Adaptive multiple reduction method based on primary wave protection

Abstract

The present invention belongs to the technical field of exploration data processing and specifically discloses a method for adaptively reducing multiples based on primary wave protection. Based on well data, the method first identifies primary and multiple wave regions through data calibration to obtain prior information about the primary waves. This prior information is then mathematically processed. Finally, this mathematically processed information is incorporated into the objective function of the adaptive reduction algorithm to solve and suppress the multiples, thereby achieving the goal of protecting the primary waves. This method integrates the prior information and the multiple wave model into the least squares method of the adaptive reduction algorithm, proposing a least squares adaptive reduction method based on prior information such as well data. The method of the present invention can effectively suppress multiples while protecting the primary waves. It is suitable for data processing involving both primary and multiple waves.

Description

Technical Field

[0001] The invention belongs to the technical field of exploration data processing, and relates to a method for suppressing multiple waves, in particular to a method for adaptively reducing multiple waves based on primary wave protection. Background Art

[0002] Multiples are a common type of interfering wave in seismic exploration. Their presence can distort the amplitude, frequency, and phase of effective reflections, significantly impacting the identification of the true attributes of the effective waves. Therefore, suppressing multiples is a critical step in processing seismic exploration data. Currently, there are two main methods for suppressing multiples: mathematical transformation algorithms based on the time difference between the primary and multiple waves, and adaptive subtraction algorithms. However, in actual data processing, the first method often proves ineffective due to the small time difference between the primary and multiple waves.

[0003] While the second method offers a wide variety of adaptive subtraction algorithms, such as pattern recognition adaptive subtraction and curvelet transform adaptive subtraction, each with its own specific application scenarios, their optimal application relies on two assumptions: orthogonality between significant waves and multiples, and wavelet consistency. When these assumptions are not met, the adaptive subtraction algorithm can suffer from undermatching or overmatching. These issues can lead to residual multiples or damage to the primary during the adaptive subtraction process. In particular, when the multiples and primary events intersect or nearly overlap, conventional adaptive subtraction algorithms struggle to protect the primary when suppressing the multiples. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for adaptively reducing multiple waves based on primary wave protection. By establishing a multiple wave model and primary wave prior information, performing mathematical processing, and utilizing the least squares method, the purpose of suppressing multiple waves by using the method for adaptively reducing multiple waves while protecting the primary wave is achieved.

[0005] To achieve the above-mentioned object, the present invention provides a method for adaptively reducing multiple waves based on primary wave protection, which comprises the following steps performed in sequence:

[0006] S1. Generate work area masking operator

[0007] Based on well data, using seismic records, VSP corridor stacked sections and acoustic logging synthetic record information, the data is calibrated in the stacked sections without multiple wavefronts to obtain the primary wave area and the multiple wave area;

[0008] The primary wave region and the multiple wave region both include coordinate information and time information;

[0009] If it is not marked as a multiple wave area, it is assigned a value of 0, and other areas are assigned a value of 1 to generate the work area masking operator f;

[0010] S2. Synthesizing prior information

[0011] Seismic data is calibrated by VSP corridor stacking sections and acoustic logging synthetic record information, and the horizon information is obtained by picking the primary wave phase axis.

[0012] Use acoustic logging to synthesize record information and layer information to synthesize a priori information of the primary wave There are m1 layers in total, written in matrix form, and we get the primary wave prior information X1;

[0013] S3. Prediction of Multiple Wave Model

[0014] The multiple wave model X2 is predicted by the multiple wave prediction algorithm, and the corrected multiple wave model X'2 is obtained by processing;

[0015] S4. Generate seismic sections with common offset and common azimuth

[0016] Perform dynamic correction processing and offset vector slice data domain sorting processing on the stacked section without multiple wavefronts to generate the seismic section Y with common offset and common azimuth;

[0017] S5. Establishing the objective function

[0018] For each offset vector slice data domain, in the sense of least squares, establish the objective function J(A) = argmin||Y-AX||+λA T A;

[0019] Where X = [X1, X'2], which represents the matrix composed of the primary wave prior information X1 and the multiple wave model X'2;

[0020] A=[A1,A2], where A1 represents the adaptive matching operator of the primary wave prior information X1, A2 represents the adaptive matching operator of the multiple wave model X'2, and A is the total adaptive matching operator;

[0021] λA T A is the regularization term, λ is the regularization parameter;

[0022] S6. Solve the objective function and suppress the multiple waves to obtain the seismic data after suppressing the multiple waves.

[0023] As a limitation of the present invention, in step S3, the predicted multiple wave model is There are m2 layers in total, written in matrix form, we get the multiple wave model X2;

[0024] The post-NMO multiple wave model X'2 is obtained by performing NMO processing and offset vector slice data domain sorting processing on the multiple wave model X2 to generate a seismic profile with common offset and common azimuth.

[0025] Among them, in step S5, the mathematically processed prior information is incorporated into the adaptive subtraction algorithm to achieve the purpose of protecting the primary wave.

[0026] As another limitation of the present invention, in step S6, the objective function is solved to obtain the total adaptive matching operator A and the matched multiple waves A2X2.

[0027] As a third limitation of the present invention, in step S6, the multiple wave suppression is performed by using the formula Y-fA2X'2 to obtain the seismic data after subtracting the multiple waves and then performing a reaction correction process to obtain the seismic data after suppressing the multiple waves.

[0028] As a fourth limitation of the present invention, the VSP corridor superimposed profile is obtained by processing VSP data.

[0029] As a fifth limitation of the present invention, the stacked section without multiple wavefronts is obtained by interpreting the primary wave velocity based on the acoustic logging velocity as a reference value and in combination with geological knowledge.

[0030] As a further limitation of the present invention, the geological knowledge includes acoustic wave velocity, lithology and structural information.

[0031] Due to the adoption of the above solution, the present invention has the following beneficial effects compared with the prior art:

[0032] The present invention uses prior information for adaptive subtraction to effectively protect the primary wave, while the conventional method in the industry does not use the prior information of the primary wave, but directly uses the original data and the predicted multiple wave model for adaptive subtraction, which is easy to damage the effective primary wave.

[0033] The present invention establishes a priori information of the primary wave, performs mathematical processing, and utilizes the improved least squares method to overcome the problems of insufficient matching and overmatching during adaptive matching, thereby making the adaptive subtraction process more fidelity. While protecting the primary wave, the multiple waves can be effectively suppressed by using the adaptive subtraction method of the multiple waves.

[0034] The invention is applicable to the multiple wave adaptive subtraction technology in exploration data processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 This is a seismic data diagram of suppressing multiple wavefronts in an embodiment of the present invention;

[0037] Figure 2 This is a diagram of seismic data obtained after suppressing multiple waves in an embodiment of the present invention;

[0038] Figure 3 This is a diagram of seismic data after multiple wave suppression obtained by conventional adaptive subtraction processing in an embodiment of the present invention.

[0039] Figure 4 This is a seismic data diagram showing the suppression of multiple wavefronts in Experiment I, which verifies the embodiment of the present invention;

[0040] Figure 5 This is a graph of the prior information of the primary wave obtained in Experiment I for verifying the embodiment of the present invention;

[0041] Figure 6 This is a multiple wave model diagram obtained in Experiment I for verifying the embodiment of the present invention;

[0042] Figure 7 This is a diagram of seismic data after suppressing multiple waves obtained in Experiment I, which verifies the embodiment of the present invention;

[0043] Figure 8 This is a diagram of seismic data after multiple wave suppression obtained by conventional adaptive subtraction processing in Experiment I, which verifies the embodiment of the present invention;

[0044] Figure 9 This is a seismic data diagram showing the suppression of multiple wavefronts in Experiment II, which verifies the embodiment of the present invention;

[0045] Figure 10 This is a diagram of the prior information of the primary wave in Experiment II for verifying the embodiment of the present invention;

[0046] Figure 11 This is a diagram of the multiple wave model used in Experiment II to verify the embodiment of the present invention;

[0047] Figure 12 This is a diagram of seismic data after suppressing multiple waves obtained in Experiment II to verify the embodiment of the present invention;

[0048] Figure 13 This is a diagram of seismic data after suppressing multiple waves obtained by conventional adaptive subtraction processing in Experiment II, which verifies the embodiment of the present invention. DETAILED DESCRIPTION

[0049] The present invention will be further described below with reference to the following embodiments. However, those skilled in the art should understand that the present invention is not limited to the following embodiments, and any improvements and equivalent changes made based on the specific embodiments of the present invention are within the scope of protection of the claims of the present invention.

[0050] Embodiment Multiple wave adaptive reduction method based on primary wave protection

[0051] In a field seismic survey, seismic data are obtained. In the seismic profile, multiple waves are intermittent high-frequency phase axes. Before suppressing the multiple waves, such as Figure 1 ,Affected by the multiple waves, the primary wave is seriously interfered by the multiple waves. If the multiple waves are suppressed by the conventional adaptive subtraction process, the primary wave event axis is easily damaged. Focus on the primary earthquake wave in the white box to observe whether the adaptive subtraction causes damage to the primary wave.

[0052] This embodiment is a method for adaptively reducing multiple waves based on primary wave protection. This method effectively suppresses high-frequency multiple waves while protecting the primary wave in seismic profile data.

[0053] (1) The specific method of this embodiment is as follows:

[0054] S1. Generate work area masking operator

[0055] Based on well data, using seismic records, VSP corridor stacked sections and acoustic logging synthetic record information, the data is calibrated in the stacked sections without multiple wavefronts to obtain the primary wave area and the multiple wave area;

[0056] The primary wave area and the multiple wave area both include coordinate information and time information;

[0057] If it is not marked as a multiple wave area, it is assigned a value of 0, and other areas are assigned a value of 1 to generate the work area masking operator f;

[0058] S2. Synthesizing prior information

[0059] Seismic data is calibrated by VSP corridor stacking sections and acoustic logging synthetic record information, and the horizon information is obtained by picking the primary wave phase axis.

[0060] Use acoustic logging to synthesize record information and layer information to synthesize a priori information of the primary wave There are m1 layers in total, written in matrix form, and we get the primary wave prior information X1;

[0061] S3. Prediction of Multiple Wave Model

[0062] Through the multiple wave prediction algorithm, the multiple wave model is predicted to be There are m2 layers in total, written in matrix form, we get the multiple wave model X2;

[0063] Performing dynamic correction processing and offset vector slice data domain sorting processing on the multiple wave model X2 to generate a seismic section with common offset and common azimuth to obtain the dynamic correction multiple wave model X'2;

[0064] S4. Generate seismic sections with common offset and common azimuth

[0065] Perform dynamic correction processing and offset vector slice data domain sorting processing on the stacked section without multiple wavefronts to generate the seismic section Y with common offset and common azimuth;

[0066] S5. Establishing the objective function

[0067] For each offset vector slice data domain, in the sense of least squares, establish the objective function J(A) = argmin||Y-AX||+λA T A;

[0068] Where X = [X1, X'2], which represents the matrix composed of the primary wave prior information X1 and the multiple wave model X'2;

[0069] A=[A1,A2], where A1 represents the adaptive matching operator of the primary wave prior information X1, A2 represents the adaptive matching operator of the multiple wave model X'2, and A is the total adaptive matching operator;

[0070] λA T A is the regularization term, λ is the regularization parameter;

[0071] S6. Solve the objective function and suppress the multiple waves to obtain the seismic data after suppressing the multiple waves.

[0072] Solve the objective function and obtain the total adaptive matching operator A and the matched multiple waves A2X2;

[0073] Using the formula Y-fA2X'2, we can get the seismic data after subtracting the multiple waves;

[0074] Among them, the seismic data after suppressing multiple waves, such as Figure 2 shown.

[0075] (2) Comparative Example:

[0076] This comparative embodiment uses conventional adaptive subtraction processing, that is, there is no prior information of the primary wave in the adaptive subtraction process, and the original data and the predicted multiple wave model are directly used for adaptive subtraction to obtain seismic data after suppressing the multiple waves, such as Figure 3 shown.

[0077] in, Figure 3 It is shown that conventional adaptive subtraction processing causes serious damage to the primary wave, e.g. Figure 1 The white box selects the area affected by multiple waves. Figure 3 The primary wave is severely damaged in the corresponding area, and the method of the present invention obtains Figure 2 The results show that compared with conventional adaptive subtraction processing, the present invention has a better primary wave protection effect when suppressing high-frequency multiple waves in seismic profile data processing.

[0078] (3) Verification experiment:

[0079] This experiment generates model data with known relevant information including prior information through forward modeling to verify whether the objective function containing prior information in the method of the present invention is effective.

[0080] Verification Experiment I is a case where the multiple waves and the primary wave phase axis cross, verifying whether the objective function containing prior information in the method of the present invention can effectively suppress the multiple waves.

[0081] S11. Data Preprocessing

[0082] Before suppressing multiple waves, the model data is generated by forward modeling, and the seismic data obtained are as follows: Figure 4 shown.

[0083] S12. Generate work area masking operator

[0084] Since this is model data and the multiple wave model is known, the multiple wave area is assigned a value of 1 and the others are assigned a value of 0.

[0085] S13. Synthesizing prior information

[0086] Since it is model data, the prior information of the primary wave is known, such as Figure 5 .

[0087] S14. Prediction of Multiple Wave Models

[0088] This step is basically the same as S3, except that the data substituted is generated by forward modeling or obtained from steps S11 to S13. The multiple wave model diagram is obtained by the multiple wave prediction algorithm, as shown in Figure 6 shown.

[0089] S15. Generate seismic sections with common offset and common azimuth

[0090] Perform dynamic correction processing and offset vector slice data (OVT) domain sorting processing on the stacked section without multiple wavefronts to generate a seismic section Y with common offset and common azimuth.

[0091] S16. Establishing the objective function

[0092] For each offset vector slice data domain, in the sense of least squares, establish the objective function J(A) = argmin||Y-AX||+λA T A;

[0093] Where X = [X1, X'2], which represents the matrix composed of the primary wave model X1 and the multiple wave model X'2;

[0094] A=[A1,A2], where A1 represents the adaptive matching operator of the primary wave model X1, A2 represents the adaptive matching operator of the multiple wave model X'2, and A is the total adaptive matching operator;

[0095] λA T A is the regularization term, λ is the regularization parameter;

[0096] S17. Solve the objective function

[0097] Solve the objective function and obtain the total adaptive matching operator A and the matched multiple waves A2X2;

[0098] Using the formula Y-fA2X'2, we can get the seismic data after subtracting the multiple waves;

[0099] The seismic data after multiple wave subtraction is subjected to reaction correction processing to obtain the seismic data after multiple wave suppression, such as Figure 7 shown.

[0100] Comparative experiment:

[0101] This comparative experiment uses conventional adaptive subtraction processing, that is, there is no prior information of the primary wave in the adaptive subtraction process, and the original data and the predicted multiple wave model are directly used for adaptive subtraction to obtain the seismic data after suppressing the multiple waves, such as Figure 8 shown.

[0102] in, Figure 8 The circle marks the intersection of the multiple waves and the primary wave. Conventional adaptive subtraction changes the amplitude characteristics of the primary wave, while the method of this verification experiment Figure 7 The results demonstrated that the primary wave amplitude characteristics are effectively maintained. The results show that, compared to conventional adaptive subtraction processing, the objective function containing prior information in the method of the present invention can effectively suppress multiple waves in the case of a crossover of multiple and primary events, demonstrating that the present invention has a good primary wave protection effect.

[0103] Verification Experiment II is a case where the multiple waves and the primary wave events are close in time, to verify whether the objective function containing prior information in the method of the present invention can effectively suppress the multiple waves.

[0104] The specific method is basically the same as that in Verification Experiment I. The only difference is that the model data processed is different, so the data processing results are different.

[0105] In step S11, before suppressing the multiple wavefronts, the seismic data obtained in this verification experiment are as follows: Figure 9 shown.

[0106] In step S13, the primary wave prior information diagram obtained in this verification experiment is as follows: Figure 10 shown.

[0107] In step S14, the multiple wave model diagram obtained in this verification experiment is as follows: Figure 11 shown.

[0108] In step S17, this verification experiment performs a reaction correction process on the seismic data after subtracting the multiple waves, and obtains the seismic data after suppressing the multiple waves, such as Figure 12 shown.

[0109] According to the comparative experiment in the verification experiment I, conventional adaptive subtraction processing is performed to obtain the seismic data after suppressing multiple waves, as shown in the following example: Figure 13 shown.

[0110] in, Figure 13 It shows that conventional adaptive subtraction processing causes serious damage to the primary wave, while the method of the present invention obtains Figure 12 The results show that compared with the conventional adaptive subtraction process, the present invention has a better primary wave protection effect when the multiple waves and the primary wave are close in time.

[0111] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art may still modify the technical solutions described in the above embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for adaptively reducing multiple waves based on primary wave protection, characterized in that: The method comprises the following steps performed in sequence: S1. Generate work area masking operator Using seismic records, VSP corridor stacked sections, and acoustic logging synthetic record information, the data were calibrated in the stacked sections after removing the multiple wavefronts to obtain the primary wave area and the multiple wave area. The primary wave region and the multiple wave region both include coordinate information and time information; If it is not marked as a multiple wave area, it is assigned a value of 0, and other areas are assigned a value of 1 to generate the work area masking operator f; S2. Synthesizing prior information Seismic data is calibrated by VSP corridor stacking sections and acoustic logging synthetic record information, and the horizon information is obtained by picking the primary wave phase axis. Use acoustic logging to synthesize record information and layer information to synthesize a priori information of the primary wave There are m1 layers in total, written in matrix form, and we get the primary wave prior information X1; S3. Prediction of Multiple Wave Model The multiple wave model X2 is predicted by the multiple wave prediction algorithm, and the corrected multiple wave model X'2 is obtained by processing; S4. Generate seismic sections with common offset and common azimuth Perform dynamic correction processing and offset vector slice data domain sorting processing on the stacked section without multiple wavefronts to generate the seismic section Y with common offset and common azimuth; S5. Establishing the objective function For each offset vector slice data domain, in the sense of least squares, establish the objective function J(A) = arg min||Y-AX||+λA T A; Where X = [X1, X'2], which represents the matrix consisting of the primary wave prior information X1 and the multiple wave model after normal motion correction X'2; A=[A1,A2], where A1 represents the adaptive matching operator of the primary wave prior information X1, A2 represents the adaptive matching operator of the multiple wave model X'2 after normal motion correction, and A is the total adaptive matching operator; λA T A is the regularization term, λ is the regularization parameter; S6. Solve the objective function and use the formula Y-fA2X'2 to obtain the seismic data after subtracting the multiple waves and then perform reaction correction processing to obtain the seismic data after suppressing the multiple waves.

2. The method for adaptively reducing multiple waves based on primary wave protection according to claim 1, characterized in that: In step S3, the predicted multiple wave model is There are m2 layers in total, written in matrix form, we get the multiple wave model X2; The post-NMO multiple wave model X'2 is obtained by performing NMO processing and offset vector slice data domain sorting processing on the multiple wave model X2 to generate a seismic profile with common offset and common azimuth.

3. The method for adaptively reducing multiple waves based on primary wave protection according to claim 1, characterized in that: In step S6, the objective function is solved to obtain the total adaptive matching operator A and the matched multiple waves A2X2.

4. The method for adaptively reducing multiple waves based on primary wave protection according to claim 1, characterized in that: The VSP corridor superimposed profile is obtained by processing VSP data.

5. The method for adaptively reducing multiple waves based on primary wave protection according to any one of claims 1 to 4, characterized in that: The stacked section without multiple wavefronts is obtained by interpreting the primary wave velocity based on the acoustic logging velocity as a reference value and in combination with geological knowledge.

6. The method for adaptively reducing multiple waves based on primary wave protection according to claim 5, characterized in that: The geological knowledge includes acoustic wave velocity, lithology and structural information.

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