Multi-stage dispersive igneous rock velocity description method

Abstract

The invention relates to a multi-stage dispersive igneous rock velocity description method. The method comprises the following steps: acquiring seismic data to be analyzed; performing velocity analysis on the seismic data to obtain a first velocity body; performing depth migration on the first velocity body, and converting the first velocity body into a time domain to obtain a time domain migration gather; processing the time domain offset gather to obtain a first result; performing first preset mathematical operation on the first achievement body to obtain a second achievement body; and carrying out lane-by-lane speed pickup on the time domain migration gather to obtain a second speed body, and carrying out second preset mathematical operation on the first speed body, the first achievement body, the second achievement body and the second speed body to obtain an igneous rock achievement speed body reflecting igneous rock speed characteristics. According to the method, various technical means such as seismic data processing, velocity analysis, depth migration and mathematical operation are comprehensively utilized, so that the velocity of the multi-stage dispersed igneous rocks is finely described.

Description

Technical Field

[0001] The invention relates to the field of oil and gas reservoir seismic exploration, and in particular to a multi-stage dispersed igneous rock velocity characterization method. Background Art

[0002] The difficulty of fine velocity characterization encountered in the exploration and development of igneous oil and gas reservoirs. Specifically, because igneous rocks have the characteristics of multi-stage development, uneven thickness, and various shapes, and their velocity is quite different from the velocity of the surrounding rock, this leads to complex features on the seismic profile, such as the low signal-to-noise ratio of the underlying strata due to the high-resistance shielding effect of igneous rocks, the inability to image, or the generation of false faults. These problems have brought challenges to the exploration and development of igneous oil and gas reservoirs, so it is necessary to accurately characterize the velocity of igneous rocks to solve a series of problems arising from this.

[0003] However, the existing velocity tomography methods have many difficulties in dealing with igneous rocks. For example, conventional grid tomography has strong multi-solution in the igneous rock area and cannot meet the needs of fine characterization; although phase-controlled igneous rock velocity modeling can better solve the problem of velocity characterization of thicker igneous rocks with clear regional knowledge, it is difficult to apply to thin and dispersed igneous rocks; although first-arrival tomography can be used for fine characterization when the igneous rock is shallowly buried and there is a first-arrival wave passing through, it cannot be performed when the igneous rock is deeply buried; although reflection wave FWI can be used to finely characterize the velocity of multi-stage dispersed igneous rocks, it is not economical and has not yet been industrialized in China. Summary of the invention

[0004] The invention provides a multi-stage dispersed igneous rock velocity characterization method, which can solve the problem of fine velocity characterization encountered in the exploration and development of igneous rock oil and gas reservoirs.

[0005] In order to solve the above technical problems, the method comprises the following steps:

[0006] S1: Obtain the seismic data to be analyzed;

[0007] S2: performing velocity analysis on the seismic data to obtain a first velocity body;

[0008] S3: performing depth migration on the first velocity body and converting it into the time domain to obtain a time domain migration gather;

[0009] S4: Processing the time domain migration gather to obtain a first result volume;

[0010] S5: performing a first preset mathematical operation on the first result to obtain a second result;

[0011] S6: performing velocity picking on the time domain migration gather track by track to obtain a second velocity body;

[0012] S7: performing a second preset mathematical operation on the first velocity body, the first result body, the second result body and the second velocity body to obtain an igneous rock result velocity body reflecting the velocity characteristics of the igneous rock.

[0013] In one embodiment, the method further comprises:

[0014] Performing self-ratio processing on the velocity body of the igneous rock result back to the depth domain to obtain a velocity body in the depth domain;

[0015] The depth domain velocity body is subjected to depth migration and grid velocity iteration to obtain a final igneous rock result velocity body reflecting the velocity characteristics of the igneous rock.

[0016] In one embodiment, the depth migration of the depth domain velocity body and the grid velocity iteration to obtain the final igneous rock result velocity body reflecting the velocity characteristics of the igneous rock include:

[0017] Performing depth migration processing on the depth-domain velocity body to obtain a velocity result after migration;

[0018] Using the velocity result after migration as input of the velocity model to perform grid velocity iteration;

[0019] During the iteration process, the changes in the phase axis of the conventional strata under the igneous rock are obtained to adjust the velocity model parameters and re-image until the phase axis is flat and meets the preset standards. At this time, the velocity model is the final igneous rock result velocity body.

[0020] In one embodiment, the step S2 includes:

[0021] Velocity tomography is performed on the seismic data until the velocity residual approaches zero, so as to obtain a first velocity body.

[0022] In one embodiment, step S4 includes:

[0023] Suppressing residual noise on the time domain migration gather, and performing a cutting and stacking operation to obtain a time domain stacking section;

[0024] Performing igneous rock amplitude value characteristic analysis on the time domain stacked profile to obtain igneous rock position data;

[0025] A first quality control process is performed on the igneous rock position data to obtain a first result body.

[0026] In one embodiment, the step of suppressing residual noise on the time domain migration gather and performing a cutting and stacking operation to obtain a time domain stacking profile includes:

[0027] Performing residual noise suppression on the time domain migration gather to obtain a first signal-to-noise ratio gather;

[0028] The first signal-to-noise ratio gather is subjected to excision and stacking processing to obtain a time domain stacking section.

[0029] In one embodiment, the performing igneous rock amplitude value characteristic analysis on the time domain stacked profile to obtain igneous rock position data includes:

[0030] Obtaining a preset amplitude value feature corresponding to the time domain stacked section; wherein the preset amplitude value feature includes an igneous rock characteristic threshold and a surrounding rock amplitude threshold;

[0031] According to the igneous rock characteristic threshold and the surrounding rock amplitude threshold, a delineation operation is performed on the time domain stacked profile to obtain igneous rock position data.

[0032] In one embodiment, performing a first quality control process on the igneous rock position data to obtain a first result body includes:

[0033] Performing quality control processing on the igneous rock position data and the time domain stacked profile;

[0034] Calculating the igneous rock position data and the igneous rock position difference of the time domain stacked profile;

[0035] Determining whether the position difference of the igneous rock meets a preset range;

[0036] If not satisfied, repeatedly performing igneous rock amplitude value characteristic analysis on the time domain stacked profile;

[0037] To obtain a first result body in which the position difference of the igneous rock meets a preset range.

[0038] In one embodiment, step S5 includes:

[0039] Filling the first result body with numerical values ​​to obtain a filled first result body;

[0040] Performing a preset mathematical operation on the filled first result body to obtain a second result body;

[0041] Wherein, the first preset mathematical operation includes:

[0042] B = |1-A|;

[0043] In the formula, B is the second achievement body; A is the first achievement body.

[0044] In one embodiment, the step S6 includes:

[0045] The second velocity body is subjected to a second quality control process to obtain a second velocity body after quality control.

[0046] The implementation of the present invention has the following beneficial effects: The present invention relates to a method for characterizing the velocity of multi-period dispersed igneous rocks, wherein the steps of the method include: obtaining seismic data to be analyzed; performing velocity analysis on the seismic data to obtain a first velocity body; performing depth migration on the first velocity body and converting it into the time domain to obtain a time domain migration track set; processing the time domain migration track set to obtain a first result body; performing a first preset mathematical operation on the first result body to obtain a second result body; performing track-by-track velocity picking on the time domain migration track set to obtain a second velocity body. The first velocity body, the first result body, the second result body, and the second velocity body are subjected to a second preset mathematical operation to obtain an igneous rock result velocity body reflecting the velocity characteristics of igneous rocks. The present invention realizes a fine characterization of the velocity of multi-period dispersed igneous rocks by comprehensively using a variety of technical means such as seismic data processing, velocity analysis, depth migration, and mathematical operations. This method not only improves the accuracy and reliability of velocity characterization, but also effectively reduces the risks and costs of exploration and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0048] Figure 1 It is a schematic flow chart of an embodiment of the multi-stage dispersed igneous rock velocity characterization method provided by the present invention;

[0049] Figure 2 It is a schematic flow chart of another embodiment of the multi-stage dispersed igneous rock velocity characterization method provided by the present invention;

[0050] Figure 3 It is a schematic diagram of the spatial distribution of three-dimensional igneous rocks provided by the present invention;

[0051] Figure 4 It is a schematic diagram of the spatial distribution of three-dimensional igneous rocks provided by the present invention;

[0052] Figure 5 It is a schematic diagram of velocity picking by track in the time domain migration gather provided by the present invention;

[0053] Figure 6 is a schematic diagram of a second speed result provided by the present invention;

[0054] Figure 7 It is a schematic diagram of seismic wave reflection tomography of igneous rock after being carefully characterized provided by the present invention. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] The invention provides a multi-stage dispersed igneous rock velocity characterization method, which can solve the problem of fine velocity characterization encountered in the exploration and development of igneous rock oil and gas reservoirs.

[0057] like Figure 1 As shown, the steps of the multi-stage dispersed igneous rock velocity characterization method include:

[0058] S1: Obtain the seismic data to be analyzed;

[0059] It should be noted that seismic data can be land seismic data or marine seismic data. The present invention takes marine seismic data as an example. The seismic data to be analyzed are original seismic records collected from seismic exploration equipment. These data contain the response of underground structures to artificially excited seismic waves, including reflection, refraction and scattering information.

[0060] S2: Perform velocity analysis on the seismic data to obtain a first velocity body;

[0061] Specifically, velocity analysis is accomplished by analyzing the propagation speed of seismic waves at different depths.

[0062] S3: Perform depth migration on the first velocity body and convert it into the time domain to obtain a time domain migration gather;

[0063] Specifically, this process involves converting the depth information in the first velocity body into time domain information through a migration algorithm. Depth migration is a complex seismic data processing technology that can correct the propagation path of seismic waves according to the velocity changes of the underground medium, thereby more accurately reflecting the true form of the underground structure. After depth migration, the results are converted to the time domain to obtain the time domain migration gather. This step provides key data for subsequent time domain analysis and interpretation.

[0064] S4: Processing the time domain migration gather to obtain the first result volume;

[0065] Specifically, the process of processing time domain migration gathers includes multiple steps, such as residual noise suppression, amplitude value feature analysis, etc.

[0066] S5: performing a first preset mathematical operation on the first result to obtain a second result;

[0067] S6: performing velocity picking on the time domain migration gather track by track to obtain a second velocity body;

[0068] Specifically, by setting the amplitude threshold value and adjusting different time windows, a velocity result body is formed for the purpose of accurately picking up the velocity of igneous rocks.

[0069] S7: Performing a second preset mathematical operation on the first velocity body, the first result body, the second result body and the second velocity body to obtain an igneous rock result velocity body reflecting the velocity characteristics of the igneous rock.

[0070] Specifically, the second preset mathematical operation includes A*A1+B*B1, wherein A is the first result body; A1 is the first velocity body; B is the second result body; B1 is the second velocity body; and the igneous rock result velocity body reflecting the igneous rock velocity characteristics is obtained through the second mathematical operation.

[0071] like Figure 2 As shown, in one embodiment, marine seismic data is obtained to accurately characterize the velocity characteristics of multi-stage dispersed igneous rocks. First, without considering the influence of igneous rocks, multiple rounds of tomographic iterations are performed on the actual seismic wave propagation velocity until the velocity residual tends to zero, thereby obtaining the initial velocity body A1. Then, A1 is used for depth migration, and the migration gather is converted to the time domain, and then residual noise is suppressed to improve the signal-to-noise ratio, and then the processed gather is excised and stacked to obtain the time domain stacking results.

[0072] By analyzing the amplitude value characteristics in the superposition results, especially the difference in amplitude threshold values ​​between igneous rock and surrounding rock, the preliminary position of igneous rock can be delineated. Subsequently, this position profile is superimposed with the superimposed profile for quality control. If the position difference is significant, the above amplitude analysis steps are repeated until the two are consistent to ensure the accuracy of the igneous rock position.

[0073] On the quality-controlled igneous rock position profile, numerical filling processing is performed, the igneous rock position is filled with 0, and the rest of the space is filled with 1, generating result volume A. By performing mathematical operations |1-A| on A, result volume B is obtained. Since conventional velocity tomography often underestimates the true velocity of igneous rocks, based on the time domain result gather, the amplitude characteristics are used as one of the reference bases, and the velocity is automatically picked up one by one, forming a velocity result volume B1 specifically used for accurately picking up the velocity of igneous rocks.

[0074] To ensure the accuracy of the picked velocity, more than three igneous rock gathers in the work area are randomly selected for quality control to check whether they are leveled under the velocity body B1 correction. If not, the velocity picking steps are repeated until all quality control points meet the requirements.

[0075] Finally, the initial velocity body A1, the igneous rock velocity result body B1, and the result bodies A and B are combined, and the result velocity body C with the initial igneous rock velocity is obtained through a specific mathematical operation AA1+BB1. C is returned to the depth domain to form a depth domain velocity body D. D is used for depth migration and high-precision grid velocity iteration until the conventional formation phase axis becomes flat again. The velocity obtained at this time is the optimal imaging velocity after the igneous rock velocity is finely portrayed. This velocity not only has a high degree of overlap with the stacked profile, but also is consistent with the theoretical rock velocity analysis. At the same time, the imaging gathers are flattened, realizing an accurate description of the igneous rock velocity.

[0076] Further, step S2 includes:

[0077] Velocity tomography is performed on the seismic data until the velocity residual approaches zero to obtain the first velocity body.

[0078] Specifically, in order to accurately obtain the velocity information of the underground structure, the seismic data is first processed by velocity tomography, with the goal of constructing a three-dimensional velocity model of the first velocity body. This processing process follows the conventional depth migration velocity tomography process that does not consider the influence of igneous rocks. In this process, an initial model is first used to predict the propagation velocity of seismic waves at various points underground. However, due to the complexity of the underground structure, this initial prediction often differs from the actual seismic wave propagation velocity, and this difference is called the velocity residual. In order to quantify and reduce this difference, the event axes of the seismic data are observed. Event axes are a collection of points in the seismic data that represent the same seismic wave arrival time, and their shape can reflect the underground velocity distribution. When the velocity residual is large, the event axes will show obvious bending or tilt; and when the velocity residual tends to zero, the event axes will become relatively flat. Therefore, by continuously adjusting the parameters in the velocity model and observing the changes in the event axes, the velocity residual can be gradually reduced. This process is iterative until the event axes are close to flattening, that is, the velocity residual is close to zero, at which time it is considered that the picked velocity and the actual seismic wave propagation velocity have tended to be equal. Finally, when the remaining velocity reaches a preset value, a relatively accurate first velocity body is obtained. This value is set based on a comprehensive consideration of multiple factors such as actual work needs, data quality, analysis accuracy requirements, and conventional standards in the industry or research field.

[0079] Step S4 includes:

[0080] The residual noise of the time domain migration gather is suppressed, and the excision stacking operation is performed to obtain the time domain stacking section;

[0081] Analyze the amplitude characteristics of igneous rocks on the time domain stacked sections to obtain the location data of igneous rocks;

[0082] A first quality control process is performed on the igneous rock position data to obtain a first result body.

[0083] Specifically, the noise of the time domain offset gather was suppressed to improve the clarity of the data, and then the excision stacking technology was used to select and stack relevant data according to the propagation characteristics of seismic waves and the characteristics of underground geological structures, thus forming a time domain stacking profile that clearly shows the underground structure. Then, the amplitude characteristics of igneous rocks in the stacking profile were deeply analyzed, and the distribution range and morphological characteristics of igneous rocks were accurately determined by comparing the amplitude differences between igneous rocks and surrounding rocks. Finally, combining this information, the first result body was successfully constructed, which intuitively shows the distribution and characteristic information of underground igneous rocks, providing reliable data support for geological research and resource exploration.

[0084] Furthermore, the residual noise of the time domain migration gather is suppressed, and a cutting and stacking operation is performed to obtain a time domain stacking profile including:

[0085] Perform residual noise suppression on the time domain migration gather to obtain the first signal-to-noise ratio gather;

[0086] The first signal-to-noise ratio gather is subjected to excision and stacking processing to obtain a time domain stacking section.

[0087] Specifically, first, the residual noise suppression step is performed on the time domain offset gather. The purpose of this step is to reduce unnecessary interference information in the data and improve the signal-to-noise ratio of the data. Residual noise may come from various interference factors in the seismic data acquisition process, such as environmental noise, instrument errors, etc. By applying advanced signal processing techniques, such as filtering, denoising algorithms, etc., the impact of these noises can be effectively reduced to obtain the first signal-to-noise ratio gather. Compared with the original gather, this gather has higher signal clarity and less interference information. Next, the first signal-to-noise ratio gather is subjected to excision and stacking processing. Excision and stacking is a seismic data processing technology that enhances the visibility and interpretability of seismic wave signals by selectively extracting and stacking data in the gather. In this step, according to the propagation law of seismic waves and the characteristics of underground geological structures, the appropriate excision range and stacking method are determined to obtain a time domain stacking profile.

[0088] Furthermore, the amplitude characteristic analysis of igneous rocks is performed on the time domain stacked profile to obtain the igneous rock location data including:

[0089] Obtaining preset amplitude value features corresponding to the time domain stacked profile; wherein the preset amplitude value features include an igneous rock characteristic threshold and a surrounding rock amplitude threshold;

[0090] According to the igneous rock characteristic threshold and the surrounding rock amplitude threshold, the delineation operation is performed on the time domain stacked section to obtain the igneous rock location data.

[0091] It should be noted that in the process of analyzing the amplitude value characteristics of igneous rocks to obtain igneous rock location data, the determination of preset amplitude value characteristics (including igneous rock characteristic threshold and surrounding rock amplitude threshold) is one of the key steps. The setting of these thresholds is based on the experience of previous geological surveys, rock physical properties analysis and seismic data processing in similar geological environments. The igneous rock characteristic threshold is used to distinguish the significant difference in amplitude response between igneous rocks and surrounding rocks, while the surrounding rock amplitude threshold is used to define the upper limit of the amplitude of background noise or irrelevant rock reflections.

[0092] Specifically, Figure 3 and Figure 4 As shown in the figure, both the old and new PSTM (seismic wave reflection tomography) results show that igneous rocks are distributed from top to bottom and are uneven in thickness, but their amplitude energy is relatively strong, significantly higher than the amplitude value of the surrounding rock. According to the amplitude characteristics of the igneous rocks in the work area, the amplitude threshold value is set, and then continuous experiments are carried out to finally identify the location of the igneous rocks. Figure 3 Slices taken at different times show that the igneous rocks cut out on the slices have a good correspondence with the positions of the igneous rocks on the profile. The slices also reflect the trend from wide distribution in shallow layers to less distribution in deep layers. Figure 4 The location of the igneous rock is shown in three dimensions.

[0093] Further, the igneous rock position data is subjected to a first quality control process to obtain a first result body including:

[0094] The igneous rock location data and the time domain stacking profile are superimposed for quality control;

[0095] Calculate the igneous rock position data and the igneous rock position difference of the time domain stack section;

[0096] Determine whether the position difference of igneous rocks meets the preset range;

[0097] If not satisfied, repeat the analysis of igneous rock amplitude characteristics on the time domain stacked profile;

[0098] To obtain the first result body in which the position difference of igneous rock meets the preset range.

[0099] Further, step S5 includes:

[0100] Filling the first result body with numerical values ​​to obtain the filled first result body;

[0101] A preset mathematical operation is performed on the filled first result body to obtain a second result body.

[0102] The first preset mathematical operation includes:

[0103] B = |1-A|;

[0104] In the formula, B is the second achievement body; A is the first achievement body.

[0105] Specifically, numerical filling processing was performed on the igneous rock position profile after quality control, specifically filling the position of the igneous rock with the number 0, and filling other spaces with the number 1. After this step was completed, a preliminary data body was obtained, namely the first result body A. In order to further analyze and use this data body, a specific mathematical operation was performed on the first result body A, namely |1-A|, and through this operation, a new data body was obtained, namely the second result body B.

[0106] Specifically, step S6 is to automatically pick up the velocity of each track based on the time domain migration gather, in which the automatic picking criteria not only consider other factors, but also take the amplitude as an important reference basis. By accurately setting the amplitude threshold value and combining the adjustment of different time windows, the igneous rock velocity is accurately picked up to form the second velocity body.

[0107] Furthermore, step S6 includes:

[0108] The second velocity body is subjected to a second quality control process to obtain a second velocity body after quality control.

[0109] It should be noted that the second quality control process is intended to further improve the quality and accuracy of the data. This process includes one or more of data verification, outlier processing, data smoothing or filtering, etc., depending on the characteristics of the data and the processing objectives.

[0110] In one embodiment, three or more igneous rock gathers are randomly selected in the work area for quality control (QC). The main purpose of the QC is to check whether the causality corresponding to these igneous rocks has been flattened under the correction of the velocity body. If it is found through inspection that the causality has not been flattened, the above-mentioned step S6 of picking up the velocity one by one will be repeated, and this process will continue until the causality corresponding to the igneous rocks at the selected QC points has been flattened. After completing this step, the second velocity body will also be subjected to a second round of QC processing to ensure that its quality meets the requirements, and finally a second velocity body after QC is obtained. This series of QC steps is crucial to ensure the accuracy of subsequent geological analysis and resource assessment.

[0111] In one embodiment, after conventional velocity tomography, the phase axis on the corresponding gather of igneous rock cannot be flattened. Figure 5 The leftmost picture shows. Figure 4The spatial position of the igneous rock has been obtained. Now we only need to pick up the igneous rock velocity and fill it into the corresponding position of the igneous rock to achieve a fine description of the igneous rock velocity. Through the strong amplitude characteristics of igneous rock and different tests, the igneous rock phase axis is automatically flattened one by one, such as Figure 5 The middle picture shows that when the igneous rock phase axis is flattened, a velocity body is automatically generated based on the igneous rock velocity picking standard, such as Figure 5 The rightmost picture shows. Figure 5 The igneous rock velocity is obtained by Figure 4 The igneous rock position is circled and taken out, and then added back to the velocity results obtained by conventional tomography to obtain the following Figure 6 Speed ​​results.

[0112] Furthermore, the method also includes:

[0113] The velocity body of igneous rock results is processed back to the depth domain by self-ratio to obtain the velocity body in the depth domain;

[0114] The depth domain velocity body is depth-migrated and the grid velocity iteration is performed to obtain the final igneous rock result velocity body reflecting the velocity characteristics of the igneous rock.

[0115] Specifically, in order to obtain the final result reflecting the velocity characteristics of igneous rocks, the velocity volume of the igneous rock result is first processed by self-proportioning back to the depth domain to obtain the velocity volume in the depth domain. Then, the depth domain velocity volume is subjected to depth migration, and high-precision grid velocity iteration is performed in this process. After this series of operations, the final igneous rock result velocity volume that can more accurately reflect the velocity characteristics of igneous rocks is obtained.

[0116] Furthermore, the depth domain velocity body is subjected to depth migration and grid velocity iteration to obtain the final igneous rock result velocity body reflecting the velocity characteristics of igneous rock, including:

[0117] Performing depth migration processing on the depth domain velocity body to obtain the velocity result after migration;

[0118] The velocity results after migration are used as the input of the velocity model to perform grid velocity iteration;

[0119] During the iteration process, the changes in the phase axis of the conventional strata under the igneous rock are obtained to adjust the velocity model parameters and re-image until the phase axis is flat and meets the preset standards. At this time, the velocity model is the final igneous rock result velocity body.

[0120] Specifically, in order to obtain the final igneous rock result velocity body that can accurately reflect the velocity characteristics of igneous rocks, the depth domain velocity body is first subjected to depth migration processing to obtain the velocity result after migration. Subsequently, the velocity result after migration is used as input to start the grid velocity iteration process. During the iteration, attention is paid to the changes in the phase axis of the conventional strata under the igneous rock, and the phase axis becomes flat and meets the preset quality standards by continuously adjusting the velocity model parameters and re-imaging. At this time, it is determined that the velocity model has reached the optimal state and is used as the final igneous rock result velocity body. It is worth noting that during the iteration process, when the phase axis of the conventional strata becomes flat again, it indicates that the velocity iteration can be stopped. Usually, only one velocity iteration is required to obtain a fine characterization of the igneous rock velocity. At this time, the imaging velocity not only matches the stacked profile height, but also is consistent with the theoretical velocity analysis of the rock. In addition, the velocity outside the igneous rock can also effectively flatten the imaging gathers, thereby ensuring the velocity accuracy and reliability of the final result.

[0121] Specifically, Figure 7 The leftmost image is the result of PSDM (prestack depth migration) migration with conventional tomography velocity, and the middle image is PSDM (prestack depth migration) migration with conventional velocity tomography plus igneous rock velocity characterization. Comparison between the two shows that after igneous rock velocity characterization, the formation pull-up illusion is eliminated and the underlying formation structure is restored. This proves that the method of the present invention can accurately characterize multi-stage igneous rock velocities in marine seismic data, and its application effect is obvious.

[0122] When the present invention is implemented, it is possible to obtain a velocity body with a velocity residual of nearly zero without considering the influence of igneous rocks, which significantly improves the accuracy of seismic data processing. At the same time, the amplitude characteristics are used to clearly divide the boundaries of igneous rocks, providing a reliable way to effectively identify igneous rocks. In addition, the present invention uses a data-driven track-by-track velocity picking method. This method can automatically perform track-by-track velocity picking based on the amplitude characteristics of the igneous rock phase axis on the track set, thereby generating a velocity body specifically for igneous rock velocity picking. The present invention uses a multi-period dispersed igneous rock velocity characterization method for marine seismic data. This method achieves accurate depiction of igneous rock velocity by relying on data-driven track-by-track velocity picking technology.

[0123] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A method for characterizing the velocity of multi-stage dispersed igneous rocks, characterized in that: The method comprises: S1: Obtain the seismic data to be analyzed; S2: performing velocity analysis on the seismic data to obtain a first velocity body; S3: performing depth migration on the first velocity body and converting it into the time domain to obtain a time domain migration gather; S4: Processing the time domain migration gather to obtain a first result volume; S5: performing a first preset mathematical operation on the first result to obtain a second result; S6: performing velocity picking on the time domain migration gather track by track to obtain a second velocity body; S7: performing a second preset mathematical operation on the first velocity body, the first result body, the second result body and the second velocity body to obtain an igneous rock result velocity body reflecting the velocity characteristics of the igneous rock.

2. The multi-stage dispersed igneous rock velocity characterization method according to claim 1, characterized in that: The method further comprises: Performing self-ratio processing on the velocity body of the igneous rock result back to the depth domain to obtain a velocity body in the depth domain; The depth domain velocity body is subjected to depth migration and grid velocity iteration to obtain a final igneous rock result velocity body reflecting the velocity characteristics of the igneous rock.

3. The multi-stage dispersed igneous rock velocity characterization method according to claim 2, characterized in that: The depth migration of the depth domain velocity body and the grid velocity iteration to obtain the final igneous rock result velocity body reflecting the velocity characteristics of the igneous rock include: Performing depth migration processing on the depth-domain velocity body to obtain a velocity result after migration; Using the velocity result after migration as input of the velocity model to perform grid velocity iteration; During the iteration process, the changes in the phase axis of the conventional strata under the igneous rock are obtained to adjust the velocity model parameters and re-image until the phase axis is flat and meets the preset standards. At this time, the velocity model is the final igneous rock result velocity body.

4. The multi-stage dispersed igneous rock velocity characterization method according to claim 1, characterized in that: The step S2 comprises: Velocity tomography is performed on the seismic data until the velocity residual approaches zero, so as to obtain a first velocity body.

5. The multi-stage dispersed igneous rock velocity characterization method according to claim 1, characterized in that: The step S4 comprises: Suppressing residual noise on the time domain migration gather, and performing a cutting and stacking operation to obtain a time domain stacking section; Performing igneous rock amplitude value characteristic analysis on the time domain stacked profile to obtain igneous rock position data; A first quality control process is performed on the igneous rock position data to obtain a first result body.

6. The multi-stage dispersed igneous rock velocity characterization method according to claim 5, characterized in that: The step of suppressing residual noise on the time domain migration gather and performing a cutting and stacking operation to obtain a time domain stacking profile includes: Performing residual noise suppression on the time domain migration gather to obtain a first signal-to-noise ratio gather; The first signal-to-noise ratio gather is subjected to excision and stacking processing to obtain a time domain stacking section.

7. The multi-stage dispersed igneous rock velocity characterization method according to claim 6, characterized in that: The performing igneous rock amplitude value characteristic analysis on the time domain stacked profile to obtain igneous rock position data includes: Obtaining a preset amplitude value feature corresponding to the time domain stacked section; wherein the preset amplitude value feature includes an igneous rock characteristic threshold and a surrounding rock amplitude threshold; According to the igneous rock characteristic threshold and the surrounding rock amplitude threshold, a delineation operation is performed on the time domain stacked profile to obtain igneous rock position data.

8. The multi-stage dispersed igneous rock velocity characterization method according to claim 7, characterized in that: The performing a first quality control process on the igneous rock position data to obtain a first result body comprises: Performing quality control processing on the igneous rock position data and the time domain stacked profile; Calculating the igneous rock position data and the igneous rock position difference of the time domain stacked profile; Determining whether the position difference of the igneous rock meets a preset range; If not satisfied, repeatedly performing igneous rock amplitude value characteristic analysis on the time domain stacked profile; To obtain a first result body in which the position difference of the igneous rock meets a preset range.

9. The multi-stage dispersed igneous rock velocity characterization method according to claim 5, characterized in that: The step S5 comprises: Filling the first result body with numerical values ​​to obtain a filled first result body; Performing a preset mathematical operation on the filled first result body to obtain a second result body; Wherein, the first preset mathematical operation includes: B = |1-A|; In the formula, B is the second achievement body; A is the first achievement body.

10. The multi-stage dispersed igneous rock velocity characterization method according to claim 6, characterized in that: The step S6 then includes: The second velocity body is subjected to a second quality control process to obtain a second velocity body after quality control.

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