A method and apparatus for prestack depth migration of seismic data

Abstract

The application discloses a pre-stack depth migration seismic data processing method and device, and relates to the field of seismic data processing. The method comprises the following steps: establishing a near-surface velocity model and a surface smoothing plane of a processing area; determining a static correction amount of the surface smoothing plane according to the near-surface velocity model and the surface smoothing plane; obtaining a seismic wave first arrival time based on the surface smoothing plane and an elevation based on the surface smoothing plane according to the static correction amount; obtaining a shallow layer velocity model based on the surface smoothing plane by using a first arrival tomography inversion method according to the seismic wave first arrival time based on the surface smoothing plane and the elevation based on the surface smoothing plane; fusing the shallow layer velocity model and a deep layer velocity model to obtain a velocity model to be used for pre-stack depth migration processing; and performing migration processing on pre-stack data based on the surface smoothing plane by using the velocity model to be used for pre-stack depth migration processing to obtain depth migration seismic data.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of seismic data processing, and in particular to a pre-stack depth migration seismic data processing method and device. BACKGROUND

[0002] In conventional pre-stack depth migration processing of seismic data, pre-stack depth migration processing based on a floating surface is usually used. In general seismic data processing, static correction processing is needed to eliminate the distortion of seismic imaging events caused by the change of the velocity of the low-velocity zone so as to ensure the reliability of the reflection event shape. However, such a method removes the low-velocity zone of the near-surface and replaces it with a high-velocity layer, which eliminates the influence of the static correction problem on the event shape, but the shallow layer in the pre-stack depth migration velocity is replaced by a relatively uniform high-velocity layer, rather than the original underground true velocity, so that the true seismic wave travel time and wave field propagation path cannot be restored, and thus the obtained image is approximate and the precision is limited. In order to obtain the true structure of the underground stratum more accurately, a more accurate pre-stack depth migration velocity model needs to be established. Complete true-surface pre-stack depth migration requires a completely accurate near-surface and underground velocity model. The true surface usually has large fluctuations and is prone to high-frequency velocity fluctuations and large errors, so it is difficult to achieve accurate imaging in actual production. In order to overcome these deficiencies, a surface flat smoothing velocity modeling and pre-stack depth migration are needed, and thus an integrated modeling of near-surface modeling based on surface flat smoothing and pre-stack depth migration velocity modeling is needed. SUMMARY

[0003] The present application inventors have found that:

[0004] In order to obtain the true structure of the underground stratum more accurately, a more accurate pre-stack depth migration velocity model needs to be established for data processing. Complete true-surface pre-stack depth migration requires a completely accurate near-surface and underground velocity model. The true surface usually has large fluctuations and is prone to high-frequency velocity fluctuations and large errors, so it is difficult to achieve accurate imaging in actual production. In order to overcome these deficiencies, the present application inventors propose an integrated modeling method of near-surface velocity modeling based on surface flat smoothing and pre-stack depth migration velocity modeling.

[0005] In a first aspect, the present application provides a pre-stack depth migration seismic data processing method, which comprises:

[0006] establishing a near-surface velocity model of a processing area to be processed and a surface flat smoothing surface;

[0007] determining a static correction amount of the surface flat smoothing surface according to the near-surface velocity model and the surface flat smoothing surface;

[0008] obtaining a surface smoothing plane based on the near-surface velocity model and the surface smoothing plane;

[0009] obtaining a surface smoothing plane based on the near-surface velocity model and the surface smoothing plane;

[0010] fusing the shallow velocity model and the deep velocity model to obtain a velocity model for pre-stack depth migration processing;

[0011] performing migration processing on the pre-stack data based on the surface smoothing plane by using the velocity model for pre-stack depth migration processing to obtain depth-migrated seismic data.

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

[0013] determining seismic wave first arrival times of a processing area;

[0014] obtaining a near-surface velocity model by using the first arrival tomographic inversion method based on the seismic wave first arrival times.

[0015] In an exemplary embodiment, the process of establishing the surface smoothing plane comprises:

[0016] interpolating discrete elevation data of receiver points and shot points to obtain surface elevation data;

[0017] performing smoothing processing on the surface elevation data to obtain a surface smoothing plane.

[0018] In an exemplary embodiment, the process of determining the static correction amount of the surface smoothing plane based on the near-surface velocity model and the surface smoothing plane comprises:

[0019] performing filling processing on the velocity in the near-surface velocity model based on the surface smoothing plane to obtain a filled velocity model;

[0020] calculating the static correction amount of the surface smoothing plane according to a static correction formula based on the filled velocity model and the surface smoothing plane.

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

[0022]

[0023]

[0024] In the above formula, S S_FD is the static correction amount of a shot point to the surface smoothing plane, S R_FDZ S is the elevation of the shot point, Z S_FD is the elevation of the surface smooth plane corresponding to the position of the shot point, Z R is the elevation of the receiver point, Z R_FD is the elevation of the surface smooth plane corresponding to the position of the receiver point, V is the average velocity.

[0025] In an exemplary embodiment, the average velocity is determined from the filled velocity model between the surface and the surface smooth plane.

[0026] In an exemplary embodiment, the filling processing of the velocity in the near-surface velocity model according to the surface smooth plane to obtain the filled velocity model comprises:

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

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

[0029] if the surface elevation data is greater than or equal to the elevation data corresponding to the surface smooth plane, no filling is needed, and the filled velocity model is established by the velocity in the near-surface velocity model.

[0030] In an exemplary embodiment, the fusion of the shallow velocity model and the deep velocity model based on the surface smooth plane to obtain the velocity model for pre-stack depth migration processing comprises:

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

[0032] fusing the shallow velocity model and the deep velocity model in the longitudinal direction by the high-velocity top interface to obtain the velocity model for pre-stack depth migration processing.

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

[0034] determining the static correction amount from the fixed reference plane to the surface smooth plane;

[0035] obtaining the pre-stack data based on the surface smooth plane according to the determined static correction amount and the data on the fixed reference plane.

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

[0037]

[0038]

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

[0040] In a second aspect, the embodiments of the present application provide a pre-stack depth migration seismic data processing device, the device comprising: a memory and a processor; the memory is used to save the program for pre-stack depth migration seismic data processing, and the processor is used to read and execute the program for pre-stack depth migration seismic data processing, and execute the method in any one of the above embodiments.

[0041] In a third aspect, the embodiments of the present application provide a computer readable storage medium, and the computer readable storage medium stores a data processing program, and the data processing program is executed by a processor to execute the pre-stack depth migration seismic data processing method in any one of the above embodiments.

[0042] Compared with the related art, the application provides a pre-stack depth migration seismic data processing method and device, the method comprising: establishing a near-surface velocity model and a surface smoothing plane of a processing area; determining a static correction amount of the surface smoothing plane according to the near-surface velocity model and the surface smoothing plane; obtaining a seismic wave first arrival time based on the surface smoothing plane and an elevation based on the surface smoothing plane according to the static correction amount; obtaining a shallow layer velocity model based on the surface smoothing plane by using a first arrival tomography inversion method according to the seismic wave first arrival time based on the surface smoothing plane and the elevation based on the surface smoothing plane; fusing the shallow layer velocity model and a deep layer velocity model to obtain a velocity model to be processed by pre-stack depth migration; and performing migration processing on pre-stack data based on the surface smoothing plane by using the velocity model to be processed by pre-stack depth migration to obtain depth-migrated seismic data. In the application, the near-surface velocity based on the surface smoothing plane is fused into the velocity of pre-stack depth migration, so that the real stratum velocity is recovered, the real seismic wave propagation path is recovered, the accurate seismic data migration imaging result is obtained, and the success rate of exploration is improved.

[0043] Other features and advantages of the application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. Other advantages of the application will be realized and attained by the methods and compositions particularly pointed out in the written description and claims hereof. BRIEF DESCRIPTION OF DRAWINGS

[0044] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. The drawings are included solely for purposes of illustrating the application and are not to be construed as a limitation of the application.

[0045] Figure 1 A flow chart of the pre-stack depth migration seismic data processing method in the embodiment of the application;

[0046] Figure 2 A schematic diagram of the pre-stack depth migration seismic data processing device in the embodiment of the application.

[0047] Figure 3 A schematic diagram of the relief surface elevation and the surface smoothing plane in an exemplary embodiment;

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

[0049] Figure 5 A shallow layer velocity model based on the surface smoothing plane in an exemplary embodiment;

[0050] Figure 6The velocity model to be used for pre-stack depth migration processing is formed by fusing the shallow velocity model and the deep velocity model based on the surface smoothing plane in an exemplary embodiment. DETAILED DESCRIPTION

[0051] The present application describes a number of embodiments, but the description is exemplary rather than limiting and it will be apparent to those of ordinary skill in the art that numerous more embodiments and implementations are possible within the scope of the embodiments described in the present application. Although a number of possible combinations of features have been set forth in the appended figures and discussed in the detailed description, many other combinations of features are possible. Unless specifically intended otherwise, any feature or element of any embodiment can be used in combination with any other feature or element of any other embodiment, or in combination with any other feature or element of the same 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 herein can also be combined with any conventional features or elements to form unique inventive solutions within the scope of the claims. Any feature or element of any embodiment can also be combined with features or elements from other inventive solutions to form another unique inventive solution within the scope of the claims. Therefore, it is to be understood that any feature shown and / or discussed in the present application can be implemented alone or in any suitable combination. Embodiments are, therefore, not to be limited to anything discussed in the present application unless otherwise specifically intended to be restricted. Moreover, various modifications and changes can be made within the scope of the appended claims.

[0053] Furthermore, in describing representative embodiments, the specification can have presented the method and / or process as a particular sequence of steps. However, to the extent that the method or process depends on more than one step, the method or process should not be limited to the particular sequence of steps described. Other sequences of steps can be possible, and are within the scope of the present application. Therefore, the particular order in which the steps are presented in the specification is not an implied limitation on the order in which the steps can be performed. Moreover, the specification can present the steps in a specific order in accordance with the implementation described. But the steps can be performed in any order that is practicable or that the recipient or user of the application deems appropriate.

[0054] Embodiments of the present application provide a method for pre-stack depth migration of seismic data, as shown in Figure 1 The apparatus comprises steps S100-S150;

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

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

[0057] S120: obtaining a first arrival time based on the surface smoothing plane and an elevation based on the surface smoothing plane according to the static correction amount;

[0058] S130: obtaining a shallow layer velocity model based on the surface smoothing plane by using a first arrival tomography inversion method according to the first arrival time based on the surface smoothing plane and the elevation based on the surface smoothing plane;

[0059] S140: fusing the shallow layer velocity model and a deep layer velocity model to obtain a velocity model for pre-stack depth migration processing;

[0060] S150: performing migration processing on pre-stack data based on the surface smoothing plane by using the velocity model for pre-stack depth migration processing to obtain depth-migrated seismic data.

[0061] In the embodiment, before the seismic data processing method for pre-stack depth migration is performed, relevant data of a processing area to be processed need to be obtained, including full offset seismic shot gather data, elevation data of geophones and elevation data of shot points in the whole processing area.

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

[0063] Firstly, seismic wave first arrival times of the processing area to be processed are picked up;

[0064] Secondly, a near-surface velocity model is obtained by using a first arrival tomography inversion method according to the picked-up seismic wave first arrival times.

[0065] In an exemplary embodiment, a surface smoothing plane is established:

[0066] Firstly, elevation data of surfaces is obtained by interpolating elevation data of discrete geophones and shot points;

[0067] Secondly, a surface smoothing plane is obtained by performing smoothing processing on the surface elevation data.

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

[0069] In an exemplary embodiment, the static correction amount of the surface smoothing plane is determined according to the near-surface velocity model and the surface smoothing plane, including:

[0070] According to the surface smoothing surface, the velocity in the near-surface velocity model is filled to obtain a filled velocity model.

[0071] According to the filled velocity model and the surface smoothing surface, a static correction amount of the surface smoothing surface is calculated according to a static correction formula.

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

[0073]

[0074]

[0075] In the above formula, S S_FD is a static correction amount of a shot point to the surface smoothing surface, S R_FD is a static correction amount of a receiver point to the surface smoothing surface, Z S is an elevation of the shot point, Z S_FD is an elevation of the surface smoothing surface corresponding to the position of the shot point, Z R is an elevation of the receiver point, Z R_FD is an elevation of the surface smoothing surface corresponding to the position of the receiver point, and V is an average velocity.

[0076] In an example embodiment, the filling of the velocity in the near-surface velocity model according to the surface smoothing surface to obtain the filled velocity model comprises:

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

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

[0079] If the surface elevation data is greater than or equal to the elevation data corresponding to the surface smoothing surface, no filling is needed, and the original velocity is used to establish the filled velocity model.

[0080] In an example embodiment, the average velocity is determined according to the filled velocity model from the surface to the surface smoothing surface.

[0081] In the present embodiment, the seismic wave first arrival time based on the surface smoothing surface is obtained according to the static correction amount, and the shallow velocity model based on the surface smoothing surface is obtained by using the first arrival tomography inversion method.

[0082] In an example embodiment, the shallow velocity model and the deep velocity model based on the surface smoothing surface are fused to obtain a velocity model to be subjected to pre-stack depth migration processing, comprising:

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

[0084] fusing the shallow velocity model and the deep velocity model in the vertical direction according to the high-velocity top boundary to obtain a velocity model for pre-stack depth migration processing.

[0085] In an example embodiment, the pre-stack data based on the surface smoothing plane is obtained by the following steps:

[0086] determining a static correction amount from the fixed reference plane to the surface smoothing plane;

[0087] obtaining the pre-stack data based on the surface smoothing plane according to the determined static correction amount and the data on the fixed reference plane.

[0088] In an example embodiment, the static correction amount from the fixed reference plane to the surface smoothing plane is calculated, comprising:

[0089]

[0090]

[0091] In the above formula, S S_cor is the shot correction amount from the fixed reference plane to the surface smoothing plane, S S_SRD is the shot static correction amount of the fixed reference plane, Z S_HIV is the high elevation of the high-velocity top boundary corresponding to the shot position,

[0092] S R_cor is the receiver correction amount from the fixed reference plane to the surface smoothing plane, S R_SRD is the receiver static correction amount of the fixed reference plane, Z R_HIV is the high elevation of the high-velocity top boundary corresponding to the receiver position, Z SRD is the elevation of the fixed reference plane, V R is the replacement velocity, V i is the velocity value of the i-th panel in the velocity model based on the surface smoothing plane, ΔZ is the vertical grid size value of the velocity model based on the surface smoothing plane, and N is the vertical grid number of the velocity model based on the surface smoothing plane from the high-velocity top boundary to the surface smoothing plane.

[0093] The method provided in the embodiment includes: using seismic wave first arrival time and first arrival tomographic inversion algorithm to invert a near-surface velocity model; smoothing the near-surface elevation to obtain a near-surface smoothing surface, and using the near-surface smoothing surface as a reference surface for velocity modeling and depth migration; filling the velocity model in the region where the surface elevation is less than the near-surface smoothing surface by upward extrapolation with a velocity close to the surface; calculating the static correction amount between the shot point and the receiver point and the near-surface smoothing surface; correcting the seismic wave first arrival time to the near-surface smoothing surface, and transforming the shot point and the receiver point elevation to the corresponding near-surface smoothing surface elevation; performing near-surface velocity inversion based on the near-surface smoothing surface to obtain a near-surface velocity model based on the near-surface smoothing surface; calibrating the high-velocity top interface and using the high-velocity top interface as the bottom interface of the near-surface velocity model; longitudinally fusing the near-surface velocity model based on the near-surface smoothing surface and the velocity model obtained by other methods along the high-velocity top interface, setting an excessive region, and smoothing to obtain a pre-stack depth migration initial velocity model based on the near-surface smoothing surface; calculating the static correction update amount when correcting the data on the fixed reference surface to the near-surface smoothing surface, and applying the static correction update amount to the data to correct the data on the fixed reference surface to the near-surface smoothing surface; using the seismic data corrected to the near-surface smoothing surface as input, combining the seismic data reflection wave information, updating the velocity below the high-velocity top interface through reflection wave imaging iteration, and forming a final pre-stack depth migration velocity model. The velocity model based on the near-surface smoothing surface basically realizes the near-surface fine velocity modeling of the pre-stack depth migration near-surface based on the near-surface smoothing 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 vibration of the non-smooth velocity of the true surface migration, and corrects the pre-stack data on the near-surface smoothing surface using the data on the fixed reference surface. The velocity model based on the near-surface smoothing surface and the pre-stack data on the near-surface smoothing surface can realize relatively accurate migration imaging.

[0094] The embodiment of the present application also provides a pre-stack depth migration seismic data processing device, as shown in the accompanying drawings, the device comprises a memory 200 and a processor 210; the memory is used to save a program for pre-stack depth migration seismic data processing, and the processor is used to read and execute the program for pre-stack depth migration seismic data processing, and execute the method in any one of the above embodiments. Figure 2

[0095] The embodiment of the present application provides a computer readable storage medium, and the computer readable storage medium stores a data processing program, and the data processing program is executed by a processor to execute the pre-stack depth migration seismic data processing method in any one of the above embodiments.

[0096] Example one

[0097] ​The implementation process of the pre-stack depth migration seismic data processing method is illustrated below with an example, including:

[0098] Step 1. First arrival picking is performed on the pre-stack data of the processing area to obtain the seismic wave first arrival time;

[0099] Step 2. Based on the seismic wave first arrival time, a first arrival tomographic inversion method is used to obtain a near-surface velocity model based on the real surface, as shown in Figure 4 The surface velocity model of the study area is shown.

[0100] First arrival tomographic inversion is an algorithm that uses the time and path of seismic first arrival wave rays to obtain the medium velocity within a limited depth range of the near surface, which is a conventional technique in the art.

[0101] Step 3. Establish a surface smoothing plane;

[0102] Step 31. Interpolate the elevation data of discrete geophones 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 the surface smoothing plane.

[0104] The surface smoothing plane is the reference plane 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 the obtained surface smoothing plane is used as the reference plane for migration. In general, the smoothing radius is less than 500 meters. As shown in Figure 3 The true undulating surface elevation and the surface smoothing plane in a study area are shown.

[0105] Step 4. Fill the velocity in the near-surface velocity model according to the surface smoothing plane to obtain a filled velocity model;

[0106] The near-surface velocity model is filled with near-surface velocity in the area where the surface elevation is less than the surface smoothing plane until the surface smoothing plane, forming a filled velocity model. The specific steps include:

[0107] Step 41. Compare the size of the surface elevation data and the elevation data corresponding to the surface smoothing plane;

[0108] Step 42. If the surface elevation data is less than the elevation data corresponding to the surface smoothing plane, fill the velocity in the blank area to 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 smoothing plane, no filling is needed.

[0110] Step 5. Calculate the static correction amount S of the real ground surface to the ground surface smoothing surface R_FD and S S_FD .

[0111]

[0112]

[0113] wherein S S_FD is the static correction amount of the shot point to the ground surface smoothing surface, Z S is the shot point elevation, Z S_FD is the ground surface smoothing surface elevation corresponding to the shot point position, S R_FD is the static correction amount of the receiver point to the ground surface smoothing surface, Z R is the receiver point elevation, Z R_FD is the ground surface smoothing surface elevation corresponding to the receiver point position, and V is the longitudinal average velocity of the shot point and the receiver point to the ground surface smoothing surface (when the ground surface elevation is greater than the ground surface smoothing surface elevation), or is the filling velocity selected close to the ground surface (when the ground surface elevation is less than the ground surface smoothing surface elevation).

[0114] Step 6. Correct the seismic wave first arrival time according to the static correction amount to the seismic wave first arrival time corresponding to the ground surface smoothing surface, and correct the elevation of the seismic pre-stack data to the elevation data corresponding to the ground surface smoothing surface; the first arrival time and the elevation are in a one-to-one correspondence.

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

[0116] Step 8. Track and demarcate the high-speed top interface on the shallow layer velocity model based on the ground surface smoothing surface, as the bottom interface of the shallow layer velocity model, and as the interface for fusion with the deep layer velocity model.

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

[0118] Step 9. Fuse the shallow layer velocity model based on the ground surface smoothing surface and the deep layer velocity model to obtain the velocity model to be processed for pre-stack depth migration. Figure 6 is the velocity model to be processed for pre-stack depth migration formed by fusion of the shallow layer velocity model based on the ground surface smoothing surface and the deep layer velocity model in the study area.

[0119] The shallow velocity model generally represents the velocity of the range of several hundred meters below the surface, and the depth is limited, but the imaging of depth migration is greatly affected. The depth of the general depth domain imaging velocity model reaches 7-8 kilometers or even more than 10 kilometers, therefore, the shallow velocity model and the velocity model obtained by other methods reaching a certain depth need to be vertically fused to meet the requirements of depth migration.

[0120] Step 10. Correct the seismic data on the fixed reference surface to the migration reference surface corresponding to the surface smoothing surface.

[0121] Calculate the static correction update amount when the data on the fixed reference surface is corrected to the surface smoothing surface, and apply it to the data to correct the data already corrected to the fixed reference surface in the conventional processing to the surface smoothing surface.

[0122] The basic data processing before conventional migration is processed based on the fixed reference surface, and in order to perform depth migration with the surface smoothing surface as the migration reference surface, the data needs to be reference surface converted, and the data needs to be corrected to the migration reference surface corresponding to the surface smoothing surface. The following correction calculation is performed, and the static correction amount is applied to correct the data to the migration reference surface corresponding to the surface smoothing surface, and the correction method is as follows:

[0123]

[0124]

[0125] In the above formula, S S_cor is the shot correction amount required to correct the data on the fixed reference surface to the surface smoothing surface, S S_SRD is the shot static correction amount of the fixed reference surface already applied in the data, Z S_HIV is the elevation of the high-speed top interface corresponding to the shot position; S R_cor is the receiver correction amount required to correct the data on the fixed reference surface to the surface smoothing surface, S R_SRD is the receiver static correction amount of the fixed reference surface already applied in the data, Z R_HIV is the elevation of the high-speed top interface corresponding to the receiver position; Z SRD is the elevation of the fixed reference surface, V R is the replacement velocity; V i is the velocity value of the i-th bin in the surface smoothing surface-based velocity model obtained by the first arrival tomographic inversion, ΔZ is the vertical grid size value of the surface smoothing surface-based velocity model obtained by the first arrival tomographic inversion; N is the vertical grid number of the surface smoothing surface-based velocity model obtained by the first arrival tomographic inversion from the high-speed top interface to the surface smoothing surface.

[0126] Step 11. With the data corrected to the surface smooth surface and the obtained surface smooth surface based pre-stack depth migration initial velocity model as input, the velocity below the high-velocity top boundary is iteratively updated by reflection imaging combined with the seismic data reflection information, to form a final pre-stack depth migration interval velocity model.

[0127] In the embodiment, the "pseudo-real surface" pre-stack depth migration near-surface fine velocity modeling based on the surface smooth surface provides a corresponding data correction algorithm, overcomes the wave field propagation distortion caused by the inaccurate velocity of the shallow layer of the floating surface pre-stack depth migration and the error caused by the high-frequency jitter of the non-smooth velocity of the real surface migration, and can realize relatively accurate migration imaging effect.

[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 herein can also be combined with any conventional features or elements to form unique inventive solutions defined by the claims. Any feature or element of any embodiment can also be combined with features or elements from other inventive solutions to form another unique inventive solution defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in the present application can be implemented alone or in any appropriate combination. Accordingly, the embodiments are not to be limited by other than according to the claims made and their equivalents. Moreover, various modifications and changes can be made within the scope of the claims.

[0129] Furthermore, in describing representative embodiments, the specification can have presented the method and / or process as a particular sequence of steps. However, to the extent that the method or process depends on the particular order of steps, this description should not be construed as limiting. Other steps can be performed in between described steps without departing from the scope of the method and / or process, as can be understood by one of ordinary skill in the art upon reading the present description. The particular order of steps disclosed in the specification should not be construed as a limitation on the claims. Furthermore, the claims should not be limited to the steps of the method and / or process in the order in which they are written, as this could vary and still fall within the scope of the embodiments.

Claims

1. A method for processing seismic data via pre-stack depth migration, characterized in that, The method includes: Establish a near-surface velocity model and a smooth surface model for the work area to be processed; The static correction amount of the smooth surface is determined based on the near-surface velocity model and the smooth surface. The arrival time of the seismic wave based on the smooth surface is obtained based on the static correction value; A shallow velocity model based on the smooth surface of the ground is obtained by using the first arrival time of seismic waves based on the smooth surface of the ground and the elevation of the smooth surface of the ground using the first arrival tomography inversion method. The shallow velocity model and the deep velocity model are fused to obtain the velocity model with pre-stack depth migration processing. The velocity model of the pre-stack depth migration process is used to migrate the pre-stack data based on small smooth surfaces to obtain the depth-migrated seismic data. The shallow velocity model based on the smooth surface is obtained by using the first arrival time of seismic waves based on the smooth surface and the elevation of the smooth surface using the first arrival tomography inversion method. This includes: The velocity model near the ground surface is filled with the velocity based on the smooth surface of the ground surface to obtain the filled velocity model. Based on the filled velocity model and the smooth surface, the static correction amount of the smooth surface is calculated according to the static correction formula. The step of filling the velocity in the near-surface velocity model based on the smooth surface of the land surface to obtain the filled velocity model includes: Compare the surface elevation data with the elevation data corresponding to the smooth surface. If the surface elevation data is less than the elevation data corresponding to the smooth surface, the velocity of the blank area is filled to establish a velocity model after filling. If the surface elevation data is greater than or equal to the elevation data corresponding to the smooth surface, then no filling is required, and the filled velocity model is established based on the velocity in the near-surface velocity model.

2. The seismic data processing method for pre-stack 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 seismic waves in the work area to be addressed; Based on the first arrival time of the seismic waves, the near-surface velocity model is obtained using the first arrival tomography inversion method.

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

4. The seismic data processing method for pre-stack depth migration according to claim 1, characterized in that, The static correction formula is: In the above formula, S S_FD S is the static correction amount from the shot point to the smooth surface of the ground. R_FD Z is the static correction from the receiver point to the smooth surface of the earth. S Z is the elevation of the firing point. S_FD Z represents the elevation of the smooth surface corresponding to the location of the shot point. R For the elevation of the receiver point, Z R_FD V represents the elevation of the smooth surface corresponding to the location of the receiver point, and V represents the average velocity.

5. The seismic data processing method for pre-stack depth migration according to claim 4, characterized in that, The average velocity is the average velocity from the ground surface to the smooth surface, determined according to the filled velocity model.

6. The seismic data processing method for pre-stack depth migration according to claim 1, characterized in that, The process of fusing the shallow velocity model and the deep velocity model based on the smooth surface to obtain the pre-stack depth migration velocity model includes: The high-speed top interface is determined based on the shallow velocity model. The high-speed top interface is used to fuse the shallow velocity model and the deep velocity model in the longitudinal direction to obtain a velocity model with pre-stack depth offset processing.

7. The seismic data processing method for pre-stack depth migration according to claim 6, characterized in that, The pre-stack data based on small smooth surfaces of the land surface was obtained through the following steps: Determine the static correction amount when the fixed reference plane is aligned with the smooth surface of the earth. Pre-stack data based on a smooth surface are obtained based on the determined static correction and data on a fixed reference surface.

8. The seismic data processing method for pre-stack depth migration according to claim 7, characterized in that, The static correction amount from the fixed reference plane to the smooth surface includes: In the above formula, S S_cor S is the shot point correction amount from the fixed reference plane to the smooth surface of the ground. S_SRD Z is the static correction amount for the shot point on the fixed reference surface. S_HIV S represents the elevation of the high-speed top interface corresponding to the shot point location. R_cor S is the correction amount for the receiver point on the fixed reference plane to the smooth surface of the earth. R_SRD Z is the static correction amount for the detector point on the fixed reference plane. R_HIV Z represents the elevation of the high-speed top interface corresponding to the location of the detector point. SRD To fix the elevation of the reference surface, V R For replacement speed, V i Let ΔZ be the velocity value of the i-th surface element in the velocity model based on the smooth surface, ΔZ be the vertical grid size of the velocity model based on the smooth surface, and N be the number of vertical grids in the velocity model based on the smooth surface from the high-speed top interface to the smooth surface.

9. A seismic data processing apparatus for pre-stack depth migration, characterized in that, The apparatus includes a memory and a processor; the memory is used to store a program for a seismic data processing method for pre-stack depth migration, and the processor is used to read and execute the program for the seismic data processing method for pre-stack depth migration, and execute the method according to any one of claims 1-8.

10. A computer-readable storage medium storing a data processing program, the data processing program being executed by a processor using the seismic data processing method for pre-stack depth migration according to any one of claims 1-8.

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