A velocity modeling method for complex volcanic rock development areas

Abstract

The present invention provides a method for velocity modeling in complex volcanic rock development areas, comprising: performing multi-angle comprehensive denoising on prestack seismic data; establishing a depth-domain initial velocity model and performing multiple rounds of velocity tomography along the layers; obtaining a background velocity field using a small-grid tomography velocity optimization technique; using the anomalous amplitude method to pick the volcanic rock distribution range in the time-domain prestack imaging data volume to obtain volcanic rock distribution attributes; multiplying the volcanic rock distribution attributes with the residual velocity to obtain a residual velocity field in the volcanic rock development area; and adding the residual velocity field in the volcanic rock development area to the background velocity field to obtain a final velocity field in the volcanic rock development area. The present invention avoids the problems of low efficiency and poor accuracy associated with existing manual volcanic rock picking methods. By pre-delineating the volcanic rock development area and then accurately obtaining the residual velocity in the volcanic rock development area, the present invention improves the accuracy of velocity modeling in volcanic rock development areas.

Description

Technical Field

[0001] The present invention belongs to the technical field of reflection seismic data processing in seismic exploration, and in particular relates to a velocity modeling method for a complex volcanic rock development area. Background Art

[0002] Seismic wavefields in areas with volcanic rock development are complex and highly variable, leading to blurred and poor-quality seismic data and making high-quality seismic imaging extremely difficult. Therefore, precisely characterizing the spatial extent of volcanic rock development and obtaining high-precision volcanic rock velocity volumes is crucial for eliminating volcanic rock shielding and improving the accuracy of imaging of the underlying strata, all of which contribute to high-quality imaging. Currently, the industry primarily uses two methods for velocity modeling in volcanic rock development areas: migration velocity iteration and grid tomography. While these methods can highlight anomalies in volcanic rock and surrounding rock velocities through continuous iteration, they also have limitations due to the signal-to-noise ratio of seismic data and the complexity of volcanic rock development. These limitations primarily arise when dealing with widely distributed, multi-stage, and complex volcanic rock formations, leading to inaccurate identification of volcanic rock development areas and unstable volcanic rock velocity model accuracy. The industry has yet to develop effective solutions to these problems. Summary of the Invention

[0003] In order to solve the problems of high difficulty and low precision in existing velocity modeling methods for complex volcanic rock development areas, the embodiments of the present application provide a velocity modeling method for complex volcanic rock development areas, which reduces the difficulty of velocity modeling in volcanic rock development areas and improves the precision of velocity modeling in volcanic rock development areas.

[0004] The present application provides a velocity modeling method for a complex volcanic rock development area, including:

[0005] S1, conduct multi-angle comprehensive denoising on pre-stack seismic data volume;

[0006] S2, establish the initial velocity model in the depth domain and carry out multiple rounds of velocity tomography iteration along the layer;

[0007] S3, using small-scale grid tomography velocity optimization technology to obtain the background velocity field;

[0008] S4, picking the volcanic rock distribution range on the time domain prestack imaging data volume to obtain the volcanic rock distribution attributes;

[0009] S5, multiplying the volcanic rock distribution attributes with the residual velocity to obtain the residual velocity field in the volcanic rock development area;

[0010] S6, obtaining a final velocity field of the volcanic rock development area according to the residual velocity field of the volcanic rock development area obtained in step S5 and the background velocity field obtained in step S3.

[0011] Among them, S1 performs multi-angle comprehensive denoising on pre-stack seismic data, including:

[0012] First, remove abnormal energy, low-frequency surface waves, residual surface waves, and linear noise by type, region, time, and frequency in the shot area angle; then remove residual noise in the detection point domain; finally, suppress random noise in the gather domain.

[0013] Among them, S2 establishes the initial velocity model in the depth domain and carries out multiple rounds of velocity tomography iteration along the layer, including:

[0014] First, a large-scale smoothing operation is performed on the time-domain velocity model. Then, the acoustic velocity obtained from well logging in the work area is used to constrain the time-domain velocity model and convert it to the depth domain. Based on the initial model, the velocity model is gradually optimized through pre-stack depth migration and main reflection layer tomography iteration.

[0015] Among them, S3 uses small-scale grid tomography velocity optimization technology to obtain the background velocity field, including:

[0016] The velocity model generated in step S2 is used as the initial model for small-scale grid tomography iteration. By gradually reducing the spatial grid scale, the global residual delay is picked up, the residual travel time residual matrix is ​​established, and the final residual velocity is solved by the least squares algorithm to obtain the background velocity field.

[0017] In step S4, the distribution range of volcanic rocks is picked up using the abnormal amplitude method.

[0018] Among them, S4 picks the volcanic rock distribution range on the time domain prestack imaging data volume and obtains the volcanic rock distribution attributes, including:

[0019] First, calculate the maximum amplitude A of the time domain prestack imaging section, then divide all amplitude values ​​by A to obtain the amplitude normalized prestack imaging section P; then use all the logging information in the work area to mark the volcanic rocks on the prestack imaging data volume and record the corresponding amplitude A. xy , where x is the number and y is the time depth in ms, from A xy Find the minimum value, record it as A min , its absolute value is |A min |; On the time domain prestack imaging data volume, the absolute amplitude value greater than |A min The amplitude value of the imaging point is set to 1, otherwise it is set to 0, and the volcanic rock distribution attributes are finally obtained.

[0020] Among them, S5, by multiplying the volcanic rock distribution attribute with the residual velocity, obtains the residual velocity field of the volcanic rock development area, including:

[0021] The volcanic rock distribution attribute obtained in step S4 is multiplied by the residual velocity generated in step S3. Since the representative value of the volcanic rock development area is 1 and the representative value of the non-volcanic rock development area is 0 in the volcanic rock distribution attribute, the multiplication result is the residual velocity field of the volcanic rock development area.

[0022] Wherein, S6, obtaining the final velocity field of the volcanic rock development area according to the residual velocity field of the volcanic rock development area obtained in step S5 and the background velocity field obtained in step S3, includes:

[0023] The residual velocity field of the volcanic rock development area obtained in step S5 is added to the background velocity field obtained in step S3 to obtain the final velocity field of the volcanic rock development area.

[0024] Wherein, S6, obtaining the final velocity field of the volcanic rock development area according to the residual velocity field of the volcanic rock development area obtained in step S5 and the background velocity field obtained in step S3, includes:

[0025] The background velocity field obtained in step S3 and the residual velocity field of the volcanic rock development area obtained in step S5 are algebraically added to obtain an updated velocity model of the volcanic rock development area.

[0026] The velocity modeling method for complex volcanic rock development areas in the embodiment of the present application has the following beneficial effects:

[0027] The present invention improves the accuracy of velocity modeling of volcanic rock development areas and reduces the difficulty of velocity modeling by describing the volcanic rock development areas in advance and then accurately calculating the residual velocity of the volcanic rock development areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of the velocity modeling method for complex volcanic rock development areas according to an embodiment of the present application;

[0029] Figure 2 This is a schematic diagram of a time domain prestack imaging cross section in an embodiment of the present application;

[0030] Figure 3 This is a schematic diagram of the distribution properties of volcanic rocks in the embodiment of this application;

[0031] Figure 4 This is a schematic diagram of the background velocity field in the embodiment of this application;

[0032] Figure 5 This is a schematic diagram of the final velocity field in the embodiment of this application. DETAILED DESCRIPTION

[0033] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0034] The following description provides multiple embodiments of the present invention. Different embodiments may be replaced or combined, and thus this application may be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments that include one or more of all other possible combinations of features A, B, C, and D, even though such embodiments may not be explicitly described in the following text.

[0035] Example 1

[0036] like Figure 1 As shown, the velocity modeling method for complex volcanic rock development areas of the present application includes: S1, performing multi-angle comprehensive denoising on the pre-stack seismic data volume; S2, establishing an initial velocity model in the depth domain and performing multiple rounds of velocity tomography iterations along the layer; S3, using small-scale grid tomography velocity optimization technology to obtain the background velocity field; S4, picking the volcanic rock distribution range on the time domain pre-stack imaging data volume to obtain the volcanic rock distribution attributes; S5, multiplying the volcanic rock distribution attributes with the residual velocity to obtain the residual velocity field of the volcanic rock development area; S6, obtaining the final velocity field of the volcanic rock development area based on the residual velocity field of the volcanic rock development area obtained in step S5 and the background velocity field obtained in step S3.

[0037] The present application reduces the difficulty of velocity modeling in volcanic rock development areas and improves the accuracy of velocity modeling in volcanic rock development areas.

[0038] Example 2

[0039] The velocity modeling method for complex volcanic rock development areas in this application, taking seismic data from an eastern oil field as an example, specifically includes:

[0040] Step 1: Perform multi-angle comprehensive denoising on the pre-stack seismic data volume.

[0041] On the prepared pre-stack seismic data volume, firstly, the abnormal energy, low-frequency surface waves, residual surface waves, linear noise, etc. are removed by type, region, time and frequency at the shot field angle; then the residual noise is removed in the detection point domain; finally, random noise suppression is carried out in the data gather domain.

[0042] Step 2: Establish an initial velocity model in the depth domain and perform multiple rounds of velocity tomography iterations along the layer.

[0043] First, the time-domain velocity model is smoothed on a large scale. The time-domain velocity model is then constrained using acoustic velocities obtained through well logging within the work area and converted to the depth domain. Based on the initial model, the velocity model is then gradually optimized through pre-stack depth migration and major reflector layer tomography iteration. Pre-stack depth migration is a processing technique for spatially repositioning geological structures. It includes Kirchhoff integral-based pre-stack depth migration and wave equation-based pre-stack depth migration, which uses a differential solution of the wave equation. Establishing the velocity model is a crucial step in the pre-stack depth migration process.

[0044] Step 3: Use small-scale grid tomography velocity optimization technology to obtain the background velocity field.

[0045] like Figure 2 As shown, the velocity model generated in step 2 is used as the initial model for the small-scale grid tomography iteration. By gradually reducing the spatial grid size, the global residual delay is picked up, and the residual traveltime residual matrix is ​​established. The final residual velocity is solved using the least squares algorithm, and the background velocity field is obtained. The least squares method, also known as the least squares method, is a mathematical optimization technique that finds the best function matching the data by minimizing the sum of squared errors. The least squares method can be used to easily obtain unknown data and minimize the sum of squared errors between the obtained data and the actual data.

[0046] Step 4: On the time domain prestack imaging data volume, the abnormal amplitude method is used to pick up the distribution range of volcanic rocks and obtain the distribution attributes of volcanic rocks.

[0047] Figure 3 What is shown is the time domain prestack imaging data section, such as Figure 3-4 As shown in the figure, first calculate the maximum amplitude A of the time domain prestack imaging section, then divide all amplitude values ​​by A to obtain the amplitude normalized prestack imaging section P; then use all the logging information in the work area to mark the volcanic rocks on the prestack imaging data volume and record the corresponding amplitude A xy , where x is the number and y is the time depth in ms, from A xy Find the minimum value, record it as A min , its absolute value is |A min |. In the time domain prestack imaging data volume, the absolute amplitude value greater than |A min The amplitude value of the imaging point is set to 1, otherwise it is set to 0, and the volcanic rock distribution attributes are finally obtained.

[0048] Step 5: Multiply the volcanic rock distribution attributes by the residual velocity to obtain the residual velocity field in the volcanic rock development area.

[0049] The volcanic rock distribution attribute obtained in step 4 is multiplied by the residual velocity generated in step 3. Since the representative value of the volcanic rock development area is 1 and the representative value of the non-volcanic rock development area is 0 in the volcanic rock distribution attribute, the multiplication result is the residual velocity field of the volcanic rock development area.

[0050] Step 6: Add the residual velocity field of the volcanic rock development area obtained in step 5 to the background velocity field obtained in step 3 to obtain the final velocity field of the volcanic rock development area.

[0051] By algebraically adding the background velocity field obtained in step 3 and the residual velocity field of the volcanic rock development area obtained in step 5, we can obtain the updated velocity model of the volcanic rock development area, as shown in the following example: Figure 5 By comparison Figure 2 and Figure 5 It can be seen that Figure 5 The details of the velocity bodies of the intermediate volcanic rocks are clearer and their range is more defined.

[0052] This method utilizes time-domain prestack imaging data to determine the distribution range of volcanic rocks using the anomalous amplitude method, avoiding the inefficiency and poor accuracy associated with existing manual volcanic rock picking methods. By pre-delineating the volcanic rock development zone and then accurately determining the residual velocity within that zone, this method improves the accuracy of velocity modeling within that zone while also reducing its difficulty.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A velocity modeling method for complex volcanic rock development areas, characterized by: include: S1, conduct multi-angle comprehensive denoising on pre-stack seismic data volume; S2, establish the initial velocity model in the depth domain and carry out multiple rounds of velocity tomography iteration along the layer; S3, using small-scale grid tomography velocity optimization technology to obtain the background velocity field; S4, picking the volcanic rock distribution range on the time domain prestack imaging data volume to obtain the volcanic rock distribution attributes; S5, multiplying the volcanic rock distribution attributes with the residual velocity to obtain the residual velocity field in the volcanic rock development area; S6, obtaining a final velocity field of the volcanic rock development area according to the residual velocity field of the volcanic rock development area obtained in step S5 and the background velocity field obtained in step S3.

2. The velocity modeling method for complex volcanic rock development areas according to claim 1, characterized in that: S1, conducts multi-angle comprehensive denoising on pre-stack seismic data, including: First, remove abnormal energy, low-frequency surface waves, residual surface waves, and linear noise by type, region, time, and frequency in the shot area angle; then remove residual noise in the detection point domain; finally, suppress random noise in the gather domain.

3. The velocity modeling method for complex volcanic rock development areas according to claim 1 or 2, characterized in that: S2: Establish an initial velocity model in the depth domain and conduct multiple rounds of velocity tomography iterations along the layer, including: First, a large-scale smoothing operation is performed on the time-domain velocity model. Then, the acoustic velocity obtained from well logging in the work area is used to constrain the time-domain velocity model and convert it to the depth domain. Based on the initial model, the velocity model is gradually optimized through pre-stack depth migration and main reflection layer tomography iteration.

4. The velocity modeling method for complex volcanic rock development areas according to claim 1 or 2, characterized in that: S3, using small-scale grid tomography velocity optimization technology to obtain the background velocity field, including: The velocity model generated in step S2 is used as the initial model for small-scale grid tomography iteration. By gradually reducing the spatial grid scale, the global residual delay is picked up, the residual travel time residual matrix is ​​established, and the final residual velocity is solved by the least squares algorithm to obtain the background velocity field.

5. The velocity modeling method for complex volcanic rock development areas according to claim 1 or 2, characterized in that: In step S4, the distribution range of volcanic rocks is picked up using the abnormal amplitude method.

6. The velocity modeling method for complex volcanic rock development areas according to claim 1 or 2, characterized in that: S4, on the time domain prestack imaging data volume, pick the volcanic rock distribution range and obtain the volcanic rock distribution attributes, including: First, calculate the maximum amplitude A of the time domain prestack imaging section, then divide all amplitude values ​​by A to obtain the amplitude normalized prestack imaging section P; then use all the logging information in the work area to mark the volcanic rocks on the prestack imaging data volume and record the corresponding amplitude A. xy , where x is the number and y is the time depth in ms, from A xy Find the minimum value, record it as A min , its absolute value is |A min |; On the time domain prestack imaging data volume, the absolute amplitude value greater than |A min The amplitude value of the imaging point is set to 1, otherwise it is set to 0, and the volcanic rock distribution attributes are finally obtained.

7. The velocity modeling method for complex volcanic rock development areas according to claim 1 or 2, characterized in that: S5, multiplying the volcanic rock distribution attributes by the residual velocity to obtain the residual velocity field in the volcanic rock development area, including: The volcanic rock distribution attribute obtained in step S4 is multiplied by the residual velocity generated in step S3. Since the representative value of the volcanic rock development area is 1 and the representative value of the non-volcanic rock development area is 0 in the volcanic rock distribution attribute, the multiplication result is the residual velocity field of the volcanic rock development area.

8. The velocity modeling method for complex volcanic rock development areas according to claim 1 or 2, characterized in that: S6, obtaining a final velocity field of the volcanic rock development area based on the residual velocity field of the volcanic rock development area obtained in step S5 and the background velocity field obtained in step S3, including: The residual velocity field of the volcanic rock development area obtained in step S5 is added to the background velocity field obtained in step S3 to obtain the final velocity field of the volcanic rock development area.

9. The velocity modeling method for complex volcanic rock development areas according to claim 1 or 2, characterized in that: S6, obtaining a final velocity field of the volcanic rock development area based on the residual velocity field of the volcanic rock development area obtained in step S5 and the background velocity field obtained in step S3, including: The background velocity field obtained in step S3 and the residual velocity field of the volcanic rock development area obtained in step S5 are algebraically added to obtain an updated velocity model of the volcanic rock development area.

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