Pre-stack depth migration seismic data processing method and device

Abstract

The invention discloses a seismic data processing method and device for prestack depth migration. The method comprises the following steps: establishing a near-surface velocity model and a surface smooth surface of a work area to be processed; according to the near-surface velocity model and the surface smooth surface, determining a static correction value of the surface smooth surface; obtaining the seismic wave first arrival time based on the surface smooth surface and the elevation based on the surface smooth surface according to the static correction value; according to the seismic wave first arrival time based on the ground surface smooth surface, a shallow velocity model based on the ground surface smooth surface is obtained by adopting a first arrival tomography inversion method based on the elevation of the ground surface smooth surface; fusing the shallow velocity model and the deep velocity model to obtain a velocity model to be subjected to pre-stack depth migration processing; and carrying out migration processing on the pre-stack data based on the small smooth surface of the earth surface by adopting the speed model of the pre-stack depth migration processing to obtain seismic data after depth migration.

Description

Technical Field

[0001] The present invention relates to the technical field of seismic data processing, and in particular to a method and device for seismic data processing of pre-stack depth migration. Background Art

[0002] In the conventional prestack depth migration processing of seismic data, the prestack depth migration processing is usually based on the floating surface. In the usual seismic data processing, static correction processing needs to be done first to eliminate the distortion of seismic imaging events caused by the change of velocity in the low-velocity zone to ensure the reliability of the reflection event shape. This approach removes the low-velocity zone near the surface and replaces it with a high-speed layer with a filling velocity. Although this eliminates the influence of the static correction problem on the event shape, the shallow layer is replaced with a relatively uniform high-speed layer in the velocity of prestack depth migration, rather than the original underground real velocity, so it is impossible to restore the real seismic wave travel time and wave field propagation path, so the obtained imaging is approximate and the accuracy is limited. In order to obtain the real structural morphology of the underground strata more accurately, it is necessary to establish a more accurate prestack depth migration velocity model. The complete true surface prestack depth migration requires a completely accurate near-surface and underground velocity model. The true surface usually has large fluctuations, which is also easy to form high-frequency velocity jitter and introduce large errors, so it is difficult to achieve accurate imaging in actual production. In order to overcome these shortcomings, velocity modeling of small smooth surfaces on the surface and prestack depth migration are required, so it is necessary to carry out integrated modeling of near-surface modeling based on smooth surfaces and prestack depth migration velocity modeling. Summary of the invention

[0003] The inventors of this application discovered that:

[0004] In order to obtain the true structural morphology of underground strata more accurately, it is necessary to establish a more accurate pre-stack depth migration velocity model for data processing. A completely true surface pre-stack depth migration requires a completely accurate near-surface and underground velocity model. The true surface usually has large fluctuations, which is also prone to high-frequency jitter of velocity and the introduction of large errors. Therefore, it is difficult to achieve accurate imaging in actual production. In order to overcome these shortcomings, the inventors of this application propose an integrated modeling method based on near-surface velocity modeling of a smooth surface and pre-stack depth migration velocity modeling.

[0005] In a first aspect, the present application provides a seismic data processing method for prestack depth migration, the method comprising:

[0006] Establish near-surface velocity model and surface smoothing surface of the work area to be processed;

[0007] Determining a static correction amount of the surface smooth surface according to the near-surface velocity model and the surface smooth surface;

[0008] Obtaining the first arrival time of the seismic wave based on the smooth surface of the ground and the elevation based on the smooth surface of the ground according to the static correction amount;

[0009] Obtaining a shallow velocity model based on the smooth surface of the ground using a first-arrival tomographic inversion method according to the first-arrival time of the seismic wave based on the smooth surface of the ground and the elevation of the smooth surface of the ground;

[0010] The shallow velocity model and the deep velocity model are merged to obtain a velocity model processed by prestack depth migration;

[0011] The velocity model of the pre-stack depth migration processing is used to perform migration processing on the pre-stack data based on the small smooth surface on the surface, so as to obtain seismic data after depth migration.

[0012] In an exemplary embodiment, the process of establishing the near-surface velocity model includes:

[0013] Determine the first arrival time of the seismic wave in the work area to be treated;

[0014] A near-surface velocity model is obtained according to the first arrival time of the seismic wave and using the first arrival tomographic inversion method.

[0015] In an exemplary embodiment, the process of establishing the smooth surface includes:

[0016] Interpolate the elevation data of discrete detection points and shot points to obtain surface elevation data;

[0017] The surface elevation data is smoothed to obtain a surface smooth surface.

[0018] In an exemplary embodiment, determining the static correction amount of the surface smooth surface according to the near-surface velocity model and the surface smooth surface includes:

[0019] Filling the velocity in the near-surface velocity model according to the surface smooth surface to obtain a filled velocity model;

[0020] The static correction amount of the smooth surface of the ground is calculated according to the filled velocity model and the smooth surface of the ground according to the static correction formula.

[0021] In an exemplary embodiment, the static correction formula is:

[0022]

[0023]

[0024] In the above formula, S S_FD S is the static correction from the shot point to the smooth surface of the ground, R_FDis the static correction from the detection point to the smooth surface of the ground, Z S is the shot point elevation, Z S_FD is the elevation of the smooth surface corresponding to the shot point position, Z R is the elevation of the detection point, Z R_FD is the elevation of the smooth surface corresponding to the detection point position, and V is the average velocity.

[0025] In an exemplary embodiment, the average velocity is an average velocity from the ground surface to a smooth surface of the ground surface determined according to the filled velocity model.

[0026] In an exemplary embodiment, the filling process is performed on the velocity in the near-surface velocity model according to the surface smooth surface to obtain the filled velocity model, including:

[0027] Comparing the surface elevation data with the elevation data corresponding to the surface smooth surface;

[0028] If the surface elevation data is smaller than the elevation data corresponding to the surface smooth surface, the velocity of the blank area is filled to establish a filled velocity model;

[0029] If the surface elevation data is greater than or equal to the elevation data corresponding to the surface smooth surface, no filling is required, and the filled velocity model is established with the velocity in the near-surface velocity model.

[0030] In an exemplary embodiment, the fusion of the shallow velocity model based on the smooth surface and the deep velocity model to obtain the velocity model for prestack depth migration processing includes:

[0031] Determining a high-speed top interface according to the shallow velocity model;

[0032] The high-speed top interface is used to vertically fuse the shallow velocity model and the deep velocity model to obtain a velocity model processed by prestack depth migration.

[0033] In an exemplary embodiment, the pre-stack data based on the small smooth surface of the ground surface is obtained by the following steps:

[0034] Determine the static correction amount when the fixed reference surface is aligned with the smooth surface of the ground;

[0035] Prestack data based on the smooth surface of the ground are obtained according to the determined static correction amount and the data on the fixed reference surface.

[0036] In an exemplary embodiment, the static correction amount from the fixed reference surface to the ground smooth surface includes:

[0037]

[0038]

[0039] In the above formula, S S_cor S is the correction amount of the shot point from the fixed reference surface to the smooth surface of the ground, S_SRD is the static correction of the shot point on the fixed reference surface, Z S_HIV is the elevation of the high-speed top interface corresponding to the shot point position, S R_cor S is the correction value from the fixed reference surface to the detection point on the smooth surface of the ground, R_SRD is the static correction of the detection point of the fixed reference surface, Z R_HIV is the elevation of the high-speed top interface corresponding to the detection point position, Z SRD is the fixed datum elevation, V R is the replacement speed, V i is the velocity value of the i-th surface element in the velocity model based on the smooth surface, ΔZ is the longitudinal grid size value of the velocity model based on the smooth surface, and N is the number of longitudinal grids from the high-speed top interface to the smooth surface of the velocity model based on the smooth surface.

[0040] In a second aspect, an embodiment of the present invention provides a seismic data processing device for pre-stack depth migration, the device comprising: a memory and a processor; the memory is used to store a program for seismic data processing for pre-stack depth migration, and the processor is used to read and execute the program for seismic data processing for pre-stack depth migration, and execute any one of the methods described in the above embodiments.

[0041] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium having a data processing program stored thereon, and the data processing program is executed by a processor in the seismic data processing method for pre-stack depth migration described in any one of the above embodiments.

[0042] Compared with the related art, the present application provides a method and device for processing seismic data of pre-stack depth migration, the method comprising: establishing a near-surface velocity model and a surface smooth surface of a work area to be processed; determining the static correction of the surface smooth surface according to the near-surface velocity model and the surface smooth surface; obtaining the first arrival time of seismic waves based on the surface smooth surface and the elevation based on the surface smooth surface according to the static correction; obtaining a shallow velocity model based on the surface smooth surface by using the first arrival tomographic inversion method according to the first arrival time of seismic waves based on the surface smooth surface and the elevation based on the surface smooth surface; fusing the shallow velocity model and the deep velocity model to obtain a velocity model to be processed by pre-stack depth migration; using the velocity model processed by pre-stack depth migration to perform migration processing on pre-stack data based on a small surface smooth surface, and obtaining seismic data after depth migration. The present application fuses the near-surface velocity based on the surface smooth surface into the velocity of pre-stack depth migration, thereby restoring a more realistic formation velocity, thereby restoring a more realistic seismic wave propagation path, and obtaining accurate seismic data migration imaging results, so as to improve the success rate of exploration.

[0043] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0045] Figure 1 This is a flow chart of a seismic data processing method for prestack depth migration in an embodiment of the present application;

[0046] Figure 2 Schematic diagram of a seismic data processing device for prestack depth migration in an embodiment of the present application.

[0047] Figure 3 A schematic diagram of an undulating surface elevation and a smooth surface in an exemplary embodiment;

[0048] Figure 4 is a surface velocity model in an exemplary embodiment;

[0049] Figure 5 A shallow velocity model based on a smooth surface of the ground in an exemplary embodiment;

[0050] Figure 6It is a velocity model to be processed for prestack depth migration that is formed by fusing a shallow velocity model and a deep velocity model based on a smooth surface of the ground in an exemplary embodiment. DETAILED DESCRIPTION

[0051] The present application describes multiple embodiments, but the description is exemplary rather than restrictive, and it is obvious to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described in the present application. Although many possible feature combinations are shown in the drawings and discussed in the specific embodiments, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0052] The present application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features and elements disclosed in the present application may also be combined with any conventional features or elements to form a unique invention scheme defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other invention schemes to form another unique invention scheme defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in the present application may be implemented individually or in any appropriate combination. Therefore, except for the limitations made according to the attached claims and their equivalents, the embodiments are not subject to other restrictions. In addition, various modifications and changes may be made within the scope of protection of the attached claims.

[0053] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps of the specific order described. As will be understood by those of ordinary skill in the art, other sequences of steps are also possible. Therefore, the specific sequence of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to the steps of performing them in the order written, and those skilled in the art can easily understand that these sequences can be changed and still remain within the spirit and scope of the embodiments of the present application.

[0054] The embodiment of the present invention provides a seismic data processing method for pre-stack depth migration, such as Figure 1 As shown, the device includes steps S100 to S150;

[0055] S100: Establishing a near-surface velocity model and a surface smoothing surface of the work area to be processed;

[0056] S110: determining a static correction amount of the surface smooth surface according to the near-surface velocity model and the surface smooth surface;

[0057] S120: obtaining the first arrival time of the seismic wave based on the smooth surface and the elevation based on the smooth surface according to the static correction amount;

[0058] S130: obtaining a shallow velocity model based on the smooth surface of the ground using a first-arrival tomographic inversion method according to the first-arrival time of the seismic wave based on the smooth surface of the ground and the elevation of the smooth surface of the ground;

[0059] S140: Fusing the shallow velocity model and the deep velocity model to obtain a velocity model for prestack depth migration processing;

[0060] S150: Using the velocity model of the pre-stack depth migration processing, the pre-stack data based on the small smooth surface on the surface are migrated to obtain seismic data after depth migration.

[0061] In this embodiment, before performing the seismic data processing method of pre-stack depth migration, it is necessary to obtain relevant data of the work area to be processed, including: full-offset seismic shot gather data, geophone point elevation data of the whole work area, and shot point elevation data.

[0062] In an exemplary embodiment, a near-surface velocity model based on the real surface is established:

[0063] The first step is to pick up the first arrival time of the seismic wave in the work area to be processed;

[0064] The second step is to obtain the near-surface velocity model based on the first arrival time of the picked seismic waves using the first arrival tomographic inversion method.

[0065] In an exemplary embodiment, a smooth surface is created:

[0066] The first step is to interpolate the elevation data of discrete detection points and shot points to obtain surface elevation data;

[0067] The second step is to smooth the surface elevation data to obtain a smooth surface.

[0068] In the second step, appropriate smoothing parameters can be selected for smoothing, and the smoothing parameters need to be determined based on the actual geological conditions of the work area.

[0069] In an exemplary embodiment, determining the static correction amount of the surface smooth surface according to the near-surface velocity model and the surface smooth surface includes:

[0070] Filling the velocity in the near-surface velocity model according to the surface smooth surface to obtain a filled velocity model;

[0071] The static correction amount of the smooth surface of the ground is calculated according to the filled velocity model and the smooth surface of the ground according to the static correction formula.

[0072] In an exemplary embodiment, the static correction formula is:

[0073]

[0074]

[0075] In the above formula, S S_FD S is the static correction from the shot point to the smooth surface of the ground, R_FD is the static correction from the detection point to the smooth surface of the ground, Z S is the shot point elevation, Z S_FD is the elevation of the smooth surface corresponding to the shot point position, Z R is the elevation of the detection point, Z R_FD is the elevation of the smooth surface corresponding to the detection point position, and V is the average velocity.

[0076] In an exemplary embodiment, the filling process of the velocity in the near-surface velocity model according to the surface smooth surface to obtain the filled velocity model includes:

[0077] Comparing the surface elevation data with the elevation data corresponding to the surface smooth surface;

[0078] If the surface elevation data is smaller than the elevation data corresponding to the surface smooth surface, the velocity of the blank area is filled to establish a filled velocity model;

[0079] If the surface elevation data is greater than or equal to the elevation data corresponding to the surface smooth surface, no filling is required, and the filled velocity model is established with the original velocity.

[0080] In an exemplary embodiment, the average velocity is an average velocity from the ground surface to a smooth surface of the ground surface determined according to the populated velocity model.

[0081] In this embodiment, the first arrival time of the seismic wave based on the smooth surface is obtained according to the static correction value; and the shallow velocity model based on the smooth surface is obtained according to the first arrival time of the seismic wave based on the smooth surface by using the first arrival tomographic inversion method.

[0082] In an exemplary embodiment, the shallow velocity model based on the smooth surface and the deep velocity model are fused to obtain a velocity model to be processed for prestack depth migration, including:

[0083] determining a high-speed top interface according to the shallow velocity model;

[0084] The shallow velocity model and the deep velocity model are vertically fused according to the high-speed top interface to obtain a velocity model processed by prestack depth migration.

[0085] In an exemplary embodiment, pre-stack data based on a small smooth surface on the ground surface is obtained by the following steps:

[0086] Determine the static correction amount when the fixed reference surface is aligned with the smooth surface of the ground;

[0087] Prestack data based on the smooth surface of the ground are obtained according to the determined static correction amount and the data on the fixed reference surface.

[0088] In an exemplary embodiment, calculating the static correction amount from a fixed reference surface to a smooth surface on the ground includes:

[0089]

[0090]

[0091] In the above formula, S S_cor S is the correction amount of the shot point from the fixed reference surface to the smooth surface of the ground, S_SRD is the static correction of the shot point on the fixed reference surface, Z S_HIV is the elevation of the high-speed top interface corresponding to the shot point position,

[0092] S R_cor S is the correction value from the fixed reference surface to the detection point on the smooth surface of the ground, R_SRD is the static correction of the detection point of the fixed reference surface, Z R_HIV is the elevation of the high-speed top interface corresponding to the detection point position, Z SRD is the fixed datum elevation, V R is the replacement speed, V i is the velocity value of the i-th surface element in the velocity model based on the smooth surface, ΔZ is the longitudinal grid size value of the velocity model based on the smooth surface, and N is the number of longitudinal grids from the high-speed top interface to the smooth surface of the velocity model based on the smooth surface.

[0093] The present embodiment provides a velocity modeling method based on a smooth surface and a seismic data processing method, the method comprising: inverting a near-surface velocity model using a seismic wave first arrival time and a first arrival tomographic inversion algorithm; smoothing the near-surface elevation to obtain a near-surface smooth surface and using it as a reference surface for velocity modeling and depth migration; filling the velocity model of an area where the surface elevation is less than the smooth surface with a velocity close to the surface by upward extrapolation; calculating static corrections between shot points, receiver points and the smooth surface; correcting the seismic wave first arrival time to the smooth surface, and at the same time transforming the shot points and receiver points elevations to the corresponding smooth surface elevations; performing near-surface velocity inversion based on the smooth surface to obtain a near-surface velocity based on the smooth surface. The invention discloses a method for prestack depth migration of a surface smooth surface and a prestack depth migration velocity model; a high-speed top interface is calibrated and used as the bottom of a near-surface velocity model; the near-surface velocity model based on the surface smooth surface and the velocity model with a depth that meets imaging requirements obtained by other methods are longitudinally merged along the high-speed top interface, and a transition area is set and smoothed to obtain an initial velocity model of prestack depth migration based on the surface smooth surface; a static correction update amount when the data on the fixed reference surface is corrected to the surface smooth surface is calculated and applied to the data to correct the data on the fixed reference surface to the surface smooth surface; the seismic data corrected to the surface smooth surface is used as input, and the velocity below the high-speed top interface is iteratively updated through reflection wave imaging in combination with the reflection wave information of the seismic data to form a final prestack depth migration velocity model. The velocity model based on the surface smooth surface basically realizes the near-surface fine velocity modeling of "simulated surface" pre-stack depth migration based on the surface smooth surface, overcomes the wave field propagation distortion caused by the inaccurate shallow layer velocity of the floating surface pre-stack depth migration and the error caused by the high-frequency jitter and uneven velocity of the true surface migration, and corrects the data of the fixed reference surface to the pre-stack data on the surface smooth surface. The velocity model based on the surface smooth surface and the pre-stack data on the surface smooth surface can achieve a more accurate migration imaging effect.

[0094] The embodiment of the present invention also provides a seismic data processing device for pre-stack depth migration, such as Figure 2 As shown, the device includes: a memory 200 and a processor 210; the memory is used to store a program for seismic data processing for pre-stack depth migration, and the processor is used to read and execute the program for seismic data processing for pre-stack depth migration, and execute any one of the methods in the above embodiments.

[0095] An embodiment of the present invention provides a computer-readable storage medium, on which a data processing program is stored. The data processing program is executed by a processor to perform the seismic data processing method for pre-stack depth migration described in any one of the above embodiments.

[0096] Example 1

[0097] The following example illustrates the implementation of the seismic data processing method for prestack depth migration, including:

[0098] Step 1. Pick the first arrival of the pre-stack data in the processing area to obtain the first arrival time of the seismic wave;

[0099] Step 2. According to the first arrival time of the seismic wave, the first arrival tomographic inversion method is used to obtain the near-surface velocity model based on the real surface, such as Figure 4 Shown is the surface velocity model for the study area.

[0100] First-arrival tomographic inversion is an algorithm that uses the time and path of the seismic first-arrival wave ray to invert and obtain the medium velocity within a limited depth range near the surface. It is a conventional technology in this field.

[0101] Step 3. Create a smooth surface;

[0102] Step 31. Interpolate the elevation data of discrete detection points and shot points to obtain elevation data based on the real surface;

[0103] Step 32: Select appropriate smoothing parameters to smooth the elevation data to obtain a smooth surface.

[0104] The surface smoothing surface is the reference surface for calculating static correction and migration velocity modeling. In order to best approximate the real surface, it is usually necessary to smooth the surface elevation to a small extent and use the obtained surface smoothing surface as the reference surface for migration. Usually, the smoothing radius is less than 500 meters. Figure 3 As shown, this is a schematic diagram of the actual undulating surface elevation and smooth surface in a study area.

[0105] Step 4. Filling the velocity in the near-surface velocity model according to the surface smooth surface to obtain a filled velocity model;

[0106] The near-surface velocity model is filled with a velocity close to the surface for a region where the surface elevation is less than the surface smooth surface, until the surface smooth surface is reached, to form a filled velocity model, the specific steps comprising:

[0107] Step 41. Compare the surface elevation data with the elevation data corresponding to the surface smooth surface;

[0108] Step 42: If the surface elevation data is smaller than the elevation data corresponding to the smooth surface, fill the velocity of the blank area and establish a filled velocity model;

[0109] Step 43: If the surface elevation data is greater than or equal to the elevation data corresponding to the surface smooth surface, no filling is required.

[0110] Step 5. Calculate the static correction S from the real surface to the smooth surface R_FD and S S_FD .

[0111]

[0112]

[0113] Among them, S S_FD is the static correction from the shot point to the smooth surface of the ground, Z S is the shot point elevation, Z S_FD is the elevation of the smooth surface corresponding to the shot point position, S R_FD is the static correction from the detection point to the smooth surface of the ground, Z R is the elevation of the detection point, Z R_FD is the elevation of the smooth surface corresponding to the detection point position, V is the longitudinal average velocity from the shot point, the detection point to the smooth surface (when the surface elevation is greater than the smooth surface elevation), or is the selected filling velocity close to the surface velocity (when the surface elevation is less than the smooth surface elevation).

[0114] Step 6. According to the static correction amount, the first arrival time of the seismic wave is corrected to the first arrival time of the seismic wave corresponding to the smooth surface of the surface, and the elevation of the seismic pre-stack data is corrected to the elevation data corresponding to the smooth surface of the surface; the first arrival time and the elevation are in a one-to-one correspondence.

[0115] Step 7. Obtain a shallow velocity model based on the smooth surface of the surface according to the first arrival time of the seismic wave based on the smooth surface of the surface, the elevation data corresponding to the smooth surface of the surface and the first arrival tomographic inversion method. Figure 5 It is the shallow velocity model of the study area based on the smooth surface.

[0116] Step 8. Track and calibrate the high-speed top interface on the shallow velocity model based on the smooth surface of the ground, which serves as the bottom boundary of the shallow velocity model and the interface for fusion with the deep velocity model.

[0117] In this step, the high-speed top interface, that is, the bottom interface of the near-surface low-velocity layer, is an interface where the velocity of refraction of seismic waves is relatively stable, which is generally close to the replacement velocity usually specified in the work area. Therefore, the high-speed top interface can generally be obtained by automatic tracking with a given replacement velocity value.

[0118] Step 9. The shallow velocity model based on the smooth surface and the deep velocity model are fused to obtain a velocity model to be processed for prestack depth migration. Figure 6 It is the velocity model to be processed for prestack depth migration, which is formed by the fusion of the shallow velocity model based on the smooth surface and the deep velocity model in the study area.

[0119] The shallow velocity model generally represents the velocity within a few hundred meters below the surface. Although the depth is limited, it has a great impact on the imaging of depth migration. The depth of the general depth domain imaging velocity model is 7,000 to 8,000 meters or even more than 10,000 meters. Therefore, it is necessary to vertically integrate the shallow velocity model with the velocity model of a certain depth obtained by other methods to meet the needs of depth migration.

[0120] Step 10. Correct the seismic data on the fixed datum plane to the offset datum plane corresponding to the smooth surface.

[0121] The static correction update amount when correcting the data on the fixed reference surface to the smooth surface of the ground is calculated and applied to the data, and the data that has been corrected to the fixed reference surface in conventional processing is corrected to the smooth surface of the ground.

[0122] The basic data processing before conventional migration is all based on a fixed datum. If you want to perform depth migration with the smooth surface as the migration datum, you need to convert the data to the datum. When correcting the data to the migration datum corresponding to the smooth surface, you need to do the following correction calculations, and apply this static correction to correct the data to the migration datum corresponding to the smooth surface. The correction method is as follows:

[0123]

[0124]

[0125] In the above formula, S S_cor S is the shot point correction required to correct the data on the fixed reference surface to the smooth surface of the ground. S_SRD is the shot static correction of the fixed datum plane that has been applied in the data, Z S_HIV is the elevation of the high-speed top interface corresponding to the shot point position; S R_cor The correction amount of the detection point required to correct the data on the fixed reference surface to the smooth surface of the ground surface, S R_SRD is the static correction of the fixed datum surface of the correction applied in the data, Z R_HIV is the elevation of the high-speed top interface corresponding to the detection point position; Z SRD is the fixed datum elevation, V R is the replacement speed; V i is the velocity value of the i-th face element in the velocity model based on the surface smooth surface obtained by the first arrival tomographic inversion, ΔZ is the longitudinal grid size value of the velocity model based on the surface smooth surface obtained by the first arrival tomographic inversion; N is the longitudinal grid number from the high-speed top interface to the surface smooth surface of the velocity model based on the surface smooth surface obtained by the first arrival tomographic inversion.

[0126] Step 11. Using the data corrected to the surface smooth surface and the obtained pre-stack depth migration initial velocity model based on the surface smooth surface as input, combined with the seismic data reflection wave information, the velocity below the high-speed top interface is iteratively updated through reflection wave imaging to form the final pre-stack depth migration layer velocity model.

[0127] In this embodiment, based on the near-surface fine velocity modeling of "simulated surface" pre-stack depth migration of the smooth surface, a corresponding data correction algorithm is provided to overcome the wave field propagation distortion caused by the inaccurate shallow layer velocity of the floating surface pre-stack depth migration and the error caused by the uneven high-frequency velocity jitter of the true surface migration, and a more accurate migration imaging effect can be achieved.

[0128] The present application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features and elements disclosed in the present application may also be combined with any conventional features or elements to form a unique invention scheme defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other invention schemes to form another unique invention scheme defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in the present application may be implemented individually or in any appropriate combination. Therefore, except for the limitations made according to the attached claims and their equivalents, the embodiments are not subject to other restrictions. In addition, various modifications and changes may be made within the scope of protection of the attached claims.

[0129] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps of the specific order described. As will be understood by those of ordinary skill in the art, other sequences of steps are also possible. Therefore, the specific sequence of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to the steps of performing them in the order written, and those skilled in the art can easily understand that these sequences can be changed and still remain within the spirit and scope of the embodiments of the present application.

Claims

1. A seismic data processing method for prestack depth migration, characterized in that: The method comprises: Establish near-surface velocity model and surface smoothing surface of the work area to be processed; Determining a static correction amount of the surface smooth surface according to the near-surface velocity model and the surface smooth surface; Obtaining the first arrival time of the seismic wave based on the smooth surface of the ground and the elevation based on the smooth surface of the ground according to the static correction amount; Obtaining a shallow velocity model based on the smooth surface of the ground using a first-arrival tomographic inversion method according to the first-arrival time of the seismic wave based on the smooth surface of the ground and the elevation of the smooth surface of the ground; The shallow velocity model and the deep velocity model are merged to obtain a velocity model processed by prestack depth migration; The velocity model of the pre-stack depth migration processing is used to perform migration processing on the pre-stack data based on the small smooth surface on the surface, so as to obtain seismic data after depth migration.

2. The seismic data processing method for prestack depth migration according to claim 1, characterized in that: The process of establishing the near-surface velocity model includes: Determine the first arrival time of the seismic wave in the work area to be treated; A near-surface velocity model is obtained according to the first arrival time of the seismic wave and using the first arrival tomographic inversion method.

3. The seismic data processing method for prestack depth migration according to claim 1, characterized in that: The process of establishing the smooth surface includes: Interpolate the elevation data of discrete detection points and shot points to obtain surface elevation data; The surface elevation data is smoothed to obtain a surface smooth surface.

4. The seismic data processing method for prestack depth migration according to claim 1, characterized in that: Determining the static correction amount of the surface smooth surface according to the near-surface velocity model and the surface smooth surface includes: Filling the velocity in the near-surface velocity model according to the surface smooth surface to obtain a filled velocity model; The static correction amount of the smooth surface of the ground is calculated according to the filled velocity model and the smooth surface of the ground according to the static correction formula.

5. The seismic data processing method for prestack depth migration according to claim 4, characterized in that: The static correction formula is: In the above formula, S S_FD S is the static correction from the shot point to the smooth surface of the ground, R_FD is the static correction from the detection point to the smooth surface of the ground, Z S is the shot point elevation, Z S_FD is the elevation of the smooth surface corresponding to the shot point position, Z R is the elevation of the detection point, Z R_FD is the elevation of the smooth surface corresponding to the detection point position, and V is the average velocity.

6. The seismic data processing method for prestack depth migration according to claim 5, characterized in that: The average velocity is the average velocity from the ground surface to the ground surface smooth surface determined according to the filled velocity model.

7. The seismic data processing method for prestack depth migration according to claim 5, characterized in that: The filling process of the velocity in the near-surface velocity model according to the surface smooth surface to obtain the filled velocity model comprises: Comparing the surface elevation data with the elevation data corresponding to the surface smooth surface; If the surface elevation data is smaller than the elevation data corresponding to the surface smooth surface, the velocity of the blank area is filled to establish a filled velocity model; If the surface elevation data is greater than or equal to the elevation data corresponding to the surface smooth surface, no filling is required, and the filled velocity model is established with the velocity in the near-surface velocity model.

8. The seismic data processing method for prestack depth migration according to claim 1, characterized in that: The method of fusing the shallow velocity model based on the smooth surface with the deep velocity model to obtain a velocity model for prestack depth migration processing includes: determining a high-speed top interface according to the shallow velocity model; The high-speed top interface is used to vertically fuse the shallow velocity model and the deep velocity model to obtain a velocity model processed by prestack depth migration.

9. The seismic data processing method for prestack depth migration according to claim 8, characterized in that: The pre-stack data based on the small smooth surface of the surface is obtained by the following steps: Determine the static correction amount when the fixed reference surface is aligned with the smooth surface of the ground; Prestack data based on the smooth surface of the ground are obtained according to the determined static correction amount and the data on the fixed reference surface.

10. The seismic data processing method for prestack depth migration according to claim 9, characterized in that: The static correction amount from the fixed reference surface to the ground smooth surface includes: In the above formula, S S_cor S is the correction amount of the shot point from the fixed reference surface to the smooth surface of the ground, S_SRD is the static correction of the shot point on the fixed reference surface, Z S_HIV is the elevation of the high-speed top interface corresponding to the shot point position, S R_cor S is the correction value from the fixed reference surface to the detection point on the smooth surface of the ground, R_SRD is the static correction of the detection point of the fixed reference surface, Z R_HIV is the elevation of the high-speed top interface corresponding to the detection point position, Z SRD is the fixed reference elevation, V R is the replacement speed, V i is the velocity value of the i-th surface element in the velocity model based on the smooth surface, ΔZ is the longitudinal grid size value of the velocity model based on the smooth surface, and N is the number of longitudinal grids from the high-speed top interface to the smooth surface of the velocity model based on the smooth surface.

11. A seismic data processing device for pre-stack depth migration, characterized in that: The device includes: a memory and a processor; the memory is used to store a program of a seismic data processing method for pre-stack depth migration, and the processor is used to read and execute the program of the seismic data processing method for pre-stack depth migration, and execute the method described in any one of claims 1-10.

12. A computer-readable storage medium having a data processing program stored thereon, wherein the data processing program is executed by a processor to implement the seismic data processing method for prestack depth migration according to any one of claims 1 to 10.

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