A VSP residual statics correction method and system based on alignment tracking of event traces

Abstract

The application provides a VSP residual static correction method and system based on alignment tracking of the same phase axis, and belongs to the field of seismic data processing. The method uses the autocorrelation peak position and the cross-correlation peak position to obtain the residual static correction amount of each trace. The method comprises the following steps: step one, inputting VSP data and obtaining a data subset; step two, calculating the amplitude average value of each trace in the data subset and obtaining a processed trace set by using the amplitude average value; step three, obtaining a stacked trace by using the processed trace set and obtaining a reference trace by using the stacked trace; step four, obtaining the position index of the autocorrelation peak by using the reference trace and obtaining the position index of the cross-correlation peak by using the processed trace set and the reference trace; and step five, obtaining the residual static correction amount by using the position index of the autocorrelation peak and the position index of the cross-correlation peak. The method is simple to operate, has good processing effect on actual data, and can be popularized and applied to the field of VSP data processing.

Description

Technical Field

[0001] This invention belongs to the field of seismic data processing, specifically relating to a VSP residual static correction method and system based on phase axis alignment tracking. Background Technology

[0002] The goal of VSP static correction is to eliminate the influence of all lateral inhomogeneities above the target layer, including lateral variations in the seismic wave time field caused by surface undulations and lateral changes in low-velocity zones, so that the final processing results can more accurately reveal the structural characteristics of the target layer. In 2005, a common method for static correction in VSP processing with variable well source spacing was proposed: applying a reference surface static correction from surface seismic measurements and a residual static correction from the VSP first arrival time. The residual static correction method is based on fitting the first arrival time with a symmetric polynomial in the common receiver point gather (assuming zero dip in the subsurface) and treating this smooth surface as the static correction amount for calculation. In 2011, an adaptive static correction method was proposed based on the characteristics of Walkaway VSP and 3D VSP observation systems and data. This includes an adaptive elevation static correction method that calculates the static correction amount based on the elevation after obtaining the replacement velocity from the VSP first arrival time and the excitation point elevation, and a residual static correction method that calculates the theoretical first arrival time using the VTI anisotropic velocity model. In 2012, researchers addressed the issue of biased VSP data processing in piedmont belts characterized by large surface undulations, steep dips in subsurface thrust structures, and complex fault relationships. To resolve the static correction problem, they modified the VSP imaging strategy, shifting from traditional time-domain imaging to depth-domain imaging. Following imaging, a unified reference surface correction was performed, thus eliminating closure errors between traditional biased VSP imaging profiles in multiple orientations. In 2021, researchers summarized seismic data processing workflows and parameters, developing a well-seismic matching optimization processing technique. Employing micro-logging-constrained tomographic static correction effectively solves the long-wavelength static correction problem.

[0003] However, these conventional VSP residual static correction methods usually require velocity, first arrival time, or ground seismic data, and are relatively cumbersome to operate. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the prior art and provide a VSP residual static correction method and system based on phase axis alignment tracking. VSP residual static correction is performed based on phase axis alignment tracking. No other information is needed. Only the autocorrelation peak position of the reference trace and the cross-correlation peak position of the reference trace and the seismic trace can be used to obtain the residual static correction amount that each seismic trace needs to move.

[0005] This invention is achieved through the following technical solution:

[0006] In a first aspect, the present invention provides a VSP residual static correction method based on in-phase axis aligned tracking, wherein the method obtains the residual static correction amount for each channel using the autocorrelation peak position and the cross-correlation peak position.

[0007] Preferably, the method includes:

[0008] Step 1: Input VSP data and obtain a subset of the data;

[0009] Step 2: Calculate the average amplitude of each trace in the data subset, and use the average amplitude to obtain the processed trace set;

[0010] Step 3: Obtain the superimposed trace using the processed trace set, and obtain the reference trace using the superimposed trace;

[0011] Step 4: Obtain the location index of the autocorrelation peak using the reference channel, and obtain the location index of the cross-correlation peak using the processed channel set and the reference channel;

[0012] Step 5: Obtain the remaining static correction amount using the location index of the autocorrelation peak and the location index of the cross-correlation peak.

[0013] Preferably, step one includes the following operations:

[0014] Input the VSP data that needs to be processed for residual static correction, and open a time window, with the target layer included in the time window;

[0015] The data within the time window in the VSP data is extracted as a data subset, which contains n seismic traces.

[0016] Preferably, step two includes the following operations:

[0017] Calculate the average amplitude of each channel in the data subset;

[0018] Perform the following operation on each channel in sequence to obtain the processed channel set: subtract the average amplitude of the channel from the amplitude value of each sample point of the channel data.

[0019] Preferably, step three includes the following operations:

[0020] Add all the tracks in the processed track set to obtain the superimposed track;

[0021] The average amplitude value of the superimposed channel is obtained by summing the amplitude values ​​of all sample points in the superimposed channel and dividing by the number of sample points in the superimposed channel.

[0022] The reference trace is obtained by subtracting the average amplitude value of the stacked trace from the amplitude value of each sample point of the stacked trace.

[0023] Preferably, step four includes the following operations:

[0024] Perform autocorrelation on the reference trace to obtain the location index of the autocorrelation peak;

[0025] Perform the following operations on each track in the processed track set:

[0026] Cross-correlation is performed between this channel and the reference channel to obtain the location index of the cross-correlation peak.

[0027] Preferably, step five includes the following operations:

[0028] Perform the following operations on each track in the processed track set:

[0029] The remaining static correction amount that needs to be moved for this track can be obtained using the following formula:

[0030] Residual static correction = Location index of cross-correlation peak - Location index of autocorrelation peak.

[0031] A second aspect of the present invention provides a VSP residual static correction system based on in-phase axis aligned tracking, wherein the system obtains the residual static correction amount for each channel using the autocorrelation peak position and the cross-correlation peak position.

[0032] Preferably, the system includes:

[0033] Input unit: Used to input VSP data and obtain a subset of the data;

[0034] Calculation unit: Linked to the input unit, it is used to calculate the average amplitude of each trace in the data subset and to obtain the processed trace set using the average amplitude.

[0035] Trace processing unit: Connected to the computing unit, used to obtain superimposed traces from the processed trace set, and to obtain reference traces from the superimposed traces;

[0036] Location index acquisition unit: connected to the trace processing unit and the calculation unit respectively, used to obtain the location index of the autocorrelation peak using the reference trace, and to obtain the location index of the cross-correlation peak using the processed trace set and the reference trace;

[0037] Residual static correction acquisition unit: connected to the position index acquisition unit, used to obtain the residual static correction using the position index of the autocorrelation peak and the position index of the cross-correlation peak.

[0038] A third aspect of the present invention provides a computer-readable storage medium storing at least one computer-executable program, which, when executed by the computer, causes the computer to perform steps in a VSP residual static correction method based on in-phase axis alignment tracking according to the present invention.

[0039] Compared with the prior art, the beneficial effects of the present invention are: the method of the present invention is simple to operate, has a better processing effect on actual data, and can be widely applied to the field of VSP data processing. Attached Figure Description

[0040] Figure 1 A flowchart illustrating the steps of the method of this invention;

[0041] Figure 2 VSP data after the downwave is horizontally straightened;

[0042] Figure 3 Reference signal;

[0043] Figure 4-1 A diagram of the horizontal in-phase shaft before residual static correction;

[0044] Figure 4-2 Diagram after static correction of the horizontal in-phase axis. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings:

[0046] This invention provides a VSP residual static correction method based on in-phase axis aligned tracking. The method utilizes the autocorrelation peak position and cross-correlation peak position to obtain the residual static correction amount for each channel. This method is simple to operate, provides stable results, is easy to implement, and has high potential for widespread application.

[0047] like Figure 1 As shown, the method of the present invention includes:

[0048] Step 1: Input VSP data and obtain a subset of the data;

[0049] Step 2: Calculate the average amplitude of each trace in the data subset, and use the average amplitude to obtain the processed trace set;

[0050] Step 3: Obtain the superimposed trace using the processed trace set, and obtain the reference trace using the superimposed trace;

[0051] Step 4: Obtain the location index of the autocorrelation peak using the reference channel, and obtain the location index of the cross-correlation peak using the processed channel set and the reference channel;

[0052] Step 5: Obtain the remaining static correction amount using the location index of the autocorrelation peak and the location index of the cross-correlation peak.

[0053] The embodiments of the method of the present invention are as follows:

[0054] Example 1:

[0055] Step one includes the following operations:

[0056] Input the VSP data (data) to be subjected to residual static correction, and open a time window t1:t2, where t1 represents the start time of the time window and t2 represents the end time of the time window. t1 and t2 are selected according to the location of the target layer, which is contained within the t1:t2 time window. This invention aims to perform residual static correction on the horizontal axis within the t1:t2 time window.

[0057] The data within the time window in the VSP data is extracted as a data subset, which contains n seismic traces.

[0058] Example 2:

[0059] Step two includes the following operations:

[0060] The average amplitude of each channel in the data subset is calculated. The average amplitude is obtained by adding the values ​​of all samples in that channel and dividing by the number of samples.

[0061] Perform the following operation on each channel in sequence: subtract the average amplitude of that channel from the amplitude value of each sample point of that channel's data;

[0062] After processing all channels in the data subset, the processed channel set subdata is obtained.

[0063] Example 3:

[0064] Step three includes the following operations:

[0065] The summation of all traces in the processed trace set subdata yields the superimposed traces.

[0066] The average amplitude value of the superimposed channel is obtained by summing the amplitude values ​​of all sample points in the superimposed channel and dividing by the number of sample points in the superimposed channel.

[0067] The reference channel pilot is obtained by subtracting the average amplitude value of the stacked channel from the amplitude value of each sample point of the stacked channel, which makes the average cross-correlation value 0.

[0068] Example 4:

[0069] Step four includes the following operations:

[0070] Perform autocorrelation on the reference track pilot to obtain the position index acmax of the autocorrelation peak;

[0071] Perform the following operations on each trace in the processed trace set subdata:

[0072] Cross-correlate this track (e.g., trace1) with the reference track pilot to obtain the position index ccmax of the cross-correlation peak.

[0073] We use existing methods to perform autocorrelation and cross-correlation to obtain the location index acmax of the autocorrelation peak and the location index ccmax of the cross-correlation peak, which will not be elaborated here.

[0074] Example 5:

[0075] Step five includes the following operations:

[0076] Perform the following operations on each trace in the processed trace set subdata:

[0077] The remaining static correction amount that needs to be moved for this track can be obtained using the following formula:

[0078] Residual static correction = Cross-correlation peak position index ccmax - Autocorrelation peak position index acmax.

[0079] The steps above yielded the static correction amount required for each trace in the gather. Based on this static correction amount, the corresponding trace in the VSP data was then subjected to time-shift correction along the time axis to obtain the horizontally aligned and track-corrected seismic gather.

[0080] Example 6:

[0081] To verify the VSP residual static correction method based on phase axis alignment tracking of the present invention, experimental verification was conducted on VSP seismic data. Figure 2 This involves time-stamping the downlink wave according to apparent velocity and shot-receiver distance using VSP (Video Segmentation Recording), and aligning and tracking the in-phase axes within a time window of 0.006s to 0.039s. First, the average value is calculated for all gathers. The average gather is then subtracted from each gather to obtain the averaged gather. Finally, the averaged gathers are summed to obtain the reference gather, such as... Figure 3 As shown. Using the method in step four above, autocorrelate the reference channel, crosscorrelate the reference channel with each channel in the channel set, and subtract the positions of the peaks of the two to obtain the remaining static correction.

[0082] Figure 4-1 and Figure 4-2 The image shows a comparison of the VSP residual static correction before and after using the in-phase axis alignment tracking provided by this invention. Figure 4-2 It can be seen that after residual static correction, the continuity of the in-phase axis within the time window from 0.006s to 0.039s is better, and some in-phase axes with a certain time difference are well corrected.

[0083] The present invention also provides a VSP residual static correction system based on in-phase axis alignment tracking, wherein the system obtains the residual static correction amount for each channel using the autocorrelation peak position and the cross-correlation peak position.

[0084] An embodiment of the system is as follows:

[0085] Example 7:

[0086] The system includes:

[0087] Input unit: Used to input VSP data and obtain a subset of the data;

[0088] Calculation unit: Linked to the input unit, it is used to calculate the average amplitude of each trace in the data subset and to obtain the processed trace set using the average amplitude.

[0089] Trace processing unit: Connected to the computing unit, used to obtain superimposed traces from the processed trace set, and to obtain reference traces from the superimposed traces;

[0090] Location index acquisition unit: connected to the trace processing unit and the calculation unit respectively, used to obtain the location index of the autocorrelation peak using the reference trace, and to obtain the location index of the cross-correlation peak using the processed trace set and the reference trace;

[0091] Residual static correction acquisition unit: connected to the position index acquisition unit, used to obtain the residual static correction using the position index of the autocorrelation peak and the position index of the cross-correlation peak.

[0092] Specifically, the input unit performs the following operations:

[0093] Input the VSP data (data) to be subjected to residual static correction, and open a time window t1:t2, where t1 represents the start time of the time window and t2 represents the end time of the time window. t1 and t2 are selected according to the location of the target layer, which is contained within the t1:t2 time window. This invention aims to perform residual static correction on the horizontal axis within the t1:t2 time window.

[0094] The data within the time window in the VSP data is extracted as a data subset, which contains n seismic traces.

[0095] The computing unit performs the following operations:

[0096] The average amplitude of each channel in the data subset is calculated. The average amplitude is obtained by adding the values ​​of all samples in that channel and dividing by the number of samples.

[0097] Perform the following operation on each channel in sequence: subtract the average amplitude of that channel from the amplitude value of each sample point of that channel's data;

[0098] After processing all channels in the data subset, the processed channel set subdata is obtained.

[0099] The processing unit performs the following operations:

[0100] The summation of all traces in the processed trace set subdata yields the superimposed traces.

[0101] The average amplitude value of the superimposed channel is obtained by summing the amplitude values ​​of all sample points in the superimposed channel and dividing by the number of sample points in the superimposed channel.

[0102] The reference channel pilot is obtained by subtracting the average amplitude value of the stacked channel from the amplitude value of each sample point of the stacked channel, which makes the average cross-correlation value 0.

[0103] The location index acquisition unit performs the following operations:

[0104] Perform autocorrelation on the reference track pilot to obtain the position index acmax of the autocorrelation peak;

[0105] Perform the following operations on each trace in the processed trace set subdata:

[0106] Cross-correlate this track (e.g., trace1) with the reference track pilot to obtain the position index ccmax of the cross-correlation peak.

[0107] We use existing methods to perform autocorrelation and cross-correlation to obtain the location index acmax of the autocorrelation peak and the location index ccmax of the cross-correlation peak, which will not be elaborated here.

[0108] The residual static correction acquisition unit performs the following operations:

[0109] Perform the following operations on each trace in the processed trace set subdata:

[0110] The remaining static correction amount that needs to be moved for this track can be obtained using the following formula:

[0111] Residual static correction = Cross-correlation peak position index ccmax - Autocorrelation peak position index acmax.

[0112] The above operations yielded the static correction amount required for each trace in the gather. Based on this static correction amount, the corresponding trace in the VSP data was then subjected to time-shift correction along the time axis to obtain the horizontally aligned and track-corrected seismic gather.

[0113] The present invention also provides a computer-readable storage medium storing at least one computer-executable program, which, when executed by the computer, causes the computer to perform steps in a VSP residual static correction method based on in-phase axis alignment tracking according to the present invention.

[0114] The above technical solution is only one embodiment of the present invention. For those skilled in the art, based on the principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the technical solutions described in the specific embodiments of the present invention. Therefore, the foregoing description is only a preferred option and is not restrictive.

Claims

1. A VSP residual static correction method based on in-phase axis alignment tracking, characterized in that: The method uses the autocorrelation peak position and the cross-correlation peak position to obtain the residual static correction for each channel; The method includes: Step 1: Input VSP data and obtain a subset of the data; Step 2: Calculate the average amplitude of each trace in the data subset, and use the average amplitude to obtain the processed trace set; Step 3: Obtain the superimposed trace using the processed trace set, and obtain the reference trace using the superimposed trace; Step 4: Obtain the location index of the autocorrelation peak using the reference channel, and obtain the location index of the cross-correlation peak using the processed channel set and the reference channel; Step 5: Obtain the remaining static correction amount using the location indices of the autocorrelation peak and the cross-correlation peak; Step five includes the following operations: Perform the following operations on each track in the processed track set: The remaining static correction amount that needs to be moved for this track can be obtained using the following formula: Residual static correction = Location index of cross-correlation peak - Location index of autocorrelation peak.

2. The VSP residual static correction method based on in-phase axis alignment tracking according to claim 1, characterized in that: Step one includes the following operations: Input the VSP data that needs to be processed for residual static correction, and open a time window, with the target layer included in the time window; The data within the time window in the VSP data is extracted as a data subset, which contains n seismic traces.

3. The VSP residual static correction method based on in-phase axis alignment tracking according to claim 1, characterized in that: Step two includes the following operations: Calculate the average amplitude of each channel in the data subset; Perform the following operation on each channel in sequence to obtain the processed channel set: subtract the average amplitude of the channel from the amplitude value of each sample point of the channel data.

4. The VSP residual static correction method based on in-phase axis alignment tracking according to claim 1, characterized in that: Step three includes the following operations: Add all the tracks in the processed track set to obtain the superimposed track; The average amplitude value of the superimposed channel is obtained by summing the amplitude values ​​of all sample points in the superimposed channel and dividing by the number of sample points in the superimposed channel. The reference trace is obtained by subtracting the average amplitude value of the stacked trace from the amplitude value of each sample point of the stacked trace.

5. The VSP residual static correction method based on in-phase axis alignment tracking according to claim 1, characterized in that: Step four includes the following operations: Perform autocorrelation on the reference trace to obtain the location index of the autocorrelation peak; Perform the following operations on each track in the processed track set: Cross-correlation is performed between this channel and the reference channel to obtain the location index of the cross-correlation peak.

6. A VSP residual static correction system based on in-phase axis alignment tracking, characterized in that: The system uses the autocorrelation peak position and the cross-correlation peak position to obtain the residual static correction for each channel; The system includes: Input unit: Used to input VSP data and obtain a subset of the data; Calculation unit: Linked to the input unit, it is used to calculate the average amplitude of each trace in the data subset and to obtain the processed trace set using the average amplitude. Trace processing unit: Connected to the computing unit, used to obtain superimposed traces from the processed trace set, and to obtain reference traces from the superimposed traces; Location index acquisition unit: connected to the trace processing unit and the calculation unit respectively, used to obtain the location index of the autocorrelation peak using the reference trace, and to obtain the location index of the cross-correlation peak using the processed trace set and the reference trace; Residual static correction acquisition unit: connected to the position index acquisition unit, used to obtain the residual static correction using the position index of the autocorrelation peak and the position index of the cross-correlation peak; The residual static correction acquisition unit performs the following operations on each track in the processed track gather: The remaining static correction amount that needs to be moved for this track can be obtained using the following formula: Residual static correction = Location index of cross-correlation peak - Location index of autocorrelation peak.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one computer-executable program, which, when executed by the computer, causes the computer to perform the steps of the VSP residual static correction method based on in-phase axis alignment tracking as described in any one of claims 1-5.

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