CN102798889B - Phased source consistency determining method - Google Patents
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- CN102798889B CN102798889B CN201210125291.8A CN201210125291A CN102798889B CN 102798889 B CN102798889 B CN 102798889B CN 201210125291 A CN201210125291 A CN 201210125291A CN 102798889 B CN102798889 B CN 102798889B
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Abstract
The invention relates to a phased source consistency determining method. The determining method comprises the following steps that: the vertical positioning accuracy error of a phased source is not more than 2m; for the improvement capability of an actual signal-to-noise ratio compared with a theoretical value, the signal-to-noise ratio decreases by not more than 3 dB; each source excitation signal has high linearity; different source signals are superposed in an out-of-phase manner to cause the signal signal-to-noise ratio; the phases of two quantitative signal waveforms are consistent; and if the conditions are met, the phased sources are regarded as consistent phased sources; otherwise, the phased sources are regarded as inconsistent phased sources. Tests prove that the determining method is applicable to the consistency testing process of any phased sources, combined sources and a plurality of controlled sources, and provides necessary collection quality assurance measures for field data collection of phased source seismic prospecting methods. Testing results show that the signal-to-noise ratio of the collected data is improved to a great extent. The phased source consistency determining method provides a basis for phased source performance evaluation, phased source system maintenance and effective collection of phased source seismic data, and simultaneously also can provide effective technical means for phased source maintenance and qualification testing.
Description
Technical field:
The present invention relates to a kind of method of seismic prospecting, the conforming decision method of especially phased focus.
Background technology:
Seismic Exploration with Vibrator method, due to destructive to the nothing of environment, is subject to paying close attention to all the more widely in seismic prospecting.The subject matter that Seismic Exploration with Vibrator exists is that seismic source energy is weak, and ground unrest is strong, receives data SNR lower.For improving Seismic Source System power output, improving vibroseis earthquake data quality, phased Seismic Source System can be adopted.Phased focus is a kind of array focus technology, requires higher consistance, and there is no phased focus method for evaluating consistency at present to each focus of the work of participation.If do not carry out consistency checking, phased epicenter excitation directionally seismic wave cannot be ensured, in seismic exploration data, there will be false reflection ripple, cause the explanation of error to underground structure, cause phased focus unavailable.Namely phased focus consistency checking method mentions necessary condition before ensureing the application of phased focus method of seismic prospecting.
Summary of the invention:
Object of the present invention is just for above-mentioned the deficiencies in the prior art, provides a kind of phased focus consistency checking method.
For the requirement of vibroseis high precision seismic exploration, propose phased focus consistency checking criterion.According to this criterion, propose a kind of based on correlation analysis in time domain, adopt Fourier transform (FFT) spectrum analysis to be auxiliary phased focus consistance quantitative judgement method.By the method, can ensure the phased Seismic Source System meeting consistency criterion, vertical positioning precision error is no more than 2m; Actual signal noise ratio improve ability is compared with theoretical value, and signal to noise ratio (S/N ratio) declines and is no more than 3dB; For the Seismic Source System not meeting coherence request, except Time Domain Analysis, in frequency field, give the aided quantification analytical approach of inconsistency, for focus adjustment, safeguard foundation is provided.
The main advantage of the inventive method is following two aspects: one is give quantitative analysis method to phased focus consistance, and consistency checking and accuracy of seismic exploration is linked together; Two is the inventive method is that field phased focus high-quality earthquake data acquisition provides necessary guarantee.
Object of the present invention realizes in the following manner:
Phased focus consistency checking method, comprises following order and step:
Step one, for high precision seismic exploration demand, first determine conformance criteria, namely meet the following system required and be considered to consistent: phased focus geological data is after coherent detection, and vertical positioning precision error is no more than 2m; Actual signal noise ratio improve ability is compared with theoretical value, and signal to noise ratio (S/N ratio) declines and is no more than 3dB; Each epicenter excitation signal has higher line degree;
Step 2, first, according to above-mentioned conformance criteria, provide phased focus correlation analysis in time domain evaluation method, the phased focus of specific requirement consistance should meet following three conditions simultaneously:
(1) first analyze the non-in-phase stacking of different source signal and cause Signal-to-Noise decline situation.If s
1(t), s
2t () represents two different source signals.By phased focus principle of work, be positioned at the wave detector in far field, the phased source signal of objective body reflection can be expressed as
S
2(t)＝s
1(t)+s
2(t)(1)
Work as s
1(t)=s
2t (), namely two source signals are completely the same, then obtain desirable phased source signal
S
1(t)＝s
1(t)+s
1(t)(2)
If
for related operation symbol, order
Calculate R
2t () be R comparatively
1t the signal to noise ratio (S/N ratio) decline degree of (), if be no more than 3dB, then meets first condition of consistency checking;
(2) consider that the vertical positioning error of phased Seismic Source System is not more than the requirement of 2m.Because the seismic event of non-in-phase stacking there will be main lobe time shift after coherent detection, this time shift will cause the vertical positioning error on stratum.According to Kinematic Tomography of Seismic Waves, if underground medium average velocity is V, formation at target locations degree of depth D, for the double whilst on tour T of seismic event, exists
2D＝V*T (4)
Visible, if vertical positioning precision error is Δ D, then double whilst on tour error
ΔT＝2ΔD/V (5)
In p wave interval velocity for 1400 ~ 3500m/s, for Δ D≤2m, Δ T is no more than 1.14 ~ 2.86ms.I.e. R
2(t) maximum of points and ideal signal R
1t time error corresponding to () maximum of points should be no more than 1.14 ~ 2.86ms, this is second condition of consistency checking;
(3) employing method has relative analysis method method, and quantize the phase equalization of two signal waveforms, specific requirement two source signal cross-correlation coefficients are not less than 0.95, and this is the 3rd condition of consistency checking;
(4) if phased focus meets above-mentioned 3 conditions, be considered as the phased source of consistance, judge to terminate; Otherwise, be considered as the phased focus of nonuniformity, perform step 3, analyze further;
Step 3, not meeting the phased focus of coherence request for time-domain analysis, in order to grasp inconsistent specific features, phased focus consistance assistant analysis link in frequency field can be increased; Method is as follows: adopt FFT method, ask its amplitude-frequency and phase frequency feature, thus obtain the response characteristic difference of each focus at different frequency range, instruct adjustment and the maintenance of focus;
Beneficial effect: through test, phased focus consistency checking method disclosed by the invention, be suitable for the consistency detection process of any phased focus, combination focus and multiple stage vibroseis, for the field data collection of phased focus method of seismic prospecting, provide necessary acquisition quality safeguard measure, testing result shows, image data signal to noise ratio (S/N ratio) is improved largely.For phased focus performance evaluation, the maintenance of phased Seismic Source System, phased focus geological data effectively gather and provide foundation.Meanwhile, the present invention also can be used as phased focus safeguard and qualified detection provide effect technique means.
Accompanying drawing illustrates:
Fig. 1 is phased focus consistency checking method 2 source signal time domain waveform comparison diagrams;
Fig. 2 is phased focus consistency checking method 2 source signal related test results comparison diagrams;
Fig. 3 is another group source signal amplitude spectrum and phase spectrum comparison diagram of phased focus consistency checking method;
(a) amplitude spectrogram, (b) phase place spectrogram.
Embodiment
Phased focus consistency checking method, for the requirement of vibroseis high precision seismic exploration, propose a kind of based on correlation analysis in time domain, FFT spectrum analysis is auxiliary comprehensive quantitative evaluation method.By this decision method, can ensure the phased Seismic Source System meeting consistency criterion, vertical positioning precision error is no more than 2m; Actual signal noise ratio improve ability is compared with theoretical value, and signal to noise ratio (S/N ratio) declines and is no more than 3dB; For the Seismic Source System not meeting coherence request, except time-domain analysis result, in frequency field, give inconsistent aided quantification judge, for focus adjustment, safeguard foundation be provided.The inventive method is ensure that phased focus earthquake data acquisition quality provides necessary instrument quality decision method.
For the phased focus of Unit 2 in the present embodiment, describe consistency checking concrete grammar.
Method enforcement order and step as follows:
1, phased focus consistency checking method, comprises following order and step:
Step one, for high precision seismic exploration demand, first determine conformance criteria, namely meet the following system required and be considered to consistent: phased focus geological data is after coherent detection, and vertical positioning precision error is no more than 2m; Actual signal noise ratio improve ability is compared with theoretical value, and signal to noise ratio (S/N ratio) declines and is no more than 3dB; Each epicenter excitation signal has higher line degree;
Step 2, first, according to above-mentioned conformance criteria, provide phased focus correlation analysis in time domain decision method, the phased focus of specific requirement consistance should meet following three conditions simultaneously:
(1) first analyze the non-in-phase stacking of different source signal and cause Signal-to-Noise decline situation.If s
1(t), s
2t () represents two different source signals.By phased focus principle of work, be positioned at the wave detector in far field, the phased source signal of objective body reflection can be expressed as
S
2(t)＝s
1(t)+s
2(t)(1)
Work as s
1(t)=s
2t (), namely two source signals are completely the same, then obtain desirable phased source signal
S
1(t)＝s
1(t)+s
1(t)(2)
If
for related operation symbol, order
Calculate R
2t () be R comparatively
1t the signal to noise ratio (S/N ratio) decline degree of (), if be no more than 3dB, then meets first condition of consistency checking;
(2) consider that the vertical positioning error of phased Seismic Source System is not more than the requirement of 2m.Because the seismic event of non-in-phase stacking there will be main lobe time shift after coherent detection, this time shift will cause the vertical positioning error on stratum.According to Kinematic Tomography of Seismic Waves, if underground medium average velocity is V, formation at target locations degree of depth D, for the double whilst on tour T of seismic event, exists
2D＝V*T (4)
Visible, if vertical positioning precision error is Δ D, then double whilst on tour error
ΔT＝2ΔD/V (5)
Take p wave interval velocity as 1400-3500m/s, for Δ D≤2m, Δ T is no more than 1.14-2.86ms.I.e. R
2(t) maximum of points and ideal signal R
1t time error corresponding to () maximum of points should be no more than 1.14-2.86ms, this is second condition of consistency checking;
(3) employing method has correlation analysis method, and quantize the phase equalization of two signal waveforms, specific requirement two source signal cross-correlation coefficients are not less than 0.95, and this is the 3rd condition of consistency checking;
(4) if phased focus meets above-mentioned 3 conditions, be considered as the phased source of consistance, judge to terminate; Otherwise, be considered as the phased focus of nonuniformity, step 3 can be performed and analyze further;
For one group of phased focus of embodiment, the time domain waveform sig.1 of two source signals and sig.2 as shown in Figure 1, can find out that the waveform variation tendency of sig.1 and sig.2 is consistent; Use time domain method for evaluating consistency to analyze sample data sig.1 and sig.2, the reality obtained and the phased focus seismic wavelet of ideal are as shown in Fig. 2 (a), and the waveform that Fig. 2 (b) is Fig. 2 (a) amplifies.As shown in Figure 2, the seismic event of the epicenter excitation in phased Seismic Source System then deviation is 0, and signal to noise ratio (S/N ratio) drops to 0.4242dB, is less than 3dB, and related coefficient is 0.9850, meets coherence request.Actual phased focus output signal signal to noise ratio (S/N ratio) decline 0.4242dB compared with theoretical output signals, meets and is less than 3dB condition;
Step 3, not meeting the phased focus of coherence request for time-domain analysis, in order to grasp inconsistent specific features, phased focus consistance assistant analysis link in frequency field can be increased; Method is as follows: adopt FFT method, ask its amplitude-frequency and phase frequency feature, thus obtain the response characteristic difference of each focus at different frequency range, instruct adjustment and the maintenance of focus.
From Fig. 2 and Fig. 3, the time domain waveform sig.3 of two source signals and sig.4 is in 130Hz to 150Hz frequency range, and larger deviation has appearred in amplitude, and the changes in amplitude trend of two groups of data is basically identical in the change of other frequency ranges, but amplitude has relatively big difference.Concrete, in 120 ~ 140Hz frequency range, the amplitude of sig.3 is greater than sig.4, and in 140 ~ 200Hz frequency range, is then the amplitude that sig.4 is greater than sig.3; Sig.3 with sig.4 phase spectrum variation tendency is substantially identical, but the phase place of sig.3 is more advanced than the phase place of sig.4 generally, and deviation appears in the global consistency that result in system.
Claims (1)
1. a phased focus consistency checking method, is characterized in that, comprise the following steps:
Step one, for high precision seismic exploration requirement, first determine conformance criteria, namely meet the following system required and be considered to consistent: the vertical positioning precision error of phased focus geological data is no more than 2m; Actual signal noise ratio improve ability is compared with theoretical value, and signal to noise ratio (S/N ratio) declines and is no more than 3dB; Each epicenter excitation signal has higher line degree;
Step 2, according to above-mentioned conformance criteria, provide phased focus correlation analysis in time domain decision method, the phased focus of specific requirement consistance should meet following three conditions simultaneously:
(1) first analyze the non-in-phase stacking of different source signal and cause Signal-to-Noise decline situation, if
, represent two different source signals, be positioned at the wave detector in far field, the phased source signal of objective body reflection can be expressed as
（1）
When
, namely two source signals are completely the same, then obtain desirable phased source signal
（2）
If
for related operation symbol, order
（3）
Calculate
comparatively
signal to noise ratio (S/N ratio) decline degree, if be no more than 3dB, then meet first condition of consistency checking;
(2) consider that the vertical positioning precision error of phased focus geological data is not more than the requirement of 2m, because the seismic event of non-in-phase stacking there will be main lobe time shift after coherent detection, this time shift will cause the vertical positioning precision error on stratum, according to Kinematic Tomography of Seismic Waves, if underground medium average velocity is
v, the formation at target locations degree of depth
d, for the double whilst on tour of seismic event
t, exist
（4）
Visible, if vertical positioning precision error is
, then double whilst on tour error
（5）
In p wave interval velocity for 1400-3500m/s, for
,
be no more than 1.14-2.86ms, namely
maximum of points and ideal signal
time error corresponding to maximum of points should be no more than 1.14-2.86ms, and this is second condition of consistency checking;
(3) adopt correlation analysis method, quantize the phase equalization of two signal waveforms, specific requirement is that two source signal cross-correlation coefficients are not less than 0.95, and this is the 3rd condition of consistency checking;
(4) if phased focus meets above-mentioned 3 conditions, be considered as the phased focus of consistance, judge to terminate; Otherwise, be considered as the phased focus of nonuniformity, perform step 3, judge further;
Step 3, do not meet the phased focus of coherence request for time-domain analysis, adopt Fourier transform (FFT) method, ask its amplitude-frequency and phase frequency feature, thus obtain the response characteristic difference of each focus at different frequency range, instruct adjustment and the maintenance of focus.
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| CN104536046B (en) * | 2014-12-26 | 2017-03-29 | 吉林大学 | Epicenter excitation signal conformance evaluation methodology based on earthquake record |
| CN104536034B (en) * | 2015-01-08 | 2017-02-22 | 吉林大学 | Multi-seismic-resource parallel motivation collecting and hybrid seismic record separating method |
| CN112180469B (en) * | 2019-07-03 | 2023-10-27 | 中国石油天然气集团有限公司 | Method for testing wired consistency of seismic source |
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| Title |
|---|
| 基于采用相关检测法的漏水检测系统设计;刘利等;《煤炭技术》;20110131;第30卷(第1期);199-201 * |
| 相控震源定向地震波信号分析;姜弢等;《地球物理学报》;20080930;第51卷(第5期);1551-1556 * |
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