Method for acquiring the moment of vibration of a vibroseis

Abstract

The application provides a method for acquiring the starting time of vibration of a controllable source, comprising the following steps: connecting a signal recorder with a controllable source box through a cable to record the pulse signal output by the controllable source; reading the pulse signal data output by the signal recorder and intercepting the pulse signal generated by a certain shot as a reference signal delta; obtaining the correlation signal of the reference signal according to the reference signal delta and taking the maximum value as Max; in the time domain, obtaining the correlation signal S of the pulse signal according to the recorded pulse signal and the reference signal delta; comparing the correlation signal S with Max and taking the time Ti corresponding to Si >= Max*lambda as the starting time of vibration of the controllable source. The method has the characteristics of simplicity and flexibility, can acquire the starting time of vibration of the controllable source with high precision, is indispensable in the independent scanning of the controllable source and the acquisition of full-node seismic data, and provides the accurate starting time of vibration for the cutting and synthesis of full-node seismic data.

Description

Technical Field

[0001] This invention relates to the application of controlled seismic sources in engineering geophysics, coalfield and oil seismic exploration, and in particular to a method for obtaining the excitation and initiation time of a controlled seismic source. Background Technology

[0002] The controlled-source excitation start-up time is the synchronization time between controlled-source excitation and seismic instrument recording. Its main function is to control the synchronous start of controlled-source excitation and data acquisition. High accuracy is required for this timing; the actual time difference between excitation and acquisition must not exceed one sampling rate or higher. In controlled-source seismic exploration acquisition, the controlled-source excitation start-up time is mainly recorded through real-time communication between the controlled-source housing (DSD) and the seismic instrument's electrical control housing (DGP).

[0003] In recent years, efficient seismic acquisition methods with controlled sources have been continuously updated, especially when used in conjunction with nodal seismographs, which has changed the application methods of controlled sources. Nodal seismographs store and acquire seismic data themselves, eliminating the need for operation and recording of seismic data. They only need to provide the excitation and initiation time of the controlled source for the extraction of nodal seismic data. Especially in the construction of efficient single-excitation methods with controlled sources, conventional seismographs can be completely eliminated.

[0004] Chinese patent application CN201511030924.7 discloses a control method and apparatus for a pulse excitation system, comprising: setting excitation time points for each of a plurality of excitation devices; configuring a synchronous clock in each of the plurality of excitation devices according to the set excitation time points; the synchronous clock in each of the plurality of excitation devices continuously timing; and when the excitation time point of the excitation device itself is reached, the synchronous clock triggers a pulse signal to excite the excitation device containing the synchronous clock. This method and apparatus primarily constrain the excitation time, effectively preventing overlap of excitation times between different excitation devices, improving the construction efficiency of node instruments, and avoiding simultaneous excitation or aftershock interference. The method and apparatus still employ the real-time communication and active recording methods of conventional instruments.

[0005] Chinese patent application CN201810635653.5 discloses a method, electronic device, and computer storage medium for acquiring designated shot gather records, applied to wired seismic instruments. The method includes: providing microseismic data; the microseismic data; seismic data samples in the microseismic data being aligned with or having uniform intervals with the edge of satellite second-by-second pulses and recorded sequentially; acquiring excitation information; the excitation information including at least the excitation time; the excitation time being used to characterize the start time point of the designated shot gather record; determining a target time range based on the excitation time; matching the excitation time with the microseismic data to acquire seismic data within the target time range from the microseismic data, which is then used as the designated shot gather record. Through this method, the single-shot data can be separated without adding hardware.

[0006] Chinese patent application CN202010766404.7 discloses a method and apparatus for generating aliased acquisition jitter times, relating to the field of geophysical exploration technology. The method includes: acquiring a range parameter, a precision parameter, and an initial jitter time value; determining multiple candidate jitter time values ​​based on the range parameter and precision parameter; determining the selection probability of each candidate jitter time value corresponding to the excitation time of the target seismic source based on the range parameter, precision parameter, and initial jitter time value; and generating the aliased acquisition jitter time corresponding to the excitation time of the target seismic source based on the selection probability. This invention can improve the randomness of the difference between adjacent jitter times corresponding to the excitation time of the target seismic source based on probability weighting, providing support for obtaining better seismic data separation results.

[0007] The existing technologies described above differ significantly from the present invention. Therefore, there is an urgent need to develop a method for obtaining the start-up time of a controllable source excitation that is simple in method and flexible in application. To this end, we have invented a method for obtaining the start-up time of a controllable source excitation, which solves the above technical problems and can obtain a high-precision start-up time of a controllable source excitation. Summary of the Invention

[0008] The purpose of this invention is to provide a method for obtaining the start-up time of a controllable seismic source, which provides a high-precision start-up time for controllable seismic source acquisition, enabling independent scanning excitation of a controllable seismic source and acquisition of seismic data from a full-node instrument in the absence of traditional large-scale seismic instruments and other excitation systems.

[0009] The objective of this invention can be achieved through the following technical measures: a method for obtaining the initiation time of controlled vibration source excitation, the method comprising:

[0010] Step 1: Connect the signal recorder to the controllable vibration source enclosure via a cable and record the pulse signal output by the controllable vibration source.

[0011] Step 2: Read the excitation output pulse signal data of the signal recorder and extract the pulse signal generated by a certain excitation as the reference signal δ;

[0012] Step 3: Obtain the correlation signal of the reference signal based on the reference signal δ, and take the maximum value as Max;

[0013] Step 4: In the time domain, obtain the correlation signal S of the pulse signal based on the recorded pulse signal and the reference signal δ;

[0014] Step 5: Compare the relevant signal S with Max, and take S. i The time T corresponding to when ≥Max*λ i This refers to the moment when the controlled seismic source triggers the vibration.

[0015] The objective of this invention can also be achieved through the following technical measures:

[0016] In step 1, the signal recorder is connected to the controllable seismic source housing via a cable to record the pulse signal output by the controllable seismic source. The signal recorder has satellite time synchronization and can record precise time synchronously.

[0017] In step 1, the signal recorder uses a dedicated electrical signal recorder or a seismic instrument commonly used in seismic acquisition.

[0018] In step 1, the controllable source housing has excitation pulse, reference signal and force signal output ports, which can record the excitation pulse or reference signal for application.

[0019] In step 2, the excitation output pulse signal data of the signal recorder is read, and a pulse signal generated by a certain excitation is extracted as a reference signal δ. The first sample point of this signal is the excitation start time.

[0020] In step 3, the reference signal δ obtained in step 2 is subjected to autocorrelation operation to obtain the autocorrelation signal of the reference signal, and the maximum value is extracted and denoted as Max.

[0021] In step 4, in the time domain, the recorded pulse signal is subjected to sliding cross-correlation with the reference signal δ starting from the first sample point to obtain the correlation signal S of the pulse signal.

[0022] In step 5, the relevant signal S calculated in step 4 is compared with Max, and the similarity coefficient λ is set. Then, S is calculated. i The sample points corresponding to when ≥Max*λ are transformed to the corresponding time T. i , which is the moment when the vibration is triggered by the controllable seismic source;

[0023] In step 5, λ = 95%.

[0024] In step 5, the sampling rate of the signal recorder in step 1 is adjusted to improve the accuracy of obtaining the start-up time.

[0025] The present invention discloses a method for obtaining the initiation time of controlled seismic source excitation. In the absence of traditional large-scale seismic instruments and other excitation systems, it enables independent scanning excitation of controlled seismic sources and acquisition of seismic data from all nodes. It is characterized by its simplicity and flexibility of application, and can improve the production efficiency of controlled seismic source construction at all nodes.

[0026] This invention addresses the problem of not being able to obtain the start-up time of controlled seismic source excitation when traditional large-scale seismic instruments are unavailable. It proposes a better solution for obtaining the start-up time of controlled seismic source excitation, which is simple and flexible in application. It can obtain high-precision start-up time of controlled seismic source excitation, and is especially indispensable in independent scanning of controlled seismic sources and full-node seismic data acquisition, providing accurate start-up time for the segmentation and synthesis of full-node seismic data. Attached Figure Description

[0027] Figure 1 This is a flowchart of a specific embodiment of a method for obtaining the vibration initiation time of a controllable vibration source according to the present invention;

[0028] Figure 2 This is a waveform diagram of the reference signal δ extracted from the pulse signal generated by the controllable vibration source in a specific embodiment of the present invention;

[0029] Figure 3 This is a waveform diagram of the pulse signal generated by two excitations of a controllable vibration source in a specific embodiment of the present invention;

[0030] Figure 4 The image shows the cross-correlation waveform between the pulse signal generated by two excitations of the controllable vibration source and the reference signal δ in a specific embodiment of the present invention. Detailed Implementation

[0031] To make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in conjunction with the accompanying drawings to clearly and completely illustrate the technical solutions in the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0032] This invention connects a signal recorder with satellite timing to a controllable seismic source enclosure via a cable to record the pulse signal output by the controllable seismic source. It reads the pulse signal data from the signal recorder and extracts a pulse signal generated during a specific excitation as a reference signal δ. The reference signal δ is then subjected to autocorrelation to obtain its correlation signal, and its maximum value, Max, is taken. In the time domain, the recorded pulse signal and the reference signal δ are subjected to sliding cross-correlation to obtain the correlation signal S. The correlation signal S is compared with Max, and S is selected. i The time T corresponding to when ≥Max*λ i This refers to the start-up time of controlled-source excitation. This method is simple and flexible, capable of obtaining high-precision start-up times for controlled-source excitation. It is especially indispensable for independent controlled-source scanning and full-node seismic data acquisition, providing accurate start-up times for the segmentation and synthesis of full-node seismic data.

[0033] The following are several specific embodiments of the application of the present invention.

[0034] Example 1

[0035] In a specific embodiment 1 of the present invention, a method for obtaining the vibration initiation time of a controllable vibration source includes the following steps:

[0036] In step 1, a signal recorder with satellite time synchronization is connected to the controllable seismic source enclosure via a cable to record the pulse signal output by the controllable seismic source. The signal recorder can be a dedicated electrical signal recorder or a seismic instrument commonly used in seismic acquisition, but it must have satellite time synchronization to record accurate time synchronously. In addition, commonly used controllable seismic source enclosures generally have excitation pulse, reference signal and force signal output ports, which can record the excitation pulse or reference signal for application.

[0037] In step 2, the excitation output pulse signal data of the signal recorder is read, and a pulse signal generated by a certain excitation is extracted as a reference signal δ. The first sample point of this signal is the excitation start time.

[0038] In step 3, the reference signal δ obtained in step 2 is subjected to autocorrelation operation to obtain the autocorrelation signal of the reference signal, and the maximum value is extracted and denoted as Max.

[0039] In step 4, in the time domain, the recorded pulse signal is subjected to sliding cross-correlation with the reference signal δ starting from the first sample point to obtain the correlation signal S of the pulse signal.

[0040] In step 5, the relevant signal S calculated in step 4 is compared with Max, and a similarity coefficient λ is set, typically λ = 95%, and then S is calculated. iThe sample points corresponding to when ≥Max*λ are transformed to the corresponding time T. i This is the start time of vibration triggered by the controllable seismic source; and the accuracy of obtaining the start time can be improved by adjusting the sampling rate of the signal recorder in step 1.

[0041] Example 2

[0042] In a specific embodiment 2 of the present invention, such as Figure 1 The diagram shown is a flowchart of a method for obtaining the start-up time of a controllable vibration source according to the present invention.

[0043] In step 101, a signal recorder with satellite time synchronization is connected to the controllable seismic source enclosure via a cable to record the pulse signal output by the controllable seismic source. Simultaneously, step 102 is performed.

[0044] In step 102, the excitation output pulse signal data of the signal recorder is read, and a pulse signal generated by a certain excitation is extracted as a reference signal δ. The process then proceeds to step 103.

[0045] In step 103, the autocorrelation operation is performed on the reference signal δ to obtain the correlation signal of the reference signal, and the maximum value is taken as Max. The process then proceeds to step 104.

[0046] In step 104, in the time domain, the recorded pulse signal is subjected to a sliding cross-correlation operation with the reference signal δ to obtain the correlation signal S of the pulse signal. The process then proceeds to step 105.

[0047] In step 105, the relevant signal S is compared with Max, and S is taken. i The time T corresponding to when ≥Max*λ i This refers to the moment when the controlled seismic source triggers the vibration.

[0048] Example 3:

[0049] In a specific embodiment 3 of the present invention, nodal instruments commonly used in seismic exploration are employed to record the excitation pulse signal of a controllable source, and the excitation pulse signal of a particular vibration is extracted, such as... Figure 2 As shown, point A is the starting point of vibration, and point B is the ending point of vibration. The time difference between A and B is the scanning length. The waveform record from point A to point B is denoted as the reference signal δ. The reference signal δ is compared with the excitation pulse signal of the controllable source (…). Figure 3 Cross-correlation is performed to obtain the cross-correlation signal. Figure 4 ),from Figure 4 The cross-correlation signal shows that the excitation initiation point of the controllable source becomes an extreme point, which is easy to identify and determine. From Figure 4 It can accurately identify the start time of the two scans, A and C.

[0050] The method for obtaining the start-up time of controlled seismic source excitation of the present invention is simple and highly operable. It can accurately obtain the start-up time of controlled seismic source excitation with an accuracy that reaches one sampling rate set by the node instrument for acquiring pulse signals. The accuracy is high and meets the requirements of seismic exploration technology.

[0051] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0052] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

Claims

1. A method for obtaining the initiation time of vibration excitation by a controllable seismic source, characterized in that, The method for obtaining the vibration initiation time of the controllable seismic source includes: Step 1: Connect the signal recorder to the controllable source housing via a cable and record the pulse signal output by the controllable source. Step 2: Read the excitation output pulse signal data of the signal recorder and extract the pulse signal generated by a certain excitation as the reference signal δ; Step 3: Obtain the correlation signal of the reference signal based on the reference signal δ, and take the maximum value as Max. This includes: performing autocorrelation operation on the reference signal δ obtained in Step 2 to obtain the autocorrelation signal of the reference signal, and extracting the maximum value, denoted as Max. ; Step 4, in To obtain the correlation signal S of the pulse signal, the following steps are taken: In the time domain, the recorded pulse signal is subjected to a sliding cross-correlation operation with the reference signal δ starting from the first sample point to obtain the correlation signal S of the pulse signal. ; Step 5, Time T i This refers to the start-up time of controlled vibration source excitation, which includes: comparing the relevant signal S calculated in step 4 with Max, setting the similarity coefficient λ, and then calculating S. i The sample points corresponding to when ≥Max*λ are transformed to the corresponding time T. i , which is the moment when the controllable source excites and starts vibration, is taken as λ=95%.

2. The method for obtaining the vibration initiation time of a controllable seismic source according to claim 1, characterized in that, In step 1, the signal recorder is connected to the controllable seismic source housing via a cable to record the pulse signal output by the controllable seismic source. The signal recorder has satellite time synchronization and can record precise time synchronously.

3. The method for obtaining the vibration initiation time of a controllable seismic source according to claim 2, characterized in that, In step 1, the signal recorder uses a dedicated electrical signal recorder or a seismic instrument commonly used in seismic acquisition.

4. The method for obtaining the vibration initiation time of a controllable seismic source according to claim 2, characterized in that, In step 1, the controllable source housing has excitation pulse, reference signal and force signal output ports, which can record the excitation pulse or reference signal for application.

5. The method for obtaining the vibration initiation time of a controllable seismic source according to claim 1, characterized in that, In step 2, the excitation output pulse signal data of the signal recorder is read, and a pulse signal generated by a certain excitation is extracted as a reference signal δ. The first sample point of this signal is the excitation start time.

6. The method for obtaining the vibration initiation time of a controllable seismic source according to claim 1, characterized in that, In step 5, the sampling rate of the signal recorder in step 1 is adjusted to improve the accuracy of obtaining the start-up time.

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