A method for suppressing interference waves based on the differences in excited lithology

Abstract

The present invention discloses a method for suppressing interference waves based on the difference in excitation lithology, which relates to the technical field of oil and gas geophysical exploration and includes the following contents: S1. According to the excitation lithology identified by the acquisition daily report, digital numbers are assigned to the lithology. At the same time, 1 represents rock, 2 represents laterite, 3 represents loess, and 4 represents gravel, and a relationship table between shot numbers and lithology is established. S2. According to the shot identification number, the lithology identification data is imported into the data trace header, and then different lithology data is sorted according to the trace header. By adjusting and optimizing the denoising technology and denoising parameters according to different excitation lithologies, the present invention avoids the phenomenon of incomplete suppression of interference waves or loss of effective signals during the interference wave suppression process caused by using unified parameters in the conventional denoising idea, and effectively improves the signal-to-noise ratio of seismic data.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas geophysical exploration, and specifically relates to a method for suppressing interference waves according to the difference in excitation lithology. Background Art

[0002] In areas with complex surface lithology (such as loess tableland areas, hills and mountains), seismic data interference waves are very developed, and the types of interference waves are also relatively complex. The signal-to-noise ratio of the original seismic data is low and there are large differences in time, space, vertical and horizontal directions. During the seismic data processing, according to the difference in the type of interference wave, adopting the corresponding noise removal technology is an important part of the data processing. The interference wave suppression technology generally adopts different technical methods according to the type of noise. The conventional noise removal adopts the "six-division method" noise removal idea of dividing regions, time windows, frequencies, seismic data domains, and steps.

[0003] However, in the prior art, due to the difference in excitation lithology, the performance characteristics of the same type of noise in each domain are different. In actual production applications, the influence of excitation lithology on the type and strength of noise is often not taken into account, which results in insufficient noise removal for some excitation lithologies according to the conventional idea, and thus the value of the collected data cannot be maximally exerted. Summary of the Invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for suppressing interference waves according to the difference in excitation lithology, including the following steps:

[0007] S1. According to the excitation lithology marked in the acquisition report form, assign a digital number to the lithology. At the same time, represent rock as 1, red soil as 2, loess as 3, and gravel as 4, and establish a relationship table between shot numbers and lithologies;

[0008] S2. Import the lithology identification data into the data trace header according to the shot identification number, and then sort different lithology data according to the trace header;

[0009] S3. Use the lithology information in the seismic trace header to sort and rearrange the seismic data in multiple data domains, analyze the noise characteristics of different excitation lithologies in different seismic data domains, summarize the differences between the effective signal domain and the interference signal caused by the difference in excitation lithology, find out the seismic data domain with the most prominent interference wave characteristics related to the difference in excitation lithology, and sort and rearrange the original seismic data;

[0010] S4. For the seismic data sorted and rearranged according to the difference in excitation lithology, carry out targeted selection and optimization of interference wave suppression methods and parameters.

[0011] Furthermore, it includes the following:

[0012] It is established by decomposition in the shot domain, geophone domain, common midpoint domain, and offset domain. The surface wave only develops locally abnormally and does not have the above capabilities. By using this difference, the surface wave is removed. The surface wave mainly consists of three parts: (a) amplitude picking, (b) amplitude coherence decomposition, and (c) noise removal;

[0013] (a) Amplitude picking

[0014] Calculate the root mean square amplitude, maximum amplitude, and dominant frequency amplitude of the seismic trace;

[0015] (b) Amplitude coherence decomposition

[0016] Decompose the picked amplitude values into the shot domain, geophone domain, common midpoint domain, and offset domain related to the surface. In addition, the amplitude of the effective wave is the result of the joint contribution of the above four domains A ijkn = S i R j G k M n ;

[0017] Si Amplitude decomposition term at the i-th shot point position;

[0018] Rj Amplitude decomposition term at the j-th geophone position;

[0019] Gk Amplitude decomposition term at the k-th common midpoint position;

[0020] Mn Amplitude decomposition term for the n-th offset group;

[0021] Taking the log of the amplitude values of the above four items for the above formula, we get logA ijkn = logS i + logR j + l·logG k + l·logM n Solve each decomposition term using the Gauss-Seidel iteration method;

[0022] (c) Noise removal

[0023] Calculate and apply a scaling factor to each seismic trace. The scaling factor is the ratio of the combined decomposed values to the actual seismic trace. There is a maximum allowable scaling factor parameter, which is selected according to the test scan results.

[0024] Furthermore, the specific operation steps are as follows:

[0025] After inputting the noise data, it is sorted by the system. When sorting, the lithology is confirmed. If the confirmed lithology is 1, the lithology 1 is excited. If the lithology is 2, the lithology 2 is excited, and so on. According to the confirmed lithology, the corresponding lithology is excited. By comparing the lithology, specific noise in the database is mobilized to overlap with the input noise data. By removing the overlapping area, the denoising production operation can be carried out. When the denoising production operation is carried out, all the data are merged to output the imaging data.

[0026] Furthermore, the threshold parameter for lithology compromise is 0.4. The threshold parameter is optimized using the lithology-based idea. For a single shot excited by loess, the appropriate parameter is 0.5; for a single shot excited by rock, the appropriate parameter is 0.3.

[0027] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0028] 1. According to different excited lithologies, the present invention adjusts and optimizes the denoising technology and the idea of denoising parameters, avoiding the phenomenon of incomplete suppression of interference waves or loss of effective signals during the suppression of interference waves caused by using unified parameters in the conventional denoising idea, and effectively improving the signal-to-noise ratio of seismic data.

[0029] 2. For the single shot records collected with different excited lithologies in the present invention, there are differences in noise due to different excited lithologies. This difference is usually ignored in the conventional denoising idea. Since the influence of the excited lithology is not considered in parameter selection, the selected parameters will not perfectly match a specific lithology. In this way, the noise of individual lithologies cannot be completely removed or over-denoised, and the maximum utilization value of the collected seismic data cannot be exerted, resulting in an unsatisfactory improvement in the signal-to-noise ratio of the data. Denoising by different excited lithologies can avoid the above situation. By refining the noise characteristics according to the excited lithology and optimizing the process parameters, the signal-to-noise ratio of the data can be maximally improved and the imaging quality of the data can be enhanced.

[0030] 3. By utilizing the differences in the reflection characteristics and interference wave characteristics of the original seismic data brought by different excited lithologies of seismic waves, the present invention conducts a refined analysis of the effective signals and interference signals of the original seismic data, finely processes the types and characteristics of interference waves, and increases the adjustment of the interference wave suppression process, methods, and parameters according to the differences in seismic signals brought by different excited lithologies to achieve the best signal-to-noise separation effect and effectively improve the signal-to-noise ratio of seismic data. Compared with the conventional denoising method, the denoising technology by different excited lithologies protects the effective reflection signals better and suppresses the interference waves more thoroughly, achieving the effect of maximizing the value of seismic data and improving the signal-to-noise ratio of seismic data. Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is the lithology identification diagram with the TR.ROCKID of the present invention being null;

[0033] Figure 2 It is the display diagram of loading the well report lithology relationship table of the present invention into the seismic data trace header TR.ROCKID;

[0034] Figure 3 It is the loess lithology map with the seismic data lithology marker trace header TR.ROCKID of the present invention being 3;

[0035] Figure 4 It is the whole-region seismic data lithology excitation marker diagram of the present invention;

[0036] Figure 5 It is the schematic diagram of lithology-based denoising of the present invention;

[0037] Figure 6 It is the flowchart of lithology-based denoising of the present invention;

[0038] Figure 7 It is the schematic diagram of the energy of loess shot surface waves of the present invention;

[0039] Figure 8 It is the schematic diagram of the energy of rock shot surface waves of the present invention;

[0040] Figure 9 It is the schematic diagram of the parameters of loess shots with a threshold of 0.3 for the present invention;

[0041] Figure 10 It is the schematic diagram of the parameters of loess shots with a threshold of 0.3 for the present invention;

[0042] Figure 11 It is the schematic diagram of the parameters of loess shots with a threshold of 0.4 for the present invention;

[0043] Figure 12 It is the schematic diagram of the parameters of loess shots with a threshold of 0.4 for the present invention;

[0044] Figure 13 It is the schematic diagram of the parameters of loess shots with a threshold of 0.5 for the present invention;

[0045] Figure 14 It is the schematic diagram of the parameters of loess shots with a threshold of 0.5 for the present invention;

[0046] Figure 15Schematic diagram of the parameters of the loess cannon with a threshold of 0.6 according to the present invention;

[0047] Figure 16 Schematic diagram of the parameters of the loess cannon with a threshold of 0.6 according to the present invention;

[0048] Figure 17 Schematic diagram of the parameters of the rock cannon with a threshold of 0.3 according to the present invention;

[0049] Figure 18 Schematic diagram of the parameters of the rock cannon with a threshold of 0.3 according to the present invention;

[0050] Figure 19 Schematic diagram of the parameters of the rock cannon with a threshold of 0.4 according to the present invention;

[0051] Figure 20 Schematic diagram of the parameters of the rock cannon with a threshold of 0.4 according to the present invention;

[0052] Figure 21 Schematic diagram of the parameters of the rock cannon with a threshold of 0.5 according to the present invention;

[0053] Figure 22 Schematic diagram of the parameters of the rock cannon with a threshold of 0.5 according to the present invention;

[0054] Figure 23 Schematic diagram of the parameters of the rock cannon with a threshold of 0.6 according to the present invention;

[0055] Figure 24 Schematic diagram of the parameters of the rock cannon with a threshold of 0.6 according to the present invention;

[0056] Figure 25 Demonstration diagram of the noise effect of the compromise threshold of 0.4 of the loess cannon according to the present invention;

[0057] Figure 26 Demonstration diagram of the noise effect of the compromise threshold of 0.4 of the rock cannon according to the present invention;

[0058] Figure 27 Demonstration diagram of the noise effect of the optimal parameter of 0.5 of the loess cannon according to the present invention;

[0059] Figure 28 Demonstration diagram of the noise effect of the optional optimal parameter of 0.3 of the lithology cannon according to the present invention;

[0060] Figure 29 Demonstration diagram of the denoising effect of the lithology-separated loess cannon according to the present invention;

[0061] Figure 30 Demonstration diagram of the lithology-separated denoising technology according to the present invention. Detailed implementation manners

[0062] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0063] An embodiment of the present invention discloses a method for suppressing interference waves according to the difference in excitation lithology.

[0064] The present invention provides a Figure 1-28 method for suppressing interference waves according to the difference in excitation lithology as shown below, including the following contents:

[0065] S1. According to the excitation lithology marked in the acquisition daily report, assign digital numbers to the lithology. At the same time, represent rock as 1, red soil as 2, loess as 3, and gravel as 4, and establish a relationship table between shot numbers and lithology. Red soil is also called red soil. Generally, there are many metal compounds with four - coordinate and six - coordinate in red soil, including iron compounds and aluminum compounds. Loess refers to the yellow silt sediment transported by wind during the Quaternary period in geological time. Gravel refers to rock or mineral debris with an average particle size greater than 2 mm and less than 60 mm, which is formed by the weathering of rocks exposed on the surface), etc., and establish a relationship table between shot numbers and lithology;

[0066]

[0067]

[0068] S2. Import the lithology identification data into the data trace header according to the shot identification number, and then sort different lithology data according to the trace header;

[0069] S3. Use the lithology information in the seismic trace header to sort and rearrange the seismic data in multiple data domains, analyze the noise characteristics of different excitation lithologies in different seismic data domains, summarize the differences between the effective signal domain and the interference signal caused by the difference in excitation lithology, find out the seismic data domain with the most prominent interference wave characteristics related to the difference in excitation lithology, and sort and rearrange the original seismic data;

[0070] S4. For the seismic data sorted and rearranged according to the difference in excitation lithology, carry out targeted interference wave suppression method and parameter selection and optimization. When conducting single - shot excitation, the vibration generated by the vibration source causes vibration of the underground where the shot position is located. The depth will affect the vibration wave, and the established noise characteristics will also be affected. First, in the ideal state, rock, red soil, loess, and gravel convey certain noise information. However, in actual measurement, depth, rock volume, rock pores, gravel pores, gravel volume, soil humidity will all affect the noise of the lithology. How to accurately filter the noise is an ongoing task throughout the processing process.

[0071] Further, it includes the following contents:

[0072] The method for surface wave removal selects the surface consistent surface wave suppression technology, which is a method for noise removal using the surface consistency principle; the theoretical basis is that the distribution of effective waves conforms to the regional consistency law, that is, it can be decomposed in the shot domain, geophone domain, common midpoint domain and offset domain, while the surface wave is only abnormally developed locally and does not have the above capabilities. Therefore, this difference can be used to remove surface waves. By using the fact that it can be established by decomposition in the shot domain, geophone domain, common midpoint domain and offset domain, while the surface wave is only abnormally developed locally and does not have the above capabilities, and by using this difference, surface waves can be removed. Surface waves are mainly composed of three parts: (a) amplitude picking, (b) amplitude consistency decomposition, and (c) noise removal;

[0073] (a) Amplitude picking

[0074] Calculate the root mean square amplitude, maximum amplitude and dominant frequency amplitude of the seismic trace;

[0075] (b) Amplitude consistency decomposition

[0076] Decompose the picked amplitude values into the shot domain, geophone domain, common midpoint domain and offset domain related to the surface. In addition, the amplitude of the effective wave is the result of the joint contribution of the above four domains, Aijkn = Si * Rj * Gk * Mn;

[0077] Si is the amplitude decomposition term at the i-th shot point position;

[0078] Rj is the amplitude decomposition term at the j-th geophone position;

[0079] Gk is the amplitude decomposition term at the k-th common midpoint position;

[0080] Mn is the amplitude decomposition term for the n-th offset group;

[0081] Take the log of the amplitude values of the above four items for the above formula to get logA ijkn = logS i + logR j + l·logG k + l·logM n Use the Gauss - Seidel Iteration (an iterative algorithm for solving linear equations) to solve each decomposition term;

[0082] (c) Noise removal

[0083] Calculate and apply a scale factor for each seismic trace. The scale factor is the ratio of the combined decomposition value calculation to the actual seismic trace. Here, there is a maximum allowable scale factor parameter (MAX_AMP_RATIO_LIMIT, threshold), which is selected according to the experimental scan results.

[0084] Further, the specific operation steps are as follows:

[0085] After inputting the noise data, it is sorted by the system. When sorting, the lithology is confirmed. If the confirmed lithology is 1, then lithology 1 is excited; if the lithology is 2, then lithology 2 is excited, and so on. According to the confirmed lithology, the corresponding lithology is excited. By comparing the lithology, specific noise in the database is mobilized to overlap with the input noise data. By removing the overlapping area, the denoising production operation can be carried out. When the denoising production operation is in progress, all data are merged to output imaging data.

[0086] The threshold parameter for lithology compromise is 0.4. The threshold parameter is optimized using the lithology-based idea. For a single shot excited by loess, the appropriate parameter is 0.5; for a single shot excited by rock, the appropriate parameter is 0.3. When removing surface waves, parameter scanning is performed on the single shots of the two excited lithologies respectively. Here, the scanning factor is the threshold. The larger the threshold, the more noise is removed; at the same time, the probability of damage to the effective signal increases. The appropriate parameter should be to remove the most noise while retaining the effective signal to the greatest extent. If the conventional method does not consider the differences in excitation lithology, the threshold parameter for all lithologies to be compromised is 0.4. If the threshold parameter is optimized using the lithology-based idea, for a single shot excited by loess, the appropriate parameter is 0.5; for a single shot excited by rock, the appropriate parameter is 0.3. By denoising according to the excitation lithology, the denoising of loess is further enhanced; for rock excitation, damage to the effective signal is avoided. After the denoising idea based on excitation lithology, the signal-to-noise ratio of the final stack is significantly improved.

[0087] Only some exemplary embodiments of the present invention have been described by way of illustration above. Undoubtedly, for those of ordinary skill in the art, without departing from the spirit and scope of the present invention, the described embodiments can be modified in various different ways. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for suppressing interference waves based on the difference in stimulating lithology, characterized in that: Includes the following: S1. According to the stimulating lithology marked in the acquisition class report, the lithology is numbered, and 1 represents rock, 2 represents red soil, 3 represents loess, and 4 represents gravel, and a relationship table between the blast number and the lithology is established; S2. Import the lithology identification data into the data header according to the shot identification number, and then sort the different lithology data according to the header; S3. Use the lithology information in the seismic header information to sort and rearrange the seismic data in multiple data domains, analyze the noise characteristics of different stimulated lithologies in different seismic data domains, summarize the differences in interference signals in the effective signal domain caused by the differences in stimulated lithologies, find the seismic data domain with the most prominent interference wave characteristics related to the differences in stimulated lithologies, and sort and rearrange the original seismic data; S4. Carry out targeted interference wave suppression methods and parameter selection and optimization for seismic data that are sorted and rearranged based on lithology differences.

2. The method for suppressing interference waves according to the difference in stimulating lithology according to claim 1 is characterized in that: Includes the following: By utilizing the features that can be decomposed and established in the shot domain, receiver domain, common center point domain and offset domain, the surface roll is only abnormally developed locally and does not have the consistent features. By utilizing this difference, the surface roll is removed. The removal of surface roll mainly consists of three parts: (a) amplitude picking, (b) amplitude consistency decomposition, and (c) noise removal. (a) Amplitude Pickup Calculate the RMS amplitude, maximum amplitude and main frequency amplitude of the seismic trace; (b) Amplitude consistency decomposition The picked-up amplitude value is decomposed into the surface-related shot domain, detection point domain, common center point domain and offset distance domain. In addition, the amplitude of the effective wave is the result of the joint contribution of the above four domains. ijkn =S i R j G k M n ; S i The amplitude decomposition term of the i-th shot position; R j The amplitude decomposition term at the jth detection point; G k The amplitude decomposition term of the position of the kth common center point; M n Amplitude decomposition term of the nth offset group; A ijh The amplitude values ​​of the above four items are logarithmized by the above formula to obtain logA ijkn =logS i +logR j +l·logG k +l·logM n The Gauss-Seidel iteration method is used to solve each decomposition term; (c) Noise Removal Calculate and apply the scaling factor for each seismic trace. The scaling factor is the ratio of the calculated decomposition value combination to the actual seismic trace. There is a maximum allowable scaling factor parameter, which is selected based on the test scan results.

3. The method for suppressing interference waves according to the difference in stimulating lithology according to claim 1 is characterized in that: The specific steps are as follows: After the noise data is input, the system will sort it. During the sorting, the lithology is confirmed. If the confirmed lithology is 1, lithology 1 is stimulated. If the lithology is 2, lithology 2 is stimulated, and so on. The corresponding lithology is stimulated according to the confirmed lithology. Through the compared lithology, the specific noise in the database is mobilized to overlap with the input noise data. By removing the overlapping area, the denoising production operation can be performed. When the denoising production operation is performed, all the data are merged to output the imaging data.

4. The method for suppressing interference waves according to the difference in stimulating lithology according to claim 1, characterized in that: The threshold parameter for lithologic compromise is 0.

4. The threshold parameter is optimized by adopting the lithologic method. For a single shot stimulated by loess, the appropriate parameter is 0.5; for a single shot stimulated by rock, the appropriate parameter is 0.3.

Images