Seismic data dynamic correction stretching removal method

Abstract

The invention relates to a seismic data dynamic correction stretching resection method, which belongs to the technical field of seismic exploration, and comprises the following steps: determining a common midpoint gather data resection position to obtain an initial resection library, and generating an initial stacked section by using the initial resection library; the method comprises the following steps: performing offset grouping on seismic data according to offsets, generating limited offset stacking sections in different ranges, comparing the limited offset stacking sections in different ranges to select an optimal limited offset stacking section, and comparing the optimal limited offset stacking section with an initial stacking section, the initial resection library is modified according to the comparison result, and the initial superposition section is compared with the optimal limited offset superposition section, so that the position needing to be resection can be more accurately obtained, the loss of effective signals is reduced, the processing effect of amplitude preservation and fidelity is achieved, the workload and time of manual adjustment of shallow resection are reduced, and the working efficiency is improved. And meanwhile, the accuracy of cutting off the near-offset shallow layer of the seismic data is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of seismic exploration, and particularly relates to a method for cutting off stretch distortion of seismic data. BACKGROUND

[0002] In the process of seismic data processing, the cutting off of stretch distortion is an indispensable step in pre-processing and is also a key step in the processing of shallow data. Since the shallow data is greatly affected by acquisition factors, the incidence angle and reflection angle thereof are greater than those of medium-deep data. After dynamic correction, dynamic correction stretch is very serious. Dynamic correction is to provide basic data for common-midpoint stacking and is also an indispensable step in the processing of seismic data. Since the information of far traces is less than that of near traces before dynamic correction, especially the far traces of shallow data only have a few sampling points or even none. However, after dynamic correction, the sampling points of far traces and near traces are the same. Therefore, the extra sampling points are generated by waveform stretch, and thus stretch distortion is generated. In order to reduce the influence of dynamic correction stretch, the direct method for solving stretch distortion in actual processing is cutting off. Since the coverage number of shallow data is low, the cutting off processing should be very fine for the processing of shallow data. In theory, when the stretch distortion of dynamic correction is greater than 1 / 3 wavelength, the stacking effect will be seriously affected. Therefore, the cutting off of stretch distortion of shallow refracted waves generated after dynamic correction is a key step in the processing of shallow data. If the stretch distortion information of shallow refracted waves generated after dynamic correction cannot be accurately cut off, the subsequent imaging will be affected, the data will be lost or false seismic imaging will be caused, and thus the understanding of seismic profile will be affected. With the continuous progress of technical methods, the cutting off method is also continuously updated and optimized.

[0003] At present, the method for cutting off seismic data is mainly to manually pick up the cutting off position of stretch distortion of refracted waves generated by dynamic correction stretch at far offset on common-midpoint gathers (CMP) by relying on the working experience accumulation of workers. When the seismic data is complex and the cutting off position of CMP gathers at near offset is difficult to grasp by manual picking, the shallow data may be lost or insufficiently cut off. The seismic data processing personnel may spend a long time and cannot obtain accurate cutting off. The working efficiency and quality cannot be guaranteed, the accuracy of data cannot be quickly and accurately grasped, and the imaging of shallow data at near offset is affected. Therefore, the cutting off technology of shallow data at near offset of seismic data needs to be further improved. SUMMARY

[0004] The present application aims to provide a method for cutting off stretch distortion of seismic data, so as to solve the problem of low cutting off accuracy caused by manual cutting off of shallow data at near offset of seismic data.

[0005] To solve the above technical problems, the application provides a method for cutting off the stretching of seismic data, which comprises the following steps:

[0006] 1) determining an initial cutting position on the seismic data arranged according to the common midpoint gather, generating an initial cutting library by using the initial cutting position, and generating an initial stacking profile by using the initial cutting library;

[0007] 2) grouping the seismic data according to the offset distance, and generating different range limited offset stacking profiles by using different range offset distances in the offset distance group;

[0008] 3) comparing the different range limited offset stacking profiles with each other to select an optimal limited offset stacking profile, and comparing the optimal limited offset stacking profile with the initial stacking profile, if the parameter performance of the optimal limited offset stacking profile is better than that of the initial stacking profile, determining the initial stacking profile modification range according to the parameter performance, and modifying the initial cutting library according to the initial stacking profile modification range.

[0009] Further, the parameters include the shallow signal-to-noise ratio, and the parameter performance of the limited offset stacking profile is better than that of the initial stacking profile means that the shallow signal-to-noise ratio of the limited offset stacking profile is higher than that of the initial stacking profile.

[0010] Further, the specific steps for modifying the initial cutting library are determining the common depth point range, time and offset distance to be modified according to the comparison between the limited offset stacking profile and the initial stacking profile, and modifying the time and offset distance in the initial cutting library in the corresponding common depth point range.

[0011] Further, if the common depth point range to be modified only has an upper limit or a lower limit in the initial cutting library, the lower limit or the upper limit of the common depth point range is added, the data of the upper limit or the lower limit of the common depth point range in the initial cutting library is copied to the added common depth point, and the time and offset distance of the upper limit or the lower limit of the common depth point range and the added common depth point in the initial cutting library are modified.

[0012] Further, if the upper limit and the lower limit of the common depth point range to be modified do not exist in the initial cutting library, the upper limit and the lower limit of the common depth point range are added, the data of the nearest common depth point is copied to the upper limit and the lower limit, and the time and offset distance of the added upper limit and lower limit in the initial cutting library are modified.

[0013] Further, if the common depth point range to be modified does not contain the time to be modified, the time and offset distance to be modified are added in the common depth point range to be modified.

[0014] The beneficial effects of the above technical solutions are: the present application is an improved invention, the present application obtains an initial cutout library by determining the cutout position of common center point gather data and generates an initial stack profile using the initial cutout library, groups the seismic data according to offset distance and generates limited offset stack profiles of different ranges, compares the limited offset stack profiles of different ranges with each other to select an optimal limited offset stack profile, compares the optimal limited offset stack profile with the initial stack profile, modifies the initial cutout library according to the comparison result, compares the initial stack profile with the optimal limited offset stack profile to obtain the position that needs to be cut out more accurately, reduces the loss of effective signals, achieves the processing effect of amplitude preservation and fidelity, reduces the workload and time of manual adjustment of shallow layer cutout, and improves the accuracy of cutout of near offset shallow layer of seismic data. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a method flowchart of the cutout method for seismic data dynamic correction stretching of the present application;

[0016] Figure 2 is a CMP gather schematic diagram of the cutout method for seismic data dynamic correction stretching of the present application;

[0017] Figure 3 is an initial cutout library schematic diagram of the cutout method for seismic data dynamic correction stretching of the present application;

[0018] Figure 4 is an initial cutout library stack profile schematic diagram of the cutout method for seismic data dynamic correction stretching of the present application;

[0019] Figure 5 is offset distance grouping of the cutout method for seismic data dynamic correction stretching of the present application;

[0020] Figure 6 is a 0-50m offset distance stack profile schematic diagram of the cutout method for seismic data dynamic correction stretching of the present application;

[0021] Figure 7 is a 0-130m offset distance stack profile schematic diagram of the cutout method for seismic data dynamic correction stretching of the present application;

[0022] Figure 8 is a 0-210m offset distance stack profile schematic diagram of the cutout method for seismic data dynamic correction stretching of the present application;

[0023] Figure 9 is a 0-290m offset distance stack profile schematic diagram of the cutout method for seismic data dynamic correction stretching of the present application;

[0024] Figure 10 is a schematic diagram of a 0-370m offset stack section of a seismic data moveout stretch cut method embodiment of the present application;

[0025] Figure 11 is a schematic diagram of a 0-450m offset stack section of a seismic data moveout stretch cut method embodiment of the present application;

[0026] Figure 12 is a schematic diagram of a 0-530m offset stack section of a seismic data moveout stretch cut method embodiment of the present application;

[0027] Figure 13 is a schematic diagram of a modified cut library of a seismic data moveout stretch cut method embodiment of the present application;

[0028] Figure 14 is a schematic diagram of a cut completed seismic section of a seismic data moveout stretch cut method embodiment of the present application;

[0029] Figure 15 is a schematic diagram of a conventional CMP gather cut stack section of a seismic data moveout stretch cut method embodiment of the present application;

[0030] Figure 16 is a schematic diagram of a modified cut stack section according to offset of a seismic data moveout stretch cut method embodiment of the present application. DETAILED DESCRIPTION

[0031] The present application focuses on providing a seismic data moveout stretch cut method, comprising the following steps:

[0032] 1) determining an initial cut position on seismic data arranged according to common midpoint gather, generating an initial cut library using the initial cut position, and generating an initial stack section using the initial cut library;

[0033] 2) grouping the seismic data according to offset size, and generating different range limited offset stack sections using different range offsets in the offset group;

[0034] 3) comparing different range limited offset stack sections to select an optimal limited offset stack section, and comparing the optimal limited offset stack section with the initial stack section, if the parameter performance of the optimal limited offset stack section is superior to that of the initial stack section, determining an initial stack section modification range according to the parameter performance, and modifying the initial cut library according to the initial stack section modification range.

[0035] The present invention obtains an initial resection library by determining the resection position of the common center point gather data and generates an initial stacking section using the initial resection library, groups the seismic data according to the offset distance and generates stacking sections with limited offset distances in different ranges, compares the stacking sections with limited offset distances in different ranges with each other to select the optimal stacking section with limited offset distances, and then compares the optimal stacking section with the initial stacking section. According to the comparison result, the initial resection library is modified, and the position to be resected is obtained more accurately by comparing the initial stacking section with the optimal stacking section with limited offset distances, thereby reducing the loss of effective signals, achieving the processing effect of maintaining amplitude and fidelity, reducing the workload and time of manual adjustment of shallow resection, and improving the accuracy of resection of shallow layers near the offset of seismic data.

[0036] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0037] Example of a method for removing seismic data by dynamic correction stretching:

[0038] A method for resectioning of seismic data dynamic correction stretching in this embodiment is to group the near offset distances in the common center point gather (CMP) into different ranges and then perform stacking processing, and determine the need to modify the resection range based on the comparison of the superimposed sections of the limited offset distances in different ranges. When shallow resection is difficult to grasp, this method can more efficiently and accurately determine the shallow resection position. It effectively solves the problem of not being able to efficiently and accurately resection the stretched distortion information generated by the shallow refraction wave after dynamic correction. The specific process of this method is as follows Figure 1 As shown, the following uses a certain 3D seismic data as an example to explain the specific implementation process of this method in detail. Specifically, it includes the following steps:

[0039] 1) Prepare the common midpoint gather (CMP), the common midpoint gather is as follows Figure 2 As shown, manual excision is performed to obtain the initial excision library, as shown in Figure 3 As shown; the initial superposition section generated using the initial resection library is as follows Figure 4 As shown. Figure 2 and Figure 3 It can be seen that the resection library is mainly determined by the common depth point (cdp), time and offset. Figure 2 The CMP gather is the correspondence between time and offset, with the horizontal direction representing offset and the vertical direction representing time. Figure 3 In the shown resection library, the green area represents the cdp value, M represents time, and X represents offset.

[0040] 2) Group the offsets to obtain offset values ​​in different ranges from small to large, such as Figure 5As shown in the table, R1 represents the serial number, which means that the offset distance is divided into 25 groups, R2 represents the offset distance range value, which is 0-50m offset distance range, 0-90m offset distance range, 0-130m offset distance range, and so on.

[0041] The interval of offset distance grouping is determined according to the size of the offset distance of the seismic data. Since the offset distance of the data is 40m, the offset distance is gradually increased by 40, that is, 50, 90, 130, 170, 210, and so on. According to the situation of the seismic data, the maximum offset distance grouping value is determined.

[0042] 3) Organize the limited offset stacking operation, and generate limited offset stacking profiles in different offset distances by using the offset distance grouping in step 2), as shown in the table. Figures 6-12 Figure 6 0-50m limited offset stacking profile is shown in the table. Figure 7 0-130m limited offset stacking profile is shown in the table. Figure 8 0-210m limited offset stacking profile is shown in the table. Figure 9 0-290m limited offset stacking profile is shown in the table. Figure 10 0-370m limited offset stacking profile is shown in the table. Figure 11 0-450m limited offset stacking profile is shown in the table. Figure 12 0-530m limited offset stacking profile is shown in the table.

[0043] 4) According to the different limited offset stacking profiles obtained in step 3), the optimal limited offset stacking profile is selected by comparing different range limited offset stacking profiles with each other. Then, the optimal limited offset stacking profile is compared with the initial stacking profile generated in step 1) for analysis. It is analyzed whether the shallow signal-to-noise ratio of the optimal limited offset stacking profile is higher than that of the initial stacking profile. If the shallow signal-to-noise ratio of the optimal limited offset stacking profile is higher than that of the initial stacking profile, the initial cutout library needs to be modified, and the offset distance size is the offset distance value that needs to be modified. Otherwise, it is not necessary to modify. After the comparison is completed, the cutout position that needs to be modified, that is, the offset distance value, the cdp range on the limited offset stacking profile, and the time corresponding to the cdp are determined. As shown in the table. Figure 3 ​The purple area in the figure is the determined range of the cutout to be modified, and there are four places, for example, the first place, after superimposing the different limited offset distance profiles and comparing them with the initial superimposed profile, the limited offset distance profile of 0-290 meters at the cdp range of 1310-1360 and the time of 110 ms has a higher signal-to-noise ratio, so the first place of the cutout cdp range to be modified is 1310-1360, and the corresponding time M = 110 ms and the offset distance X = 290 meters; similarly, the second place of the cdp range is 1370-1680, the corresponding time M = 220 ms and the offset distance X = 490 meters; the third place of the cdp range is 1700-1840, the corresponding time M = 110 ms and the offset distance X = 210 meters; and the fourth place of the cdp range is 1850-1920, the corresponding time M = 220 ms and the offset distance X = 490 meters. The positions of the four places on the superimposed profile are as shown in Figure 4 The blue, red and yellow boxes are used to enclose them, respectively.

[0044] 5) Determine the modified cdp, time and offset distance range according to step 4), and modify the time and offset distance values in the cutout library within the corresponding cdp range, as shown in Figure 13 The red and blue colors represent the modified positions, for example, the first place, the cdp range determined according to step 4 is 1310-1360, and the corresponding cdp in the initial cutout library is 1310-1680, so a cdp = 1360 cutout line control needs to be added after 1310, and the cutout point of cdp = 1310 is copied to cdp = 1360, according to the time M = 110 ms and the offset distance X = 290 meters determined in step 4, so the original M = 110 and X = 450 corresponding to cdp = 1310 and 1360 are modified to M = 110 and X = 290; similarly, the second place of the cdp range is 1370-1680, so a cdp = 1370 control needs to be added after 1360, and the corresponding time is M = 220 ms and the offset distance is X = 490 meters, so a time and offset distance control point of M = 220 and X = 490 is added after M = 110 and X = 450. The last two places are modified in the same way, and after the modification is completed, the cutout library modified according to the scanning limited offset distance superimposed profile is obtained. If the upper limit and the lower limit of the common depth point range to be modified do not exist in the initial cutout library, the upper limit and the lower limit of the common depth point range are added, and the upper limit and the lower limit are respectively copied to the nearest common depth point data added to the upper limit and the lower limit, and the time and offset distance of the upper limit and the lower limit added in the initial cutout library are modified.

[0045] 6) Use the new cutout library modified in step 5) to superimpose to obtain the modified superimposed profile, as shown in Figure 14 The same as Figure 4It can be seen that the shallow modification is obviously improved in all aspects, and the signal-to-noise ratio is improved.

[0046] To sum up, the method of the present application takes different range limited offset stack sections as targets, first groups the shallow near offset distance, generates multiple limited offset stack sections, compares different limited offset stack sections with each other to select the optimal limited offset stack section, compares the optimal limited offset stack section with the initial stack section to determine the cdp range, corresponding time and offset distance that need to be modified, modifies the initial cutout library, and finally obtains the modified cutout generated stack seismic section. The conventional CMP gather cutout stack section is specifically as shown in Figure 15 The modified cutout stack section according to the offset distance is as shown in Figure 16 .

[0047] The above gives a specific implementation, but the present application is not limited to the described implementation. The basic idea of the present application is the above basic scheme, and according to the teaching of the present application, various deformed models, formulas and parameters can be designed without creative labor for ordinary skilled in the art. Changes, modifications, replacements and variations of the implementation without departing from the principles and spirits of the present application still fall within the protection scope of the present application.

Claims

1. A method for removing stretching of seismic data by dynamic correction, characterized in that: The following steps are involved: 1) determining an initial resection position on seismic data arranged according to a common center point gather, generating an initial resection library using the initial resection position, and generating an initial stacking section using the initial resection library; 2) grouping the seismic data according to the offset size, and generating offset-limited stack sections of different ranges using offsets of different ranges in the offset group; 3) The limited offset stacking sections of different ranges are compared with each other to select the optimal limited offset stacking section, and then the optimal limited offset stacking section is compared with the initial stacking section. If the parameter performance of the optimal limited offset stacking section is better than that of the initial stacking section, the modification range of the initial stacking section is determined according to the parameter performance, and the initial resection library is modified according to the modification range of the initial stacking section.

2. The seismic data dynamic correction stretching removal method according to claim 1, characterized in that: The parameters include shallow layer signal-to-noise ratio. The parameter performance of the limited offset stack section is better than the parameter performance of the initial stack section, which means that the shallow layer signal-to-noise ratio of the limited offset stack section is higher than the shallow layer signal-to-noise ratio of the initial stack section.

3. The method for removing seismic data by dynamic correction stretching according to claim 1, characterized in that: The specific steps for modifying the initial resection library are to determine the common depth point range, time and offset that need to be modified based on the comparison of the limited offset stacking section and the initial stacking section, and to modify the time and offset in the initial resection library within the corresponding common depth point range.

4. The method for removing seismic data by dynamic correction stretching according to claim 3, characterized in that: If the common depth point range to be modified only has the upper or lower limit of the common depth point range to be modified in the initial resection library, then add the lower or upper limit of the common depth point range that does not exist, and copy the upper or lower limit data of the common depth point range in the initial resection library to the added common depth point, and modify the upper or lower limit of the common depth point range in the initial resection library and the time and offset of the added common depth point.

5. The method for removing seismic data by dynamic correction stretching according to claim 3, characterized in that: If the upper and lower limits of the common depth point range that need to be modified do not exist in the initial resection library, then add the upper and lower limits of the common depth point range, copy the common depth point data closest to the upper limit and add it to the upper limit, copy the common depth point data closest to the lower limit and add it to the lower limit, and modify the time and offset of the upper and lower limits added in the initial resection library.

6. The method for removing seismic data by dynamic correction stretching according to claim 3, 4 or 5, characterized in that: If the time to be modified is not included in the range of the common depth points to be modified, add the time to be modified and the offset to the range of the common depth points to be modified.

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