Seismic exploration node instrument GNSS TB time-break signal extraction method adopting vibroseis for construction

Abstract

The invention discloses a seismic exploration node instrument GNSS TB time-break signal extraction method adopting a vibroseis for construction. The method comprises the following steps: S101, obtaining a vibroseis encoder scanning signal and a TB signal; s102, recording a single scanning signal and a TB signal of the vibroseis encoder; s103, intercepting a complete single scanning signal as a standard scanning reference signal; and S104, during normal construction, reading original scanning signals continuously recorded by the encoder, and comparing the standard scanning reference signals with the original scanning signals to obtain TB time of each earthquake frequency, thereby obtaining a GNSS TB timestamp at the moment. According to the scheme, the TB timestamps of all seismic times excited by the seismic source during node instrument construction can be rapidly extracted, repeated blasting is effectively avoided, and even if TB signals independently recorded through an auxiliary channel are lost, the TB signals can be effectively extracted and generated.

Description

Technical Field

[0001] The present application relates to the technical field of petroleum seismic exploration, and in particular to a method for extracting GNSS TB time-interrupted signals using a controllable vibrator for construction of a seismic exploration node instrument, which belongs to the field of special technology. Background Art

[0002] Seismic exploration is based on the principles of geology and physics, using electronics and informatics to artificially cause the crust to vibrate and generate elastic waves, which propagate into the underground medium. Instruments are then used to record the vibrations at various points on the ground after the explosion, indirectly inferring the underground geological structure and then looking for possible oil and gas traps. Seismic exploration methods are widely used in the survey and exploration of oil, natural gas, and coal fields.

[0003] As seismic acquisition technology develops towards "two wides and two highs" (broadband, wide azimuth, high density, and efficient acquisition), the exploration level of each exploration area is gradually improved, and the exploration targets are becoming more complex. The description accuracy and resolution requirements for small, fragmented, and thin underground complex target geological bodies are getting higher and higher. Single-point high-density seismic acquisition technology is becoming an effective means to solve the exploration of complex geological targets. Controllable vibrator + node instrument acquisition is an effective way to achieve low-cost and high-density exploration.

[0004] GNSS TB (Time Break) signal represents a time mark. In seismic exploration, it indicates the moment of explosion of explosive source or the start time of seismic wave generated by vibrator. Both seismic excitation control system and data acquisition system need to use GNSS TB time pulse signal to maintain synchronization of excitation and acquisition. The GNSS timestamp signal should be accurately recorded in the cable instrument shift report file and stored in the corresponding position of the seismic data file header. If the GNSS TB signal of one or more earthquakes is lost when vibrator is used for excitation during full node construction or mixed construction of cable and node instruments, the node instrument data cannot be cut and synthesized if it cannot be retrieved or restored, resulting in failure to obtain valid seismic data.

[0005] Generally, when using node instrument for construction, the two channels of the node instrument auxiliary station are connected to the scanning signal and TB signal port of the source encoder respectively to record the information in real time. During construction, it is inevitable that the TB signal cannot be effectively recorded. If the TB signal cannot be read correctly and the TB timestamp cannot be restored, it will lead to repeated construction.

[0006] It can be seen that how to solve the deficiencies of the above-mentioned existing technologies will effectively ensure the safety of seismic data acquisition, improve work efficiency, and significantly reduce labor intensity, which has become the direction of efforts of technical personnel in this field. Summary of the invention

[0007] The present application relates to a method for extracting GNSS TB time-interrupted signals by using a controllable vibrator to construct a seismic exploration node instrument, and belongs to the special technical field of petroleum seismic exploration.

[0008] The purpose of this application is to overcome the problems existing in the prior art and provide a method for extracting GNSS TB time-interrupted signals using a controllable seismic source for a seismic exploration node instrument, which can effectively restore the TB timestamp of each earthquake, avoid repeated construction, and improve the integrity and security of seismic data, thereby effectively improving the project collection quality and efficiency.

[0009] To solve the above technical problems, this application is implemented through the following technical solutions:

[0010] A method for extracting GNSS TB time-interrupted signals from a seismic exploration node instrument using a controllable source. During the construction of all nodes in seismic exploration or the mixed construction of cables and node instruments, if the GNSS TB signals of a certain earthquake or multiple earthquakes are lost when a controllable source is used for excitation, the original data collected by the node instrument cannot be cut and synthesized if it cannot be retrieved or restored, resulting in failure to obtain effective seismic data. Generally, when a node instrument is used for construction, the two channels of the node instrument auxiliary station are respectively connected to the scanning signal of the source encoder and the GNSS TB signal port to record the information in real time. During construction, it is inevitable that the TB signal cannot be effectively recorded. If the TB signal cannot be read correctly and the TB timestamp cannot be restored, repeated construction will result. The method for extracting GNSS TB time-interrupted signals from a seismic exploration node instrument using a controllable source belongs to the field of special technology. In order to solve the problem of GNSS TB signal loss, the purpose of this application is achieved through the following technical solutions: by separately recording the complete scanning signal and TB time of a single scan of the earthquake source, and then comparing the single scanning signal with the full-time scanning signal recorded in the node instrument auxiliary station during the construction period, and performing mathematical correlation operations on the single scanning signal and the scanning signal recorded in the full period, the GNSS TB time of any earthquake in the full-time scanning signal is calculated, thereby obtaining the GNSS TB timestamp of that moment. In this way, the seismic data cutting of the earthquake can be successfully completed to ensure the integrity of the seismic data. If the same project uses different scanning signals selected by different earthquake sources, it is necessary to record each type of scanning signal and the corresponding TB time separately for mathematical correlation operations with the corresponding scanning signal recorded in the node auxiliary channel.

[0011] This application can provide an effective backup solution for the GNSS TB timestamp of source construction, and back up the normal TB signal, thereby effectively improving the security of the collected seismic data, improving work efficiency, ensuring that the collected data will not be missing due to GNSS TB signal problems, and will not cause problems with existing node instrument collection technology or construction methods.

[0012] Preferably, the method has a node instrument auxiliary station recording device, which has at least two channels, respectively connected to the scanning signal and TB signal of the controllable source encoder box, for completely recording the two signals. The node instrument auxiliary station recording device must normally receive and lock the GNSS signal to ensure normal operation.

[0013] Preferably, relevant scanning parameters of the controllable seismic source electric control box are set, and after the encoder shakes hands by radio communication, the encoder starts scanning, and the node instrument auxiliary station records the complete scanning signal and GNSS TB time during a single scan of the seismic source, and obtains the corresponding relationship between the complete waveform of the single scanning signal and the TB time as a reference system.

[0014] Preferably, the original data of the normal operation scanning signal of the controllable source encoder in the node instrument auxiliary station recording device is downloaded, and the TB time of each earthquake is compared with the reference system, so as to calculate the corresponding GNSS TB timestamp of each earthquake through mathematical correlation operations.

[0015] Preferably, the GNSS TB timestamps of all earthquakes can be extracted and generated at one time by programming. If different earthquake sources use different scanning signals, each type of scanning signal and the corresponding GNSS TB time need to be recorded once for comparison with the corresponding scanning signal recorded in the node auxiliary channel.

[0016] Beneficial Effects of the Invention

[0017] By collecting and recording a single scan of a single source and performing mathematical correlation operations on the signal with the collected complete scan signal, the GNSS TB time of any earthquake in the continuous scan signal recorded in the node instrument auxiliary station is calculated, thereby obtaining the TB timestamp of that moment, thereby successfully completing the seismic data cutting of that earthquake and ensuring the integrity of the seismic data. Under this condition, on-site operators can quickly complete the extraction of TB timestamps of each earthquake stimulated by the source during node instrument construction, effectively avoiding repeated blasting, and even if the TB signal recorded separately through the auxiliary channel is lost, it can be effectively extracted and generated. The invention can provide an effective backup for the TB timestamp of the source construction, and back up each other, thereby effectively improving the security of the collected seismic data, improving work efficiency, ensuring that the collected data will not cause data loss due to GNSS TB signal problems, and will not cause trouble to the existing node instrument acquisition technology or construction methods.

[0018] The application fields of this application include oil and gas field exploration technology, coal field exploration technology, fracturing and microseismic exploration, etc. As long as the node instrument + controllable source construction is used, this technology and method can be used to ensure that the node instrument can stably obtain GNSS TB time, thereby ensuring the acquisition quality. The construction of the node instrument is the trend of future seismic exploration, so this application has a very broad application prospect.

[0019] As a preferred solution of this application, a cabled instrument can be used in combination with a node instrument, or a cabled instrument can be used as a background noise monitoring tool to simultaneously control the efficient collection of each source, and other types of excitation sources can be used for mixed construction. In this case, the cabled instrument host needs to access the GNSS signal to accurately record the GNSSTB timestamps of each type of source excitation for each earthquake, which is used to cut and synthesize single-shot data of other types of excitation sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of the solution of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the embodiments of the present application are further described in detail in combination with the embodiments and drawings. Here, the illustrative embodiments of the embodiments of the present application and their descriptions are used to explain the embodiments of the present application, but are not intended to limit the embodiments of the present application.

[0022] The specific implementation of the embodiment of the present application is further described in detail below in conjunction with the accompanying drawings.

[0023] Figure 1 It is a flowchart of a method for extracting GNSS TB time-interrupted signals using a vibrator for seismic exploration node instrument in an embodiment of the present application, and the method specifically includes:

[0024] S101, two channels of the node instrument auxiliary station recording device are used to connect the controllable source encoder scanning signal and TB signal respectively.

[0025] When vibroseis is used for excitation, since the node instrument works in GNSS synchronization mode, each sample point of all node data contains a GNSS timestamp. Therefore, when cutting and synthesizing data, it is necessary to obtain the starting excitation time (GNSS TB) of each earthquake of the vibroseis. Therefore, the node instrument auxiliary station is generally used to record the scanning signal and TB signal separately. Since the TB signal generated by the vibroseis encoder is a pulse signal, when the signal starts, it will appear at a sample point of the node instrument auxiliary station, and each sample point of the auxiliary channel has a corresponding GNSS timestamp, so the corresponding relationship between the starting time of a single scanning signal and the GNSS timestamp of the TB signal can be calculated, thereby obtaining the GNSS TB timestamp of the scan.

[0026] S102, after the vibrator encoder and the decoder have completed the communication handshake, the decoder is stimulated to record the single scan signal and TB signal of the vibrator encoder respectively.

[0027] Before the controllable vibrator is excited, it is necessary to communicate and shake hands with the electronic control box of each vibrator decoder through the encoder to send the acquisition scanning parameters, vibrator output, vibrator station number, etc.

[0028] S103, reading the single scan signal and the TB signal, and intercepting the complete single scan signal according to the TB signal, the scan length, and the sampling rate as a standard scan reference signal.

[0029] Mathematical correlation technology must be used when using vibrator construction. Correlation technology is the basis for the application of vibrator in seismic exploration. When the recorded original scanning signal is mathematically correlated with the standard scanning reference signal, it can be expressed by the following formula:

[0030]

[0031] In formula (1), X(t) represents the standard scanning reference signal, Y(t) represents the original scanning signal, Represents correlation operation, which is a special term in mathematics, i.e., the similarity comparison operation of two sequences. After the two signals are correlated, it is equivalent to using the known reference scanning signal sequence and the received original seismic data signal sequence for correlation operation. The starting point of the most similar sequence is the location of the maximum diameter, thereby obtaining the TB signal. Y1(t) represents the waveform of the original scanning signal and time correspondence after the correlation operation. If the original scanning signal comes from the continuous output of the scanning signal of the encoder, the obtained correlation signal Y1(t) is equivalent to autocorrelation, and the obtained waveform is a sharp pulse, which corresponds to the TB signal of each earthquake.

[0032] Generally, a project uses one type of source and the same scanning parameters. There are also cases where different types of sources are used for construction with different scanning signals. If the TB signal is lost or the data is disordered during normal construction, each type of scan and the corresponding TB signal can be recorded separately, and the internal correspondence between the two can be compared and analyzed to generate the standard scanning reference signal set for each type of source.

[0033] S104, read the original scanning signal of the encoder continuously recorded by the node instrument auxiliary station device during normal construction, perform mathematical correlation operation on the standard scanning reference signal and the original signal, obtain the TB time of each earthquake, and thus obtain the GNSSTB timestamp of the moment, thereby realizing effective cutting and synthesis of seismic data.

[0034] Depend on Figure 1 As can be seen from the flowchart, the embodiment of the present application adopts a controllable seismic source to excite the node instrument receiving, and calculates the GNSS TB time of any earthquake in the continuous scanning signal recorded in the node instrument auxiliary station by collecting and recording a single scan of a single seismic source and performing mathematical correlation operations on the signal and the collected complete scanning signal, thereby obtaining the TB timestamp of that moment, thereby successfully completing the seismic data cutting of the earthquake, ensuring the integrity of the seismic data, and solving the problem of being unable to cut the synthetic seismic data once the TB signal is lost during normal construction.

[0035] It can be seen from the above-mentioned embodiments of the present application that the embodiments of the present application can use the recorded original continuous scanning signal to calculate and extract the GNSS TB time-interrupted signal when the node instrument adopts a controllable source for construction. This method is easy to implement in the field, and the accuracy of the GNSS TB timestamp of each earthquake obtained meets the error requirement within one sample point, effectively avoiding the problem of repeated construction due to the loss of TB signal, thereby improving construction efficiency.

[0036] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above is only a specific embodiment of the present application, and does not limit the scope of patent protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application. The technical features not described in the embodiments of this application can be achieved by or using existing technologies, which will not be repeated here.

Claims

1. A method for extracting GNSS TB time-interrupted signals using a vibrator for seismic exploration node instrument, characterized in that It includes the following steps: S101, obtaining a vibroseis encoder scanning signal and a TB signal; S102, recording a single scan signal of the vibrator encoder and a TB signal; S103, intercepting a complete single scan signal as a standard scan reference signal; S104. During normal construction, read the original scanning signal continuously recorded by the encoder, compare the standard scanning reference signal with the original scanning signal, obtain the TB time of each earthquake, and thus obtain the GNSS TB timestamp of the moment.

2. The method according to claim 1, characterized in that In S101, a node instrument auxiliary station recording device is used, and the recording device includes at least two channels, and the two channels are respectively connected to the scanning signal and the TB signal of the controllable source encoder box to obtain the scanning signal and the TB signal.

3. The method according to claim 2, characterized in that The node meter auxiliary station recording device must normally receive and lock the GNSS signal to ensure normal operation.

4. The method according to claim 1, characterized in that In S102, after the controllable source encoder and the decoder have completed a communication handshake, the decoder is stimulated to record the single scan signal and the TB signal of the controllable source encoder respectively.

5. The method according to claim 1, characterized in that In S103, a complete single scan signal is intercepted according to the TB signal, the scan length, and the sampling rate.

6. The method according to claim 1, characterized in that In S103, the relevant scanning parameters of the controllable seismic source electric control box are set. After the encoder shakes hands by radio communication, the encoder starts scanning. The node instrument auxiliary station recording device records the complete scanning signal and GNSS TB time during a single scan of the seismic source, and obtains the corresponding relationship between the complete waveform of the single scanning signal and the TB time as a standard scanning reference signal.

7. The method according to claim 1, characterized in that In S103, the scanning signal used by the same source is the same, and only the scanning signal and the corresponding GNSS TB time are recorded once as a standard scanning reference signal.

8. The method according to claim 1, characterized in that In S103, different seismic sources use different scanning signals, and each type of scanning signal and the corresponding GNSS TB time need to be recorded once respectively as a standard scanning reference signal.

9. The method according to claim 1, characterized in that In S104, the original scanning signal and TB signal of the controllable source encoder are obtained through the node instrument auxiliary station recording device.

10. The method according to claim 1, characterized in that In S104, the comparison is performed by the following formula: Where X(t) represents the standard scanning reference signal, Y(t) represents the original scanning signal, represents the correlation operation, Y1(t) represents the waveform of the corresponding relationship between the original scanning signal and time after the operation; the corresponding waveform corresponds to the TB signal of each earthquake one by one.

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