Multi-stage dispersed igneous rock velocity characterization method

Abstract

This invention relates to a method for characterizing the velocities of multi-phase dispersed igneous rocks. The method includes the following steps: acquiring seismic data to be analyzed; performing velocity analysis on the seismic data to obtain a first velocity volume; performing depth migration on the first velocity volume and converting it to the time domain to obtain a time-domain migrated gather; processing the time-domain migrated gather to obtain a first result volume; performing a first preset mathematical operation on the first result volume to obtain a second result volume; performing velocity picking on each trace of the time-domain migrated gather to obtain a second velocity volume; and performing a second preset mathematical operation on the first velocity volume, the first result volume, the second result volume, and the second velocity volume to obtain an igneous result velocity volume reflecting the velocity characteristics of igneous rocks. This invention achieves a detailed characterization of the velocities of multi-phase dispersed igneous rocks by comprehensively utilizing multiple techniques including seismic data processing, velocity analysis, depth migration, and mathematical operations.

Description

Technical Field

[0001] This invention relates to the field of seismic exploration of oil and gas reservoirs, and in particular to a method for characterizing the velocity of multi-stage dispersed igneous rocks. Background Technology

[0002] The exploration and development of igneous oil and gas reservoirs presents a significant challenge in accurately characterizing igneous velocities. Specifically, igneous rocks are characterized by multi-stage development, uneven thickness, and diverse morphologies, and their velocities differ considerably from those of the surrounding rocks. This results in complex features on seismic profiles, such as low signal-to-noise ratios, inability to image, or the appearance of false faults due to the high resistivity of the underlying igneous strata. These issues pose challenges to the exploration and development of igneous oil and gas reservoirs, thus necessitating precise characterization of igneous velocities to address the resulting problems.

[0003] However, existing velocity tomography methods face numerous challenges when dealing with igneous rocks. For example, conventional grid tomography exhibits strong ambiguity in igneous regions, failing to meet the requirements for fine characterization; while phase-controlled igneous velocity modeling can effectively address the velocity characterization of thicker igneous rocks with well-defined regional characteristics, it is difficult to apply to thin, dispersed igneous rocks; first-arrival tomography can provide fine characterization when igneous rocks are shallowly buried and first-arrival waves are present, but it is not feasible when igneous rocks are deeply buried; reflected wave FWI can provide fine characterization of multi-phase dispersed igneous velocities, but it is not economically viable and has not yet been industrialized in China. Summary of the Invention

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

[0005] To solve the above-mentioned technical problems, the method includes the following steps:

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

[0007] S2: Perform velocity analysis on the earthquake data to obtain a first velocity volume;

[0008] S3: Perform depth offset on the first velocity volume and convert it to the time domain to obtain the time domain offset gather;

[0009] S4: Process the time-domain offset gather to obtain the first result body;

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

[0011] S6: Perform track-by-track velocity picking on the time-domain offset gather to obtain the second velocity volume;

[0012] S7: Perform 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 that reflects the velocity characteristics of igneous rocks.

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

[0014] The velocity volume of the igneous rock is subjected to self-proportional depth domain processing to obtain the depth domain velocity volume.

[0015] The depth domain velocity volume is depth-shifted and the mesh velocity is iterated to obtain the final igneous rock velocity volume that reflects the velocity characteristics of igneous rocks.

[0016] In one embodiment, the process of performing depth migration on the depth domain velocity volume and iterating the mesh velocity to obtain a final igneous rock velocity volume reflecting the velocity characteristics of igneous rocks includes:

[0017] The depth domain velocity volume is subjected to depth offset processing to obtain the offset velocity result;

[0018] The offset velocity result is used as input to the velocity model for mesh velocity iteration;

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

[0020] In one embodiment, step S2 includes:

[0021] The seismic data is subjected to velocity tomography until the velocity residual approaches zero to obtain the first velocity volume.

[0022] In one embodiment, step S4 includes:

[0023] The time-domain offset gather is subjected to residual noise suppression and a cut-and-overlay operation is performed to obtain a time-domain overlay profile.

[0024] The time-domain overlay profile was analyzed to obtain igneous rock location data.

[0025] The location data of the igneous rocks are subjected to a first quality control process to obtain a first result.

[0026] In one embodiment, the step of suppressing residual noise and performing a cut-and-stack operation on the time-domain offset gather to obtain a time-domain stacked profile includes:

[0027] Residual noise is suppressed on the time-domain offset gather to obtain a first signal-to-noise ratio gather.

[0028] The first signal-to-noise ratio gather is subjected to cut-and-overlay processing to obtain a time-domain overlay profile.

[0029] In one embodiment, the step of performing igneous rock amplitude characteristic analysis on the time-domain overlay profile to obtain igneous rock location data includes:

[0030] Obtain the preset amplitude value features corresponding to the time-domain superimposed profile; wherein, the preset amplitude value features include igneous rock feature threshold and surrounding rock amplitude threshold;

[0031] Based on the igneous rock characteristic threshold and the surrounding rock amplitude threshold, a delineation operation is performed on the time-domain superimposed profile to obtain igneous rock location data.

[0032] In one embodiment, the first quality control processing of the igneous rock location data to obtain a first result includes:

[0033] The location data of the igneous rocks are superimposed with the time-domain overlay profile for quality control processing.

[0034] Calculate the difference in igneous rock location between the igneous rock location data and the igneous rock location in the time-domain superimposed profile;

[0035] Determine whether the positional differences of the igneous rocks meet a preset range;

[0036] If not satisfied, repeat the analysis of igneous rock amplitude characteristics on the time-domain superimposed profile;

[0037] To obtain a first result body in which the positional differences of the igneous rocks meet a preset range.

[0038] In one embodiment, step S5 includes:

[0039] The first result body is numerically filled to obtain the filled first result body;

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

[0041] The first preset mathematical operation includes:

[0042] B = |1-A|;

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

[0044] In one embodiment, step S6 is followed by:

[0045] The second velocity body undergoes a second quality control process to obtain a quality-controlled second velocity body.

[0046] The present invention offers the following advantages: It relates to a method for characterizing the velocities of multi-phase dispersed igneous rocks. The method includes the following steps: acquiring seismic data to be analyzed; performing velocity analysis on the seismic data to obtain a first velocity volume; performing depth migration on the first velocity volume and converting it to the time domain to obtain a time-domain migrated gather; processing the time-domain migrated gather to obtain a first result volume; performing a first preset mathematical operation on the first result volume to obtain a second result volume; performing velocity picking on each trace of the time-domain migrated gather to obtain a second velocity volume; and performing a second preset mathematical operation on the first velocity volume, the first result volume, the second result volume, and the second velocity volume to obtain an igneous rock result velocity volume reflecting the velocity characteristics of the igneous rocks. This invention, by comprehensively utilizing seismic data processing, velocity analysis, depth migration, and mathematical operations, achieves a refined characterization of the velocities of multi-phase dispersed igneous rocks. This method not only improves the accuracy and reliability of velocity characterization but also effectively reduces the risks and costs of exploration and development. Attached Figure Description

[0047] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

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

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

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

[0052] Figure 5 This is a schematic diagram of the time-domain offset gather for track-by-track velocity picking provided by the present invention;

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

[0054] Figure 7 This is a schematic diagram of seismic wave reflection tomography after the igneous rock has been thoroughly analyzed, provided by the present invention. Detailed Implementation

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

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

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

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

[0059] It should be noted that the seismic data can be terrestrial or marine. This invention uses marine seismic data as an example. The seismic data to be analyzed is raw seismic records collected from seismic exploration equipment. This data contains information on the response of subsurface structures to artificially induced seismic waves, including reflection, refraction, and scattering.

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

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

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

[0063] Specifically, this process involves converting depth information from the first velocity volume into time-domain information using a migration algorithm. Depth migration is a complex seismic data processing technique that corrects the propagation path of seismic waves based on velocity variations in the subsurface medium, thus more accurately reflecting the true morphology of subsurface structures. After depth migration, the results are converted to the time domain to obtain time-domain migrated gathers. This step provides crucial data for subsequent time-domain analysis and interpretation.

[0064] S4: Process the time-domain offset gather to obtain the first result body;

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

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

[0067] S6: Perform per-track velocity picking on the time-domain offset gather to obtain the second velocity volume;

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

[0069] S7: Perform 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 the igneous rock result velocity body that reflects the velocity characteristics of igneous rocks.

[0070] Specifically, the second preset mathematical operation includes A*A1+B*B1, where 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 velocity characteristics of igneous rocks is obtained through this mathematical operation.

[0071] like Figure 2 As shown, in one embodiment, marine seismic data is acquired to accurately characterize the velocity features of dispersed igneous rocks across multiple phases. 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 approaches zero, thereby obtaining an initial velocity volume A1. Next, depth migration is performed using A1, and the migrated gathers are converted to the time domain. Subsequently, residual noise is suppressed to improve the signal-to-noise ratio. Finally, cut-and-stack operations are performed based on the processed gathers to obtain the time-domain stacking results.

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

[0073] On the quality-controlled igneous rock location profile, numerical filling was performed, with igneous rock locations filled with 0 and the remaining spaces filled with 1, generating result volume A. By performing the mathematical operation |1-A| on A, result volume B was obtained. Since conventional velocity tomography often underestimates the true velocity of igneous rocks, based on the time-domain result gathers and using amplitude characteristics as one of the reference criteria, velocity was automatically picked up channel by channel, forming a velocity result volume B1 specifically designed for accurately picking igneous rock velocities.

[0074] To ensure the accuracy of the picking speed, three or more igneous rock gathers in the work area are randomly selected for quality control. The gathers are checked to see if they are flattened under the speed body B1 correction. If they are not flattened, the speed picking steps are repeated until all quality control points meet the requirements.

[0075] Finally, the initial velocity volume A1, the igneous rock velocity volume B1, and the igneous rock velocities A and B are combined using a specific mathematical operation AA1+BB1 to obtain the initial velocity volume C containing the igneous rock velocity. C is then transferred back to the depth domain to form the depth domain velocity volume D. Depth migration is performed using D, followed by high-precision grid velocity iteration until the conventional stratigraphic phase axis flattens again. The velocity obtained at this point is the optimal imaging velocity after fine characterization of the igneous rock velocity. This velocity not only has a high degree of superposition with the stacked profile but also matches the theoretical velocity analysis of the rock, while simultaneously flattening the imaging gathers, thus achieving an accurate description of the igneous rock velocity.

[0076] Furthermore, step S2 includes:

[0077] Seismic data is subjected to velocity tomography until the velocity residual approaches zero to obtain the first velocity volume.

[0078] Specifically, to accurately obtain velocity information of subsurface structures, the seismic data is first processed using velocity tomography to construct a three-dimensional velocity model of the first velocity volume. This process follows the conventional depth migration velocity tomography workflow, which does not consider the influence of igneous rocks. In this workflow, an initial model is first used to predict the propagation velocity of seismic waves at various points underground. However, due to the complexity of subsurface structures, this initial prediction often differs from the actual seismic wave propagation velocity; this difference is called the velocity residual. To quantify and reduce this difference, the phase axes of the seismic data gathers are observed. Phase axes are sets of points in seismic data that represent the same arrival time of seismic waves, and their shape reflects the distribution of subsurface velocities. When the velocity residual is large, the phase axes will show obvious curvature or tilt; while when the velocity residual approaches zero, the phase axes will become relatively flat. Therefore, by continuously adjusting the parameters in the velocity model and observing the changes in the phase axes, the velocity residual is gradually reduced. This process is iterative until the phase axes are nearly flattened, i.e., the velocity residual is close to zero. At this point, the picked velocity is considered to be close to equal to the actual seismic wave propagation velocity. Finally, when the remaining velocity reaches the preset value, a relatively accurate first velocity volume is obtained. This value is set by comprehensively considering various factors such as actual work requirements, data quality, analytical accuracy requirements, and conventional standards in the industry or research field.

[0079] Step S4 includes:

[0080] Residual noise is suppressed in the time-domain offset gathers, and a cut-and-stack operation is performed to obtain a time-domain stacked profile.

[0081] Analyze the amplitude characteristics of igneous rocks by time-domain superimposed profiles to obtain igneous rock location data.

[0082] The location data of igneous rocks were subjected to the first quality control processing to obtain the first result.

[0083] Specifically, noise suppression was performed on the time-domain migrated gathers to improve data clarity. Subsequently, a cut-and-stack technique was employed, selecting and overlaying relevant data based on the propagation characteristics of seismic waves and the features of the subsurface geological structure, thus forming a time-domain overlay profile that clearly displays the subsurface structure. Next, the amplitude characteristics of igneous rocks in the overlay profile were analyzed in depth. By comparing the amplitude differences between igneous rocks and surrounding rocks, the distribution range and morphological characteristics of the igneous rocks were accurately determined. Finally, by integrating this information, the first result module was successfully constructed. This result module visually displays the distribution and characteristic information of subsurface igneous rocks, providing reliable data support for geological research and resource exploration.

[0084] Furthermore, residual noise is suppressed in the time-domain offset gather, and a cut-and-stack operation is performed to obtain a time-domain stacked profile, including:

[0085] Residual noise is suppressed on the time-domain offset gather to obtain the first signal-to-noise ratio gather;

[0086] The first signal-to-noise ratio gather is subjected to cut-and-stack processing to obtain a time-domain stacked profile.

[0087] Specifically, firstly, residual noise suppression is performed on the time-domain migrated gathers. The purpose of this step is to reduce unnecessary interference information in the data and improve the signal-to-noise ratio (SNR). Residual noise may originate from various interference factors during seismic data acquisition, such as environmental noise and instrument errors. By applying advanced signal processing techniques, such as filtering and denoising algorithms, the impact of this noise can be effectively reduced, thereby obtaining a gather with a higher SNR. This gather has higher signal clarity and less interference information compared to the original gather. Next, the first SNR gather undergoes cut-and-stack processing. Cut-and-stack is a seismic data processing technique that enhances the visibility and interpretability of seismic wave signals by selectively extracting and stacking data from the gathers. In this step, based on the propagation laws of seismic waves and the characteristics of the underground geological structure, an appropriate cut range and stacking method are determined to obtain a time-domain stacked profile.

[0088] Furthermore, the amplitude characteristics of igneous rocks were analyzed by superimposed time-domain profiles to obtain location data of igneous rocks, including:

[0089] Obtain the preset amplitude value features corresponding to the time-domain overlay profile; wherein, the preset amplitude value features include igneous rock feature threshold and surrounding rock amplitude threshold;

[0090] Based on the characteristic threshold of igneous rocks and the amplitude threshold of surrounding rocks, a delineation operation is performed on the time-domain superimposed profile to obtain the location data of igneous rocks.

[0091] It should be noted that determining the preset amplitude characteristics (including igneous rock characteristic thresholds and surrounding rock amplitude thresholds) is a crucial step in obtaining igneous rock location data through amplitude characteristic analysis. These thresholds are set based on prior geological surveys, rock physical property analysis, and experience processing seismic data in similar geological environments. The igneous rock characteristic threshold is used to distinguish significant differences in amplitude response between igneous rocks and surrounding rocks, while the surrounding rock amplitude threshold is used to define the upper limit of amplitude reflections from background noise or irrelevant rocks.

[0092] Specifically, such as Figure 3 and Figure 4 As shown, both old and new PSTM (Seismic Reflection Tomography) results indicate that igneous rocks are distributed from top to bottom with uneven thickness, but their amplitude energy is strong, significantly higher than that of the surrounding rock. Based on the amplitude characteristics of the igneous rocks in the work area, an amplitude threshold value was set, and then through continuous experiments, the location of the igneous rocks was finally delineated. Figure 3 The slices taken at different times show a good correspondence between the igneous rocks cut out on the slices and the igneous rocks on the cross section. The slices also reflect the trend of the igneous rocks being widely distributed in shallow layers and less distributed in deep layers. Figure 4 The location defined by the igneous rocks was shown in three-dimensional space.

[0093] Furthermore, the igneous rock location data undergoes a first quality control process to obtain the first output, including:

[0094] The location data of igneous rocks were overlaid with time-domain profiles and subjected to quality control processing.

[0095] Calculate the difference in igneous rock location between igneous rock location data and time-domain superimposed profiles;

[0096] Determine whether the locational differences of igneous rocks meet the preset range;

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

[0098] To obtain the first result body where the positional differences of igneous rocks meet the preset range.

[0099] Furthermore, step S5 includes:

[0100] Numerical filling is performed on the first result body to obtain the filled first result body;

[0101] Perform preset mathematical operations on the first completed result to obtain the second result.

[0102] The first preset mathematical operation includes:

[0103] B = |1-A|;

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

[0105] Specifically, numerical filling was performed on the igneous rock location profile after quality control. The igneous rock locations were filled with the number 0, while other spaces were filled with the number 1. This step yielded a preliminary data volume, the first result volume A. To further analyze and utilize this data volume, a specific mathematical operation, |1-A|, was performed on the first result volume A, resulting in a new data volume, the second result volume B.

[0106] Specifically, step S6 involves automatic velocity picking based on time-domain offset gathers. The criteria for automatic picking not only consider other factors but also take amplitude as an important reference. By precisely setting the amplitude threshold value and adjusting different time windows, the aim is to accurately pick up igneous rock velocities, thereby forming a second velocity volume.

[0107] Furthermore, step S6 includes the following:

[0108] The second velocity body undergoes a second quality control process to obtain a quality-controlled second velocity body.

[0109] It should be noted that the second quality control process aims to further improve the quality and accuracy of the data. This process includes one or more of the following: data validation, outlier handling, data smoothing, or filtering, depending on the characteristics of the data and the processing objectives.

[0110] In one embodiment, three or more igneous rock gathers are randomly selected within the work area for quality control. The main purpose of quality control is to check whether the phase axes corresponding to these igneous rocks have been flattened under the correction of the velocity volume. If the check finds that the phase axes have not been flattened, the above step S6, velocity picking, is repeated. This process continues until the phase axes corresponding to the igneous rocks at the selected quality control points have been flattened. After this step, a second round of quality control is performed on the second velocity volume to ensure that its quality meets the requirements, ultimately obtaining the quality-controlled second velocity volume. This series of quality control steps is crucial to ensuring the accuracy of subsequent geological analysis and resource assessment.

[0111] In one embodiment, conventional velocity chromatography often fails to flatten the in-phase axes on the corresponding gathers of igneous rocks, such as... Figure 5 The image on the far left is shown. (Example) Figure 4The spatial location of igneous rocks has been obtained. Now, by simply extracting the igneous rock velocity and filling it into the corresponding location, a fine characterization of igneous rock velocity can be achieved. Automatic leveling of the igneous rock phase axis is performed channel by channel based on the strong amplitude characteristics of igneous rocks and different experiments. Figure 5 The middle image shows that after the igneous rock phase axis is flattened, a velocity volume is automatically generated based on the igneous rock velocity pickup standard, such as... Figure 5 The image on the far right is shown. Figure 5 The obtained igneous rock velocity is obtained through Figure 4 The igneous rock was extracted from its location and then added back to the rate results obtained from conventional chromatography, yielding the following results: Figure 6 Speed ​​and results.

[0112] Furthermore, the methods also include:

[0113] The velocity volume of igneous rock is subjected to self-scale return to the depth domain to obtain the depth domain velocity volume.

[0114] Depth migration is performed on the depth domain velocity volume, and mesh velocity iteration is carried out to obtain the final igneous result velocity volume that reflects the velocity characteristics of igneous rocks.

[0115] Specifically, to obtain the final result reflecting the velocity characteristics of igneous rocks, the velocity volume of the igneous rock result is first subjected to self-scaled return to the depth domain, thus obtaining the depth domain velocity volume. Next, depth migration is performed on the depth domain velocity volume, and high-precision mesh velocity iteration is conducted during this process. After this series of operations, the final igneous rock result velocity volume, which can more accurately reflect the velocity characteristics of igneous rocks, is obtained.

[0116] Furthermore, depth migration is performed on the depth domain velocity volume, and mesh velocity iteration is conducted to obtain the final igneous rock velocity volume reflecting the velocity characteristics of igneous rocks, including:

[0117] The velocity volume in the depth domain is subjected to depth offset processing to obtain the offset velocity result;

[0118] The offset velocity results are used as input to the velocity model for mesh velocity iteration;

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

[0120] Specifically, to obtain a final igneous velocity volume that accurately reflects the velocity characteristics of igneous rocks, the depth-domain velocity volume is first subjected to depth migration to obtain the migrated velocity results. Then, this migrated velocity result is used as input to initiate a grid velocity iteration process. During iteration, the changes in the phase axis of the conventional strata beneath the igneous rocks are monitored. The velocity model parameters are continuously adjusted and re-imaged until the phase axis becomes flat and meets the preset quality standards. At this point, the velocity model is considered to have reached its optimal state and is used as the final igneous velocity volume. It is worth noting that during the iteration process, when the phase axis of the conventional strata becomes flat again, the velocity iteration can be stopped. Typically, only one velocity iteration is needed to obtain a detailed characterization of igneous velocities. At this point, the imaging velocity not only matches the stacked profile height but also aligns with the theoretical velocity analysis of the rocks. Furthermore, velocities outside the igneous rocks can also effectively flatten the imaging gathers, thus ensuring the accuracy and reliability of the final velocity results.

[0121] Specifically, such as Figure 7 The leftmost image shows the result of PSDM (pre-stack depth migration) based on conventional tomography velocity, while the middle image shows the result of PSDM (pre-stack depth migration) based on conventional velocity tomography combined with igneous rock velocity characterization. A comparison of the two images shows that the strata uplift artifact is eliminated after igneous rock velocity characterization, and the underlying stratigraphic structure is restored. This demonstrates that the method of this invention can accurately characterize multi-stage igneous rock velocities in marine seismic data, and its application effectiveness is significant.

[0122] When implementing this invention, a velocity volume with near-zero velocity residual can be obtained without considering the influence of igneous rocks, significantly improving the accuracy of seismic data processing. Simultaneously, the amplitude characteristics are used to clearly delineate igneous rock boundaries, providing a reliable method for effective igneous rock identification. Furthermore, this invention employs a data-driven, channel-by-channel velocity picking method. This method, based on the amplitude characteristics of igneous rock phase axes in the gather, can automatically perform channel-by-channel velocity picking, thereby generating a velocity volume specifically for igneous rock velocity picking. This invention also utilizes a multi-phase, dispersed igneous rock velocity characterization method for marine seismic data. This method, through data-driven, channel-by-channel velocity picking technology, achieves accurate depiction of igneous rock velocities.

[0123] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope 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: Step S1: Obtain the seismic data to be analyzed; Step S2: Perform velocity analysis on the seismic data to obtain a first velocity volume; Step S3: Perform depth offset on the first velocity volume and convert it to the time domain to obtain the time domain offset gather; Step S4: Process the time-domain offset gather to obtain the first result body; Step S5: Perform a first preset mathematical operation on the first result to obtain a second result; Step S6: Perform track-by-track velocity picking on the time-domain offset gather to obtain the second velocity volume; Step S7: Perform 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 igneous rocks; wherein, step S4 includes: The time-domain offset gather is subjected to residual noise suppression and a cut-and-overlay operation is performed to obtain a time-domain overlay profile. The amplitude characteristics of igneous rocks are analyzed by performing time-domain overlay profile analysis to obtain igneous rock location data; The location data of the igneous rocks are subjected to a first quality control process to obtain a first result. Step S5 includes: The first result body is numerically filled to obtain the filled first result body; Perform a first preset mathematical operation on the filled first result body to obtain a second result body; The first preset mathematical operation includes: B = |1-A|; In the formula, B is the second result body; A is the first result body, which shows the distribution and characteristic information of underground igneous rocks.

2. The method for characterizing the velocity of multi-stage dispersed igneous rocks according to claim 1, characterized in that, The method further includes: The velocity volume of the igneous rock is subjected to self-scale return to the depth domain to obtain the depth domain velocity volume; The depth domain velocity volume is depth-shifted and the mesh velocity is iterated to obtain the final igneous rock velocity volume that reflects the velocity characteristics of igneous rocks.

3. The method for characterizing the velocity of multi-stage dispersed igneous rocks according to claim 2, characterized in that, The process of performing depth migration on the depth domain velocity volume and iterating the mesh velocity to obtain the final igneous rock velocity volume reflecting the velocity characteristics of igneous rocks includes: The depth domain velocity volume is subjected to depth offset processing to obtain the offset velocity result; The offset velocity result is used as input to the velocity model for mesh velocity iteration; During the iteration process, the changes in the phase axis of the conventional strata under the igneous rocks are obtained to adjust the velocity model parameters and re-image until the phase axis is flat and meets the preset standard. At this time, the velocity model is the final velocity volume of the igneous rocks.

4. The method for characterizing the velocity of multi-stage dispersed igneous rocks according to claim 1, characterized in that, Step S2 includes: The seismic data is subjected to velocity tomography until the velocity residual approaches zero to obtain the first velocity volume.

5. The method for characterizing the velocity of multi-stage dispersed igneous rocks according to claim 1, characterized in that, The step of suppressing residual noise in the time-domain offset gather and performing a cut-and-stack operation to obtain a time-domain stacked profile includes: Residual noise is suppressed on the time-domain offset gather to obtain a first signal-to-noise ratio gather. The first signal-to-noise ratio gather is subjected to cut-and-overlay processing to obtain a time-domain overlay profile.

6. The method for characterizing the velocity of multi-stage dispersed igneous rocks according to claim 5, characterized in that, The step of performing igneous rock amplitude characteristic analysis on the time-domain superimposed profile to obtain igneous rock location data includes: Obtain the preset amplitude value features corresponding to the time-domain superimposed profile; wherein, the preset amplitude value features include igneous rock feature threshold and surrounding rock amplitude threshold; Based on the igneous rock characteristic threshold and the surrounding rock amplitude threshold, a delineation operation is performed on the time-domain superimposed profile to obtain igneous rock location data.

7. The method for characterizing the velocity of multi-stage dispersed igneous rocks according to claim 6, characterized in that, The first quality control processing of the igneous rock location data to obtain the first result includes: The location data of the igneous rocks are superimposed with the time-domain overlay profile for quality control processing. Calculate the difference in igneous rock location between the igneous rock location data and the igneous rock location in the time-domain superimposed profile; Determine whether the positional differences of the igneous rocks meet a preset range; If not satisfied, repeat the analysis of igneous rock amplitude characteristics on the time-domain superimposed profile; To obtain a first result body in which the positional differences of the igneous rocks meet a preset range.

8. The method for characterizing the velocity of multi-stage dispersed igneous rocks according to claim 5, characterized in that, Step S6 is followed by: The second velocity body undergoes a second quality control process to obtain a quality-controlled second velocity body.

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