to be able to measure the signal-to-noise ratio,is the SNR (n, t) of all signal-to-noise ratiosj) Maximum value of (1), 2, …, N1，N1Is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2is the total number of time samples, α0It is to set the coefficients of the coefficients,
in the embodiment of the invention, the noise suppression parameter setting unit can adaptively set the noise suppression parameter to suppress noise and can effectively protect effective signals, so that the pre-stack seismic channel gather noise suppression method has a better noise suppression effect.
In an embodiment, the expression of the denoised DSST time frequency spectrum generated by the denoised DSST time frequency spectrum generating unit 3140 is as follows:
wherein,is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,is the vector, λ (N, j) is the squelch parameter, N is 1,2, …, N1，N1Is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2Is the total number of time samples, fmDenotes the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples is,is the denoised DSST time spectrum.
In an embodiment, the expression of the noise suppressed pre-stack seismic gather generated by the pre-stack seismic gather reconstructing unit 3150 is as follows:
where s (0) is an integration constant, Δ ω is a discrete interval of discrete angular frequencies,
is constant coefficientThe inverse number of (c) is,is the conjugate function of the fourier spectrum of the mother wavelet ψ, b and t are time, t > 0.
According to the pre-stack seismic channel gather noise suppression device, the DSST time-frequency spectrum generation unit achieves pre-stack seismic channel gather noise suppression processing based on derivative synchronous compression transformation DSST, and high signal-to-noise ratio seismic data are provided for subsequent AVO inversion. According to the pre-stack seismic channel gather noise suppression device, the time-frequency decomposition is carried out on the pre-stack seismic channel gather from derivative synchronous compression transformation DSST, the energy cluster distribution on a time-frequency spectrum has good focusing performance, and the local time-frequency resolution is high; separating effective signals from random noise on a frequency spectrum during DSST by using a vector space projection mode, and setting a plurality of adjustable parameters to respectively realize noise adaptive suppression and effective signal protection; and reconstructing a signal according to the filtered DSST time spectrum to obtain a denoised prestack gather. The prestack noise suppression technology based on the DSST can well suppress random noise, protect effective signals, enhance the transverse continuity of a gather and highlight the characteristic of a same-phase axial wave group.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (15)
1. A pre-stack seismic trace gather denoising method, comprising:
step 1: performing derivative synchronous compression transform (DSST) on each record of the pre-stack seismic gather to generate a DSST time frequency spectrum of the pre-stack seismic gather;
step 2: estimating vectors in the pre-stack seismic trace set parallel to the effective signals according to the DSST time spectrum;
and step 3: setting a noise suppression parameter according to the pre-stack seismic gather;
and 4, step 4: performing noise suppression processing on the pre-stack seismic gather according to the DSST time spectrum, the vector and the noise suppression parameter to generate a denoised DSST time spectrum;
and 5: and reconstructing according to the DSST time spectrum after noise suppression to obtain the pre-stack seismic gather after noise suppression.
2. The pre-stack seismic gather denoising method of claim 1, wherein setting a denoising parameter based on the pre-stack seismic gather comprises:
performing quality analysis on the pre-stack seismic gather, and estimating to obtain the signal-to-noise ratio of the pre-stack seismic gather;
and calculating the noise suppression parameter according to the signal-to-noise ratio.
3. The prestack seismic trace gather denoising method of claim 1, after step 5, comprising:
calculating residual data of the pre-stack seismic channel sets before and after noise suppression according to the difference value of the pre-stack seismic channel set and the pre-stack seismic channel set after noise suppression;
and performing amplitude preservation analysis on the pre-stack seismic gather subjected to noise suppression according to the residual data, and if the effective signal is damaged, repeatedly executing the step 3 to the step 5.
4. The pre-stack seismic gather denoising method of claim 3, wherein performing amplitude preserving analysis on the denoised pre-stack seismic gather from the residual data comprises: and combining well information, and performing amplitude preservation analysis on the pre-stack seismic gather subjected to noise suppression according to the residual data.
5. The prestack seismic gather denoising method of claim 1, wherein the DSST time frequency spectrum is complex; the method comprises the following steps:
respectively executing the steps 2 to 4 on the real part and the imaginary part of the DSST time frequency spectrum to obtain the real part and the imaginary part of the denoised DSST time frequency spectrum;
and combining the real part and the imaginary part of the denoised DSST time spectrum to generate the denoised DSST time spectrum.
6. The prestack seismic gather denoising method of claim 1, wherein the DSST-time spectrum is expressed as:
wherein, ω islIs the l-th discrete angular frequency, Δ ω is the discrete interval of the discrete angular frequency, Ws(akAnd b) is the wavelet coefficient of the prestack seismic gather signal, akIs the kth discrete scale, b is time, ωs(akAnd b) is the angular frequency of the prestack seismic gather signal, (Δ a)k＝ak+1-akP-2, k-1, 2, …, N are discrete numbers.
7. The prestack seismic gather denoising method of claim 1, wherein the vector is expressed as:
wherein,is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,
N1is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2Is the total number of time samples, fmDenotes the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples.
8. The prestack seismic gather denoising method of claim 2, wherein the denoising parameter is expressed by:
wherein the parameter lambda1(n,tj) For suppressing noise in pre-stack seismic trace concentration, parameter lambda1(n,tj) Has a value range of [ lambda ]D,λU]Parameter λ2(n,tj) For protecting effective signals, lambda, in prestack seismic trace gathersDAnd λUIs a setting parameter, SNR (n, t)j) Is the signal-to-noise ratio, max [ SNR (n, t), of the prestack seismic gatherj)]Is the SNR (n, t) of all signal-to-noise ratiosj) Maximum value of (1), 2, …, N1，N1Is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2is the total number of time samples, α0It is to set the coefficients of the coefficients, is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,is the vector.
9. The prestack seismic gather denoising method of claim 2, wherein the denoised DSST time spectrum is expressed by:
wherein,is the temporal spectrum of the pre-stack seismic gather of different traces at the same time,is the vector, λ (N, j) is the squelch parameter, N is 1,2, …, N1，N1Is the total trace number, t, of the prestack seismic gatherjDenotes the jth time sample, j ═ 1,2, …, N2，N2Is the total number of time samples, fmDenotes the mth frequency sample, m is 1,2, …, N3，N3The total number of frequency samples is,is the denoised DSST time spectrum.
10. The pre-stack seismic gather denoising method of claim 9, wherein the expression of the denoised pre-stack seismic gather is:
where s (0) is an integration constant, Δ ω is a discrete interval of discrete angular frequencies,is constant coefficientThe inverse number of (c) is,is the conjugate function of the fourier spectrum of the mother wavelet ψ, b and t are time, t > 0.
11. A pre-stack seismic trace gather squelch apparatus, the apparatus comprising:
a DSST time frequency spectrum generating unit, configured to perform derivative synchronous compression transform DSST on each record of the pre-stack seismic gather, and generate a DSST time frequency spectrum of the pre-stack seismic gather;
a vector generation unit, configured to estimate a vector parallel to the effective signal in the pre-stack seismic trace set according to the DSST time spectrum;
the noise suppression parameter setting unit is used for setting a noise suppression parameter according to the pre-stack seismic gather;
a post-denoising DSST time spectrum generating unit, configured to perform denoising processing on the pre-stack seismic gather according to the DSST time spectrum, the vector, and the denoising parameter, and generate a denoised DSST time spectrum;
and the pre-stack seismic gather reconstruction unit is used for reconstructing the post-noise-suppression DSST time spectrum to obtain the post-noise-suppression pre-stack seismic gather.
12. The pre-stack seismic gather denoising device of claim 11, wherein the denoising parameter setting unit comprises:
the signal-to-noise ratio generation module is used for carrying out quality analysis on the pre-stack seismic gather and estimating the signal-to-noise ratio of the pre-stack seismic gather;
and the noise suppression parameter generating module is used for calculating the noise suppression parameter according to the signal-to-noise ratio.
13. The pre-stack seismic trace gather noising apparatus of claim 11, wherein the apparatus comprises:
a residual data generating unit, configured to calculate residual data of the pre-stack seismic trace sets before and after noise suppression according to a difference between the pre-stack seismic trace set and the post-noise-suppression pre-stack seismic trace set;
and the noise suppression control unit is used for carrying out amplitude preservation analysis on the pre-stack seismic gather subjected to noise suppression according to the residual data, and if the effective signal is damaged, the noise suppression parameter setting unit, the post-noise suppression DSST time-frequency spectrum generating unit and the pre-stack seismic gather reconstruction unit are repeatedly operated.
14. The pre-stack seismic trace gather denoising apparatus of claim 13, wherein the re-denoising control unit comprises:
and the amplitude preservation analysis module is used for carrying out amplitude preservation analysis on the pre-stack seismic gather after noise suppression according to information on a well.
15. The pre-stack seismic trace gather noising apparatus of claim 11, wherein the apparatus comprises:
the time spectrum real part and imaginary part splitting unit is used for respectively processing the real part and the imaginary part of the DSST time spectrum through the vector generating unit, the noise suppression parameter setting unit and the post-noise-suppression DSST time spectrum generating unit to obtain the real part and the imaginary part of the post-noise-suppression DSST time spectrum;
and the time-frequency spectrum real part and imaginary part combination unit is used for combining the real part and the imaginary part of the denoised DSST time spectrum to generate the denoised DSST time spectrum.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021020982A1 (en) * | 2019-07-31 | 2021-02-04 | Saudi Arabian Oil Company | Enhancement of seismic data |
| WO2021020984A1 (en) * | 2019-07-31 | 2021-02-04 | Saudi Arabian Oil Company | Enhancement of seismic data |
| WO2021020983A1 (en) * | 2019-07-31 | 2021-02-04 | Saudi Arabian Oil Company | Enhancement of seismic data |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019156586A1 (en) | 2018-02-08 | 2019-08-15 | Andrey Bakulin | Systems and methods to enhance 3-d prestack seismic data based on non-linear beamforming in the cross-spread domain |
| US11994639B2 (en) | 2019-05-15 | 2024-05-28 | Saudi Arabian Oil Company | Seismic velocity modeling |
| CN110221349B (en) * | 2019-07-15 | 2020-08-14 | 桂林电子科技大学 | Transient electromagnetic signal noise reduction method based on wavelet transformation and sine wave estimation |
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| CN113589384B (en) * | 2020-04-30 | 2023-07-28 | 中国石油化工股份有限公司 | Pre-stack gather amplitude-preserving denoising method based on characteristic that signal changes along with offset distance |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6253175B1 (en) * | 1998-11-30 | 2001-06-26 | International Business Machines Corporation | Wavelet-based energy binning cepstal features for automatic speech recognition |
| CN102053273A (en) * | 2009-10-29 | 2011-05-11 | 中国石油化工股份有限公司 | Inverse Q filtering method for seismic wave signal |
| CN102305945B (en) * | 2011-06-20 | 2013-09-25 | 电子科技大学 | Linear noise eliminating method |
| CN103630932A (en) * | 2013-09-23 | 2014-03-12 | 中国海洋石油总公司 | Seismic data fractal amplitude preservation method |
-
2015
- 2015-08-12 CN CN201510494159.8A patent/CN106443787B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6253175B1 (en) * | 1998-11-30 | 2001-06-26 | International Business Machines Corporation | Wavelet-based energy binning cepstal features for automatic speech recognition |
| CN102053273A (en) * | 2009-10-29 | 2011-05-11 | 中国石油化工股份有限公司 | Inverse Q filtering method for seismic wave signal |
| CN102305945B (en) * | 2011-06-20 | 2013-09-25 | 电子科技大学 | Linear noise eliminating method |
| CN103630932A (en) * | 2013-09-23 | 2014-03-12 | 中国海洋石油总公司 | Seismic data fractal amplitude preservation method |
Non-Patent Citations (2)
| Title |
|---|
| Seismic data decomposition into spectral components using regularized nonstationary autoregression;Sergey Fomel;《Geophysics》;20131231;第78卷(第6期);正文第1-22页 * |
| Time-frequency analysis of seismic data using synchrosqueezing wavelet transform;Yangkang Chen 等;《Journal of seismic exploration》;20141231;第303-312页 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021020982A1 (en) * | 2019-07-31 | 2021-02-04 | Saudi Arabian Oil Company | Enhancement of seismic data |
| WO2021020984A1 (en) * | 2019-07-31 | 2021-02-04 | Saudi Arabian Oil Company | Enhancement of seismic data |
| WO2021020983A1 (en) * | 2019-07-31 | 2021-02-04 | Saudi Arabian Oil Company | Enhancement of seismic data |
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