CN104950326B - The method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum - Google Patents

Abstract

The present invention provides the method for designing of a kind of controlled source nonlinear scanning signal based on target zone frequency spectrum, and the method includes: the preferably single big gun of survey area section, well logging or typical case carries out target zone spectrum analysis, and simulates spectrum curve A (f)；According to exploratory area frequency and energy requirement, design initial frequency, sweep length and start-stop slope length；Obtain time function t (f) corresponding to each sample frequency；Time function t (f) is carried out inverse transformation and asks for time-frequency function f (t)；By time-frequency function f (t) is integrated asking for instantaneous phase, and then ask for sinusoidal controlled source scanning signal.The controlled source scanning signal that the present invention produces mainly with improve survey area target zone energy and signal to noise ratio as main purpose, especially complicated work area, the design of signal can be scanned, to improve the seismic data quality that controlled source excites according to work area zones of different target zone different buried depth.

Description

The method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum

Technical field

The present invention relates to Seismic Exploration with Vibrator field, oil field, particularly refer to a kind of non-linear controlled shake Source scanning Design of Signal method.

Background technology

Controlled source is dispersedly incoming for energy underground within the long time, utilizes the relevant treatment can Signal pressure longer for duration shortens into persistent period shorter correlation wavelet signal, and it is earth reflection The set of the auto-correlation function (wavelet) of the scanning signal after repairing with propagation characteristic, scans the excellent of signal The bad controlled source that just directly affects gathers data quality.

Scanning Design of Signal method is a lot, the most frequently used linear, nonlinear scanning, wherein linear signal It is most widely used, it is achieved easily, each frequency distribution Uniform Scanning energy mean allocation, cell frequency The energy occupied is identical；And nonlinear scanning signal is mainly due to the stratum attenuation by absorption to seismic wave Not being linear and put forward, main application has two kinds, and exponential function scanning and logarithmic function scan, Can be used to supplement low frequency or radio-frequency component.

In order to improve seismic data quality, people have studied simulated frequency conversion scanning, array sweeping or puppet with The scan methods such as machine scanning, but the most extensively apply.East physical prospecting (Zhang Hongle, Cao Wuxiang etc.) proposes A kind of scanning signal improving correlation wavelet characteristic, is referred to as: " rotatable phase, logarithm segmentation " scans Signal, is characterized in scanning signal spectrum consistent with Ri cker wavelet spectrum, it is possible near prominent dominant frequency Energy.East physical prospecting (Cao Wuxiang) proposes the quantitative analysis of the nonlinear scanning factor, utilizes main mesh The spectrum signature of interval, obtain the attenuation curve that seismic wave energy changes with frequency, and then obtain the earth The compensating curve of filtering, is then scanned the design of signal, thus reaches to compensate high-frequency signal Purpose, it is to be optimized index or log scan signal in fact, adds attenuation compensation, signal Design process still have employed logarithm or exponential sweep formula is designed.Tongji University (Wang Huazhong, recklessly Jiang Tao) propose in the international geophysical meeting of SPG/SEG Shenzhen 2011: specify towards reflectance target layer The amplitude spectrum characteristic of required reflection wavelet, carry out the most in the same time, different spatial, different frequency bands, The controlled source of different scanning mode excites simultaneously so that it is laggard that the ripple simultaneously excited arrives target reflection face Row in-phase stacking can obtain seismic reflection signals high s/n ratio, wide range.It uses different focus Firing time, scan mode form a kind of natural coding function and encode the data being simultaneously received, but This scan mode also needs to the practice of further theory analysis and earthquake data acquisition and checks.

To this end, have developed the design of a kind of controlled source signal considering survey area target zone spectrum requirement Method, the method is easily understood, it is achieved simple, good for target zone exploration effects.

Summary of the invention

The present invention is by analyzing survey area target zone spectrum signature, it is proposed that a kind of nonlinear scanning signal Method for designing, establish controlled source based on target zone frequency spectrum scanning signal design cycle, mainly To improve energy and the signal to noise ratio of survey area target zone, especially complicated work area, can according to work area not The design of signal it is scanned, to improve controlled source seismic data product with region target zone different buried depth Matter.

The purpose of the present invention can be achieved by the following technical measures: controlled source based on target zone frequency spectrum The method for designing of nonlinear scanning signal, should controlled source nonlinear scanning signal based on target zone frequency spectrum Method for designing include: step 1, preferably survey area section, well logging or the single big gun of typical case carry out purpose Layer spectrum analysis, and simulate spectrum curve A (f)；Step 2, according to exploratory area frequency and energy requirement, Design initial frequency, sweep length and start-stop slope length；Step 3, obtains each sample frequency institute right Time function t (f) answered；Step 4, carries out inverse transformation by time function t (f) and asks for time-frequency function f (t)； Step 5, by time-frequency function f (t) is integrated asking for instantaneous phase, and then asks for sinusoidal controlled shake Source scanning signal.

The purpose of the present invention realizes also by following technical measures:

In step 1, be considered as when matching target zone spectrum curve A (f) exploratory area shallow, in, deep layer Frequency spectrum, and can suitably adjust or compensation spectrum as requested.

In step 3, according to the amplitude that should require with this frequency content the sweep time of each frequency in just Ratio, asks for each frequency content time of occurrence in scanning signal, relation during to determine the frequency of signal.

In step 3, according to spectrum curve A (f) in step 1 and the sweep parameter in step 2, to respectively The sweep time of individual frequency is allocated according to its relation proportional with the amplitude that this frequency content requires:

Dt (f)=kA (f) df (1)

Seek each frequency content time of occurrence in scanning signal, obtain time function t (f):

$T={k\∫}_{f1}^{f2}A\left(f\right)\mathrm{df}---\left(2\right)$

$t\left(f\right)=\frac{T{\∫}_{f1}^{f}A\left(f\right)\mathrm{df}}{{\∫}_{f1}^{f2}A\left(f\right)\mathrm{dt}}---\left(3\right)$

In formula:

T----controlled source scanning signal length；

K----calculates and uses proportionality constant；

The initial frequency of f1----controlled source scanning signal；

F2----controlled source scanning signal plays termination frequency；

A (f)----wavelet spectrum；

F----controlled source scanning signal transient frequency；

Df----controlled source scanning signal transient frequency differential.

In step 4, curve t (f) during frequency is asked for the time-frequency curve of constant duration through inverse transformation f(t)。

In steps of 5, ask for scanning the phase place of signal according to time-frequency function f (t), export sinusoidal controlled shake Source scanning signal:

$S\left(t\right)=B\left(t\right)\·\sin \left[2\mathrm{\π}{\∫}_0^{t}f\left(t\right)\mathrm{dt}\right]---\left(4\right)$

In formula:

$B\left(t\right)=\left\{\begin{array}{cc}w\left(k\right),k=\frac{t}{\mathrm{\&Delta;t}},& 0\&le;t\&le;T1\\ 1& T1<t<T2\\ w\left(k\right),k=\frac{T-t}{\mathrm{\&Delta;t}}& T2\&le;t\&le;T\end{array}\right.---\left(5\right)$

$w\left(k\right)\text{=0.42-0.5cos}\left(2\mathrm{\&pi;}\frac{k-1}{N-1}\right)\text{+0.08cos}\left(4\mathrm{\&pi;}\frac{k-1}{N-1}\right)---\left(6\right)$

K=1,2 ..., N_i

$N_i=\frac{\mathrm{Ti}}{\mathrm{\&Delta;t}}+1,i=\mathrm{1,2}---\left(7\right)$

In formula:

S (t)----controlled source scanning signal；

B (t)----Blacknam slope (Blackman) ramp function；

T1----controlled source scanning signal the initial segment slope length；

T2----controlled source scanning signal terminating section slope length；

Δ t----controlled source scanning signal sampling rate.

Along with developing and the development of controlled source Exploration Domain, survey area to more complicated earth's surface, Lower condition extends, in particular for the exploration of target zone, it is desirable to more and more higher, the most controlled The design of focus scanning signal is particularly important, directly affects high-quality and completes geological tasks.The present invention's The method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum, with the response frequency of target zone Spectrum signature, can be single according to pickup area section, well logging or typical case as the foundation of scanning Design of Signal The frequency spectrum of big gun carries out controlled source scanning Design of Signal, and the scanning signal designed has in dominant frequency band Stronger energy.With conventional linear compared with nonlinear scanning signal, the present invention scans signal at advantage frequency The band interscan time is longer, has the feature of stronger energy in dominant frequency band, and in earth-layer propagation process Lose less, and the design of signal can be scanned according to work area zones of different target zone different buried depth, Thus improve controlled source seismic data quality.The kind of the present invention uses target zone frequency spectrum to carry out non-linear letter Number design method, from the point of view of the successful Application in In A Certain Place of Xinjiang district, controlled shake based on target zone frequency spectrum The method for designing of source nonlinear scanning signal has the good suitability and application prospect.

Accompanying drawing explanation

Fig. 1 is the method for designing of the controlled source nonlinear scanning signal based on target zone frequency spectrum of the present invention The flow chart of a specific embodiment；

Fig. 2 is a specific embodiment of controlled source based on the target zone frequency spectrum scanning signal of the present invention Signal；

Fig. 3 is a specific embodiment of controlled source based on the target zone frequency spectrum scanning signal of the present invention Time-frequency tracing analysis；

Fig. 4 is a specific embodiment of controlled source based on the target zone frequency spectrum scanning signal of the present invention Spectrum analysis；

Fig. 5 is a specific embodiment of controlled source based on the target zone frequency spectrum scanning signal of the present invention Autocorrelation wavelet is analyzed；

Fig. 6 is that the scanning signal list big gun solution of In A Certain Place of Xinjiang district linear signal compiles record；

Fig. 7 is that the scanning signal list big gun solution of In A Certain Place of Xinjiang district the inventive method compiles record；

Fig. 8 is the scanning signal list big gun list big gun target zone frequency of In A Certain Place of Xinjiang district linear signal, the inventive method Rate is analyzed.

Detailed description of the invention

For making the above and other objects, features and advantages of the present invention to become apparent, cited below particularly go out Preferred embodiment, and coordinate institute's accompanying drawings, it is described in detail below.

Scanning signal principle according to controlled source, the design essence of scanning signal is exactly time-frequency curve Design, calculates further according to nonlinear scanning signal formula and is available for the sinusoidal signal that controlled source uses.

As it is shown in figure 1, the controlled source nonlinear scanning signal based on target zone frequency spectrum that Fig. 1 is the present invention The flow chart of method for designing.

In step 101, preferably survey area section, well logging or typical case's list big gun carries out target zone frequency spectrum and divides Analysis, and simulate spectrum curve A (f).Flow process enters into step 102.

In step 102, according to exploratory area frequency and energy requirement, design initial frequency f1 and f2, scanning length Spend T and start-stop slope length T1 and T2.Flow process enters into step 103.

In step 103, by spectrum curve A (f) in step 101, press according to the sweep time of each frequency The relation proportional with the amplitude that this frequency content requires according to it is allocated:

Dt (f)=kA (f) df (1)

Seek each frequency content time of occurrence in scanning signal, obtain time function t (f):

$T={k\&Integral;}_{f1}^{f2}A\left(f\right)\mathrm{df}---\left(2\right)$

$t\left(f\right)=\frac{T{\&Integral;}_{f1}^{f}A\left(f\right)\mathrm{df}}{{\&Integral;}_{f1}^{f2}A\left(f\right)\mathrm{dt}}---\left(3\right)$

In formula:

T----controlled source scanning signal length；

K----calculates and uses proportionality constant；

The initial frequency of f1----controlled source scanning signal；

F2----controlled source scanning signal plays termination frequency；

A (f)----wavelet spectrum；

F----controlled source scanning signal transient frequency；

Df----controlled source scanning signal transient frequency differential；

In one embodiment, according to the amplitude that should require with this frequency content the sweep time of each frequency in Direct ratio, asks for each frequency content time of occurrence in scanning signal, relation during to determine the frequency of signal. Flow process enters into step 104.

In step 104, seeking the instantaneous frequency in scanning signal, it is exactly inverse function f (t) of t (f), real Solved the expression formula of f (t) exactly by above formula on border；In one embodiment, relation during frequency is asked through conversion Take the time-frequency curve data of constant duration.Flow process enters into step 105.

In step 105, ask for scanning the phase place of signal according to time-frequency function f (t), export sinusoidal controlled shake Source scanning signal:

$S\left(t\right)=B\left(t\right)\&CenterDot;\sin \left[2\mathrm{\&pi;}{\&Integral;}_0^{t}f\left(t\right)\mathrm{dt}\right]---\left(4\right)$

In formula:

$B\left(t\right)=\left\{\begin{array}{cc}w\left(k\right),k=\frac{t}{\mathrm{\&Delta;t}},& 0\&le;t\&le;T1\\ 1& T1<t<T2\\ w\left(k\right),k=\frac{T-t}{\mathrm{\&Delta;t}}& T2\&le;t\&le;T\end{array}\right.---\left(5\right)$

$w\left(k\right)\text{=0.42-0.5cos}\left(2\mathrm{\&pi;}\frac{k-1}{N-1}\right)\text{+0.08cos}\left(4\mathrm{\&pi;}\frac{k-1}{N-1}\right)---\left(6\right)$

K=1,2 ..., N_i

$N_i=\frac{\mathrm{Ti}}{\mathrm{\&Delta;t}}+1,i=\mathrm{1,2}---\left(7\right)$

In formula:

S (t)----controlled source scanning signal；

B (t)----Blacknam slope (Blackman) ramp function；

T1----controlled source scanning signal the initial segment slope length；

T2----controlled source scanning signal terminating section slope length；

Δ t----controlled source scanning signal sampling rate；

In one embodiment, as in figure 2 it is shown, shown that In A Certain Place of Xinjiang district is entered based on VSP well-log information frequency spectrum The design of line scan signals, initial frequency 4-84Hz, sweep length is 26s and start-stop slope is respectively The controlled source scanning signal of 800ms, 500ms.

In a specific embodiment of the application present invention, according to exploration area, Xinjiang VSP well-log information, ask Go out spectrum curve A (f) of target zone, and according to frequency and the requirement of energy, have chosen start-stop frequency 2-100Hz and sweep length 26s, start-stop slope is respectively 1000ms, 500ms, uses the present invention to carry out Design of Signal, implements step such as Fig. 1, and the controlled source of generation scanning signal is as in figure 2 it is shown, and right The scanning signal that this invention generates carries out time frequency analysis, such as Fig. 3；Carry out spectrum analysis, such as Fig. 4；Carry out Autocorrelation wavelet is analyzed, such as Fig. 5；After qualified for the scanning signal testing of present invention generation, being input to can Control focus just can carry out operation, be that linear signal, the method are based on target zone frequency as shown in Figure 6 and Figure 7 Earthquake single shot record obtained by the scanning Design of Signal method of spectrum；Two the single big guns producing focus are carried out The frequency analysis of target zone, such as Fig. 8.The linear scanning signal that the present invention scans signal more conventional is compared, The scanning signal designed has stronger energy in dominant frequency band, and more conventional signal scanning data It is improved.

Claims (5)

1. the method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum, it is characterised in that the method for designing being somebody's turn to do controlled source nonlinear scanning signal based on target zone frequency spectrum includes:

Step 1, big gun single to survey area section, well logging or typical case carries out target zone spectrum analysis, and simulates spectrum curve A (f)；

Step 2, according to exploratory area frequency and energy requirement, design initial frequency, sweep length and start-stop slope length；

Step 3, obtains time function t (f) corresponding to each sample frequency；

Step 4, carries out inverse transformation by time function t (f) and asks for time-frequency function f (t)；

Step 5, by time-frequency function f (t) is integrated asking for instantaneous phase, and then asks for sinusoidal controlled source scanning signal.

The method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum the most according to claim 1, it is characterized in that, in step 3, the amplitude that sweep time according to each frequency should require with this frequency content is proportional, ask for each frequency content time of occurrence in scanning signal, relation during to determine the frequency of signal.

The method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum the most according to claim 2, it is characterized in that, in step 3, according to spectrum curve A (f) in step 1 and the sweep parameter in step 2, the sweep time of each frequency is allocated according to its relation proportional with the amplitude that this frequency content requires:

Dt (f)=kA (f) df (1)

Seek each frequency content time of occurrence in scanning signal, obtain time function t (f):

In formula:

T----controlled source scanning signal length；

K----calculates and uses proportionality constant；

The initial frequency of f1----controlled source scanning signal；

F2----controlled source scanning signal plays termination frequency；

A (f)----wavelet spectrum；

F----controlled source scanning signal transient frequency；

Df----controlled source scanning signal transient frequency differential.

The method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum the most according to claim 1, it is characterised in that in step 4, asks for time-frequency curve f (t) of constant duration by curve t (f) during frequency through inverse transformation.

The method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum the most according to claim 1, it is characterized in that, in steps of 5, ask for scanning the phase place of signal according to time-frequency function f (t), output sinusoidal controlled source scanning signal:

In formula:

K=1,2 ..., N_i

In formula:

S (t)----controlled source scanning signal；

B (t)----Blacknam slope (Blackman slope) function；

T1----controlled source scanning signal the initial segment slope length；

T2----controlled source scanning signal terminating section slope length；

Δ t----controlled source scanning signal sampling rate.