Primary wave automatic pickup method based on iteration method, storage medium and processor

Abstract

The invention discloses a first arrival wave automatic pickup method based on an iteration method, a storage medium and a processor, and relates to the technical field of seismic exploration processing. According to the method and the device, the original first-motion guide line is replaced by the new first-motion guide line formed on the basis of the non-abnormal first-motion wave pickup points, and the first-motion waves can be quickly and accurately picked up by repeatedly iterating and replacing for multiple times, so that the technical problems of low first-motion wave pickup efficiency and low accuracy in the prior art are effectively solved.

Description

Technical Field

[0001] The present invention relates to the field of seismic exploration processing technology, and in particular to an automatic first arrival wave picking method based on an iteration method, a storage medium and a processor. Background Art

[0002] In seismic exploration, the seismic wave excited from the shot point and first recorded by the detection point is called the first arrival wave, and the arrival time of the first arrival wave is called the first arrival time of the seismic wave, or simply the seismic first arrival wave. First arrival wave picking is the process of extracting the first arrival wave from the seismic data by distinguishing the seismic signal from the environmental noise through characteristics such as amplitude and frequency.

[0003] As we all know, first-arrival static correction is a very important step in seismic data processing, and accurate first-arrival picking is the basis of this static correction. However, picking first-arrival waves based on seismic data often takes a lot of time and energy for processing personnel, especially in mountainous areas of Sichuan, where the terrain is undulating and the lithology is different. The original seismic wave data is often affected by complex near-surface structures and large elevation differences, which makes the first-arrival time of seismic data vary greatly, making first-arrival picking more difficult. Therefore, a method for picking first-arrival waves quickly and accurately is urgently needed.

[0004] In the prior art, first arrival wave picking is often done by manually drawing first arrival guide lines near the first arrival wave after preprocessing the seismic data, and then redrawing the guide lines after a few single shots. After repeatedly drawing multiple guide lines in the three-dimensional work area, a time window is opened to determine the time window range. Then, the test parameters are automatically picked up, and the offset distance is selected for tomographic static correction. However, this picking method has the following technical problems in practical applications:

[0005] 1. Since there are many single shots in the 3D seismic data, the time window for the first arrival is also opened with many single shots apart. Since the accuracy of the time window is not checked for each single shot, and the first arrival of some single shots is far away from the guide line or even not included in the opened time window, it is impossible to accurately pick up the first arrival.

[0006] 2. The guide lines drawn by the prior art are symmetrical on the left and right sides, and cannot well include the situation where the left and right halves of a single gun are asymmetrical, thereby affecting the accuracy.

[0007] 3. In order to include more single-shot records, the time window is opened larger accordingly. For seismic data with poor signal-to-noise ratio, the picked first arrival will "jump up and down", which will eventually lead to inaccurate picking.

[0008] 4. The efficiency of picking is limited by manual intervention and is difficult to improve significantly. Picking also requires a lot of human resources.

[0009] 5. Due to factors such as near-surface conditions and external interference, the signal-to-noise ratio of a single shot is reduced, and the first arrival wave information is often submerged in the noise, and sometimes even misinterpretation occurs, resulting in the accuracy of picking failing to meet the purpose of actual application. A large amount of manual editing is still required in the later stage, which is time-consuming and labor-intensive, 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 efficiency and accuracy of first arrival wave picking by using the iterative method of detection point static correction. The technology includes: using the automatically picked first arrival to roughly calculate the datum static correction amount; performing detection point static correction on the original single shot record according to the datum correction amount; manually correcting the abnormal points and abnormal segments of the detection point static correction amount; reopening the time window to automatically pick up the first arrival on the single shot after the detection point static correction and manual correction; modifying the abnormal points of the first arrival; preprocessing the modified first arrival, and manually monitoring the remaining abnormal points on the single shot after the detection point static correction and manual correction; after the first arrival after manual monitoring is qualified, the sum of the detection point static correction amount and the manual static correction amount is subtracted, and then restored to the original data. This method can significantly improve the efficiency and accuracy of first arrival picking for high-precision three-dimensional seismic data with large changes in the original record first arrival boundary morphology and low data signal-to-noise ratio under complex near-surface geological conditions. However, this method still has the following technical problems:

[0011] 1. Since this method roughly calculates the static correction of the reference surface using the automatically picked first arrival time, there is a problem that the calculation effect of the static correction of the reference surface is not good due to the inaccurate first arrival time picked. At the same time, it takes a lot of time to calculate the static correction of the reference surface.

[0012] 2. This method involves manually correcting abnormal points and abnormal sections of the static correction value of the detection point. It takes a lot of time to find the abnormal points, and there is no disclosure on how to manually correct them.

[0013] 3. This method requires much manual participation, which affects the efficiency of picking.

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

[0015] The purpose of the present invention is to provide a method, storage medium and processor for automatically picking up first arrival waves based on an iterative method. The present invention first determines the first arrival guide line of each single shot through seismic data, and then replaces the original first arrival guide line by forming a new first arrival guide line based on first arrival wave picking points without abnormalities. By repeatedly iterating and replacing multiple times, the first arrival wave can be picked up faster and more accurately, thereby effectively solving the technical problems of low efficiency and low accuracy in first arrival wave picking in the prior art.

[0016] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0017] A method for automatically picking first arrival waves based on an iteration method, characterized by comprising the following steps:

[0018] Step 1: Obtain the seismic data of all single shots, and perform observation processing, preprocessing and lithology classification processing on the seismic data in turn;

[0019] Step 2: Based on the seismic data after lithology classification, multiple single shots with different lithologies are selected, the offset distances and linear velocities of these single shots are obtained, and the first arrival guide lines of the single shots with different lithologies are determined in combination with the time shift;

[0020] Step 3: Based on the first arrival guide line, a time window containing all the first arrival waves of single shots is opened up and down, and the first arrival waves of the seismic data of all single shots are automatically picked up within the time window, and the first arrival wave picking points of all single shots are obtained after picking up;

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

[0022] Step 5: Re-determine a new first arrival guide line based on the remaining first arrival wave picking points, and then use the new first arrival guide line to replace the first arrival guide line in step 2;

[0023] Step 6: Repeat steps 3-5 for multiple iterations by gradually narrowing the time window and adjusting the correlation coefficient. After the iterations are completed, the automatic picking of the first arrival wave is completed.

[0024] In step 2, the first arrival guide line of single shots of different lithologies is determined based on the functional relationship curve of offset distance, linear velocity and time displacement. 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 displacement.

[0025] The setting method of the correlation coefficient in step 4 is:

[0026] When the initial 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 initial arrival shape of the receiving point is completely opposite to that of the adjacent single shot, the correlation coefficient is 0;

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

[0029] The method for adjusting the accuracy of all first arrival wave picking points based on the correlation coefficient in step 4 is: sort all single shots in order of spatial position, and based on the principle that the first arrival wave morphology of two adjacent single shots at the same detection point is basically the same, use the correlation coefficient to adjust the first arrival wave picking points of all single shots.

[0030] The abnormal first arrival wave picking point in step 4 refers to the first arrival wave 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 increasing it by 0.1 each time.

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

[0033] The preprocessing in step 1 refers to the data truncation, elevation static correction, denoising and automatic gain processing of the seismic data in sequence, where:

[0034] The data truncation process refers to truncating the length of the data in the seismic data to include the earthquake first arrival wave;

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

[0036] Furthermore, the present invention also provides a computer-readable storage medium, which stores a computer program. Running the computer program can execute the above-mentioned method for automatically picking first-arrival waves based on the iteration method.

[0037] Furthermore, the present invention also provides a processor for running a computer program stored in a computer-readable storage medium.

[0038] The advantages of adopting the present invention are:

[0039] 1. The method for automatically picking first arrival waves based on iteration method described in the present invention mainly includes 6 steps, and the advantages of each step are as follows:

[0040] Step 1 performs observation processing, preprocessing and lithology classification on the seismic data of all single shots in turn. Firstly, it can reduce the size of data and thus improve the picking efficiency. Secondly, it can eliminate the influence of elevation on the first arrival wave and make the first arrival wave smoother. Thirdly, it can remove abnormal amplitude, strong energy interference, 50 Hz industrial interference, etc. in the first arrival wave to avoid these noises affecting the first arrival wave, so as to facilitate better identification of the first arrival wave and improve the accuracy of first arrival wave picking. Fourthly, it can make the amplitude energy of the data consistent, so as to facilitate the effective picking of the first arrival wave in the subsequent steps.

[0041] Step 2 determines the first arrival guide lines of single shots of different lithologies by obtaining the offset distance and linear velocity of single shots of different lithologies and combining them with the time shift. This is more conducive to the control of the picking range and more in line with the first arrival wave time of the real data.

[0042] Step 3 opens a time window including all single shot first arrival waves based on the first arrival guide line, and automatically picks the first arrival waves of the seismic data of all single shots within the time window. The advantage is that the time range for picking is determined and picked automatically, saving time and effort.

[0043] Step 4 adjusts the accuracy of all first arrival wave picking points by setting the correlation coefficient, which can eliminate interference factors in the picking process, thereby improving the accuracy of first arrival wave picking. After removing 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 a new first arrival guide line. Since the new first arrival guide line is closer to the first arrival time of the actual data, it is helpful to further improve the accuracy of first arrival wave picking.

[0045] Step 6 uses a method of gradually reducing the time window and adjusting the correlation coefficient and repeating steps 3-5 for multiple iterations to achieve the picking of the first arrival wave, which can limit the first arrival to a smaller range, and ultimately obtain the first arrival wave with less interference and higher accuracy. The picking efficiency of the first arrival wave is higher and it is more authentic and reliable.

[0046] In summary, the first arrival guide lines of single shots of different lithologies are determined by sequentially performing observation processing, preprocessing and lithology classification on the seismic data of all single shots, and then new first arrival guide lines are constructed based on the first arrival wave picking points without abnormalities to replace the original first arrival guide lines. By repeatedly iterating and replacing them multiple times, the first arrival wave can be picked up faster and more accurately, thereby effectively solving the technical problems of low efficiency and low accuracy in first arrival wave picking in the prior art.

[0047] Furthermore, the present invention is also particularly suitable for picking up first arrival waves of adjacent single shot first arrival waves with large changes in the upper and lower and left and right halves in time in areas with large changes in lithology and elevation.

[0048] 2. In the picking method in the prior art, the guide line is only a thick guide line, which is not very close to the first arrival wave time of the real data, and some are close, some are far away, and the time window is large, resulting in inaccurate part of the picking. After the abnormal first arrival picking point is deleted, there is no re-picking (reduced picking rate) or manual modification (labor-intensive and time-consuming). The accuracy of automatic picking cannot achieve the purpose of practical application, and 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. The present invention is based on the above-mentioned specific method, and the entire picking process is completed completely automatically, with less manual intervention, the guide line is very close to the first arrival wave time of the real data, the time window is small, and it is also less affected by other interferences. The accurate picking rate is higher, it is true and reliable, and it is all computer-processed, and the efficiency is high.

[0049] 3. The present invention directly uses the shot point and the detection point elevation to calculate the elevation static correction amount, 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 on the premise that the first arrival picking time is accurate, 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 It is a schematic diagram of the time window opened up and down based on the first arrival guide line;

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

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

[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 iteration method, such as Figure 1 As shown, it includes the following steps:

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

[0060] The fixed observation processing is a professional term in this field, which refers to defining the observation system, defining the geometry library according to the instrument shift report (sps file), and establishing the correspondence between the shot point and the receiving point. Determine the coordinates, elevation, arrangement relationship, etc. of the shot point and the receiver point. The purpose of defining the observation system is to identify all the points, shot points, receiver points, cmp points (surface elements) involved in the work area with a unique number (station number).

[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 data signal-to-noise ratio 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 data signal-to-noise ratio is worse. Therefore,

[0062] The lithology classification processing refers to classifying the pre-processed single-shot seismic data according to the C file in the sps and the different lithology types stimulated, 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, and the number of single shots of different lithologies is not less than three. Then, the offset distance 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 single shots of different lithologies is determined based on the functional relationship curve of 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 distance in this step refers to the distance between the shot point and the receiving point, which can be obtained after fixed observation processing. The linear velocity of the first arrival wave can be directly measured by drawing a straight line through the display software. The principle is that the offset distance and time of the receiving point are known, and the distance divided by the time is the linear velocity. The time shift is in the software. Several single shots are displayed. According to the relationship between the offset distance and the linear velocity, a curve can be displayed. The 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 a 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 up within the time window, and the first arrival wave picking points of all single shots are obtained after picking up. Figure 3 A schematic diagram showing the first arrival wave time (white) and the first arrival guide line (black) obtained when picking for the first time.

[0067] Step 4: Based on the principle that the first arrival times of adjacent single shot records are similar at the same receiving point, set the correlation coefficient to adjust the accuracy of all first arrival wave picking points, and remove abnormal first arrival wave picking points after adjustment.

[0068] This step is mainly based on the similarity of the first arrival times of adjacent single shot records at the same receiving point, increasing the correlation to control the picked first arrival time. The setting method of the correlation coefficient is:

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

[0070] When the initial arrival shape of the receiving point is completely opposite to that of the adjacent single shot, the correlation coefficient is 0.

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

[0072] Furthermore, a method for adjusting the accuracy of all first arrival wave picking points based on the correlation coefficient is as follows: all single shots are sorted in order of spatial position, and based on the principle that the first arrival wave morphologies of two adjacent single shots at the same detection point are basically the same, the first arrival wave picking points of all single shots are adjusted using the correlation coefficient. Figure 4 The figure shows a schematic diagram of the accuracy adjustment of all the first arrival wave picking points through the correlation coefficient. The horizontal axis in the figure is the receiving point pile number, and the vertical axis is the gun channel number. It can be seen from the figure that adjacent lines have a certain correlation.

[0073] Furthermore, the present invention defines the first arrival wave picking points with correlation coefficients less than 0.5 or outside the time window as abnormal first arrival wave picking points. After removing the abnormal first arrival wave picking points, the new first arrival guide line is closer to the real first arrival time.

[0074] Step 5: Re-determine a new first arrival guide line based on the remaining first arrival wave picking points, mainly by connecting the remaining first arrival wave 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.

[0075] 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 arrival wave after the iteration ends. It should be noted that the end of the iteration means that it ends automatically after completing the specified number of iterations or when the time difference between the first arrival wave picking points of more than 95% of the input and output is less than 15 milliseconds.

[0076] Preferably, in this step, the time window is gradually reduced by 50 milliseconds each time, and the correlation coefficient is adjusted by increasing by 0.1 each time. The role of the time window range is that the picking work can only be performed within the time window, and the second automatic picking is performed again, so that the picking result is more accurate and reliable. The time of the first arrival wave picked for the second time is used as the new first arrival guide line, and 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 ends with time window 150 and correlation coefficient 0.7.

[0080] After the iteration, we get Figure 5 The schematic diagram of the first arrival wave time (white) and the first arrival guide line (black) shown shows that the final first arrival guide line is more consistent with the first arrival time.

[0081] Example 2

[0082] This embodiment provides a method for automatically picking first arrival waves based on an iteration method on the basis of embodiment 1. Figure 1 As shown, it includes the following steps:

[0083] Step 1: Obtain the seismic data of all single shots, and then perform observation processing, preprocessing and lithology classification on the seismic data in turn.

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

[0085] The data truncation process refers to: shortening the length of the data in the seismic data to include the seismic first arrival wave. For example, if the length of the data in the seismic data recorded by a single shot is 6 seconds, but only 0-2 seconds of data may be needed, and there is no first arrival wave below, so the data with a length of 6 seconds can be shortened to 2 seconds. The present invention can effectively reduce the size of the data through data truncation processing, thereby shortening the time of picking up the first arrival wave and improving the efficiency of picking up the first arrival wave.

[0086] The elevation static correction refers to processing the seismic data after data truncation to eliminate the influence of elevation on the first arrival wave and make the first arrival wave smoother. The first arrival wave of the original single shot is not smooth and has more top noise, but after the elevation static correction, the first arrival wave becomes smoother, thus effectively eliminating the influence of elevation on the first arrival wave.

[0087] The denoising process means that since the collected original single-shot data contains a lot of noise, it is necessary to remove the noise that affects the first arrival picking, such as abnormal amplitude, strong energy interference, 50hz industrial interference, etc., in order to better identify the first arrival wave and improve the accuracy of the first arrival wave picking.

[0088] The automatic gain means: gaining the denoised data to make the amplitude energy of all data consistent. For example, the amplitude energy of each single shot may be inconsistent between the receiving points, time, and between shots. The automatic gain can make all single shots at the same energy level. This is not only convenient for first arrival wave identification, but also for subsequent display and picking of first arrivals.

[0089] Step 2: Based on the seismic data after lithology classification, multiple single shots of different lithologies are selected, and the number of single shots of different lithologies is not less than three. Then, the offset distance 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.

[0090] Furthermore, in this step, the first arrival guide line of single shots of different lithologies is determined based on the functional relationship curve of 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.

[0091] Step 3: Based on the first arrival guide line, open a 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 up within the time window, and the first arrival wave picking points of all single shots are obtained after picking up. Figure 3 A schematic diagram showing the first arrival wave time (white) and the first arrival guide line (black) obtained when picking for the first time.

[0092] Step 4: Based on the principle that the first arrival times of adjacent single shot records are similar at the same receiving point, set the correlation coefficient to adjust the accuracy of all first arrival wave picking points, and remove 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 as follows: all single shots are sorted in order of spatial position, and based on the principle that the first arrival wave morphology of two adjacent single shots at the same detection point is basically the same, the first arrival wave picking points of all single shots are adjusted using the correlation coefficient. Figure 4 This is a schematic diagram after the accuracy of all first arrival wave picking points is adjusted by the correlation coefficient. The horizontal axis in the figure is the receiving point pile number, and the vertical axis is the gun channel number. It can be seen from the figure that adjacent lines have a certain correlation.

[0094] Furthermore, the present invention defines the first arrival wave picking points with correlation coefficients less than 0.5 or outside the time window as abnormal first arrival wave picking points. After removing the abnormal first arrival wave picking points, the new first arrival guide line is closer to the real first arrival time.

[0095] Step 5: Re-determine a new first arrival guide line based on the remaining first arrival wave picking points, mainly by connecting the remaining first arrival wave 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 for multiple iterations by gradually reducing the time window and adjusting the correlation coefficient. After the iteration is completed, the automatic picking of the first arrival wave is completed. It should be noted that the end of the iteration means that it is automatically ended after the specified number of iterations is completed or when the time difference between the first arrival wave picking points of more than 95% of the input and output is less than 15 milliseconds. After the iteration is completed, the following is obtained Figure 5 The schematic diagram of the first arrival wave time (white) and the first arrival guide line (black) shown shows that the final first arrival guide line is more consistent with the first arrival time.

[0097] Example 3

[0098] On the basis of Example 1 or Example 2, this embodiment further provides a computer-readable storage medium, which stores a computer program. Running the computer program can execute the above-mentioned method for automatically picking first-arrival waves based on the iteration method.

[0099] Furthermore, this embodiment also provides a processor, which can run a computer program stored in a computer-readable storage medium.

[0100] Example 4

[0101] The present invention applies the method described in Example 2 to a certain actual working condition for verification, and the specific verification results are as follows: Figure 6 As shown, Figure 6 The upper part of the figure is a schematic diagram after the first picking, and the lower part is a schematic diagram of the final picking result after the iteration is completed. By comparison, it can be seen that the present invention determines the first arrival guide lines of single shots of different lithologies after sequentially performing observation processing, preprocessing and lithology classification on the seismic data of all single shots, and then replaces the original first arrival guide lines by forming new first arrival guide lines based on the first arrival wave picking points without abnormalities. Repeating the replacement by iteration multiple times can realize the picking of first arrival waves faster and more accurately, and has the advantages of higher picking efficiency and higher accuracy.

[0102] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all methods or steps in the process, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. The method of automatic first arrival wave picking based on iteration method is characterized by The following steps are involved: Step 1: Obtain the seismic data of all single shots, and perform observation processing, preprocessing and lithology classification processing on the seismic data in turn; Step 2: Based on the seismic data after lithology classification, multiple single shots with different lithologies are selected, the offset distances and linear velocities of these single shots are obtained, and the first arrival guide lines of the single shots with different lithologies are determined in combination with the time shift; Step 3: Based on the first arrival guide line, a time window containing all the first arrival waves of single shots is opened up and down, and the first arrival waves of the seismic data of all single shots are automatically picked up within the time window, and the first arrival wave picking points of all single shots are obtained after picking up; Step 4: Based on the principle that the first arrival times of adjacent single shot records are similar at the same receiving point, set the correlation coefficient to adjust the accuracy of all first arrival wave picking points, and remove abnormal first arrival wave picking points after adjustment; Step 5: Re-determine a new first arrival guide line based on the remaining first arrival wave picking points, and then use the new first arrival guide line to replace the first arrival guide line in step 2; Step 6: Repeat steps 3-5 for multiple iterations by gradually narrowing the time window and adjusting the correlation coefficient. After the iterations are completed, the automatic picking of the first arrival wave is completed.

2. The method for automatically picking first arrival waves based on iteration method according to claim 1, characterized in that: In step 2, the first arrival guide line of single shots of different lithologies is determined based on the functional relationship curve of offset distance, linear velocity and time displacement. 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 displacement.

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

4. The method for automatically picking first arrival waves based on iteration method according to claim 1, characterized in that: The method for adjusting the accuracy of all first arrival wave picking points based on the correlation coefficient in step 4 is: sort all single shots in order of spatial position, and based on the principle that the first arrival wave morphology of two adjacent single shots at the same detection point is basically the same, use the correlation coefficient to adjust the first arrival wave picking points of all single shots.

5. The method for automatically picking first arrival waves based on iteration method according to claim 1, characterized in that: The abnormal first arrival wave picking point in step 4 refers to the first arrival wave picking point with a correlation coefficient less than 0.5 or located outside the time window.

6. The method for automatically picking first arrival waves based on iteration 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 increasing it by 0.1 each time.

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

8. The method for automatically picking first arrival waves based on iteration method according to claim 1, characterized in that: The preprocessing in step 1 refers to the data truncation, elevation static correction, denoising and automatic gain processing of the seismic data in sequence, where: The data truncation process refers to truncating the length of the data in the seismic data to include the earthquake first arrival wave; The automatic gain refers to gaining the data after denoising so that the amplitude energy of all data is consistent.

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

10. A processor, characterized in that: The processor is used to run the computer program stored in the computer-readable storage medium according to claim 9.

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