CN114428266A - Time-frequency slope controllable nonlinear signal scanning method and system - Google Patents

Time-frequency slope controllable nonlinear signal scanning method and system Download PDF

Info

Publication number
CN114428266A
CN114428266A CN202011077869.8A CN202011077869A CN114428266A CN 114428266 A CN114428266 A CN 114428266A CN 202011077869 A CN202011077869 A CN 202011077869A CN 114428266 A CN114428266 A CN 114428266A
Authority
CN
China
Prior art keywords
frequency
time
scanning signal
nonlinear
slope
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202011077869.8A
Other languages
Chinese (zh)
Inventor
胡守旺
李洪建
杜杨杨
王鹏燕
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China Petroleum and Chemical Corp
Sinopec Geophysical Research Institute
Original Assignee
China Petroleum and Chemical Corp
Sinopec Geophysical Research Institute
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by China Petroleum and Chemical Corp, Sinopec Geophysical Research Institute filed Critical China Petroleum and Chemical Corp
Priority to CN202011077869.8A priority Critical patent/CN114428266A/en
Publication of CN114428266A publication Critical patent/CN114428266A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/003—Seismic data acquisition in general, e.g. survey design
    • G01V1/005—Seismic data acquisition in general, e.g. survey design with exploration systems emitting special signals, e.g. frequency swept signals, pulse sequences or slip sweep arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/02—Generating seismic energy
    • G01V1/143—Generating seismic energy using mechanical driving means, e.g. motor driven shaft
    • G01V1/147—Generating seismic energy using mechanical driving means, e.g. motor driven shaft using impact of dropping masses

Landscapes

  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Acoustics & Sound (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

The invention provides a time-frequency slope controllable nonlinear signal scanning method and system, and belongs to the field of geophysical exploration. The method comprises the steps of firstly obtaining a time-frequency slope-controllable nonlinear scanning signal, then generating the frequency of the scanning signal by controlling the falling frequency of a heavy hammer of the controllable seismic source vehicle under the condition that the initial frequency, the termination frequency and the scanning duration are the same, generating the amplitude of the scanning signal by controlling the energy generated by the collision of the heavy hammer of the controllable seismic source vehicle and the ground surface, and further generating the time-frequency slope-controllable nonlinear scanning signal. The invention solves the problem that the change trend of the slope of the time-frequency curve can not be freely controlled because the nonlinear scanning signal is limited by the starting and stopping frequency, the duration of the scanning signal and other factors, and can generate the scanning signals with different time-frequency slopes according to different geological conditions, thereby more flexibly highlighting the stratum dominant frequency band or compensating high-frequency information than the conventional nonlinear scanning signal and achieving the effect of optimizing the conventional nonlinear scanning signal.

Description

Time-frequency slope controllable nonlinear signal scanning method and system
Technical Field
The invention belongs to the field of geophysical exploration, and particularly relates to a time-frequency slope-controllable nonlinear scanning signal method and system, which can be applied to wavelet design of scanning signals in vibroseis seismic exploration.
Background
The controllable seismic source is a safe and environment-friendly artificial excitation seismic source, and has good controllability, and the wavelet frequency and amplitude can be artificially designed, so that the aim of improving the seismic data acquisition quality is fulfilled. With the development of acquisition technologies such as alternate scanning (Flip-Flop), sliding scanning (Slip-watch), Independent scanning (ISS), High Fidelity Video Scanning (HFVS), and the like, the acquisition efficiency of vibroseis Seismic exploration also becomes higher.
Unlike other manually-excited seismic sources such as explosives and air guns, which emit narrow pulse signals of very short duration, the signals emitted by a controllable seismic source are scanning signals of which the frequency changes continuously with time. The scanning signal has long duration, usually more than 20s, so as to ensure that the energy intensity of the deep signal can meet the exploration requirement; and then, performing cross correlation on the received initial vibration record and a scanning signal excited by a seismic source, and compressing the long initial vibration record into a short seismic record similar to the explosive seismic source, wherein the compression process is equal to convolution of a klauder wavelet produced by the autocorrelation of the scanning signal and a formation reflection coefficient, so that the resolution of the scanning signal is evaluated, and through the analysis of the autocorrelation klauder wavelet, the larger the main side lobe ratio of the autocorrelation wavelet is, the higher the resolution of the corresponding scanning signal is.
The scanning signals can be divided into linear scanning signals and nonlinear scanning signals through different time-frequency curve designs, wherein the nonlinear scanning signals can be further divided into pseudo-random scanning, inverse linear scanning, square root scanning, exponential scanning and the like (Baeten G, Ziolkowski a. The instantaneous frequency of the linear scanning signal linearly increases along with the time, the appearance time of each frequency band is the same, the design is simple, the operation difficulty is not high, and the realization is easy.
At present, in domestic vibroseis seismic exploration projects, linear scanning signals (King Honghu, Manshu, Schopper and the like, precision active seismic monitoring [ J ] geophysical prospecting equipment, 2001, 11 (1): 9-15, Liu Heng, Ruren Sheng and King Honghu are adopted, and Wigner-Hough transformation is used for detecting precision vibroseis signals [ J ] seismic, 2013 and 33 (3): 33-42). However, due to the fact that the frequency of the linear scanning signal changes singly, the energy of all frequency bands is the same, the frequency components of the linear scanning signal cannot be adapted to complex geological environments freely, and particularly the requirement for low-frequency energy in actual exploration is difficult to meet, so that the exploration depth and the resolution of the autocorrelation Kluader are affected. Therefore, a nonlinear scanning signal needs to be introduced, a certain dominant frequency band energy meeting the seismic geological condition is highlighted, and the resolution capability of the stratum is improved; for special work areas with serious high-frequency attenuation and great influence on signal-to-noise ratio, the high-frequency compensation function can be achieved by enhancing high-frequency components.
However, once the initial frequency, the end frequency, the scanning duration, and the like of the conventional non-linear scanning signal are determined, the time-frequency curve slope at different times is also determined, the energy distribution intensity of different frequency components is also determined, and no technology is available for solving the problem that the time-frequency curve slope of the non-linear scanning signal is not changed.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and provides a method and a system for a nonlinear sweep signal with a controllable time-frequency slope, which solve the problem that the slope of a time-frequency curve of the nonlinear sweep signal is not changed, can control the change of the time-frequency slope, and freely distribute the energy of different frequency bands of the sweep signal, thereby flexibly adapting to the requirements of different geological conditions on the frequency components of a seismic wave field.
The invention is realized by the following technical scheme:
the first aspect of the invention provides a method for generating a time-frequency slope-controllable nonlinear scanning signal, which comprises the steps of firstly obtaining the time-frequency slope-controllable nonlinear scanning signal, then generating the frequency of the scanning signal by controlling the falling frequency of a heavy hammer of a controllable seismic source vehicle under the condition that the initial frequency, the termination frequency and the scanning duration are the same, generating the amplitude of the scanning signal by controlling the energy generated by the collision between the heavy hammer of the controllable seismic source vehicle and the ground surface, and further generating the time-frequency slope-controllable nonlinear scanning signal.
A further development of the invention is that the method comprises:
(1) designing a square time-frequency function;
(2) adding a phase control factor and a primary term into the square time-frequency function to obtain a slope-controllable nonlinear time-frequency function;
(3) calculating an instantaneous phase;
(4) designing the ramp time length of a scanning signal and a corresponding amplitude envelope function thereof;
(5) generating a time-frequency slope controllable nonlinear vibroseis scanning signal;
(6) the frequency content of the non-linear sweep signal is adjusted by changing the value of the phase control factor.
A further improvement of the present invention is that the operation of step (1) comprises:
the squared time-frequency function is as follows:
Figure BDA0002717077520000031
wherein f ismaxIs the maximum frequency, i.e. the maximum number of weight drops per unit time, fminIs the minimum frequency, i.e. the minimum number of weight drops per unit time, tmaxThe time that the weight keeps hitting the ground surface is t, which is a time variable.
A further development of the invention is that f in step (1)minThe value range of (1) is 3-10 HZ;
fmaxthe value range of (1) is 80-120 HZ;
tmaxthe value range of (A) is 15s-30 s.
The invention has the further improvement that the slope-controllable nonlinear time-frequency function obtained in the step (2) is as follows:
Figure BDA0002717077520000032
a is a phase control factor, and the value range of a is between-1 and 1.
A further improvement of the present invention is that the operation of step (3) includes:
the instantaneous phase Φ (t) is obtained using the following equation:
Figure BDA0002717077520000041
a further improvement of the present invention is that the operation of step (4) includes:
the amplitude envelope function a (t) is obtained using:
Figure BDA0002717077520000042
wherein, tlIs the scan signal ramp duration.
A further improvement of the present invention is that the operation of step (5) comprises:
and (3) obtaining a time-frequency slope controllable nonlinear vibroseis scanning signal W (t) by utilizing the following formula:
W(t)＝A(t)*sin(φ(t))。
a further improvement of the invention is that the operation of step (6) comprises:
when a is 0, the energy of each frequency component in the obtained nonlinear scanning signal is the same;
when a is increased from-1 to 0, the energy proportion of low-frequency components in the obtained nonlinear scanning signal is gradually increased, and when a deeper exploration depth is required, the value of a is controlled to be between-1 and 0;
when a is increased from 0 to 1, the energy proportion of high-frequency components in the obtained nonlinear scanning signal is gradually increased, and when more accurate exploration resolution is required, the value of a is controlled to be between 0 and 1.
In a second aspect of the present invention, a system for time-frequency slope controllable nonlinear scanning signals is provided, the system comprising: a memory, a processor, and a computer program stored on the memory, the computer program when executed by the processor performing the steps of:
(1) designing a square time-frequency function;
(2) adding a phase control factor and a primary term into the square time-frequency function to obtain a slope-controllable nonlinear time-frequency function;
(3) calculating an instantaneous phase;
(4) designing the ramp time length of a scanning signal and a corresponding amplitude envelope function thereof;
(5) generating a time-frequency slope controllable nonlinear vibroseis scanning signal;
(6) the frequency content of the non-linear sweep signal is adjusted by changing the value of the phase control factor.
Compared with the prior art, the invention has the beneficial effects that:
the invention solves the problem that the change trend of the slope of the time-frequency curve can not be freely controlled because the nonlinear scanning signal is limited by the starting and stopping frequency, the duration of the scanning signal and other factors, and can generate the scanning signals with different time-frequency slopes according to different geological conditions, thereby more flexibly highlighting the stratum dominant frequency band or compensating high-frequency information than the conventional nonlinear scanning signal and achieving the effect of optimizing the conventional nonlinear scanning signal.
Drawings
FIG. 1-1 is a conventional linear scan signal;
FIGS. 1-2 are time-frequency functions of conventional linear scanning signals;
FIGS. 1-3 are frequency domain amplitude spectra of conventional linear scan signals;
FIGS. 1-4 are autocorrelation klauder wavelets for a conventional linear scanning signal;
FIG. 2 is a diagram of 6 non-linear time-frequency curves with different slopes generated by selecting different frequency control factors a according to the present invention;
fig. 3-1 shows a time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is 0.3;
fig. 3-2 is a time-frequency function of the time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is 0.3;
fig. 3-3 is a frequency domain amplitude spectrum of the time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is 0.33;
fig. 3-4 shows the autocorrelation klauder wavelet of the frequency slope controllable nonlinear scanning signal when the time frequency control factor a is 0.3;
fig. 4-1 shows a time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is 0.5;
fig. 4-2 is a time-frequency function of the time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is 0.5;
fig. 4-3 is a frequency domain amplitude spectrum of the frequency slope controllable nonlinear scanning signal when the time frequency control factor a is 0.5;
fig. 4-4 is an autocorrelation klauder wavelet of a frequency slope controllable nonlinear scanning signal when the time frequency control factor a is 0.5;
fig. 5-1 shows a time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is 0.8;
fig. 5-2 is a time-frequency function of the time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is 0.8;
fig. 5-3 is a frequency domain amplitude spectrum of the frequency slope controllable nonlinear scanning signal when the time frequency control factor a is 0.8;
fig. 5-4 is an autocorrelation klauder wavelet of a frequency slope controllable nonlinear scanning signal when the time frequency control factor a is 0.8;
fig. 6-1 shows a time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is-0.3;
fig. 6-2 is a time-frequency function of the time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is-0.3;
fig. 6-3 is a frequency domain amplitude spectrum of the frequency slope controllable nonlinear scanning signal when the time frequency control factor a is-0.3;
fig. 6-4 is an autocorrelation klauder wavelet of a nonlinear scanning signal with a controllable frequency slope when the time-frequency control factor a is-0.3;
fig. 7-1 shows a time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is-0.5;
fig. 7-2 is a time-frequency function of the time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is-0.5;
fig. 7-3 is a frequency domain amplitude spectrum of the frequency slope controllable nonlinear scanning signal when the time frequency control factor a is-0.5;
fig. 7-4 is the autocorrelation klauder wavelet of the nonlinear scanning signal with controllable frequency slope when the time frequency control factor a is-0.5;
fig. 8-1 shows a time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is-0.8;
fig. 8-2 is a time-frequency function of the time-frequency slope controllable nonlinear scanning signal when the time-frequency control factor a is-0.8;
fig. 8-3 is a frequency domain amplitude spectrum of the frequency slope controllable nonlinear scanning signal when the time frequency control factor a is-0.8;
fig. 8-4 is an autocorrelation klauder wavelet of a nonlinear scanning signal with a controllable frequency slope when the time-frequency control factor a is-0.8;
fig. 9 is a graph comparing amplitude spectra obtained by performing spectrum analysis on a nonlinear sweep signal with controllable time-frequency slope, which selects different frequency control factors of a-0.3, a-0.5, a-0.8, a-0.3, a-0.5, and a-0.8;
FIG. 10 is a block diagram of the steps of the method of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
by using the time-frequency slope controllable nonlinear scanning signal (i.e. the time-frequency slope controllable nonlinear vibroseis scanning signal W (t) obtained in the following step (5)), under the condition that the initial frequency, the termination frequency, the scanning time and other parameters are the same, the method comprises the steps of flexibly generating time-frequency curves of different forms (the time-frequency curves refer to the change trend of frequency at different time, the function expression before improvement is F (t) in the following step (1), obtaining an improved time-frequency curve F (t) with controllable slope by adding a phase control factor a, substituting the F (t) into phi (t) to obtain an instantaneous phase, substituting the instantaneous phase phi (t) into the formula in the following step (5) to obtain a nonlinear scanning signal W (t) with controllable time-frequency slope, and enabling the time-frequency curves to be controllable, so that the frequency components of the scanning signal are flexibly controlled.
The specific implementation method comprises the following steps: designing a maximum frequency, a minimum frequency, a scanning duration and a square time frequency function f (t); adding a slope control factor a and a primary term into a square time-frequency function F (t) to obtain a slope-controllable nonlinear time-frequency function F (t); integrating the nonlinear time-frequency function F (t) with controllable slope to obtain an instantaneous phase phi (t); designing a ramp time and a corresponding amplitude envelope function A (t); and combining the instantaneous phase function and the amplitude envelope function with a sine function to generate the time-frequency slope-controllable nonlinear vibroseis scanning signal.
As shown in fig. 10, the method of the present invention comprises:
(1) designing a square time-frequency function f (t) of the maximum frequency, the minimum frequency, the scanning duration and the instantaneous frequency increasing along with time, wherein the formula is as follows:
Figure BDA0002717077520000081
wherein f ismaxIs the maximum frequency, fminIs the minimum frequency, tmaxT is a time variable for the duration of the scan.
The method mainly generates the frequency of a scanning signal by controlling the falling frequency of a weight hammer of the vibroseis vehicle, and generates the amplitude of the scanning signal by the energy generated by the impact of the weight hammer on the ground surface, wherein the scanning signal is a wave field signal generated by the impact of the weight hammer.
In actual seismic exploration, the scanning signal is generated by continuously pounding a heavy hammer of a vibroseis vehicle to the ground surface to obtain a series of vibration wave fields; the actual vibroseis excitation is often a process that a heavy hammer continuously hits the earth surface, and the time used in the process can be tmaxIndicating that the falling speed of the heavy hammer gradually increases or decreases in the process; heavy hammerThe frequency of hitting the earth surface in unit time is the frequency f (t) of the formula, and the maximum frequency of falling of the heavy hammer in unit time is the maximum frequency fmaxThe minimum number of falling of the weight in a unit time, i.e. the minimum frequency fmin(ii) a The difference between the maximum frequency and the minimum frequency is the frequency band of a vibroseis wave field excited by the heavy hammer, theoretically, the smaller the minimum frequency is, the higher the maximum frequency is, the wider the frequency band is, and the higher the accuracy of the corresponding seismic exploration is, but the minimum frequency is usually selected from 3-10Hz, and the maximum frequency is selected from 80-120Hz in the practical exploration under the restriction of physical factors such as the heavy hammer, underground medium and the like; similarly, the longer the duration, the more the wave field energy obtained by the vibroseis excitation will be correspondingly enhanced, but the duration t is influenced by the actual seismic exploration acquisition efficiencymaxOften between 15s and 30 s.
(2) Adding a phase control factor a and a primary term into a square time frequency function F (t) to obtain a slope-controllable nonlinear time frequency function F (t), wherein the formula is as follows:
Figure BDA0002717077520000082
under the condition that the maximum frequency and the minimum frequency are not changed, the phase control factor a is a key point for controlling the slope change of the time-frequency curve and is also a key point of the method.
(3) The slope-controllable nonlinear time-frequency function F (t) is integrated to obtain an instantaneous phase phi (t), and the instantaneous phase calculation formula is as follows:
Figure BDA0002717077520000083
(4) designing the ramp duration of the scanning signal and the corresponding amplitude envelope function A (t), wherein the formula is as follows:
Figure BDA0002717077520000091
wherein, tlThe scanning signal is the ramp time length of the scanning signal, and because the suddenly appeared or suddenly finished scanning signal has catastrophe, the oscillation phenomenon can appear at two ends of the frequency spectrum of the signal, and the oscillation phenomenon is the Gibbs effect; in actual seismic exploration, the amplitude is gradually increased to the most expected amplitude at the beginning of excitation, the expected amplitude is gradually reduced to 0 at the end of excitation, the time for gradually increasing and obtaining gradual reduction is the ramp duration of a scanning signal, the catastrophe of the scanning signal at the beginning and the end is reduced, and the Gibbs effect can be further reduced. In the actual working process, the t is generally determined by integrating the actual earthquake acquisition efficiency and the attenuation effect of the Gibbs effectlAnd (4) taking the value of the parameter.
The purpose of the amplitude envelope function is to reduce the Gibbs effect caused by abrupt changes in frequency energy, and the amplitude ramp phenomenon with the same duration appears at both ends of the scanning signal through the setting of the function.
(5) Combining the instantaneous phase function and the amplitude envelope function with a sine function to generate a time-frequency slope-controllable nonlinear vibroseis scanning signal W (t), wherein the formula is as follows:
W(t)＝A(t)*sin(φ(t))
(6) the frequency content of the non-linear sweep signal is adjusted by changing the value of the phase control factor a.
After obtaining the scanning signal W (t) of the nonlinear vibroseis, generating a wave field signal required for seismic exploration by pounding of a heavy hammer of a vibroseis vehicle, so that by the method, the frequency component of the wave field signal for vibroseis exploration can be changed by changing the value of the parameter a, the initial frequency and the scanning duration of the scanning signal are not changed, and the acquisition efficiency of the vibroseis is not changed, which is specifically as follows:
a ranges from-1 to 1; when a is 0, the energy of each frequency component in the obtained wave field signal (namely, the nonlinear scanning signal) is the same; when the parameter a is increased from-1 to 0, the energy proportion of the low-frequency components in the obtained wave field signal is gradually increased, and the value of the parameter a can be controlled in the interval when deeper exploration depth is required; the proportion of the energy of the high frequency components in the acquired wavefield signal will gradually increase as the parameter a increases from 0 to 1, and the value of the parameter a can be controlled in this interval when a more accurate survey resolution is required.
FIGS. 1-1 through 1-4 are graphs of conventional linear scan signals and their associated properties, wherein FIG. 1-1 is a graph of a conventional linear scan signal; FIGS. 1-2 show the frequency as a function of time, with the frequency increasing linearly with time; FIGS. 1-3 are frequency domain amplitude spectra thereof, showing that the energy of each frequency component is the same; fig. 1-4 show the autocorrelation klauder wavelets, and the dominant-side lobe ratio of the wavelets can reflect the resolution of the original scanning signal from the time domain.
Examples of applications of the invention are as follows:
[ EXAMPLES one ]
Firstly, designing, wherein the maximum frequency is 84HZ, the minimum frequency is 5HZ, the slope time length at two ends is 1s, and the sampling interval is 1 ms; then 6 different time frequency slope control factors a are added, and the generated scanning signals are subjected to time frequency analysis and autocorrelation analysis, so that the scanning signal frequency component and the time frequency curve slope can be flexibly controlled. Fig. 2 shows a time-frequency curve comparison diagram obtained by selecting different frequency control factors a to 0.3, a to 0.5, a to 0.8, a to-0.3, a to-0.5, and a to-0.8, as can be seen from fig. 2, different slopes of the time-frequency curve will affect and cause different frequency components of corresponding scanning signals, and the following drawings will be described in detail. Fig. 2 also verifies that the nonlinear time-frequency curves with different time-frequency slopes can be obtained only by changing the time-frequency control factor a in controlling the slope of the time-frequency curve.
[ example two ]
Fig. 3-1 to fig. 3-4 are graphs of time-frequency slope controllable nonlinear scanning signals and their related properties when the time-frequency control factor a is 0.3, wherein fig. 3-1 is the time-frequency slope controllable nonlinear scanning signals; FIG. 3-2 is a graph showing the frequency function, the frequency increases non-linearly with time, the low frequency increase rate is less than the high frequency, and the curvature is smaller; 3-3 are frequency domain amplitude spectra obtained by performing spectral analysis on the generated scanning signal, showing that the energy of the low frequency components is stronger than the high frequency components; fig. 3-4 are autocorrelation klauder wavelets obtained by autocorrelation of a swept frequency signal, the dominant-sidelobe ratio of the wavelets being greater than that of the klauder wavelets of a linear signal.
[ EXAMPLE III ]
Fig. 4-1 to 4-4 are graphs of time-frequency slope controllable nonlinear scanning signals and their related properties when the time-frequency control factor a is 0.5, wherein fig. 4-1 is the time-frequency slope controllable nonlinear scanning signals; FIG. 4-2 is a graph of the frequency of the scanning signal in non-linear frequency increase with time, with the low frequency increase rate being less than the high frequency and the curvature being greater than the curvature of the scanning signal of FIG. 3-2; fig. 4-3 is a frequency domain amplitude spectrum obtained by performing spectrum analysis on the generated scanning signal, it can be seen that the energy of the low-frequency component is stronger than that of the high-frequency component, and the ratio of the low-frequency component to the full frequency band is greater than that of fig. 3-3; fig. 4-4 are autocorrelation klauder wavelets obtained by autocorrelation of a swept frequency signal, the dominant-sidelobe ratio of the wavelets being greater than the klauder wavelets of the swept frequency signal of fig. 3.
[ EXAMPLE IV ]
Fig. 5-1 to 5-4 are graphs of time-frequency slope controllable nonlinear scanning signals and their related properties when the time-frequency control factor a is 0.8, wherein fig. 5-1 is the time-frequency slope controllable nonlinear scanning signals; FIG. 5-2 is a graph showing the non-linear increase in frequency with time as a function of time, with the low frequency increasing rate being less than the high frequency and the curvature being greater than the curvature of the scanning signal of FIG. 4-2; FIG. 5-3 is a frequency domain amplitude spectrum obtained by performing a spectrum analysis on the generated scanning signal, showing that the energy of the low frequency component is stronger than that of the high frequency component, and the ratio of the low frequency to the full frequency band is greater than that of FIG. 4-3; fig. 5-4 shows an autocorrelation klauder wavelet obtained by performing autocorrelation on a sweep signal, wherein the dominant-to-sidelobe ratio of the wavelet is greater than that of the klauder wavelet of the sweep signal of fig. 4-4.
[ EXAMPLE V ]
Fig. 6-1 to 6-4 are graphs of time-frequency slope controllable nonlinear scanning signals and their related properties when the time-frequency control factor a is-0.3, wherein fig. 6-1 is the time-frequency slope controllable nonlinear scanning signals; FIG. 6-2 is a graph showing the frequency function, where the frequency increases non-linearly with time, the low frequency increase rate is stronger than the high frequency, the low frequency increase rate is greater than the high frequency, and the curvature is smaller; 6-3 are frequency domain amplitude spectra obtained by performing spectral analysis on the generated scanning signal, showing that the energy of the low frequency components is weaker than that of the high frequency components; fig. 6-4 are autocorrelation klauder wavelets obtained by autocorrelation of a swept frequency signal, the dominant-to-sidelobe ratio of the wavelets being smaller than the klauder wavelets of the linear sweep signal of fig. 1-4.
[ EXAMPLE six ]
Fig. 7-1 to 7-4 are graphs of time-frequency slope controllable nonlinear scanning signals and their related properties when the time-frequency control factor a is-0.5, wherein fig. 7-1 is the time-frequency slope controllable nonlinear scanning signals; FIG. 7-2 is a graph showing the non-linear increase of frequency with time as a function of time, with the low frequency increase rate being greater than the high frequency, and the curvature being greater than the curvature of the time-frequency curve in FIG. 6-2; 7-3 are frequency domain amplitude spectra obtained by performing spectral analysis on the generated scanning signal, showing that the low frequency component energy is weaker than the high frequency; fig. 7-4 is an autocorrelation klauder wavelet obtained by autocorrelation of a sweep signal, the dominant-to-sidelobe ratio of the wavelet being smaller than the klauder wavelet of the sweep signal of fig. 6-4.
[ EXAMPLE VII ]
Fig. 8-1 to 8-4 are graphs of time-frequency slope controllable nonlinear scanning signals and their related properties when the time-frequency control factor a is-0.8, wherein fig. 8-1 is the time-frequency slope controllable nonlinear scanning signals; FIG. 8-2 is a graph showing the non-linear increase of frequency with time as a function of time, with the low frequency increase rate being greater than the high frequency, and the curvature being greater than the curvature of the time-frequency curve in FIG. 7-2; 8-3 are frequency domain amplitude spectra obtained by performing spectral analysis on the generated scanning signal, showing that the low frequency component energy is weaker than the high frequency; fig. 8-4 is an autocorrelation klauder wavelet obtained by autocorrelation of a sweep signal, the dominant-to-sidelobe ratio of the wavelet being smaller than the klauder wavelet of the sweep signal of fig. 7-4.
The obtained amplitude spectrum is compared with a graph shown in fig. 9 by performing spectrum analysis on the nonlinear sweep signal with controllable time-frequency slope generated by selecting different frequency control factors of 0.3, 0.5, 0.8, 0.3, 0.5, and 0.8.
Fig. 9 shows the flexibility of the method of the present invention for controlling frequency components.
From the results obtained by the above examples, it can be easily seen that the method is very flexible in the aspect of time-frequency curve slope and frequency component control, under the condition that other parameters are not changed, the nonlinear scanning signals with different frequency components can be obtained only by changing the value of the slope control factor a, the degree of controlling the ratio of high and low frequency bands can be reached, the dominant frequency band is highlighted, and different requirements of complex geological structures on the frequency of the vibroseis in seismic exploration are met.
Finally, it should be noted that the above-mentioned technical solution is only one embodiment of the present invention, and it will be apparent to those skilled in the art that various modifications and variations can be easily made based on the application method and principle of the present invention disclosed, and the method is not limited to the above-mentioned specific embodiment of the present invention, so that the above-mentioned embodiment is only preferred, and not restrictive.

Claims (10)

1. A time frequency slope controllable nonlinear signal scanning method is characterized in that: the method comprises the steps of firstly obtaining a time-frequency slope-controllable nonlinear scanning signal, then generating the frequency of the scanning signal by controlling the falling frequency of a heavy hammer of the controllable seismic source vehicle under the condition that the initial frequency, the termination frequency and the scanning duration are the same, generating the amplitude of the scanning signal by controlling the energy generated by the collision of the heavy hammer of the controllable seismic source vehicle and the ground surface, and further generating the time-frequency slope-controllable nonlinear scanning signal.
2. The method for time-frequency slope controllable nonlinear scanning signal according to claim 1, characterized in that: the method comprises the following steps:
(1) designing a square time-frequency function;
(2) adding a phase control factor and a primary term into the square time-frequency function to obtain a slope-controllable nonlinear time-frequency function;
(3) calculating an instantaneous phase;
(4) designing the ramp time length of a scanning signal and a corresponding amplitude envelope function thereof;
(5) generating a time-frequency slope controllable nonlinear vibroseis scanning signal;
(6) the frequency content of the non-linear sweep signal is adjusted by changing the value of the phase control factor.
3. The method for time-frequency slope controllable nonlinear scanning signal according to claim 2, characterized in that: the operation of the step (1) comprises the following steps:
the squared time-frequency function is as follows:
Figure FDA0002717077510000011
wherein f ismaxIs the maximum frequency, i.e. the maximum number of weight drops per unit time, fminIs the minimum frequency, i.e. the minimum number of weight drops per unit time, tmaxThe time that the weight keeps hitting the ground surface is t, which is a time variable.
4. The method for time-frequency slope controllable nonlinear scanning signal according to claim 3, characterized in that: f in the step (1)minThe value range of (1) is 3-10 HZ;
fmaxthe value range of (1) is 80-120 HZ;
tmaxthe value range of (A) is 15s-30 s.
5. The method for time-frequency slope controllable nonlinear scanning signal according to claim 4, characterized in that: the slope-controllable nonlinear time-frequency function obtained in the step (2) is as follows:
Figure FDA0002717077510000021
a is a phase control factor, and the value range of a is between-1 and 1.
6. The method for time-frequency slope-controllable nonlinear scanning signal according to claim 5, characterized in that: the operation of the step (3) comprises:
the instantaneous phase Φ (t) is obtained using the following equation:
Figure FDA0002717077510000022
7. the method for time-frequency slope controlled nonlinear scanning signal in accordance with claim 6, wherein: the operation of the step (4) comprises the following steps:
the amplitude envelope function a (t) is obtained using:
Figure FDA0002717077510000023
wherein, tlIs the scan signal ramp duration.
8. The method for time-frequency slope controlled nonlinear scanning signal in accordance with claim 7, wherein: the operation of the step (5) comprises the following steps:
and (3) obtaining a time-frequency slope controllable nonlinear vibroseis scanning signal W (t) by utilizing the following formula:
W(t)＝A(t)*sin(φ(t))。
9. the method for time-frequency slope controlled nonlinear scanning signal in accordance with claim 8, wherein: the operation of the step (6) comprises the following steps:
when a is 0, the energy of each frequency component in the obtained nonlinear scanning signal is the same;
when a is increased from-1 to 0, the energy proportion of low-frequency components in the obtained nonlinear scanning signal is gradually increased, and when a deeper exploration depth is required, the value of a is controlled to be between-1 and 0;
when a is increased from 0 to 1, the energy proportion of high-frequency components in the obtained nonlinear scanning signal is gradually increased, and when more accurate exploration resolution is required, the value of a is controlled to be between 0 and 1.
10. A time frequency slope controllable nonlinear scanning signal system is characterized in that: the system comprises: a memory, a processor, and a computer program stored on the memory, the computer program when executed by the processor performing the steps of:
(1) designing a square time-frequency function;
(2) adding a phase control factor and a primary term into the square time-frequency function to obtain a slope-controllable nonlinear time-frequency function;
(3) calculating an instantaneous phase;
(4) designing the ramp time length of a scanning signal and a corresponding amplitude envelope function thereof;
(5) generating a time-frequency slope controllable nonlinear vibroseis scanning signal;
(6) the frequency content of the non-linear sweep signal is adjusted by changing the value of the phase control factor.
CN202011077869.8A 2020-10-10 2020-10-10 Time-frequency slope controllable nonlinear signal scanning method and system Pending CN114428266A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202011077869.8A CN114428266A (en) 2020-10-10 2020-10-10 Time-frequency slope controllable nonlinear signal scanning method and system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202011077869.8A CN114428266A (en) 2020-10-10 2020-10-10 Time-frequency slope controllable nonlinear signal scanning method and system

Publications (1)

Publication Number Publication Date
CN114428266A true CN114428266A (en) 2022-05-03

Family

ID=81309341

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202011077869.8A Pending CN114428266A (en) 2020-10-10 2020-10-10 Time-frequency slope controllable nonlinear signal scanning method and system

Country Status (1)

Country Link
CN (1) CN114428266A (en)

Similar Documents

Publication Publication Date Title
Bagaini Low-frequency vibroseis data with maximum displacement sweeps
US9551798B2 (en) Seismic vibrator to produce a continuous signal
CN103323876B (en) A kind of method determining the best low frequency sweep signal of vibroseis
US3895343A (en) Apparatus for producing adaptive pilot signals
CN1035693C (en) Shaped-sweep technology
CN103885085B (en) Method for suppressing controllable epicenter harmonic wave interference
CN104280777B (en) Method for suppressing interference of seismic data multiples on land
CN104950326B (en) The method for designing of controlled source nonlinear scanning signal based on target zone frequency spectrum
CN105572723B (en) The design method of controlled source scanning signal based on autocorrelation wavelet
Trantham Controlled-phase acquisition and processing
CN104483704A (en) Residual phase correction method based on AVO (amplitude versus offset) abnormal type constraints
CN100501450C (en) Method for performing waveform stretching compensation for seismic signal
CN112394414A (en) Two-step seismic diffraction wave field prestack separation process
CN114428266A (en) Time-frequency slope controllable nonlinear signal scanning method and system
CN109975874B (en) Controllable seismic source scanning signal design method based on damping rake wavelets
Zhang et al. Interval Q inversion based on zero-offset VSP data and applications
US9778385B2 (en) Instantaneous frequency modulation acquisition scheme for seismic sources
CN110082820B (en) Explosive source mixed distributed broadband excitation method
CN110568491B (en) Quality factor Q estimation method
CN111796325B (en) Frequency division iteration constrained random inversion method
US4604734A (en) Seismic exploration in areas where p waves are converted to s waves
CN114137606A (en) Stable spectrum simulation deconvolution method
CN105242302A (en) Multi-well combined exciting method for improving signal-noise ratio of seismic data in loess region
Zhang et al. Characteristic analysis and data comparative of linear and nonlinear low-frequency sweep in vibroseis
Korotkov et al. Vibroseis acquisition with fully controllable sweep signals based on borehole VSP data analysis

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination