First arrival automatic picking method based on iteration method, storage medium and processor

Abstract

The application discloses a first arrival automatic picking method based on an iteration method, a storage medium and a processor, relates to the technical field of seismic exploration processing, and comprises the following steps: determining a first arrival guide line of each single shot through seismic data; and replacing the original first arrival guide line with a new first arrival guide line formed by first arrival picking points based on no abnormality, and repeatedly replacing for multiple times, so that the first arrival picking can be realized more quickly and more accurately, and the technical problems of low first arrival picking efficiency and low accuracy in the prior art are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seismic exploration processing, and particularly relates to a first arrival automatic picking method based on an iteration method, a storage medium and a processor. BACKGROUND

[0002] In seismic exploration, a seismic wave first excited from a shot point and first recorded by a receiver point is called a first arrival, and a first arrival time is called a seismic first arrival, which is simply called a seismic first arrival. First arrival picking is a process of distinguishing a seismic signal from ambient noise by amplitude, frequency and other characteristics, and extracting a first arrival from seismic data.

[0003] It is known that first arrival static correction is a very important step in seismic data processing, and accurate picking of a first arrival is the basis of the static correction. However, picking of a first arrival based on seismic data often costs a lot of time and effort of a processing personnel, especially for mountainous data in Sichuan, a large terrain fluctuation, and different lithology areas, original seismic wave data are often affected by complex near-surface structures and large elevation differences, so that a first arrival time of seismic data varies greatly, and first arrival picking is more difficult, and therefore a fast and accurate first arrival picking method is urgently needed.

[0004] In the prior art, first arrival picking is often performed manually by drawing a first arrival guide line near a first arrival after pre-processing of seismic data, and then drawing a guide line again after a certain interval, and repeatedly drawing multiple guide lines in a three-dimensional work area, opening a time window, and determining a time window range. Then, automatic picking is started by testing parameters, and a migration distance is selected for tomographic static correction. However, the picking method has the following technical problems in practical application:

[0005] 1. Since a single shot of three-dimensional seismic data is large, a time window opened for a first arrival is also opened at a large interval, and since there is no check on the accuracy of the time window for each single shot, and a first arrival of a part of single shots is far away from a guide line, or even not included in the opened time window, a first arrival cannot be accurately picked accordingly.

[0006] 2. The guide line drawn by the prior art is left-right symmetrical, and for a left-right half branch of a single shot record which is not symmetrical, it cannot be well included, and thus the accuracy is affected.

[0007] 3. In order to include more single shot records, a time window is opened relatively large, and for seismic data with a poor signal-to-noise ratio, a picked first arrival will be "up and down", and finally accurate picking cannot be performed.

[0008] 4. The working efficiency of picking is limited by manual intervention, and it is difficult to greatly improve, and a lot of human resources are needed for picking.

[0009] 5、Due to the near-surface conditions and external interference and other factors, the single shot itself signal-to-noise ratio is reduced, and the first arrival wave information is often submerged in noise, sometimes even broken, resulting in the picking accuracy cannot meet the actual application purpose, and a large amount of manual editing is still needed in the later stage, which consumes time and effort and greatly reduces the picking efficiency.

[0010] In order to solve the above technical problems, the patent document with publication number CN106842325A discloses a method for improving the first arrival wave picking efficiency and accuracy by using the detection point static correction iterative method, which comprises the following steps: using the automatically picked first arrival to calculate the reference surface static correction amount; performing detection point static correction on the original single shot record according to the reference surface correction amount; manually correcting the abnormal points and abnormal segments of the detection point static correction amount; automatically picking the first arrival on the single shot after the detection point static correction and manual correction; modifying the abnormal points of the first arrival; pre-processing the modified first arrival, manually monitoring the remaining abnormal points on the single shot after the detection point static correction and manual correction; and subtracting the sum of the detection point static correction amount and the manual static correction amount from the manually monitored qualified first arrival, and then restoring it to the original data. This method can significantly improve the first arrival picking efficiency and accuracy of high-precision three-dimensional seismic data under complex near-surface geological conditions, and the first arrival boundary form of the original record changes greatly and the data signal-to-noise ratio is low. However, this method still has the following technical problems:

[0011] 1、Since the method uses the automatically picked first arrival to calculate the reference surface static correction amount, there is a problem that the calculation of the reference surface static correction amount is not accurate due to the inaccurate picking of the first arrival time, and it takes a lot of time to calculate the reference surface static correction amount.

[0012] 2、The method involves manually correcting the abnormal points and abnormal segments of the detection point static correction amount, which requires a lot of time to find the abnormal points, and how to manually correct is not disclosed.

[0013] 3、The method involves a lot of manual participation, which affects the picking efficiency.

[0014] In summary, there is an urgent need for a new technology that can further improve the first arrival wave picking efficiency and accuracy. SUMMARY

[0015] The purpose of the present application is to provide a first arrival wave automatic picking method based on iterative method, storage medium and processor. The present application first determines the first arrival guide line of each single shot by seismic data, and then replaces the original first arrival guide line with a new first arrival guide line composed of non-abnormal first arrival picking points, and iteratively replaces several times, which can faster and more accurately realize the picking of the first arrival wave, thereby effectively solving the technical problems of low first arrival wave picking efficiency and low accuracy in the prior art.

[0016] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0017] An automatic first arrival picking method based on iteration method, characterized in comprising the following steps:

[0018] Step 1: Obtain all single shot seismic data, and sequentially perform fixed observation processing, pretreatment and lithology classification processing on the seismic data;

[0019] Step 2: Select multiple single shots of different lithologies based on the lithology classified seismic data, obtain the offset and linear velocity of the single shots, and determine the first arrival guide line of the single shots of different lithologies in combination with the time shift amount;

[0020] Step 3: Open a time window containing all single shot first arrivals above and below the first arrival guide line, and automatically pick the first arrivals of all single shot seismic data within the time window, to obtain the first arrival picking points of all single shots;

[0021] Step 4: According to the principle that the first arrival times of adjacent single shots are similar at the same receiving point, set a correlation coefficient to adjust the accuracy of all first arrival picking points, and remove abnormal first arrival picking points after adjustment;

[0022] Step 5: Redetermine the new first arrival guide line based on the remaining first arrival picking points, and then replace the first arrival guide line in Step 2 with the new first arrival guide line;

[0023] Step 6: Repeat Steps 3-5 for multiple iterations by gradually reducing the time window and adjusting the correlation coefficient, and complete the automatic picking of the first arrivals after the iteration is completed.

[0024] In Step 2, the first arrival guide line of the single shots of different lithologies is determined based on the function relationship curve of offset, linear velocity and time shift amount. The specific determination method is: the offset is divided by twice the linear velocity, and then the time shift amount is added to determine the first arrival guide line.

[0025] In Step 4, the setting method of the correlation coefficient is:

[0026] When the first arrival shape of the receiving point is exactly the same as that of the adjacent single shot, the correlation coefficient is 1;

[0027] When the first arrival shape of the receiving point is exactly opposite to that of the adjacent single shot, the correlation coefficient is 0;

[0028] When the first arrival shape of the receiving point is between the completely opposite and the completely same, the correlation coefficient is 0-1.

[0029] The method for adjusting the accuracy of all the first arrival picking points in step 4 based on the correlation coefficient is: all single shots are sorted according to the spatial position, and the first arrival picking points of all single shots are adjusted based on the principle that the first arrival wave forms of adjacent two single shots are basically consistent at the same geophone.

[0030] The abnormal first arrival picking point in step 4 refers to the first arrival picking point with a correlation coefficient less than 0.5 or located outside the time window.

[0031] In step 6, the time window is gradually reduced by 50 milliseconds each time, and the correlation coefficient is adjusted by 0.1 each time.

[0032] The iteration in step 6 ends when the specified number of iterations is completed or when the time difference of more than 95% of the input and output first arrival picking points is less than 15 milliseconds.

[0033] The preprocessing in step 1 refers to sequentially performing data truncation processing, elevation static correction, denoising processing and automatic gain on the seismic data, wherein,

[0034] The data truncation processing refers to truncating the length of the data in the seismic data to contain the first arrival wave.

[0035] The automatic gain refers to performing gain on the data after denoising processing so that the amplitude energy of all data is consistent.

[0036] Further, the present application also provides a computer readable storage medium storing a computer program, and running the computer program can execute the above-mentioned first arrival automatic picking method based on the iteration method.

[0037] Further, the present application also provides a processor running the computer program stored in the computer readable storage medium.

[0038] The advantages of the present application are:

[0039] 1. The first arrival automatic picking method based on the iteration method comprises six steps, and the advantages of each step are as follows:

[0040] Step 1 can reduce the size of the data, thereby improving the picking efficiency, eliminate the influence of elevation on the first arrival wave, remove abnormal amplitude, strong energy interference, 50hz industrial interference and the like in the first arrival wave, avoid the influence of these noises on the first arrival wave, thereby facilitating better identification of the first arrival wave, and being conducive to improving the accuracy of the first arrival picking. 4. The amplitude energy of the data is consistent, thereby being conducive to the effective picking of the first arrival wave in the subsequent steps.

[0041] Step 2 determines the first arrival guide line of different lithology single shot by the offset and linear velocity of different lithology single shot obtained and the time shift amount, which is more conducive to the control of the picking range and more close to the first arrival wave time of the real data.

[0042] Step 3 opens a time window containing all single shot first arrival waves based on the first arrival guide line, and automatically picks the first arrival wave of all single shot seismic data in the time window range, which has the advantages of determining the time range of picking, automatic picking and saving time and effort.

[0043] Step 4 adjusts the accuracy of all first arrival wave picking points by the set correlation coefficient, which can eliminate the interference factors in the picking process, thereby improving the accuracy of the first arrival wave picking. After removing the abnormal first arrival wave picking points, the new first arrival guide line is closer to the real first arrival time.

[0044] Step 5 replaces the original first arrival guide line with the new first arrival guide line, which is closer to the first arrival wave time of the actual data, thereby further improving the accuracy of the first arrival wave picking.

[0045] Step 6 realizes the picking of the first arrival wave by gradually reducing the time window and adjusting the correlation coefficient and repeating steps 3-5, which can limit the first arrival within a smaller range, and finally obtain a first arrival wave with less interference, higher accuracy, higher picking efficiency and more real and reliable.

[0046] In summary, the first arrival guide line of different lithology single shot is determined after the seismic data of all single shots are sequentially processed, preprocessed and classified by lithology, and the new first arrival guide line is formed by the non-abnormal first arrival wave picking points to replace the original first arrival guide line, and the iteration is repeated several times, which can realize the picking of the first arrival wave more quickly and accurately, thereby effectively solving the technical problems of low picking efficiency and low accuracy of the first arrival wave in the prior art.

[0047] Further, the present application is particularly suitable for the picking of the first arrival wave of adjacent single shots in areas with large changes in lithology and elevation, where the first arrival wave changes greatly in time.

[0048] 2. In the picking method of the prior art, the guide line is only a thick guide line, which is not very close to the first arrival time of the real data. Some are close, some are far away, and the time window is large, resulting in inaccurate picking of some points. After the abnormal first arrival picking point is deleted, no re-picking (reduced picking rate) or manual modification (labor-intensive and time-consuming) is done. The accuracy of automatic picking cannot achieve the purpose of practical application. A large amount of manual editing is required in the later stage, which is time-consuming and labor-intensive, and greatly reduces the picking efficiency. However, based on the above-mentioned specific method, the present invention completes the entire picking process completely automatically with less manual intervention. The guide line is extremely close to the first arrival time of the real data, the time window is small, and it is also less subject to other interferences. The accurate picking rate is higher, it is true and reliable, and it is all computer-processed, so it is more efficient.

[0049] 3. The present invention directly uses the shot point and detection point elevations to calculate the elevation static correction value, and picks up the first arrival time on the basis of eliminating the jitter of the first arrival time caused by the elevation, so the accuracy is better.

[0050] 4. After repeated iterations, the present invention calculates the static correction amount of the reference surface under the premise of accurate first arrival picking time, and only calculates it once, which is not only faster but also more accurate, and is also conducive to reducing related processes such as correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a flowchart of the present invention;

[0052] Figure 2 This is a schematic diagram of the time windows opened up and down based on the first arrival guide line;

[0053] Figure 3 This is a schematic diagram of the first arrival time and first arrival guide line obtained when picking for the first time;

[0054] Figure 4 This is a schematic diagram after the accuracy of all first arrival wave picking points is adjusted by the correlation coefficient;

[0055] Figure 5 This is a schematic diagram of the first arrival time and first arrival guide line obtained when picking for the second time;

[0056] Figure 6 This is a comparison chart of the single gun pickup structure. DETAILED DESCRIPTION

[0057] Example 1

[0058] This embodiment provides a method for automatically picking first arrival waves based on an iterative method. Figure 1 As shown, it includes the following steps:

[0059] Step 1: Obtain all single shot seismic data, and then perform observation processing, preprocessing and lithology classification on the seismic data in sequence.

[0060] Observation processing, a specialized term in this field, refers to defining an observation system. This involves defining a geometry library based on the instrument's shift report (SPS file) and establishing a correspondence between shot and receiver points. The coordinates, elevations, and alignment of the shot and receiver points are determined. The goal of defining an observation system is to uniquely identify all points, shot points, receiver points, and CMP points (surface elements) within the work area with a single number (station ID).

[0061] By comparison, it is found that the linear velocity of the first arrival wave of a single shot excited by mudstone and sandstone is not much different, and the signal-to-noise ratio of the data is good. The linear velocity of the first arrival wave of a single shot excited by gravel is larger than that of sandstone and mudstone, and the signal-to-noise ratio of the data is worse. Therefore,

[0062] The lithology classification processing refers to classifying the pre-processed single-shot seismic data according to the different lithology types stimulated based on the C file in the sps, that is, the seismic data of each single shot is divided into mudstone seismic data, sandstone seismic data, gravel seismic data, etc.

[0063] Step 2: Based on the seismic data after lithology classification, multiple single shots of different lithologies are selected, with the number of single shots of different lithologies being no less than three. Then, the offset and linear velocity of these single shots are obtained, and the first arrival guide lines of the single shots of different lithologies are determined in combination with the time shift.

[0064] Furthermore, in this step, the first arrival guide line of a single shot of different lithologies is determined based on the functional relationship curve of the offset distance, linear velocity and time shift. The specific determination method is: the first arrival guide line can be determined by dividing the offset distance by 2 times the linear velocity and adding the time shift.

[0065] It should be noted that the offset in this step refers to the distance between the shot point and the receiving point, which can be determined after fixed observation processing. The linear velocity of the first arrival wave can be directly measured by drawing a straight line in the display software. The principle is that the offset and time of the receiving point are known, and the distance divided by the time is the linear velocity. The time shift is calculated by displaying several single shots in the software. Based on the relationship between the offset and linear velocity, a curve can be displayed. This curve is time-shifted to the vicinity of the first arrival wave, and the time difference is the time shift.

[0066] Step 3: Based on the first arrival guide line, open the time window containing all the first arrival waves of single shots. The time window is as follows: Figure 2 As shown, the first arrival waves of the seismic data of all single shots are automatically picked within the time window, and the first arrival wave picking points of all single shots are obtained after picking. Figure 3 A schematic diagram showing the first arrival time (white) and first arrival guide line (black) obtained when picking for the first time.

[0067] Step 4: According to the principle that the first arrival time of adjacent single shot records has similarity at the same receiving point, the correlation coefficient is set to adjust the accuracy of all first arrival picking points, and the abnormal first arrival picking points are removed after adjustment.

[0068] This step mainly controls the picked first arrival time by increasing correlation according to the principle that the first arrival time of adjacent single shot records has similarity at the same receiving point.

[0069] When the first arrival shape of the receiving point of the adjacent single shot is exactly the same, the correlation coefficient is 1.

[0070] When the first arrival shape of the receiving point of the adjacent single shot is exactly opposite, the correlation coefficient is 0.

[0071] When the first arrival shape of the receiving point of the adjacent single shot is between the completely opposite and the completely same, the correlation coefficient is 0-1. The correlation coefficient can be filled according to the actual situation of the seismic data, and is generally 0.7, 0.8, etc. The first arrival time is controlled by the correlation coefficient, and the advantage is that some interference factors can be excluded to facilitate accurate picking.

[0072] Further, the method for adjusting the accuracy of all first arrival picking points based on the correlation coefficient is: all single shots are sorted in the order of spatial position, and based on the principle that the first arrival shape of adjacent two single shots at the same geophone point is basically consistent, the correlation coefficient is used to adjust the first arrival picking points of all single shots. Figure 4 A schematic diagram after the accuracy of all first arrival picking points is adjusted by the correlation coefficient is shown, and the horizontal coordinate in the diagram is the receiving point stake number, and the vertical coordinate is the trace number. As can be seen from the diagram, the adjacent lines have a certain correlation.

[0073] Further, the present application defines the first arrival picking point with a correlation coefficient less than 0.5 or outside the time window as an abnormal first arrival picking point, and the new first arrival guide line is closer to the real first arrival time after removing the abnormal first arrival picking point.

[0074] Step 5: A new first arrival guide line is determined based on the remaining first arrival picking points, mainly connecting the remaining first arrival picking points of each single shot to form a new first arrival guide line, and then using the new first arrival guide line to replace the first arrival guide line in step 2.

[0075] Step 6: Steps 3-5 are repeated for multiple iterations by gradually reducing the time window and adjusting the correlation coefficient, and the automatic picking of the first arrival is completed after the iteration is completed. It should be noted that the iteration is completed, that is, it is automatically completed after a specified number of iterations is completed, or it is automatically completed when the time difference of more than 95% of the input and output first arrival picking points is less than 15 milliseconds.

[0076] Preferably, the time window is gradually reduced by 50 milliseconds each time in the step, and the correlation coefficient is adjusted by 0.1 each time. The time window range is used to pick up the work only in the time window, and the second automatic picking is performed again, so that the picking result is more accurate and reliable. The first arrival time picked in the second time is used as a new first arrival guide line, the values of the time window and the correlation are adjusted, and the correlation iteration is repeated; for example:

[0077] Iteration 1 Time window 250 Correlation coefficient 0.5

[0078] Iteration 2 Time window 200 Correlation coefficient 0.6

[0079] Iteration 3 Time window 150 Correlation coefficient 0.7 End.

[0080] After the iteration is completed, a schematic diagram of the first arrival time (white) and the first arrival guide line (black) as shown in Figure 5 is obtained. It can be seen that the finally obtained first arrival guide line is more fitted to the first arrival time.

[0081] Example 2

[0082] The embodiment provides a first arrival wave automatic picking method based on an iteration method on the basis of the embodiment 1, as shown in Figure 1 , which comprises the following steps:

[0083] Step 1: Obtain all single-shot seismic data, and then sequentially perform fixed observation processing, pretreatment and lithology classification processing on the seismic data. In the step,

[0084] The pretreatment refers to sequentially performing data truncation processing, elevation static correction, denoising processing and automatic gain on the seismic data, and the specific process is as follows:

[0085] The data truncation processing refers to truncating the length of data in the seismic data to contain the first arrival wave. For example, if the length of data in the seismic data of a single-shot record is 6 seconds, but only 0-2 seconds of data is needed, and there is no first arrival wave below, therefore, the data with the length of 6 seconds can be truncated to 2 seconds. The data size can be effectively reduced by the data truncation processing, so that the first arrival wave picking time is shortened, and the first arrival wave picking efficiency is improved.

[0086] The elevation static correction refers to processing the seismic data after the data truncation processing, eliminating the influence of elevation on the first arrival wave, and making the first arrival wave smooth. The first arrival wave of the original single shot is not smooth, and the top noise is more, and after the elevation static correction, the first arrival wave becomes smooth, so that the influence of elevation on the first arrival wave is effectively eliminated.

[0087] The denoising processing refers to: since the original single shot data collected contains a lot of noise, it is necessary to remove abnormal amplitude, strong energy interference, 50hz industrial interference and other noises affecting the first arrival picking, so as to better identify the first arrival wave and improve the first arrival wave picking accuracy.

[0088] The automatic gain refers to: the gain of the data after denoising processing, so that the amplitude energy of all data is consistent. For example, the amplitude energy between each single shot receiving point, in time, and between shots may not be consistent, and automatic gain can make all single shots at the same energy level. Not only is it convenient for first arrival wave identification, but also is more convenient for subsequent display and first arrival picking.

[0089] Step 2: Select multiple single shots of different lithologies based on the lithology classified seismic data, the number of single shots of different lithologies is not less than three, then obtain the offset and linear velocity of these single shots, and determine the first arrival guide line of different lithology single shots combined with the time shift amount.

[0090] Further, the first arrival guide line of different lithology single shots is determined based on the function relationship curve of offset, linear velocity and time shift amount in this step, and the specific determination method is: the first arrival guide line is determined by dividing the offset by twice the linear velocity, and then adding the time shift amount.

[0091] Step 3: Open a time window containing all single shot first arrival waves above and below the first arrival guide line, as shown in Figure 2 , then automatically pick the first arrival wave of all single shot seismic data within the time window, and obtain the first arrival wave picking point of all single shots after picking. Figure 3 The schematic diagram of the first arrival wave time (white) and the first arrival guide line (black) obtained by the first picking is shown.

[0092] Step 4: According to the principle that the first arrival time recorded by adjacent single shots is similar at the same receiving point, set the correlation coefficient to adjust the accuracy of all first arrival wave picking points, and remove the abnormal first arrival wave picking points after adjustment.

[0093] The method for adjusting the accuracy of all first arrival wave picking points based on the correlation coefficient is: sort all single shots in the order of spatial position, based on the principle that the first arrival wave form of adjacent two single shots is basically consistent at the same geophone point, use the correlation coefficient to adjust the first arrival wave picking points of all single shots. Figure 4 The schematic diagram of the accuracy adjustment of all first arrival wave picking points by the correlation coefficient is shown, the horizontal coordinate in the figure is the receiving point stake number, and the vertical coordinate is the shot trace number. As can be seen from the figure, the adjacent lines have a certain correlation.

[0094] Further, the application defines the first arrival picking point with a correlation coefficient less than 0.5 or outside the time window as an abnormal first arrival picking point, and the new first arrival guide line is closer to the real first arrival time after removing the abnormal first arrival picking point.

[0095] Step 5: Redetermine the new first arrival guide line based on the remaining first arrival picking points, mainly connect the remaining first arrival picking points of each single shot to form a new first arrival guide line, and then use the new first arrival guide line to replace the first arrival guide line in step 2.

[0096] Step 6: Repeat steps 3-5 by gradually reducing the time window and adjusting the correlation coefficient for multiple iterations, and complete the automatic picking of the first arrival after the iteration is completed. It should be noted that the iteration is completed, that is, it is automatically completed after a specified number of iterations is completed, or it is automatically completed when the time difference of more than 95% of the input and output first arrival picking points is less than 15 milliseconds. After the iteration is completed, the schematic diagram of the first arrival time (white) and the first arrival guide line (black) is obtained as shown in the figure, and it can be seen that the finally obtained first arrival guide line is more close to the first arrival time. Figure 5

[0097] Example 3

[0098] Based on the embodiment 1 or the embodiment 2, the embodiment further provides a computer readable storage medium, which stores a computer program, and the computer program can execute the automatic first arrival picking method based on the iteration method.

[0099] Further, the embodiment further provides a processor, which can run the computer program stored in the computer readable storage medium.

[0100] Example 4

[0101] The method described in the embodiment 2 is applied to a certain actual working condition for verification, and the specific verification result is shown in the figure. Figure 6 Figure 6 The upper half of the figure is a schematic diagram after the first picking, and the lower half is a schematic diagram of the final picking result after the iteration is completed. It can be known through comparison that the first arrival guide line of different lithology of each single shot is determined after the seismic data of all single shots are sequentially processed, preprocessed and classified by lithology, and the new first arrival guide line is formed by the first arrival picking points without abnormality to replace the original first arrival guide line. Through repeated iteration and replacement for multiple times, the picking of the first arrival can be realized more quickly and accurately, and the method has the advantages of higher picking efficiency and higher accuracy.

[0102] ​​The above merely provides a specific implementation of the present application, and any feature disclosed in the specification can be replaced by other equivalent or similar purpose replacement features unless specifically stated; all features disclosed, or steps in all methods or processes, can be combined in any manner unless mutually exclusive features and / or steps.

Claims

1. A first arrival automatic picking method based on an iterative method, characterized in that The method comprises the following steps: Step 1: obtaining all single-shot seismic data, and sequentially performing fixed observation processing, preprocessing and lithology classification processing on the seismic data; Step 2: selecting multiple single shots of different lithologies based on the lithology classified seismic data, obtaining the offset and linear velocity of the single shots, and determining the first arrival guide line of the single shots of different lithologies in combination with the time shift; Step 3: opening a time window containing all single-shot first arrival waves above and below the first arrival guide line, and automatically picking up the first arrival waves of all single-shot seismic data in the time window, to obtain the first arrival wave picking points of all single shots; Step 4: setting a correlation coefficient to adjust the accuracy of all first arrival wave picking points according to the similarity principle of the first arrival time recorded by adjacent single shots at the same receiving point, and removing abnormal first arrival wave picking points after adjustment; Step 5: determining a new first arrival guide line based on the remaining first arrival wave picking points, and then replacing the first arrival guide line in step 2 with the new first arrival guide line; Step 6: repeating steps 3-5 for multiple iterations by gradually reducing the time window and adjusting the correlation coefficient, and completing the automatic picking of the first arrival wave after the iteration is completed.

2. The automatic first break picking method based on iterative method according to claim 1, characterized in that: In step 2, the first arrival guide line of the single shots of different lithologies is determined based on the function relationship curve of offset, linear velocity and time shift. The specific determination method is: the offset is divided by twice the linear velocity, and then the time shift is added to determine the first arrival guide line.

3. The automatic first break picking method based on iterative method according to claim 1, characterized in that: In step 4, the setting method of the correlation coefficient is: When the first arrival shape of the receiving point of the adjacent single shot is exactly the same, the correlation coefficient is 1; When the first arrival shape of the receiving point of the adjacent single shot is exactly opposite, the correlation coefficient is 0; When the first arrival shape of the receiving point of the adjacent single shot is between the completely opposite and the completely same, the correlation coefficient is 0-1.

4. The automatic first break picking method based on iterative method according to claim 1, characterized in that: In step 4, the method for adjusting the accuracy of all first arrival wave picking points based on the correlation coefficient is: sorting all single shots in the order of spatial position, and adjusting the first arrival wave picking points of all single shots based on the principle that the first arrival wave shape of adjacent two single shots at the same geophone is basically consistent.

5. The automatic first break picking method based on iterative method according to claim 1, characterized in that: In step 4, the abnormal first arrival wave picking point refers to the first arrival wave picking point whose correlation coefficient is less than 0.5 or is located outside the time window.

6. The automatic first break picking method based on iterative method according to claim 1, characterized in that: In step 6, the time window is gradually reduced by 50 milliseconds each time, and the correlation coefficient is adjusted by 0.1 each time.

7. The automatic first break picking method based on iterative method according to claim 1, characterized in that: In step 6, the iteration is completed after a specified number of iterations, or automatically ends when the time difference between more than 95% of the input and output first arrival wave picking points is less than 15 milliseconds.

8. The automatic first break picking method based on iterative method according to claim 1, characterized in that: The preprocessing in step 1 refers to sequentially performing data truncation processing, elevation static correction, denoising processing and automatic gain on the seismic data, wherein, The data truncation processing refers to truncating the length of the data in the seismic data to contain the first arrival wave only; The automatic gain refers to performing gain on the data after denoising processing to make the amplitude energy of all data consistent.

9. A computer readable storage medium storing a computer program, characterized in that: Running the computer program can execute the first arrival wave automatic picking method based on the iteration method in any one of claims 1-8.

10. A processor, comprising: The processor is used to run the computer program stored in the computer readable storage medium of claim 9.

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