A method for extracting data from cross-domain gathers of irregular 3D seismic data

Abstract

The present invention relates to a method for extracting cross-domain gather data from irregular three-dimensional seismic data, and belongs to the technical field of seismic data processing. The method includes: obtaining the actual excitation line number and the actual excitation point number of the excitation point that deviates from the theoretical excitation line; calculating the theoretical excitation line number corresponding to the actual excitation line number based on the actual excitation line number, the theoretical initial excitation line number, and the excitation line distance and the longitudinal excitation grid point distance; obtaining the offset distance based on the actual excitation line number and the theoretical excitation line number corresponding thereto; obtaining the new pile number of the excitation point that deviates from the theoretical excitation line based on the obtained offset distance, the theoretical excitation line number corresponding to the actual excitation line number, and the actual excitation point number; using the new pile number as the new number of the excitation point that deviates from the theoretical excitation line, and extracting cross-domain gather data according to the new number. The present invention extracts more complete cross-domain gather data, and thus can better suppress interference in the expanded cross-domain noise suppression processing work.

Description

Technical Field

[0001] The invention relates to a method for extracting cross-domain gather data of irregular three-dimensional seismic data, and belongs to the technical field of seismic data processing. Background Art

[0002] Surface waves and refracted waves are the two most common types of linear regular interference waves in land seismic acquisition. Surface waves are typically characterized by low frequency, low velocity, and high energy, while refracted waves generally have higher velocities and a wide frequency distribution. Various linear interferences typically appear as regular linear patterns in near-offset records in 3D seismic recordings, while they appear as hyperbolic patterns in far-offset records.

[0003] Currently, the industry generally uses cross-domain processing methods to suppress linear interference such as surface rolls. For example, 3DFKK (three-dimensional FK filtering) filters cross-domain gathers extracted from regularized 3D seismic data. Many other researchers have also conducted extensive research on noise suppression techniques for 3D seismic data in the cross-domain. However, any cross-domain processing method requires cross-domain gather data as a technical foundation, and cross-domain gather data are based on regularized 3D seismic data, which requires a regular arrangement of excitation points.

[0004] However, although the designers will design the locations of the excitation points (i.e., shot points) and receiver points in the acquisition area before collecting seismic data, in order to ensure the uniformity of the number of coverage and the uniformity of the distribution of vector units within the surface element, the layout of the excitation points is as evenly distributed as possible on the plane. However, in the actual construction process, due to the influence of complex surface topography and obstacles, the layout of the excitation points can no longer be distributed in a linear and uniform form. The distribution is random, and many excitation points deviate from the original design position (in the design process, in order to facilitate positioning, the pile number arrangement of the shot point usually adopts a design that changes with the spatial coordinates), making the arrangement of the excitation points irregular, which will lead to the following results: Figure 1a 、 Figure 1b As shown in the figure (the horizontal lines are detection lines, and the vertical intermittent lines are excitation lines), the extracted cross-domain intersection gather data are missing (the blank areas in the figure are missing data), and interference suppression cannot be effectively performed, which leads to low accuracy of subsequent work. Summary of the Invention

[0005] The purpose of this application is to provide a method for extracting cross-domain gather data from irregular three-dimensional seismic data, so as to solve the problem that the existing extracted cross-domain intersection gather data is missing and interference suppression cannot be effectively performed.

[0006] To achieve the above objectives, the present application proposes a technical solution for extracting cross-domain gather data from irregular 3D seismic data, comprising the following steps:

[0007] 1) obtaining an actual excitation line number and an actual excitation point number where an excitation point deviates from a theoretical excitation line, wherein the theoretical excitation line is a pre-designed excitation line;

[0008] 2) calculating the theoretical excitation line number corresponding to the actual excitation line number based on the actual excitation line number, the theoretical initial excitation line number, and the excitation line spacing and the longitudinal excitation grid point spacing;

[0009] 3) Obtain the offset distance based on the actual excitation line number and its corresponding theoretical excitation line number;

[0010] 4) Obtaining a new stake number of the excitation point that deviates from the theoretical excitation line based on the obtained offset distance, the theoretical excitation line number corresponding to the actual excitation line number, and the actual excitation point number;

[0011] 5) The new pile number is used as the new number of the excitation point that deviates from the theoretical excitation line, and the cross-domain gather data is extracted according to the new number.

[0012] The beneficial effect of the technical solution of the method for extracting cross-domain gather data from irregular three-dimensional seismic data of the present invention is as follows: the present invention calculates the theoretical excitation line number close to the actual excitation line number of the excitation point that deviates from the theoretical excitation line, and then renumbers the pile number of the excitation point that deviates from the theoretical excitation line on the theoretical excitation line number, and calculates the offset distance so that the renumbering will not be repeated. Thus, when extracting the cross-domain gather data, the information of the excitation point that deviates from the theoretical excitation line is not lost. The present invention can extract more complete cross-domain gather data, and further, in the expanded cross-domain noise suppression processing work, it can better suppress interference such as surface waves and refraction waves in irregular three-dimensional seismic data, thereby improving the data signal-to-noise ratio.

[0013] Furthermore, the calculation process of the theoretical excitation line number corresponding to the actual excitation line number in step 2) includes:

[0014] A2=A1+int((A-A1) / B)*B;

[0015] B=B1 / B2;

[0016] Among them, A2 is the theoretical excitation line number corresponding to the actual excitation line number; A1 is the theoretical initial excitation line number; A is the actual excitation line number where the excitation point deviates from the theoretical excitation line; B1 is the excitation line distance; B2 is the longitudinal excitation grid point distance.

[0017] Furthermore, the calculation process of the offset distance in step 3) includes:

[0018] dist=A-A2;

[0019] Where dist is the offset distance; A2 is the theoretical excitation line number corresponding to the actual excitation line number; and A is the actual excitation line number where the excitation point deviates from the theoretical excitation line.

[0020] Furthermore, the calculation process of the new stake number of the excitation point deviating from the theoretical excitation line in step 4) includes:

[0021] Nshotstation=A2*100000+C*10+dist;

[0022] Among them, Nshotstation is the new stake number of the excitation point that deviates from the theoretical excitation line; A2 is the theoretical excitation line number corresponding to the actual excitation line number; C is the actual excitation point number where the excitation point deviates from the theoretical excitation line; dist is the offset distance.

[0023] Furthermore, before extracting data, a step of pre-processing the three-dimensional seismic data is also included, and the pre-processing includes industrial power interference suppression and abnormal amplitude suppression.

[0024] Furthermore, abnormal amplitude suppression is performed by using abnormal amplitude attenuation technology.

[0025] Furthermore, the pre-processing also includes static correction processing on the floating surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1a It is the distribution of excitation points and detection points on the cross domain when the existing technology extracts the gather according to the theoretical excitation line;

[0027] Figure 1b It is a schematic diagram of the prior art for extracting cross-domain gather data according to theoretical excitation lines;

[0028] Figure 2 This is a flow chart of the method for extracting data from cross-domain gathers of irregular three-dimensional seismic data according to the present invention;

[0029] Figure 3a The distribution of the excitation points and the detection points on the cross domain when the present invention extracts the gather according to the theoretical excitation line;

[0030] Figure 3b Schematic diagram of extracting cross-domain gather data according to theoretical excitation lines in the present invention;

[0031] Figure 4 This is a schematic diagram of a cross-domain interference suppression record obtained by the extraction method of the prior art;

[0032] Figure 5 It is a schematic diagram of the cross-domain interference suppression record obtained by the extraction method of the present invention. DETAILED DESCRIPTION

[0033] Example of a method for extracting cross-domain gather data from irregular 3D seismic data:

[0034] The main idea of ​​the present invention is to solve the problem of missing cross-domain gather data due to the irregular arrangement of excitation points. The present invention renumbers the pile numbers of the excitation points that deviate from the theoretical excitation line, so that the excitation points that deviate from the theoretical excitation line are projected onto the theoretical excitation line. The cross-domain gather data are extracted according to the new numbering, and the complete cross-domain gather data can be extracted.

[0035] Specifically, the method for extracting cross-domain gather data from irregular three-dimensional seismic data of the present invention is as follows: Figure 2 As shown, the following steps are included:

[0036] 1) Acquire 3D seismic data, pre-process the 3D seismic data, and extract the shot gather data into the cross domain.

[0037] The 3D seismic data includes the stake number, position coordinates and corresponding shot gather data of each excitation point.

[0038] The number of digits in the excitation point's stake number is determined by the shot line distance and the longitudinal grid distance of the shot point, that is, the excitation line distance and the longitudinal grid distance of the excitation point. In this embodiment, the excitation point's stake number is eight digits, with the first four digits representing the excitation line number on which the excitation point is located, and the last four digits representing the excitation point number on which the excitation point is located. The actual stake number of the excitation point is generally the same as its position on the planar grid of the work area.

[0039] The preprocessing of 3D seismic data includes: loading the observation system, removing 50Hz industrial electrical interference, and amplitude suppression. Abnormal amplitude attenuation technology is used to suppress abnormal amplitudes of traces. The preprocessed data is then sorted and the shot gather data is extracted into the cross-domain. The primary index of the cross-domain gather data is the receiving line, and the secondary index is the excitation line and excitation point.

[0040] At the same time, whether to perform floating surface static correction processing depends on the complexity of the data in the target area. For example, in areas with complex surface types, drastic changes in elevation and complex seismic wave fields, surface waves, refracted waves, etc. are reflected in a disorderly manner, which is not conducive to cross-domain wave field analysis. In this case, floating surface static correction processing must be performed. If the elevation change is small and the wave field is stable, static correction processing can be omitted.

[0041] The specific process of pretreatment is prior art and will not be introduced in detail here.

[0042] 2) Determine the actual excitation line number A and the actual excitation point number C where the excitation point deviates from the theoretical excitation line.

[0043] In the actual construction process, no matter how the actual position of the excitation point changes, there is a theoretical excitation line in the theoretical design, that is, the theoretical excitation line is a pre-designed excitation line.

[0044] 3) According to the actual excitation line number, the theoretical initial excitation line number, the excitation line distance and the longitudinal excitation grid point distance, the theoretical excitation line number corresponding to the actual excitation line number is calculated.

[0045] The specific calculation process of the theoretical excitation line number corresponding to the actual excitation line number is:

[0046] A2=A1+int((A-A1) / B)*B;

[0047] B=B1 / B2;

[0048] Among them, A2 is the theoretical excitation line number corresponding to the actual excitation line number; A1 is the theoretical initial excitation line number; A is the actual excitation line number where the excitation point deviates from the theoretical excitation line; B1 is the excitation line distance; B2 is the longitudinal excitation grid point distance.

[0049] The theoretical initial excitation line number A1 is the line number of the initial excitation line in the theoretical design, the excitation line distance B1 is the distance between the excitation lines, which is 300 meters in this embodiment, and the longitudinal excitation grid point distance B2 is the longitudinal distance between the grids where the excitation points are located, which is 50 meters in this embodiment, that is, B=6 in this embodiment.

[0050] For example, the theoretical initial excitation line number A1=1072, the actual excitation line number A=1079, and the theoretical excitation line number A2 corresponding to the actual excitation line number is obtained to be 1078.

[0051] 4) Obtain the offset distance dist according to the actual excitation line number A and its corresponding theoretical excitation line number A2.

[0052] The offset distance dist is the difference between the actual excitation line number A and its corresponding theoretical excitation line number A2, that is, dist=A-A2.

[0053] 5) Obtain a new stake number of the excitation point that deviates from the theoretical excitation line according to the obtained offset distance dist, the theoretical excitation line number A2 corresponding to the actual excitation line number, and the actual excitation point number C in step 2).

[0054] The purpose of the offset distance dist is to avoid duplication in subsequent renumbering. In this embodiment, if there are multiple excitation lines that deviate from the theoretical excitation line and have the same actual excitation point number, duplicate new pile numbers will occur. The offset distance dist can be used to distinguish these new pile numbers.

[0055] The calculation process of the new pile number includes:

[0056] Nshotstation=A2*100000+C*10+dist;

[0057] Where Nshotstation is the new shot number of the excitation point that deviates from the theoretical excitation line. The original actual shot number is eight digits. From the above formula, we can see that the new shot number is nine digits.

[0058] 6) The new pile number is used as the new number of the excitation point that deviates from the theoretical excitation line, and the cross-domain gather data is extracted according to the new number.

[0059] According to the extraction method of the present invention, the following can be extracted: Figure 3a 、 3b The complete cross-domain gather data is shown. After extraction, cross-domain processing is performed: in the cross-domain, high-precision FK spectra can be generated at different receiver locations. The dispersion curve of each surface roll can be manually or automatically picked up. A joint simulation based on the dispersion curve and seismic data is then performed to predict surface roll noise and scattering. Finally, adaptive subtraction is used from the seismic data to suppress surface roll noise.

[0060] In the above embodiment, based on the numbering rule that the original pile number is eight digits, the calculation of the new pile number is as shown in the above formula. The calculation of the new pile number is related to the number of digits of the original pile number. The present invention does not limit the calculation process of the new pile number, as long as it can correspond to the original pile number and there is no duplication of numbers.

[0061] Regarding the subsequent processing of cross-domain gather data, 3DFKK (three-dimensional FK filtering), Swami (analysis and inversion modeling of surface waves) and other methods can be used to suppress linear interference and scattering interference such as surface waves. Figure 4 、 Figure 5 The interference suppression effect shown, Figure 4 The interference suppression effect after extracting cross-domain gather data with existing technology, Figure 5 In order to obtain the interference suppression effect after the cross-domain gather data are extracted by the method of the present invention, Figure 4 、 Figure 5 It can be seen in the circle Figure 5 The interference is better suppressed.

[0062] Based on the cross-domain gather data extracted by the present invention, by renumbering the pile numbers of the excitation points that deviate from the theoretical excitation line so that the new numbers are projected onto the theoretical excitation line, more complete cross-domain gather data can be extracted. Furthermore, through the noise suppression processing of the expanded cross domain, interference such as surface waves and refracted waves in irregular three-dimensional seismic data can be better suppressed, thereby improving the signal-to-noise ratio of the data.

Claims

1. A method for extracting cross-domain gather data from irregular 3D seismic data, characterized in that: The following steps are involved: 1) obtaining an actual excitation line number and an actual excitation point number where an excitation point deviates from a theoretical excitation line, wherein the theoretical excitation line is a pre-designed excitation line; 2) calculating the theoretical excitation line number corresponding to the actual excitation line number based on the actual excitation line number, the theoretical initial excitation line number, and the excitation line spacing and the longitudinal excitation grid point spacing; 3) Obtain the offset distance based on the actual excitation line number and its corresponding theoretical excitation line number; 4) Obtaining a new stake number of the excitation point that deviates from the theoretical excitation line based on the obtained offset distance, the theoretical excitation line number corresponding to the actual excitation line number, and the actual excitation point number; 5) The new pile number is used as the new number of the excitation point that deviates from the theoretical excitation line, and the cross-domain gather data is extracted according to the new number.

2. The method for extracting cross-domain gather data from irregular 3D seismic data according to claim 1, characterized in that: The calculation process of the theoretical excitation line number corresponding to the actual excitation line number in step 2) includes: A2=A1+int((A-A1) / B)*B; B=B1 / B2; Among them, A2 is the theoretical excitation line number corresponding to the actual excitation line number; A1 is the theoretical initial excitation line number; A is the actual excitation line number where the excitation point deviates from the theoretical excitation line; B1 is the excitation line distance; B2 is the longitudinal excitation grid point distance.

3. The method for extracting cross-domain gather data from irregular 3D seismic data according to claim 2, characterized in that: The calculation process of the offset distance in step 3) includes: dist=A-A2; Where dist is the offset distance; A2 is the theoretical excitation line number corresponding to the actual excitation line number; and A is the actual excitation line number where the excitation point deviates from the theoretical excitation line.

4. The method for extracting cross-domain gather data from irregular 3D seismic data according to claim 1, characterized in that: The calculation process of the new stake number of the excitation point deviating from the theoretical excitation line in step 4) includes: Nshotstation=A2*100000+C*10+dist; Among them, Nshotstation is the new stake number of the excitation point that deviates from the theoretical excitation line; A2 is the theoretical excitation line number corresponding to the actual excitation line number; C is the actual excitation point number where the excitation point deviates from the theoretical excitation line; dist is the offset distance.

5. The method for extracting cross-domain gather data from irregular 3D seismic data according to claim 1, characterized in that: Before extracting data, the three-dimensional seismic data is preprocessed, including industrial power interference suppression and abnormal amplitude suppression.

6. The method for extracting cross-domain gather data from irregular 3D seismic data according to claim 5, characterized in that: Abnormal amplitude suppression is performed through abnormal amplitude attenuation technology.

7. The method for extracting cross-domain gather data from irregular 3D seismic data according to claim 5, characterized in that: Preprocessing also includes static correction of floating surfaces.

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