A method for simultaneous extraction and correction of moveout in seismic data acquisition

Abstract

The application discloses a method for extracting and correcting the time difference of synchronous seismic data collection while digging, which comprises the following steps: 1, establishing a seismic data collection system while digging, reading all seismic wave data in the collection system and filtering; 2, performing velocity analysis on the filtered seismic wave to obtain the propagation velocity of the seismic direct wave while digging; 3, using the seismic wave propagation velocity original data to correct the direct wave time difference of each seismic trace, and eliminating the influence of the seismic wave propagation time difference; 4, calculating the model trace data of each collection substation through the data after the time difference correction; 5, determining the reference substation according to the model trace data of each collection substation and the data of each seismic trace in the corresponding collection substation; and 6, calculating the time difference of the corresponding collection substation according to the cross-correlation time difference between the model trace of the reference substation and the model trace of each collection substation, and correcting the original data.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geophysical exploration, and particularly relates to a method for extracting and correcting synchronous time difference of real-time drilling seismic data acquisition. BACKGROUND

[0002] The real-time drilling seismic data acquisition system transmits the collected signals to the nearest distributed acquisition substation through a seismic detector.

[0003] This system improves work efficiency, reduces instrument cost and energy consumption. The acquisition substation converts analog signals into digital signals, and then transmits the seismic data to the ground server through an optical transceiver and a switch for data display and processing.

[0004] Since the underground cannot receive GPS signals, the underground distributed acquisition stations in the prior art generally use the 1588 protocol based on optical fiber Ethernet to synchronize the time of the master station to other acquisition substations in the same network segment. SUMMARY

[0005] The present application aims to provide a method for extracting and correcting synchronous time difference of real-time drilling seismic data acquisition to solve the technical problem of data error and false alarm caused by the synchronous time difference between the acquisition substations in the underground distributed acquisition stations in the prior art.

[0006] To solve the above technical problems, the present application adopts the following technical solutions:

[0007] A method for extracting and correcting synchronous time difference of real-time drilling seismic data acquisition includes the following steps:

[0008] Step 1: Establish a real-time drilling seismic data acquisition system, read all seismic wave data in the system and filter, and obtain the original data of all seismic wave channels after filtering.

[0009] Step 2: At different velocities, calculate the corresponding direct wave arrival time difference (the time difference of arrival of the direct wave in the corresponding seismic trace) based on the original data of the seismic trace; use the direct wave arrival time difference to perform time difference correction on all seismic traces in the corresponding acquisition substation; determine the direct wave velocity and the reference station by using all seismic traces in all acquisition substations after time difference correction.

[0010] Step 3: Use the direct wave velocity to correct the original time difference data of each seismic trace to obtain the model trace of the corresponding sub-station trace set.

[0011] Step 4: Calculate the cross-correlation data between each model channel and the baseline substation model channel, and determine the maximum cross-correlation value as the synchronization time difference.

[0012] Step 5: Use the synchronization time difference to perform time difference correction on all raw seismic trace data.

[0013] The present invention also has the following features:

[0014] Furthermore, in step 1, all seismic wave data in the tunneling seismic data acquisition system are bandpass filtered, with the bandpass filtering range being 5Hz–200Hz.

[0015] Furthermore, step 2 includes the following sub-steps:

[0016] Step 21, set the minimum speed V min Maximum speed V max and velocity interval d v Let p = 1, where p is the velocity V. k Select the sequence number.

[0017] Step 22, calculate the currently selected speed V k =V min +(p-1)×d v .

[0018] Step 23, establish the velocity target analysis function:

[0019]

[0020] Among them, S ij This represents the distance between the raw seismic trace data measured by the j-th geophone at the i-th acquisition station and the raw seismic trace data of the starting seismic trace (the seismic trace closest to the tunneling machine).

[0021] Δt ij This represents the time difference of arrival of the direct wave of the seismic trace measured by the j-th detector at the i-th acquisition station.

[0022] Step 24, use the direct wave arrival time difference Δt ijTime difference correction is performed on each seismic trace within the corresponding acquisition substation. The correction formula is as follows:

[0023]

[0024] Among them, f ij (t) represents the raw seismic trace data measured by the j-th detector at the i-th acquisition station.

[0025] This represents the seismic trace measured by the j-th detector at the i-th acquisition station after time difference correction, where t represents time.

[0026] Step 25: Taking each acquisition station as a unit, calculate the zero-delay cross-correlation coefficient between all corrected seismic traces within each acquisition station according to the following formula:

[0027]

[0028] Where, ψ i It represents the zero-delay cross-correlation coefficient among all time-difference data of the seismic traces within the i-th acquisition station.

[0029] M represents the total number of seismic traces in the i-th acquisition station, "·" represents the dot product operation, and "||" represents the vector modulus.

[0030] Step 26, calculate ψ i The square modulus Φ,

[0031]

[0032] Where, ψ i Let be the zero-delay cross-correlation coefficient between the time difference data after set correction within the i-th acquisition substation.

[0033] N represents the total number of data collection stations.

[0034] Step 27, if the currently selected speed V k If the corresponding Φ value is not the current maximum Φ value, let p = p + 1 and return to step 22.

[0035] If the currently selected speed V k The corresponding Φ value is the current maximum Φ value, and the currently selected speed V is... k The direct wave velocity V; the zero-delay cross-correlation coefficient ψ corresponding to this velocity. i The corresponding data acquisition station is marked as the reference station and numbered b; then proceed to step 28.

[0036] Step 28, if V k <V max Let p = p + 1, then return to step 22; if Vk ≥V max Proceed to step 3.

[0037] Furthermore, V max The value is taken as 3000m / s, V min The value is taken as 1500 m / s, d v The value is 5 m / s.

[0038] Furthermore, step 3 specifically includes the following operations:

[0039] Using the direct wave velocity V as V k Correcting the original time difference data for each seismic trace yields the model trace for the corresponding sub-station trace set:

[0040]

[0041] in, Indicates passing through (V corresponding to V) k The seismic trace record collected by the j-th geophone in the i-th acquisition station after time difference correction.

[0042] h i (t) represents the model track data of the i-th acquisition station track set.

[0043] M represents the total number of seismic traces in the i-th acquisition station.

[0044] j is the sequence number of the seismic trace.

[0045] Furthermore, step 4 specifically includes the following operations:

[0046] Calculate the cross-correlation data between the model channel data of each acquisition station and the reference station b:

[0047]

[0048] Find g in all data collection stations respectively i The time corresponding to the maximum value of (τ) is the synchronization time difference ΛT between the acquisition station i and the reference station b. i .

[0049] Among them, g i (τ) represents the cross-correlation data between the model channel data of the i-th acquisition station and the reference station b.

[0050] This represents the model trace data of reference station b;

[0051] t represents time, T represents the total duration of the data, and τ represents the cross-correlation time shift.

[0052] Furthermore, step 5 specifically includes the following operations:

[0053] Using the following formula, based on the synchronization time difference ΛT of the reference station b i Correct the original time difference data of each geophone at each acquisition station to obtain the corrected time difference data of the corresponding seismic trace:

[0054]

[0055] This represents the corrected time difference data of the seismic trace corresponding to the j-th detector at the i-th acquisition station.

[0056] Compared with the prior art, the present invention has the following technical effects:

[0057] The present invention discloses a method for extracting and correcting synchronization time difference in seismic data acquisition during tunneling. This method involves establishing a seismic data acquisition system, reading and filtering all seismic wave data from the system to obtain the raw data of all seismic channels. At different velocities, the corresponding direct wave arrival time difference (the time difference of arrival of the direct wave at the corresponding seismic channel) is calculated based on the raw data of the seismic channels. The direct wave arrival time difference is used to correct the time difference for all seismic channels within the corresponding acquisition station. The direct wave velocity and the reference station are determined using all seismic channels within all acquisition stations after time difference correction. The raw time difference data of each seismic channel is corrected using the direct wave velocity to obtain the model channel of the corresponding channel set. The cross-correlation data between each model channel and the reference station model channel is calculated, and the maximum cross-correlation value is determined as the synchronization time difference. The synchronization time difference is then used to correct the time difference for the raw data of all seismic channels. Finally, the time difference-corrected data of all acquisition stations is obtained, eliminating the synchronization time difference between acquisition stations and preventing subsequent data errors, omissions, or false alarms. Attached Figure Description

[0058] Figure 1 This is a technical flowchart of the present invention;

[0059] Figure 2 These are the seismic records during excavation before the correction method of this invention was applied;

[0060] Figure 3 These are the seismic records during excavation that have been corrected using the correction method of this invention. Detailed Implementation

[0061] The following provides specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0062] A method for extracting and correcting synchronization time difference in seismic data acquisition during tunneling includes the following steps:

[0063] Step 1: Establish a seismic data acquisition system for tunneling, read all seismic wave data from the system and filter them to obtain the raw data of all seismic traces.

[0064] Step 2: At different velocities, calculate the corresponding direct wave arrival time difference (the time difference of arrival of the direct wave in the corresponding seismic trace) based on the original data of the seismic trace; use the direct wave arrival time difference to perform time difference correction on all seismic traces in the corresponding acquisition substation; determine the direct wave velocity and the reference station by using all seismic traces in all acquisition substations after time difference correction.

[0065] Step 3: Use the direct wave velocity to correct the original time difference data of each seismic trace to obtain the model trace of the corresponding sub-station trace set.

[0066] Step 4: Calculate the cross-correlation data between each model channel and the baseline substation model channel, and determine the maximum cross-correlation value as the synchronization time difference.

[0067] Step 5: Use the synchronization time difference to perform time difference correction on all raw seismic trace data.

[0068] When determining the direct wave velocity, velocity spectrum analysis is employed. Specifically, a time window is established along the trajectory of the direct wave's phase axis. Within this time window, a suitable range of velocities is selected for velocity scanning, and dynamic corrections are applied to the gathers at each acquisition station using different velocities. Then, the sum of zero-delay cross-correlation coefficients between the gathers at each acquisition station after dynamic correction is calculated. Finally, the sums of the cross-correlation coefficients from different acquisition stations are added together, and the velocity corresponding to the maximum value is the target velocity.

[0069] To correct the time difference between the acquisition stations, a model trace is formed based on the seismic traces within each acquisition station. This model trace needs to eliminate the time differences caused by interference waves and other non-travel time factors. Then, the time difference between the model traces of each acquisition station is obtained by correlation. The obtained time difference can reflect the synchronization error between the acquisition stations.

[0070] The obtained direct wave velocity is used to dynamically correct and superimpose the gathers in each acquisition station to obtain the model traces of each acquisition station. The cross-correlation time difference between the model traces is the synchronization error between the acquisition stations, which is used to improve the data acquisition time synchronization accuracy and enhance the effect of seismic exploration during excavation.

[0071] Specifically, in step 1, all seismic wave data in the seismic data acquisition system are bandpass filtered. The bandpass filtering range is 5Hz-200Hz, which conforms to the general seismic wave pattern and ensures the filtering effect.

[0072] Specifically, step 2 includes the following sub-steps:

[0073] Step 21, set the minimum speed Vmin Maximum speed V max and velocity interval d v Let p = 1, where p is the velocity V. k Select the sequence number.

[0074] Step 22, calculate the currently selected speed V k =V min +(p-1)×d v .

[0075] Step 23, establish the velocity target analysis function:

[0076]

[0077] Among them, S ij This represents the distance between the raw seismic trace data measured by the j-th geophone at the i-th acquisition station and the raw seismic trace data of the starting seismic trace (the seismic trace closest to the tunneling machine).

[0078] Δt ij This represents the time difference of arrival of the direct wave of the seismic trace measured by the j-th detector at the i-th acquisition station.

[0079] Step 24, use the direct wave arrival time difference Δt ij Time difference correction is performed on each seismic trace within the corresponding acquisition substation. The correction formula is as follows:

[0080]

[0081] Among them, f ij (t) represents the raw seismic trace data measured by the j-th detector at the i-th acquisition station.

[0082] This represents the seismic trace measured by the j-th detector at the i-th acquisition station after time difference correction, where t represents time.

[0083] Step 25: Taking each acquisition station as a unit, calculate the zero-delay cross-correlation coefficient between all corrected seismic traces within each acquisition station according to the following formula:

[0084]

[0085] Where, ψ i It represents the zero-delay cross-correlation coefficient among all time-difference data of the seismic traces within the i-th acquisition station.

[0086] M represents the total number of seismic traces in the i-th acquisition station, "·" represents the dot product operation, and "||" represents the vector modulus.

[0087] Step 26, calculate ψi The square modulus Φ,

[0088]

[0089] Where, ψ i Let be the zero-delay cross-correlation coefficient between the time difference data after set correction within the i-th acquisition substation.

[0090] N represents the total number of data collection stations.

[0091] Step 27, if the currently selected speed V k If the corresponding Φ value is not the current maximum Φ value, let p = p + 1 and return to step 22.

[0092] If the currently selected speed V k The corresponding Φ value is the current maximum Φ value, and the currently selected speed V is... k The direct wave velocity V; the zero-delay cross-correlation coefficient ψ corresponding to this velocity. i The corresponding data acquisition station is marked as the reference station and numbered b; then proceed to step 28.

[0093] Step 28, if V k <V max Let p = p + 1, and return to step 22.

[0094] If V k ≥V max Proceed to step 3.

[0095] As a preferred value, V max The value is taken as 3000m / s, V min The value is taken as 1500 m / s, d v The value is 5 m / s.

[0096] Specifically, step 3 includes the following steps:

[0097] Using the direct wave velocity V as V k Correcting the original time difference data for each seismic trace yields the model trace for the corresponding sub-station trace set:

[0098]

[0099] in, Indicates passing through (V corresponding to V) k The seismic trace record collected by the j-th geophone in the i-th acquisition station after time difference correction.

[0100] h i (t) represents the model track data of the i-th acquisition station track set.

[0101] M represents the total number of seismic traces in the i-th acquisition station.

[0102] j is the sequence number of the seismic trace.

[0103] Specifically, step 4 includes the following operations:

[0104] Calculate the cross-correlation data between the model channel data of each acquisition station and the reference station b:

[0105]

[0106] Find g in all data collection stations respectively i The time corresponding to the maximum value of (τ) is the synchronization time difference ΛT between the acquisition station i and the reference station b. i .

[0107] Among them, g i (τ) represents the cross-correlation data between the model channel data of the i-th acquisition station and the reference station b.

[0108] This represents the model trace data of reference station b.

[0109] t represents time, T represents the total duration of the data, and τ represents the cross-correlation time shift.

[0110] Specifically, step 4 includes the following operations:

[0111] Calculate the cross-correlation data between the model channel data of each acquisition station and the reference station b:

[0112]

[0113] Find g in all data collection stations respectively i The time corresponding to the maximum value of (τ) is the synchronization time difference ΛT between the acquisition station i and the reference station b. i ;

[0114] Among them, g i (τ) represents the cross-correlation data between the model channel data of the i-th acquisition station and the reference station b;

[0115] This represents the model trace data of reference station b;

[0116] t represents time, T represents the total duration of the data, and τ represents the cross-correlation time shift;

[0117] Specifically, step 5 includes the following operations:

[0118] Using the following formula, based on the synchronization time difference ΛT of the reference station b iCorrect the original time difference data of each geophone at each acquisition station to obtain the corrected time difference data of the corresponding seismic trace:

[0119]

[0120] This represents the corrected time difference data of the seismic trace corresponding to the j-th detector at the i-th acquisition station.

[0121] After time difference correction for all seismic traces, the synchronous time difference extraction and correction of seismic data acquisition during tunneling was completed.

[0122] After time difference correction is performed on all acquisition substations, the output is |ΛT i As a data acquisition synchronization accuracy, it can display the seismic time difference synchronization accuracy during excavation in real time.

[0123] like Figure 2 As shown, in the uncorrected seismic records during excavation, there is a significant time lag between each seismic trace; for example... Figure 3 As shown, after correction using the method of the present invention, the synchronization problem between data acquisition stations is effectively solved, laying a solid foundation for ensuring the smooth progress of tunneling operations.

Claims

1. A method for extracting and correcting the synchronization time difference of seismic data acquisition during tunneling, characterized in that, Includes the following steps: Step 1: Establish a seismic data acquisition system for tunneling, read all seismic wave data from the system and filter them to obtain the raw data of all seismic traces; Step 2: At different velocities, calculate the corresponding direct wave arrival time difference based on the raw data of the seismic traces; use the direct wave arrival time difference to correct the time difference of all seismic traces in the corresponding acquisition substations; determine the direct wave velocity and the reference station by using all seismic traces in all acquisition substations after time difference correction. Step 3: Use the direct wave velocity to correct the original time difference data of each seismic trace to obtain the model trace of the corresponding sub-station trace set; Step 4: Calculate the cross-correlation data between each model channel and the baseline substation model channel, and determine the maximum cross-correlation value as the synchronization time difference; Step 5: Use the synchronization time difference to perform time difference correction on all raw seismic trace data.

2. The method for extracting and correcting synchronization time difference of seismic data acquisition during tunneling as described in claim 1, characterized in that, In step 1, all seismic wave data in the tunneling seismic data acquisition system are bandpass filtered, with the bandpass filtering range being 5Hz-200Hz.

3. The method for extracting and correcting synchronization time difference of seismic data acquisition during tunneling as described in claim 1, characterized in that, Step 2 includes the following sub-steps: Step 21, set the minimum speed. Maximum speed and speed interval ; make p =1, p For speed Select the sequence number; Step 22, calculate the currently selected speed. = +( p -1)× ; Step 23, establish the velocity target analysis function: in, This represents the distance between the raw seismic trace data measured by the j-th geophone at the i-th acquisition station and the raw seismic trace data at the starting point. This represents the time difference of arrival of the direct wave of the seismic trace measured by the j-th geophone at the i-th acquisition station; Step 24, use the direct wave arrival time difference Time difference correction is performed on each seismic trace within the corresponding acquisition substation. The correction formula is as follows: in, This represents the raw seismic trace data measured by the j-th geophone at the i-th acquisition station; This represents the seismic trace obtained by the j-th geophone at the i-th acquisition station after time difference correction. Indicates time; Step 25: Taking each acquisition station as a unit, calculate the zero-delay cross-correlation coefficient between all corrected seismic traces within each acquisition station according to the following formula: in, This represents the zero-delay cross-correlation coefficient among all time-difference data of the seismic traces within the i-th acquisition station; M represents the total number of seismic traces in the i-th acquisition station, "•" represents the dot product operation, and "||" represents the vector modulus; Step 26, Calculate square modulus , in, Let be the zero-delay cross-correlation number between the time difference data after gather correction within the i-th acquisition substation; N is the total number of data collection stations; Step 27, if the currently selected speed corresponding The value is not the largest at present. Value, let p = p +1, return to step 22; If the currently selected speed corresponding The value is the largest at present. The value will be the currently selected speed. As the direct wave velocity V; the zero-delay cross-correlation coefficient corresponding to this velocity. The corresponding data acquisition station is marked as the reference station and numbered b; then proceed to step 28; Step 28, if < ,make p = p +1, return to step 22; if ≥ Proceed to step 3.

4. The method for extracting and correcting the synchronization time difference of seismic data acquisition during tunneling as described in claim 3, characterized in that, The value is 3000 m / s. The value is taken as 1500 m / s. The value is 5 m / s.

5. The method for extracting and correcting the synchronization time difference of seismic data acquisition during tunneling as described in claim 1, characterized in that, Step 3 specifically includes the following operations: Using the direct wave velocity V as... Correcting the original time difference data for each seismic trace yields the model trace for the corresponding sub-station trace set: = in, This represents the seismic trace record collected by the j-th geophone in the i-th acquisition station after time difference correction; For the i-th collection station track set, the model track data is used. M represents the total number of seismic traces in the i-th acquisition station; j This is the sequence number of the seismic trace.

6. The method for extracting and correcting synchronization time difference of seismic data acquisition during tunneling as described in claim 1, characterized in that, Step 4 specifically includes the following operations: Calculate the cross-correlation data between the model channel data of each acquisition station and the reference station b: = in, This represents the model track data of the i-th acquisition station track set; Find all the data collection stations respectively The time corresponding to the maximum value is the synchronization time difference between the acquisition station i and the reference station b. ; in, This represents the cross-correlation data between the model channel data of the i-th acquisition station and the reference station b; This represents the model trace data of reference station b; t represents time, T represents the total duration of the data, and τ represents the cross-correlation time shift.

7. The method for extracting and correcting synchronization time difference of seismic data acquisition during tunneling as described in claim 1, characterized in that, Step 5 specifically includes the following operations: Using the following formula, based on the synchronization time difference of reference station b... Correct the original time difference data of each geophone at each acquisition station to obtain the corrected time difference data of the corresponding seismic trace: Indicates the first i The first data collection station j Corrected data for the seismic traces corresponding to each detector; Indicates the first i The first data collection station j The seismic traces received by each detector are corrected using synchronization time difference.

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