CN105277987A - Vibroseis harmonic wave suppressing method based on predictive filtering method and pure phase shifting method - Google Patents

Abstract

The present invention provides a vibroseis harmonic wave suppressing method based on a predictive filtering method and a pure phase shifting method. The method comprises a first step of inputting cross-correlation seismic records and corresponding ground force signals after pure phase shifting treatment; a second step of applying the pure phase shifting method to suppress harmonic interferences of a local blast; a third step of applying the predictive filtering method to suppress harmonic interferences of an adjacent blast; and a fourth step of acquiring vibroseis scanning data after the whole continuous harmonic interference suppression. With adoption of the vibroseis harmonic wave suppressing method provided by the present invention, interfering noises from adjacent blasts can be well suppressed, harmonic interferences inside a blast can also be partially removed, and a harmonic wave suppressing method of vibroseis mass seismic data is realized.

Description

Based on the vibroseis harmonic suppression method of predictive filtering method and pure phase-shift method

Technical field

The present invention relates to seism processing field, particularly relate to a kind of vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method.

Background technology

Traditional harmonic suppression method is utilized to carry out harmonic wave compacting, effect is unsatisfactory, reason is that in real data process, humorous wave interference comprises two parts: one is the interference from this big gun inside self, and two is the interference from other big gun (particularly the first arrival of next big gun).Ground force signal filtering is that the big gun record of supposition input does not exist humorous wave interference in big gun, so the existence of the humorous wave interference of this big gun self certainly will have influence on the effect of method.We have invented a kind of vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method newly for this reason, solve above technical matters.

Summary of the invention

The object of this invention is to provide one and can suppress adjacent big gun interfering noise preferably, partly can eliminate again the vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method of humorous wave interference in big gun.

Object of the present invention realizes by following technical measures: based on the vibroseis harmonic suppression method of predictive filtering method and pure phase-shift method, should comprise based on the vibroseis harmonic suppression method of predictive filtering method and pure phase-shift method: step 1, inputs the cross-correlation seismologic record after pure phase-shift processing and corresponding ground force signal; Step 2, application of pure phase-shift method is suppressed the humorous wave interference of this big gun; Step 3, suppresses facing the humorous wave interference of big gun by predictive filtering method: step 4, obtain whole continuous print suppress humorous wave interference after vibroseis scan-data.

Object of the present invention also realizes by following technical measures:

In step 2, application of pure phase-shift method is separated ground force signal g (t) and obtains sweep signal s (t) and harmonic component h (t), and carry out ground force signal G (w), sweep signal S (w), the harmonic component H (w) that Fourier transform obtains frequency field, ask the conjugation of S (w) to be S ^*(w).

In step 3, for linear upsweep signal, each order harmonic signal in definition time territory is shown below:

s _k(t)＝a _k·sin[2πkf(t)t]

In formula: t is sweep time; K is a positive integer, represents harmonic order; a _kt amplitude that () is each harmonic, f (t) represents sweep frequency:

$f\left(t\right)=f_L+\frac{f_H-f_L}{2T}t$

Wherein: f _lfor initial frequency, f _hfor stopping frequency, T is the sweep length of signal;

Can draw: the frequency of harmonic signal is the integral multiple of fundamental signal frequency, harmonic distortion signal is the linear superposition of fundamental signal and each harmonic component, then harmonic distortion signal can be expressed as:

$s_D\left(t\right)=\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{s}_k\left(t\right)=\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{a}_k\left(t\right)\sin \left(2\mathrm{\πkft}\right)$

In formula: s _dt () represents harmonic distortion signal; M represents the highest order of harmonic wave;

Based on convolution model, the continuous shaking record received by JiiBao Mou road wave detector is the convolution of the common midpoint place reflection coefficient that this big gun ground force signal forms with this big gun shot point and geophone station:

x _i(t)＝g _i(t)*r _im(t)

In formula: x _i(t), g _i(t), r _imt () represents the reflection coefficient of the i-th big gun vibration record, ground force signal and common midpoint position respectively, *-expression convolution operation;

Finally shake the cross-correlation that relative recording equals vibration record and focus sweep signal:

$x_i^{\′}\left(t\right)=x_i\left(t\right)\⊗s\left(t\right)$

In formula, x _i' (t) be time domain i-th Bao Mou road seismic facies close record, x _it () is vibration record, s (t) is sweep signal; for computing cross-correlation;

The humorous wave interference formula of frequency field is:

$X_{\mathrm{ih}}\left(f\right)=\underset{j}{\mathrm{\Σ}}\underset{k=2}{\overset{M}{\mathrm{\Σ}}}{H}_{\mathrm{ik}}\left(f\right)R_{\mathrm{imj}}\left(f\right)S(-f)$

In formula: X _ihf () represents the whole humorous wave interference that frequency field i-th Bao Mou road produces, H _ikf () is the harmonic component that i-th this wave-wave of big gun K produces, R _imjf () is reflection coefficient, S (-f) is sweep signal; For referred to as:

X _ih(f)＝H(f)R(f)S(-f)

Utilize G (w), S ^*w () and H (w) design filter operator:

Reflection coefficient is generally difficult to accurately ask in real data processing procedure, by above-mentioned formula, obtains another harmonic wave interference calculation formula, thus avoids asking for reflection coefficient:

$X_{\mathrm{ih}}\left(f\right)=\frac{{X_i}^{\′}\left(f\right)H\left(f\right)S(-f)}{G\left(f\right)S(-f)}=C\left(f\right){X_i}^{\′}\left(f\right)$

In formula: X _ihf () represents the whole humorous wave interference that the i-th Bao Mou road produces, X _i' (f) for frequency field i-th Bao Mou road seismic facies close record H (f) be harmonic component, C (f) is designing filter, and G (f) is ground force signal, and S (-f) is sweep signal; By ground force signal, harmonic component, sweep signal designing filter, then act on relative recording, the humorous wave interference that this big gun produces can be obtained, finally deduct from the big gun record affected by it, namely obtain the big gun record after suppressing humorous wave interference.

Step 3 comprises:

A) Fourier transform is carried out to seismic channel data x (t) and obtain X (w), be multiplied by when forward gun seismic channel data with filter operator, obtain the humorous wave interference in last big gun sympathetic earthquakes road;

B) using the big gun record after pure phase-shift processing as input, application ground force signal filter method processes.

In step 4, the vibroseis scan-data after being suppressed by the harmonic wave obtained in step 3 carries out recording and exporting.

The present invention is based on the humorous attenuation techniques of vibroseis of predictive filtering method and pure phase-shift method, for the serious harmonic wave interfering noise existed in vibroseis magnanimity image data, invent a kind of ground force signal filtering and combined harmonic suppression method with pure phase-shift method, avoided and directly use first-harmonic and harmonic wave quantitative equation to suppress the deficiency of harmonic noise.On the basis of implementation algorithm, by model and real data treatment effect known, this method can suppress adjacent big gun interfering noise preferably, partly can eliminate humorous wave interference in big gun again, and model and real data treatment effect confirm the correctness of this method and certain adaptability.

Accompanying drawing explanation

Fig. 1 is the sweep signal of the vibroseis first-harmonic sweep signal that adopts of the present invention and distortion;

Fig. 2 is the velocity field that simulation of the present invention adopts;

Fig. 3 is female record that slip scan forward simulation that the present invention carries out obtains;

Fig. 4 be mother that slip scan forward simulation that the present invention carries out obtains record relevant after big gun record;

Fig. 5 is the process flow diagram of a specific embodiment of the vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method of the present invention;

Fig. 6 is last big gun raw readings before adopting conventional process;

Fig. 7 is last big gun raw readings after adopting conventional process;

Fig. 8 is the first bombard big gun record before harmonic wave compacting;

Fig. 9 is the first bombard big gun record after adopting conventional process;

Figure 10 is the big gun record result of the first bombard Combined Treatment that method of the present invention is carried out;

Figure 11 is the big gun record result of the second big gun Combined Treatment that method of the present invention is carried out.

Embodiment

For making above and other object of the present invention, feature and advantage can become apparent, cited below particularly go out preferred embodiment, and coordinate shown in accompanying drawing, be described in detail below.

Based on the theoretical research of the people such as seriff and Li to harmonic wave, for linear upsweep signal, definition reference signal is such as formula shown:

s _k(t)＝a _k·sin[2πkf(t)t]

In formula (1): t is sweep time; K is a positive integer, represents harmonic order; a _kt amplitude that () is each harmonic, f (t) represents sweep frequency

$f\left(t\right)=f_L+\frac{f_H-f_L}{2T}t$

Can be drawn by (1) formula: the frequency of harmonic signal is the integral multiple of fundamental signal frequency.Harmonic distortion signal is the linear superposition of fundamental signal and each harmonic component, then harmonic distortion signal can be expressed as:

$s_D\left(t\right)=\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{s}_k\left(t\right)=\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{a}_k\left(t\right)\sin \left(2\mathrm{\πkft}\right)$

In formula: s _dt () represents harmonic distortion signal; M represents the highest order of harmonic wave.Harmonic distortion signal as shown in Figure 1.

As shown in Figure 2, this layer-cake model clearly can distinguish the change after lineups before compaction to the velocity field that simulation of the present invention adopts, and is the typical model of inspection harmonic wave compacting correctness of algorithm.The present invention's reflection coefficient that deep layer design is larger is in a model to strengthen harmonic wave interference strength in big gun, thus the advantage of outstanding pure phase-shift method process.Adopt ACOUSTIC WAVE EQUATION staggering mesh finite-difference algorithm in forward simulation, boundary condition is PML.Acquisition mode is: 4 focus excite in slip scan mode, and 801 roads receive continuously, and concrete sizing grid, sampling interval, slip scan parameter etc. are as shown in table 1.

Table 1 slip scan just drills parameter

Based on convolution model, the continuous shaking record (as shown in Figure 3) received by the i-th Bao Mou road wave detector is the convolution of the common midpoint place reflection coefficient that this big gun ground force signal forms with this big gun shot point and geophone station:

x _i(t)＝g _i(t)*r _im(t)

In formula: x _i(t), g _i(t), r _imt () represents the reflection coefficient of the i-th big gun vibration record, ground force signal and common midpoint position respectively, *-expression convolution operation.

Finally shake the cross-correlation that relative recording equals vibration record and focus sweep signal:

$x_i^{\′}\left(t\right)=x_i\left(t\right)\⊗s\left(t\right)$

In formula, x _i' (t) be time domain i-th Bao Mou road seismic facies close record, x _it () is vibration record, s (t) is sweep signal; for computing cross-correlation.Fig. 4 be mother that slip scan forward simulation that the present invention carries out obtains record relevant after big gun record, can see that the relevant rear big gun record not carrying out harmonic wave compacting also exists the strong humorous wave interference of adjacent big gun, have a strong impact on the signal to noise ratio (S/N ratio) of big gun record, lineups are also unintelligible, therefore carry out effective harmonic wave disturbance suppression to big gun record very necessary.

As shown in Figure 5, Fig. 5 is the process flow diagram of the vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method of the present invention.

In step 101, input the cross-correlation seismologic record after pure phase-shift processing and corresponding ground force signal.

In step 102, with pure phase-shift method, the humorous wave interference of this big gun is suppressed.Application of pure phase-shift method is separated ground force signal g (t) and obtains sweep signal s (t) and harmonic component h (t), and carry out Fourier transform and obtain G (w), S (w), H (w), ask the conjugation of S (w) to be S ^*(w);

Pure phase-shift processing is carried out to relevant front input data (the 4th big gun) of the present invention, 4th big gun big gun raw readings before treatment as shown in Figure 6, can see that rudimental energy lost by the last big gun in left arrow place more, the harmonic wave serious interference at right side arrow place, has had a strong impact on the quality of big gun record.After pure phase-shift processing, acquired results as shown in Figure 7, can be clearly seen that from figure: the 3rd big gun residual amount of energy is eliminated substantially, the multiplied frequency harmonic component simultaneously obtained due to harmonic distortion also obtains well suppressing as shown in Fig. 7 arrow, particularly obvious to shallow-layer pressing result.

In step 103, suppress facing the humorous wave interference of big gun by predictive filtering method.

The humorous wave interference formula of frequency field is:

$X_{\mathrm{ih}}\left(f\right)=\underset{j}{\mathrm{\Σ}}\underset{k=2}{\overset{M}{\mathrm{\Σ}}}{H}_{\mathrm{ik}}\left(f\right)R_{\mathrm{imj}}\left(f\right)S(-f)$

In formula: X _ihf () represents the whole humorous wave interference that frequency field i-th Bao Mou road produces, H _ikf () is the harmonic component that i-th this wave-wave of big gun K produces, R _imjf () is reflection coefficient, S (-f) is sweep signal.For referred to as:

X _ih(f)＝H(f)R(f)S(-f)

Utilize G (w), S ^*w () and H (w) design filter operator:

By ground force signal (G (f)), harmonic component (H (f)), sweep signal (S (f)) designing filter (C (f)), then act on relative recording (X _i' (f)), the humorous wave interference that this big gun produces can be obtained, finally deduct from the big gun record affected by it, namely obtain the big gun record after suppressing humorous wave interference.

$X_{\mathrm{ih}}\left(f\right)=\frac{{X_i}^{\′}\left(f\right)H\left(f\right)S(-f)}{G\left(f\right)S(-f)}=C\left(f\right){X_i}^{\′}\left(f\right)$

Fourier transform is carried out to seismic channel data x (t) and obtains X (w), be multiplied by when forward gun seismic channel data with filter operator, obtain the humorous wave interference in last big gun sympathetic earthquakes road.

Using the 4th big gun record after pure phase-shift processing as input, application ground force signal filter method carries out processing until the 1st big gun.

In step 104, obtain whole continuous print suppress humorous wave interference after slip scan data.

Fig. 8-10 respectively show the result of the mutual record before harmonic wave compacting and two kinds of methods.Before compacting, data as shown in Figure 7.Result before and after employing improves after the process of ground force signal filter method as shown in Figures 9 and 10, through carefully contrasting and can finding: in big gun and when the interference of big gun m-Acetyl chlorophosphonazo is all quite serious, tradition ground force signal filter method can only attenuation portions harmonic noise, as shown in Fig. 9 dotted line frame, residue harmonics energy is still comparatively serious, and the weak lineups in deep are clear not; And the present invention (Figure 10) treatment effect be improved significantly: become high-visible by the weak lineups in deep that harmonic noise pollutes, lineups continuity is restored.By two kinds of method associatings, not only the pressing result of the 1st big gun improves, simultaneously the 2nd big gun, and the treatment effect of the 3rd big gun also all obtains corresponding improvement.The present invention give also the rear 2nd big gun single shot record Figure 11 of harmonic wave compacting, and the aspects such as single big gun lineups continuity, signal to noise ratio (S/N ratio) are close to conventional explosives focus, and humorous wave interference obtains better compacting.

Technique scheme is one embodiment of the present invention, for those skilled in the art, on the basis that the invention discloses application process and principle, be easy to make various types of improvement or distortion, and the method be not limited only to described by the above-mentioned embodiment of the present invention, should this previously described mode be preferred, and not there is restrictive meaning.

Claims (5)

1. based on the vibroseis harmonic suppression method of predictive filtering method and pure phase-shift method, it is characterized in that, should comprise based on vibroseis harmonic suppression method of predictive filtering method and pure phase-shift method:

Step 1, inputs the cross-correlation seismologic record after pure phase-shift processing and corresponding ground force signal;

Step 2, application of pure phase-shift method is suppressed the humorous wave interference of this big gun;

Step 3, suppress facing the humorous wave interference of big gun by predictive filtering method:

Step 4, obtain whole continuous print suppress humorous wave interference after vibroseis scan-data.

2. the vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method according to claim 1, it is characterized in that, in step 2, application of pure phase-shift method is separated ground force signal g (t) and obtains sweep signal s (t) and harmonic component h (t), and carry out ground force signal G (w), sweep signal S (w), the harmonic component H (w) that Fourier transform obtains frequency field, ask the conjugation of S (w) to be S ^*(w).

3. the vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method according to claim 2, it is characterized in that, in step 3, for linear upsweep signal, each order harmonic signal in definition time territory is shown below:

s _k(t)＝a _k·sin[2πkf(t)t]

In formula: t is sweep time; K is a positive integer, represents harmonic order; a _kt amplitude that () is each harmonic, f (t) represents sweep frequency:

$f\left(t\right)=f_L+\frac{f_H-f_L}{2T}t$

Wherein: f _lfor initial frequency, f _hfor stopping frequency, T is the sweep length of signal;

Can draw: the frequency of harmonic signal is the integral multiple of fundamental signal frequency, harmonic distortion signal is the linear superposition of fundamental signal and each harmonic component, then harmonic distortion signal can be expressed as:

$s_D\left(t\right)=\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{s}_k\left(t\right)=\underset{k=1}{\overset{M}{\mathrm{\Σ}}}{a}_k\left(t\right)\sin \left(2\mathrm{\πkft}\right)$

In formula: s _dt () represents harmonic distortion signal; M represents the highest order of harmonic wave;

Based on convolution model, the continuous shaking record received by JiiBao Mou road wave detector is the convolution of the common midpoint place reflection coefficient that this big gun ground force signal forms with this big gun shot point and geophone station:

x _i(t)＝g _i(t)*r _im(t)

In formula: x _i(t), g _i(t), r _imt () represents the reflection coefficient of the i-th big gun vibration record, ground force signal and common midpoint position respectively, *-expression convolution operation;

Finally shake the cross-correlation that relative recording equals vibration record and focus sweep signal:

$x_i^{\text{'}}\left(t\right)=x_i\left(t\right)\⊗s\left(t\right)$

In formula, x _i' (t) be time domain i-th Bao Mou road seismic facies close record, x _it () is vibration record, s (t) is sweep signal; for computing cross-correlation;

The humorous wave interference formula of frequency field is:

$X_{\mathrm{ih}}\left(f\right)=\underset{j}{\mathrm{\Σ}}\underset{k=2}{\overset{M}{\mathrm{\Σ}}}{H}_{\mathrm{ik}}\left(f\right)R_{\mathrm{imj}}\left(f\right)S(-f)$

In formula: X _ihf () represents the whole humorous wave interference that frequency field i-th Bao Mou road produces, H _ikf () is the harmonic component that i-th this wave-wave of big gun K produces, R _imjf () is reflection coefficient, S (-f) is sweep signal; For referred to as:

X _ih(f)＝H(f)R(f)S(-f)

Utilize G (w), S ^*w () and H (w) design filter operator:

Reflection coefficient is generally difficult to accurately ask in real data processing procedure, by above-mentioned formula, obtains another harmonic wave interference calculation formula, thus avoids asking for reflection coefficient:

$X_{\mathrm{ih}}\left(f\right)\frac{X_i^{\text{'}}\left(f\right)H\left(f\right)S(-f)}{G\left(f\right)S(-f)}=C\left(f\right)X_i^{\text{'}}\left(f\right)$

In formula: X _ihf () represents the whole humorous wave interference that the i-th Bao Mou road produces, X _i' (f) for frequency field i-th Bao Mou road seismic facies close record H (f) be harmonic component, C (f) is designing filter, and G (f) is ground force signal, and S (-f) is sweep signal; By ground force signal, harmonic component, sweep signal designing filter, then act on relative recording, the humorous wave interference that this big gun produces can be obtained, finally deduct from the big gun record affected by it, namely obtain the big gun record after suppressing humorous wave interference.

4. the vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method according to claim 1, it is characterized in that, step 3 comprises:

A) Fourier transform is carried out to seismic channel data x (t) and obtain X (w), be multiplied by when forward gun seismic channel data with filter operator, obtain the humorous wave interference in last big gun sympathetic earthquakes road;

B) using the big gun record after pure phase-shift processing as input, application ground force signal filter method processes.

5. the vibroseis harmonic suppression method based on predictive filtering method and pure phase-shift method according to claim 1, is characterized in that, in step 4, the vibroseis scan-data after being suppressed by the harmonic wave obtained in step 3 carries out recording and exporting.