CN102305940A - Method for extracting fluid factor - Google Patents

Abstract

The invention provides a method for extracting a fluid factor. The method comprises the following steps of: detecting at least one channel seismic data in a work area; setting an initial value of a fractional order number used for fractional order Fourier transform; calculating the fractional order Fourier transform of one channel seismic data in the at least one channel seismic data according to the fractional order number; calculating an analytic signal of the fractional order Fourier transform, and Wigner-Ville distribution with suppressed cross terms of the analytic signal; calculating Radon transform of a band window of the Wigner-Ville distribution with the suppressed cross terms; reconstructing a time frequency distribution map according to the Radon transform of the band window; and extracting the fluid factor from the time frequency distribution map. According to the method for extracting the fluid factor, the fluid factor can be accurately extracted from seismic waves even though the seismic waves have a dispersion effect.

Description

The fluid factor extraction method

Technical field

The present invention relates to field of seismic exploration.More particularly, relate to a kind of fluid factor extraction method.

Background technology

In seismic prospecting, the extraction of the fluid factor is a very important technology.The accurate fluid factor can be carried out detection and Identification to underground mineral reserve more accurately.Current, can come geological data is analyzed through Time-Frequency Analysis Method, to obtain the fluid factor.Time-Frequency Analysis Method can provide the joint distribution information of time domain and frequency field, can more clearly describe the time dependent relation of frequency of signal.

Below, a kind of fluid factor extraction method of prior art is shown.

For certain given road earthquake data x (t), its Wigner (Eugene Wigner) distribution W _x(t, definition f) is following:

$W_x(t,f)={\∫}_{-\∞}^{+\∞}(t+\frac{\mathrm{\τ}}{2})x{(t-\frac{\mathrm{\τ}}{2})}^{*}{e}^{-j2\mathrm{\πf\τ}}\mathrm{d\τ}---\left(1\right)$

W _x(t, time frequency plane f) has the highest resolution, and its shortcoming is that it is that a quadratic form distributes, and the cross term of generation causes the appearance of a large amount of pseudo frequency components, has seriously restricted the extraction of the convection cell factor.Wigner distributes and has positive negative frequency; There is cross term between the positive negative frequency; For eliminating this positive and negative frequency translation item; Can remove negative frequency Wigner earlier distributes; Promptly earlier signal x (t) is done Hilbert (Hilbert) conversion; Obtain an analytic signal z (t), calculate the Wigner distribution W of this analytic signal again _z(t, f), such distribution is called Wigner-Ville (Eugene Wigner-Willie) and distributes.Here, geological data x (t) is the time series (for example, certain road earthquake data of concentrating of certain road, certain road collection carried out the post-stack seismic data that forms after overlap-add procedure etc.) of a seismologic record.

Do not have positive and negative frequency translation item although Wigner-Ville distributes, between the different frequency composition, even same frequency content is inner, still has cross term.The characteristics of cross term are: when interactional two frequency contents or same frequency content different between the frequency, by the amplitude concussion that is proportional to the distance between two frequency contents or the 2 o'clock frequencies, the direction of concussion is perpendicular to the line direction between the two.

In order to reduce the influence of the pseudo frequency component that these cross terms bring, adopt smoothing method to suppress cross term usually.This method realizes through on the ambiguity function territory, carrying out low-pass filtering.Ambiguity function is defined as:

$A_z(w,\mathrm{\τ})={\∫}_{-\∞}^{+\∞}z(t+\frac{\mathrm{\τ}}{2})z{(t-\frac{\mathrm{\τ}}{2})}^{*}{e}^{-j2\mathrm{\πwt}}\mathrm{dt}---\left(2\right)$

Between it and Wigner distribute two-dimentional inverse Fourier transform relation, promptly

$W_z(t,f)={\∫}_{-\∞}^{+\∞}{A}_z(w,\mathrm{\τ})e^{-j2\mathrm{\π}(\mathrm{wt}+\mathrm{\τf})}\mathrm{dwd\τ}---\left(3\right)$

(w is τ) to W with a low-pass filter g _z(t is f) in that (w τ) carries out smoothly on the territory, obtain the time-frequency distributions RID that suppresses with cross term _z(t, f), promptly

${\mathrm{RID}}_z(t,f)={\∫}_{-\∞}^{+\∞}g(w,\mathrm{\τ})A_z(w,\mathrm{\τ})e^{-j2\mathrm{\π}(\mathrm{wt}+\mathrm{\τf})}\mathrm{dwd\τ}---\left(4\right)$

Wherein, (w is the low-pass filter function of two dimension τ) to g, and w is a Doppler shift, and τ is a time lag.On w=0 axle and τ=0 spool, g (w τ) equals 1, and g (w, τ)=g (w ,-τ) ^*It can be the product of two one dimension lowpass functions.

Directly the Wigner-Ville distribution that suppresses with this band cross term can be done spectral factorization to geological data and obtain time frequency distribution map ρ _z(t f) obtains the fluid factor.Yet this method only is used to describe the seismic event of no chromatic dispersion situation.If there is dispersion phenomenon to exist, then the seismic event velocity of wave of different frequency is different, as far as the stratum same point, although this speed difference is very little, but the linear frequency modulation component possibly occur.Therefore, the inapplicable situation that has dispersion phenomenon to exist of this method.

Therefore, even need a kind of dispersion situation that in seismic event, exists, also can from seismic event, extract the method for the fluid factor.

Summary of the invention

The object of the present invention is to provide a kind of fluid factor extraction method.

One side of the present invention provides a kind of fluid factor extraction method, comprising: (a) detect at least one road earthquake data in the work area; (b) be provided for the initial value of the mark exponent number α of Fourier Transform of Fractional Order; (c) use mark exponent number α, calculate the Fourier Transform of Fractional Order of one geological data in said at least one road earthquake data; (d) calculate the analytic signal of Fourier Transform of Fractional Order, and calculate the Wigner-Ville distribution of the band cross term inhibition of analytic signal; (e) the Radon conversion of the band window of the Wigner-Ville distribution of calculating band cross term inhibition; (f) utilize the Radon conversion reconstruct time frequency distribution map of being with window; (g) extract the fluid factor from time frequency distribution map.

On the other hand, come the reconstruct time frequency distribution map through the mark exponent number α that will turn clockwise with the territory at the Radon conversion of window place.

On the other hand, said method also comprises: (h) use the attribute factor that extracts to make up geologic structure; (i) geologic structure that makes up and the geologic structure of obtaining according to log data are compared, confirm whether geologic structure that makes up and the geologic structure of obtaining according to log data coincide in the predictive error scope; (j) if the geologic structure that makes up is coincide in the predictive error scope with the geologic structure of obtaining according to log data, then confirm to obtain optimum mark exponent number α.

On the other hand,, then change the value of mark exponent number α in the predictive error scope, return step (c) if the geologic structure that makes up is not coincide with the geologic structure of obtaining according to log data.

On the other hand, said method also can comprise: when said at least one road earthquake data during for twice geological data at least, use optimum mark exponent number α to other road earthquake data execution in step (c)-(g) in said at least one road earthquake data.

On the other hand, the step from the time frequency distribution map extraction fluid factor can comprise from the time frequency distribution map extraction frequency attribute factor.

On the other hand, the frequency attribute factor can comprise at least one in peak value instantaneous value frequency, root mean square frequency, the frequency attenuation gradient.

On the other hand, can optimum mark exponent number α be set according to current known seismic data.

The initial value of mark exponent number α can be set according to current known seismic data on the other hand.

On the other hand, current known seismic data can be the geologic structure data in log data or contiguous work area.

On the other hand, can obtain said log data from well logging.

On the other hand, can before or after detecting said at least one road earthquake data, form said well logging.

One side of the present invention provides a kind of geologic structure detection method, comprising: use the fluid factor of extracting according to said method to detect geologic structure.

According to fluid factor extraction method of the present invention, even exist under the situation of chromatic dispersion, also can reduce the interference between the different linear frequency modulation components, thereby can realize extraction the fluid factor of the seismic event of the situation that has chromatic dispersion at seismic event.Like this, through the fluid factor of extracting, detection and Identification geologic structure more accurately.

Will be in ensuing description part set forth the present invention other aspect and/or advantage, some will be clearly through describing, and perhaps can pass through enforcement of the present invention and learn.

Description of drawings

Through the detailed description of carrying out below in conjunction with accompanying drawing, above and other objects of the present invention, characteristics and advantage will become apparent, wherein:

Fig. 1 illustrates fluid factor extraction method according to an embodiment of the invention;

Fig. 2 illustrate prior art with according to the contrast of fluid factor extraction method of the present invention.

Embodiment

Now, will describe different example embodiment more fully with reference to accompanying drawing, wherein, certain exemplary embodiment is shown in the drawings.

Fig. 1 illustrates fluid factor extraction method according to an embodiment of the invention.

In step 101, detect at least one road earthquake data in the work area.

In step 102, be provided for carrying out the initial value of the mark exponent number α of Fourier Transform of Fractional Order, the initial value of mark exponent number α can be set arbitrarily here.

In step 103, use mark exponent number α, calculate the Fourier Transform of Fractional Order X of the one geological data x (t) in said at least one road earthquake data _α(u), that is,

$X_{\mathrm{\α}}\left(u\right)=\left\{\begin{array}{cc}\sqrt{\frac{1-j\cot \mathrm{\α}}{2\mathrm{\π}}}{e}^{{\mathrm{ju}}^2\cot \mathrm{\α}/2}{\∫}_{-\∞}^{\∞}x\left(t\right)e^{{\mathrm{jt}}^2\cot \mathrm{\α}/2-\mathrm{jut}\csc }& \mathrm{dt},\mathrm{\α}\≠\mathrm{n\π}\\ X\left(u\right),& \mathrm{\α}=2\mathrm{n\π}\\ X(-u),& \mathrm{\α}=(2n\±1)\mathrm{\π}\end{array}\right.---\left(5\right)$

Wherein, n is a positive integer, the general Fourier transformation of X (u) expression x (t), and t express time, u are represented the territory that obtains after the Fourier Transform of Fractional Order.

In step 104, calculate X _α(u) analytic signal Z _αAnd calculate analytic signal Z (u), _α(u) the Wigner-Ville distribution RID that band cross term suppresses _α(u, v).Should be appreciated that, v represent to calculate the two-dimensional field of obtaining after Wigner-Ville that the band cross term suppresses distributes (u, v) in another dimension outside dimension u.

In step 105, calculate the Wigner-Ville distribution RID that the band cross term suppresses _α(u, Radon (La Dun) the conversion R of band window v) _α(u, v), that is,

$R_{\mathrm{\α}}(u,v)={\∫}_{-\∞}^{\∞}w(u^{\′}-u){\mathrm{RID}}_{\mathrm{\α}}(u,v){\mathrm{du}}^{\′}---\left(6\right)$

Wherein, w (u) is a window function.

In step 106, utilize the Radon conversion RID of band window _α(u v) comes reconstruct time frequency distribution map ρ _α(t, f).

Specifically, through will be with the Radon conversion R of window _α(u, (u, the mark exponent number α that v) turns clockwise obtains time frequency distribution map ρ in territory v) _α(t, f).Like this, the territory (u, v) and the territory (f) there is relation as follows in t:

$\left(\begin{array}{c}u\\ v\end{array}\right)=\left(\begin{array}{cc}\cos \mathrm{\α}& \sin \mathrm{\α}\\ -\sin & \cos \mathrm{\α}\end{array}\right)\left(\begin{array}{c}t\\ f\end{array}\right)---\left(7\right)$

In step 107, extract the fluid factor from time frequency distribution map.

Can extract the fluid factor from time frequency distribution map in known manner.For example, utilize time frequency distribution map in frequency domain, to extract the frequency attribute factor (for example, peak value instantaneous value frequency, root mean square frequency and/or frequency attenuation gradient etc.).

In step 108, use the fluid factor of extracting to make up geologic structure.

In step 109, geologic structure that makes up and the geologic structure that obtains according to log data are compared, confirm whether geologic structure that makes up and the geologic structure that obtains according to log data coincide in the predictive error scope.

Can obtain log data through the well logging in the work area.It should be appreciated by those skilled in the art, can be before detecting geological data or after form and log well.Because the geologic structure of obtaining and make up of log data is known, therefore no longer it is detailed.

If the geologic structure that makes up is not coincide in the predictive error scope with the geologic structure that obtains according to log data, then in step 110, change the value of mark exponent number α, return step 103.

If the geologic structure that makes up is coincide in the predictive error scope with the geologic structure that obtains according to log data,, confirm to obtain optimum mark exponent number α then in step 111.At this moment, can be used as the fluid factor of that road earthquake data extract of from confirming optimum mark exponent number α process, selecting in the fluid factor that step 107 is extracted.

Subsequently, use optimum mark exponent number α, with from other road earthquake data extract fluid factors to the per pass geological data execution in step 103-107 in other road earthquake data in said at least one road earthquake data (if exist).In addition, all right further execution in step 108 is to make up geologic structure.

After the per pass geological data extracts the fluid factor, can utilize the fluid factor of extraction to detect geologic structure.Owing to exist many known fluid factors of utilizing to detect the geologic structure method, therefore no longer detail.

In another embodiment, can the initial value of mark exponent number α be set or optimum mark exponent number α directly is set according to current known seismic data (for example, the geologic structure data in log data, contiguous work area etc.).For example; If the log data in the log data in current work area and other work areas close (perhaps the geologic structure in the represented geologic structure of the log data in current work area and other work areas is close) then can directly use the mark exponent number that execution in step 101-111 obtains in other work areas the initial value of mark exponent number α to be set or optimum mark exponent number α directly is set.Again for example, the initial value that can use the mark exponent number that uses in contiguous work area that mark exponent number α is set perhaps directly is provided with optimum mark exponent number α.

Fig. 1 illustrates one embodiment of the present of invention, in this embodiment the mark exponent number is optimized, thereby is reduced the interference between each linear frequency modulation component inside and the different linear frequency modulation components substantially.

Because based on the effect that highlights of the time-frequency distributions of fractional order to the linear frequency modulation component; In another embodiment; Can the mark exponent number be optimized; Directly use the initial value of mark exponent number α, come execution in step 101-107 to extract the fluid factor at least one road earthquake data in said at least one road earthquake data.In other words, even do not carry out the optimization of mark exponent number, also can solve technical matters of the present invention.In addition, in this embodiment, when as foregoing, the initial value of mark exponent number α being set, can further reduce interference according to current known seismic data.

Fig. 2 illustrate prior art with according to the contrast of fluid factor extraction method of the present invention.

Fig. 2 (a) illustrates the time-frequency distributions of the fluid factor extraction method acquisition of adopting prior art.Can find out that from Fig. 2 (a) though the cross term braking measure is arranged, all there is the cross interference item between two linear frequency modulation components and each linear frequency modulation component inside.

Fig. 2 (b)-2 (f) illustrates the time-frequency distributions that employing obtains according to fluid factor extraction method of the present invention.Can find out from Fig. 2 (b)-2 (f),, the linear frequency modulation component highlighted effect, and cross term is had the obvious suppression effect based on the time-frequency distributions of fractional order.When the mark exponent number at optimum, that is, during α=41 °, originally the time frequency component of two of the phase mutual interference linear frequency modulation components separates fully.

Therefore; According to fluid factor extraction method of the present invention; Not only can realize not having the fluid factor extraction of chromatic dispersion seismic event; Even and exist under the situation of chromatic dispersion at seismic event; Also can reduce the interference between the different linear frequency modulation components, thereby can realize extraction the fluid factor of the seismic event of the situation that has chromatic dispersion.Like this, through the fluid factor of extracting, detection and Identification geologic structure more accurately.

Although specifically shown and described the present invention with reference to its exemplary embodiment; But it should be appreciated by those skilled in the art; Under the situation of the spirit and scope of the present invention that do not break away from claim and limited, can carry out the various changes on form and the details to it.

Claims (12)

1. fluid factor extraction method comprises:

(a) at least one road earthquake data in the detection work area;

(b) be provided for the initial value of the mark exponent number α of Fourier Transform of Fractional Order;

(c) use mark exponent number α, calculate the Fourier Transform of Fractional Order of one geological data in said at least one road earthquake data;

(d) calculate the analytic signal of Fourier Transform of Fractional Order, and calculate the Wigner-Ville distribution of the band cross term inhibition of analytic signal;

(e) the Radon conversion of the band window of the Wigner-Ville distribution of calculating band cross term inhibition;

(f) utilize the Radon conversion reconstruct time frequency distribution map of being with window;

(g) extract the fluid factor from time frequency distribution map.

2. the method for claim 1, wherein: mark exponent number α comes the reconstruct time frequency distribution map through turning clockwise with the territory at the Radon conversion place of window.

3. the method for claim 1 also comprises:

(h) use the fluid factor of extracting to make up geologic structure;

(i) geologic structure that makes up and the geologic structure of obtaining according to log data are compared, confirm whether geologic structure that makes up and the geologic structure of obtaining according to log data coincide in the predictive error scope;

(j) if the geologic structure that makes up is coincide in the predictive error scope with the geologic structure of obtaining according to log data, then confirm to obtain optimum mark exponent number α.

4. method as claimed in claim 3 wherein, if the geologic structure that makes up is not coincide with the geologic structure of obtaining according to log data, then changes the value of mark exponent number α in the predictive error scope, return step (c).

5. method as claimed in claim 3 also comprises: when said at least one road earthquake data during for twice geological data at least, use optimum mark exponent number α to other road earthquake data execution in step (c)-(g) in said at least one road earthquake data.

6. the step of the method for claim 1, wherein extracting the fluid factor from time frequency distribution map comprises from time frequency distribution map and extracts the frequency attribute factor.

7. method as claimed in claim 6, wherein, the frequency attribute factor comprises at least one in peak value instantaneous value frequency, root mean square frequency, the frequency attenuation gradient.

8. the method for claim 1, wherein the initial value of mark exponent number α is set according to current known seismic data.

9. method as claimed in claim 8, wherein, current known seismic data is the geologic structure data in log data or contiguous work area.

10. method as claimed in claim 3, wherein, said log data is obtained in the well logging in said work area.

11. method as claimed in claim 10 wherein, formed said well logging before or after detecting said at least one road earthquake data.

12. a geologic structure detection method is characterized in that, uses the fluid factor according to any extraction among the claim 1-11 to detect geologic structure.

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