VSP residual static correction method and system based on event alignment tracking

Abstract

The invention provides a VSP residual static correction method and system based on event alignment tracking, and belongs to the field of seismic data processing. According to the method, the residual static correction value of each channel is obtained by using the autocorrelation peak value position and the cross-correlation peak value position. The method comprises the steps of 1, inputting VSP data, and obtaining a data subset; 2, calculating an amplitude average value of each trace in the data subset, and obtaining a processed trace set by using the amplitude average value; 3, obtaining a superposition channel by utilizing the processed channel set, and obtaining a reference channel by utilizing the superposition channel; 4, obtaining a position index of an autocorrelation peak value by using the reference channel, and obtaining a position index of a cross-correlation peak value by using the processed channel set and the reference channel; and 5, obtaining a residual static correction value by using the position index of the autocorrelation peak value and the position index of the cross-correlation peak value. The method is easy to operate, has a good processing effect on actual data, and can be popularized and applied to the field of VSP data processing.

Description

Technical Field

[0001] The invention belongs to the field of seismic data processing, and in particular relates to a VSP residual static correction method and system based on event axis alignment tracking. Background Art

[0002] The goal of VSP static correction is to eliminate the influence of all lateral inhomogeneities above the target layer, including the lateral changes in the seismic wave time field caused by the surface undulation and the lateral changes in the low velocity reduction zone, so that the final processing results can more accurately reveal the structural characteristics of the target layer. In 2005, someone proposed a common method for static correction in the VSP processing of variable well source distance, which is to apply the datum static correction from the surface seismic measurement and the 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 receiving point gather (assuming that the underground is zero inclination) and treating this smooth surface as the static correction amount for calculation. In 2011, someone proposed an adaptive static correction method based on the Walkaway VSP and 3D VSP observation systems and data characteristics, including an adaptive elevation static correction method that calculates the static correction amount based on the elevation after obtaining the replacement velocity through the VSP first arrival time and the elevation of the excitation point, and a residual static correction method obtained by calculating the theoretical first arrival time using the VTI anisotropic velocity model. In 2012, some people processed the biased VSP data in the foreland belt with geological characteristics such as large surface undulation, large dip angle of underground overthrust and thrust structures, and complex fault relationships. In order to solve the static correction problem, they changed the VSP imaging strategy from traditional time domain imaging to depth domain imaging, and then performed a unified datum correction after imaging, thereby eliminating the closure error between multi-directional biased VSP traditional imaging sections. In 2021, some people summarized the seismic data processing process and parameters, and formed a set of well-seismic matching optimization processing technology processes, using micro-logging constrained tomographic static correction, which can well solve the long-wavelength static correction problem.

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

[0004] The object of the present invention is to solve the above-mentioned difficulties existing in the prior art and to provide a VSP residual static correction method and system based on event axis alignment tracking. The VSP residual static correction is performed based on event axis alignment tracking without using other information. Only the autocorrelation peak position of the reference track and the cross-correlation peak position of the reference track and the seismic track can be used to obtain the residual static correction amount that needs to be moved for each seismic track.

[0005] The present invention is achieved through the following technical solutions:

[0006] A first aspect of the present invention provides a VSP residual static correction method based on event axis alignment tracking, wherein the method obtains the residual static correction amount of each trace by using the autocorrelation peak position and the cross-correlation peak position.

[0007] Preferably, the method comprises:

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

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

[0010] Step 3: Use the processed gathers to obtain stacked traces, and use the stacked traces to obtain reference traces;

[0011] Step 4: Use the reference trace to obtain the position index of the autocorrelation peak, and use the processed trace gather and the reference trace to obtain the position index of the cross-correlation peak;

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

[0013] Preferably, the operation of step one includes:

[0014] Input the VSP data that needs residual static correction and open a time window. The target layer is included in the time window.

[0015] The data in the time window of the VSP data are cut out as a data subset, and the data subset contains n seismic traces.

[0016] Preferably, the operation of step 2 includes:

[0017] Calculate the amplitude mean of each trace in the data subset;

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

[0019] Preferably, the operation of step three includes:

[0020] Add all traces in the processed trace set to obtain the superimposed trace;

[0021] Add up the amplitude values ​​of all the sample points in the stacked channel and divide it by the number of sampling points in the stacked channel to get the average amplitude value of the stacked 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 in the stacked trace.

[0023] Preferably, the operation of step 4 includes:

[0024] Perform autocorrelation on the reference trace and obtain the position index of the autocorrelation peak;

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

[0026] Cross-correlate the trace with the reference trace to obtain the position index of the cross-correlation peak.

[0027] Preferably, the operation of step five includes:

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

[0029] The remaining static correction amount that needs to be moved is obtained using the following formula:

[0030] Residual static correction amount = cross-correlation peak position index - autocorrelation peak position index.

[0031] A second aspect of the present invention provides a VSP residual static correction system based on event axis alignment tracking, wherein the system obtains the residual static correction amount of each trace by using the autocorrelation peak position and the cross-correlation peak position.

[0032] Preferably, the system comprises:

[0033] Input unit: used to input VSP data and obtain data subsets;

[0034] Calculation unit: linked to the input unit, used to calculate the amplitude average of each trace in the data subset, and use the amplitude average to obtain the processed trace gather;

[0035] Track processing unit: connected to the calculation unit, used to obtain the stacked track using the processed track gathers, and obtain the reference track using the stacked track;

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

[0037] The residual static correction amount acquisition unit is connected to the position index acquisition unit and is used to obtain the residual static correction amount by using the position index of the autocorrelation peak and the position index of the cross-correlation peak.

[0038] According to a third aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps of a VSP residual static correction method based on in-phase axis alignment tracking of 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 good processing effect on actual data, and can be promoted and applied to the field of VSP data processing. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0042] Figure 3 Reference signal;

[0043] Figure 4-1 Diagram of horizontal event axis before residual static correction;

[0044] Figure 4-2 Plot of the horizontal event after residual static correction. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0046] The present invention provides a VSP residual static correction method based on in-phase axis alignment tracking, wherein 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 of the present invention is simple to operate, has a stable effect, is easy to implement, and has a high promotion value.

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

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

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

[0050] Step 3: Use the processed gathers to obtain stacked traces, and use the stacked traces to obtain reference traces;

[0051] Step 4: Use the reference trace to obtain the position index of the autocorrelation peak, and use the processed trace gather and the reference trace to obtain the position index of the cross-correlation peak;

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

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

[0054] Embodiment 1:

[0055] The operations in step one include:

[0056] Input the VSP data data that needs to be processed by residual static correction, and open the 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, and the target layer is included in the t1:t2 time window. The present invention is to perform residual static correction on the horizontal axis within the t1:t2 time window.

[0057] The data in the time window of the VSP data data are cut out as a data subset, and the data subset contains n seismic traces.

[0058] Embodiment 2:

[0059] The operations of step 2 include:

[0060] Calculate the amplitude average of each channel in the data subset. The amplitude average is obtained by adding all the sample point values ​​in the channel data and dividing by the number of sampling points.

[0061] Perform the following operations on each channel in turn: subtract the amplitude average value of the channel from the amplitude value of each sample point of the channel data;

[0062] After completing the processing of all the traces in the data subset, the processed trace set subdata is obtained.

[0063] Embodiment three:

[0064] The operations in step three include:

[0065] Add all the traces in the processed trace set subdata to obtain the superimposed trace;

[0066] Add up the amplitude values ​​of all the sample points in the stacked channel and divide it by the number of sampling points in the stacked channel to get the average amplitude value of the stacked channel;

[0067] The reference channel pilot is obtained by subtracting the average amplitude value of the superimposed channel from the amplitude value of each sample point of the superimposed channel, so that the cross-correlation average value can be 0.

[0068] Embodiment 4:

[0069] The operations in step 4 include:

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

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

[0072] The trace (eg, trace1) is cross-correlated with the reference trace pilot to obtain the position index ccmax of the cross-correlation peak.

[0073] The existing method is used to perform autocorrelation and cross-correlation to obtain the position index acmax of the autocorrelation peak and the position index ccmax of the cross-correlation peak, which will not be described in detail here.

[0074] Embodiment five:

[0075] The operations of step five include:

[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 is obtained using the following formula:

[0078] Residual static correction amount = cross-correlation peak position index ccmax - autocorrelation peak position index acmax.

[0079] Through the above steps, the static correction amount required for each track in the gather is obtained. According to the static correction amount required for each track, the corresponding track in the VSP data is corrected along the time axis to obtain the seismic gather after horizontal alignment tracking correction.

[0080] Embodiment six:

[0081] In order to verify the VSP residual static correction method based on event alignment tracking of the present invention, an experimental verification is carried out on VSP seismic data. Figure 2 It is to straighten the downlink wave according to the apparent velocity and the shot offset in time and to align and track the event axis in the time window from 0.006s to 0.039s. First, the average value of all the gathers is calculated, and the corresponding average value is subtracted from each gather to obtain the averaged gather. The averaged gathers are added together to obtain the reference gather, such as Figure 3 Using the method in step 4 above, autocorrelate the reference trace, cross-correlate the reference trace with each trace in the trace gather, and subtract the peak positions of the two to obtain the residual static correction.

[0082] Figure 4-1 and Figure 4-2 The comparison diagram of the VSP residual static correction before and after the in-phase axis alignment tracking provided by the present invention is shown in Figure 2. Figure 4-2 It can be seen that after the residual static correction, the continuity of the event axis in the time window from 0.006s to 0.039s is better, and some events 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 of each trace by using the autocorrelation peak position and the cross-correlation peak position.

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

[0085] Embodiment seven:

[0086] The system comprises:

[0087] Input unit: used to input VSP data and obtain data subsets;

[0088] Calculation unit: linked to the input unit, used to calculate the amplitude average of each trace in the data subset, and use the amplitude average to obtain the processed trace gather;

[0089] Track processing unit: connected to the calculation unit, used to obtain the stacked track using the processed track gathers, and obtain the reference track using the stacked track;

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

[0091] The residual static correction amount acquisition unit is connected to the position index acquisition unit and is used to obtain the residual static correction amount by 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 that needs to be processed by residual static correction, and open the 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, and the target layer is included in the t1:t2 time window. The present invention is to perform residual static correction on the horizontal axis within the t1:t2 time window.

[0094] The data in the time window of the VSP data data are cut out as a data subset, and the data subset contains n seismic traces.

[0095] The calculation unit performs the following operations:

[0096] Calculate the amplitude average of each channel in the data subset. The amplitude average is obtained by adding all the sample point values ​​in the channel data and dividing by the number of sampling points.

[0097] Perform the following operations on each channel in turn: subtract the amplitude average value of the channel from the amplitude value of each sample point of the channel data;

[0098] After completing the processing of all the traces in the data subset, the processed trace set subdata is obtained.

[0099] The channel processing unit performs the following operations:

[0100] Add all the traces in the processed trace set subdata to obtain the superimposed trace;

[0101] Add up the amplitude values ​​of all the sample points in the stacked channel and divide it by the number of sampling points in the stacked channel to get the average amplitude value of the stacked channel;

[0102] The reference channel pilot is obtained by subtracting the average amplitude value of the superimposed channel from the amplitude value of each sample point of the superimposed channel, so that the cross-correlation average value can be 0.

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

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

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

[0106] The trace (eg, trace1) is cross-correlated with the reference trace pilot to obtain the position index ccmax of the cross-correlation peak.

[0107] The existing method is used to perform autocorrelation and cross-correlation to obtain the position index acmax of the autocorrelation peak and the position index ccmax of the cross-correlation peak, which will not be described in detail 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 is obtained using the following formula:

[0111] Residual static correction amount = cross-correlation peak position index ccmax - autocorrelation peak position index acmax.

[0112] Through the above operation, the static correction amount required for each track in the gather is obtained. According to the static correction amount required for each track, the corresponding track in the VSP data is corrected along the time axis to obtain the seismic gather after horizontal alignment tracking correction.

[0113] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps of a VSP residual static correction method based on in-phase axis alignment tracking of the present invention.

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

Claims

1. A VSP residual static correction method based on event axis alignment tracking, characterized by: The method uses the autocorrelation peak position and the cross-correlation peak position to obtain the residual static correction amount of each trace.

2. The VSP residual static correction method based on event axis alignment tracking according to claim 1 is characterized by: The method comprises: Step 1: Input VSP data and obtain data subset; Step 2: Calculate the amplitude average of each trace in the data subset, and use the amplitude average to obtain the processed trace gather; Step 3: Use the processed gathers to obtain stacked traces, and use the stacked traces to obtain reference traces; Step 4: Use the reference trace to obtain the position index of the autocorrelation peak, and use the processed trace gather and the reference trace to obtain the position index of the cross-correlation peak; Step 5: Obtain the residual static correction amount using the position index of the autocorrelation peak and the position index of the cross-correlation peak.

3. The VSP residual static correction method based on event axis alignment tracking according to claim 2 is characterized in that: The operations in step one include: Input the VSP data that needs residual static correction and open a time window. The target layer is included in the time window. The data in the time window of the VSP data are cut out as a data subset, and the data subset contains n seismic traces.

4. The VSP residual static correction method based on event axis alignment tracking according to claim 2 is characterized in that: The operations of step 2 include: Calculate the amplitude mean of each trace in the data subset; Perform the following operations on each channel in turn to obtain the processed channel set: subtract the amplitude average value of the channel from the amplitude value of each sample point of the channel data.

5. The VSP residual static correction method based on event axis alignment tracking according to claim 2 is characterized in that: The operations in step three include: Add all traces in the processed trace set to obtain the superimposed trace; Add up the amplitude values ​​of all the sample points in the stacked channel and divide it by the number of sampling points in the stacked channel to get the average amplitude value of the stacked channel; The reference trace is obtained by subtracting the average amplitude value of the stacked trace from the amplitude value of each sample point in the stacked trace.

6. The VSP residual static correction method based on event axis alignment tracking according to claim 2 is characterized by: The operations in step 4 include: Perform autocorrelation on the reference trace and obtain the position index of the autocorrelation peak; Perform the following operations on each trace in the processed data set: Cross-correlate the trace with the reference trace to obtain the position index of the cross-correlation peak.

7. The VSP residual static correction method based on event axis alignment tracking according to claim 2 is characterized in that: The operations of step five include: Perform the following operations on each trace in the processed data set: The remaining static correction amount that needs to be moved is obtained using the following formula: Residual static correction amount = cross-correlation peak position index - autocorrelation peak position index.

8. A VSP residual static correction system based on event alignment tracking, characterized by: The system obtains the residual static correction amount of each trace by using the autocorrelation peak position and the cross-correlation peak position.

9. The VSP residual static correction system based on event alignment tracking according to claim 8, characterized in that: The system comprises: Input unit: used to input VSP data and obtain data subsets; Calculation unit: linked to the input unit, used to calculate the amplitude average of each trace in the data subset, and use the amplitude average to obtain the processed trace gather; Track processing unit: connected to the calculation unit, used to obtain the stacked track using the processed track gathers, and obtain the reference track using the stacked track; Position index acquisition unit: connected to the trace processing unit and the calculation unit respectively, used to obtain the position index of the autocorrelation peak using the reference trace, and obtain the position index of the cross-correlation peak using the processed trace gather and the reference trace; The residual static correction amount acquisition unit is connected to the position index acquisition unit and is used to obtain the residual static correction amount by using the position index of the autocorrelation peak and the position index of the cross-correlation peak.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps of the VSP residual static correction method based on event axis alignment tracking according to any one of claims 1 to 7.

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