Method and device for separating fast and slow pure shear wave before stacking

Abstract

The application provides a pre-stack fast-slow pure transverse wave separation method and device, and belongs to the technical field of seismic exploration. A first kind of observation pre-stack pure transverse wave four-component seismic data is rotated in a direction, then separated-azimuth stacking or separated-azimuth migration stacking is performed, a second kind of observation separated-azimuth stacking pure transverse wave four-component seismic data which is convenient for analyzing transverse wave splitting characteristics is formed, then a target crack direction is obtained, fast-slow transverse wave separation is performed on the second kind of observation separated-azimuth stacking pure transverse wave four-component seismic data according to the target crack direction, a judging matrix is combined, whether the target crack direction changes with depth is judged, then fast-slow transverse wave separation is performed on seismic data, so that the pre-stack fast-slow pure transverse wave separation of transverse wave data is performed, the precision of fast-slow wave separation is improved, the pre-stack migration calculation amount of two-component seismic data except fast transverse wave and slow transverse wave is reduced, and the velocity of fast transverse wave and the velocity of slow transverse wave are conveniently adjusted subsequently.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seismic exploration, in particular to a pre-stack fast and slow pure shear wave separation method and device. BACKGROUND

[0002] When the shear wave obliquely crosses the azimuth anisotropic medium, the shear wave splitting occurs, and the physical phenomenon can be observed in the seismic exploration. At present, the three-component geophone is widely used in the seismic exploration, and the three components of the geophone record the complete seismic wave field, and accurately, the projection of the vector seismic wave field on the three components. The energy of the shear wave is mainly recorded in the two horizontal components of the three-component geophone, if the two horizontal components of the geophone are parallel and perpendicular to the crack direction respectively, then one horizontal component records the fast shear wave, and the other component records the slow shear wave, however, in the actual operation, the two horizontal components of the geophone are not usually parallel and perpendicular to the crack direction respectively, therefore, the two horizontal components of the geophone record the wave field in which the fast shear wave and the slow shear wave are mixed together, which causes the repeated occurrence of the shear wave reflection from the same reflection interface on each horizontal component at different times, and further causes the poor shear wave imaging result or even the wrong imaging result.

[0003] To solve the above problems, the fast shear wave and the slow shear wave need to be effectively separated, and then the fast shear wave and the slow shear wave are respectively imaged, that is, the fast and slow shear wave separation, or further shear wave splitting correction processing. For the fast and slow shear wave separation, the existing technical solution is that, for the 2D data, the fast and slow shear wave separation is performed on the stacked section or the migration section, and for the 3D data, the fast and slow shear wave separation is performed on the stacked section or the split-azimuth stacked section or the split-azimuth migration section. That is to say, in the aspect of the shear wave processing, the fast and slow shear wave separation is usually performed on the stacked section or the migration section after the shear wave data obtained is stacked or migrated, however, for the case that the fast and slow shear wave velocity has obvious difference, the above processing cannot completely meet the requirement of the high-precision shear wave imaging. SUMMARY

[0004] The embodiment of the present application provides a pre-stack fast and slow pure shear wave separation method and device, which can separate the fast and slow shear waves from the pre-stack pure shear wave four-component seismic data, can reduce the four times of pre-stack migration calculation for the four components to two times of pre-stack migration calculation of the fast shear wave and the slow shear wave, thereby reducing the calculation amount, and can further improve the precision of the fast and slow wave separation through the advantage of obtaining the accurate azimuth angle of each pre-stack seismic data, and simultaneously, it is convenient to subsequently adjust the velocity of the fast shear wave and the slow shear wave. The technical solution is as follows:

[0005] In one aspect, a pre-stack fast and slow pure shear wave separation method is provided, and the method comprises:

[0006] obtaining first observation pre-stack pure shear wave four-component seismic data;

[0007] rotating the source excitation direction corresponding to the first kind of observed pre-stack pure transverse wave four-component seismic data and the horizontal component receiving direction of the receiver, to obtain second kind of observed pre-stack pure transverse wave four-component seismic data, the direction corresponding to the second kind of observed pre-stack pure transverse wave four-component seismic data includes: along the direction of the shot gather and perpendicular to the direction of the shot gather;

[0008] performing azimuthal stacking or azimuthal migration stacking on the second kind of observed pre-stack pure transverse wave four-component seismic data to obtain second kind of observed azimuthal stacking pure transverse wave four-component seismic data;

[0009] based on the transverse wave splitting characteristics of the second kind of observed azimuthal stacking pure transverse wave four-component seismic data, obtaining an initial crack direction, and limiting the crack direction of the pure transverse wave splitting analysis method according to the initial crack direction to obtain a target crack direction;

[0010] based on the target crack direction, separating the fast and slow transverse waves of the second kind of observed azimuthal stacking pure transverse wave four-component seismic data to obtain azimuthal stacking and fast-slow transverse wave separation pure transverse wave four-component seismic data, and stacking the azimuthal data to obtain post-stack fast-slow transverse wave separation four-component seismic data;

[0011] based on the judgment matrix X, judging whether the target crack direction changes with depth, if two sub-diagonal components in the post-stack fast-slow transverse wave separation four-component seismic data do not exist effective signal, and the time difference of the slow transverse wave component relative to the fast transverse wave component increases with depth, the target crack direction does not change with depth;

[0012] X=D 1h R2 -1 D2R2D 1h

[0013] In the judgment matrix X, θ1 and θ2 are the first preset crack direction and the second preset crack direction respectively, and the crack positions corresponding to the first preset crack direction and the second preset crack direction are from shallow to deep;

[0014]

[0015]

[0016]

[0017] Under the condition of θ2=θ1, based on the target crack direction, the fast and slow transverse waves of the first kind of observed pre-stack pure transverse wave four-component seismic data or the second kind of observed pre-stack pure transverse wave four-component seismic data are separated.

[0018] In a possible implementation manner, after the second observed pre-stack pure transverse wave four-component seismic data is subjected to azimuthal stacking or azimuthal migration stacking to obtain second observed azimuthal stacking pure transverse wave four-component seismic data, the method further includes:

[0019] The second observed azimuthal stacking pure transverse wave four-component seismic data is subjected to pass-through processing to form second observed azimuthal stacking pure transverse wave four-component seismic data in the form of a large common gather.

[0020] In a possible implementation manner, the fast and slow transverse wave separation of the first observed pre-stack pure transverse wave four-component seismic data or the second observed pre-stack pure transverse wave four-component seismic data based on the target crack direction includes:

[0021] The corresponding index is selected to perform pre-stack seismic trace matching on the first observed pre-stack pure transverse wave four-component seismic data or the second observed pre-stack pure transverse wave four-component seismic data, and after the matching, fast and slow transverse wave separation is performed to obtain separated fast transverse waves and slow transverse waves.

[0022] In a possible implementation manner, after the fast and slow transverse wave separation of the first observed pre-stack pure transverse wave four-component seismic data or the second observed pre-stack pure transverse wave four-component seismic data based on the target crack direction, the method further includes:

[0023] The velocity of the separated fast transverse wave and the velocity of the separated slow transverse wave are adjusted.

[0024] In a possible implementation manner, the method further includes:

[0025] Under the condition that θ2≠θ1, the fast and slow transverse wave separation of the second observed pre-stack pure transverse wave four-component seismic data is performed by using layer-by-layer pre-stack transverse wave splitting correction.

[0026] In an aspect, a pre-stack fast and slow pure transverse wave separation device is provided, and the device includes:

[0027] A data acquisition module is configured to acquire first observed pre-stack pure transverse wave four-component seismic data.

[0028] A rotation module is configured to rotate a source excitation direction corresponding to the first observed pre-stack pure transverse wave four-component seismic data and a horizontal component receiving direction of a receiver to obtain second observed pre-stack pure transverse wave four-component seismic data, wherein a direction corresponding to the second observed pre-stack pure transverse wave four-component seismic data includes a direction along a shot-receiver line and a direction perpendicular to the shot-receiver line.

[0029] An azimuthal stacking module is configured to perform azimuthal stacking or azimuthal migration stacking on the second observed pre-stack pure transverse wave four-component seismic data to obtain second observed azimuthal stacking pure transverse wave four-component seismic data.

[0030] The crack direction acquisition module is configured to acquire an initial crack direction based on the shear wave splitting characteristics of the second-observation azimuthally stacked pure shear wave four-component seismic data, and limit the pure shear wave splitting analysis device based on the initial crack direction to acquire a target crack direction.

[0031] The post-stack fast and slow shear wave separation module is configured to separate the second-observation azimuthally stacked pure shear wave four-component seismic data based on the target crack direction to obtain post-stack fast and slow shear wave separation four-component seismic data.

[0032] The crack direction judgment module is configured to judge whether the target crack direction changes with depth based on the judgment matrix X. If there is no effective signal in two sub-diagonal components of the post-stack fast and slow shear wave separation four-component seismic data, and the time difference of the slow shear wave component relative to the fast shear wave component increases with depth, the target crack direction does not change with depth.

[0033] X = D 1h R2 -1 D2R2D 1h

[0034] In the judgment matrix X, θ1 and θ2 are the first preset crack direction and the second preset crack direction respectively, and the crack positions corresponding to the first preset crack direction and the second preset crack direction are from shallow to deep.

[0035]

[0036]

[0037]

[0038] The pre-stack fast and slow pure shear wave separation module is configured to separate the first-observation pre-stack pure shear wave four-component seismic data or the second-observation pre-stack pure shear wave four-component seismic data based on the target crack direction under the condition of θ2 = θ1.

[0039] In a possible implementation, the azimuthally stacked pure shear wave four-component seismic data separation module is further configured to:

[0040] The second-observation azimuthally stacked pure shear wave four-component seismic data is separated by borrowing a channel to form second-observation azimuthally stacked pure shear wave four-component seismic data in the form of a large channel set.

[0041] In a possible implementation, the pre-stack fast and slow pure shear wave separation module is configured to:

[0042] The corresponding index is selected to perform pre-stack seismic trace matching on the first kind of observed pre-stack pure shear wave four-component seismic data or the second kind of observed pre-stack pure shear wave four-component seismic data, and after the matching, fast and slow shear wave separation is performed to obtain separated fast shear wave and slow shear wave.

[0043] In a possible implementation manner, the apparatus further includes a speed adjustment module configured to:

[0044] Adjust the speed of the separated fast shear wave and the speed of the slow shear wave.

[0045] In a possible implementation manner, the pre-stack fast and slow pure shear wave separation module is further configured to:

[0046] Under the condition of θ2≠θ1, the fast and slow shear wave separation is performed on the second kind of observed pre-stack pure shear wave four-component seismic data by using layer-by-layer pre-stack shear wave splitting correction.

[0047] The technical scheme provided in the embodiments of the present application is to rotate the corresponding direction of the first kind of observed pre-stack pure shear wave four-component seismic data, and then perform azimuth-dependent stacking or azimuth-dependent migration stacking to form the second kind of observed azimuth-dependent stacking pure shear wave four-component seismic data which is convenient for analyzing shear wave splitting characteristics, obtain an initial crack direction according to the shear wave splitting characteristics of the data, limit the crack direction of shear wave splitting analysis according to the range of the initial crack direction to obtain a target crack direction, perform fast and slow shear wave separation on the second kind of observed azimuth-dependent stacking pure shear wave four-component seismic data according to the target crack direction to obtain azimuth-dependent stacking and fast and slow shear wave separation pure shear wave four-component seismic data, stack the azimuth-dependent data to obtain post-stack fast and slow shear wave separation four-component seismic data, and combine a judgment matrix to judge whether the target crack direction changes with depth. Under the condition that the target crack direction does not change with depth, perform fast and slow shear wave separation on the first kind of observed pre-stack pure shear wave four-component seismic data or the second kind of observed pre-stack pure shear wave four-component seismic data based on the target crack direction. In the technical scheme, the pre-stack fast and slow pure shear wave separation of the shear wave data improves the accuracy of fast and slow wave separation, and can reduce the pre-stack migration calculation amount of the two-component seismic data other than the fast shear wave and the slow shear wave. Meanwhile, it is convenient to subsequently adjust the speed of the fast shear wave and the speed of the slow shear wave. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical schemes in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0049] Figure 1is a flow chart of a pre-stack fast and slow pure shear wave separation method provided by an embodiment of the present application;

[0050] Figure 2 is a flow chart of a pre-stack fast and slow pure shear wave separation method provided by an embodiment of the present application;

[0051] Figure 3 is a schematic diagram of SxRx, SxRy, SyRx and SyRy four components in a case of 0-degree change of a fracture direction provided by an embodiment of the present application;

[0052] Figure 4 is a schematic diagram of SxRx, SxRy, SyRx and SyRy four components in a case of 30-degree change of a fracture direction provided by an embodiment of the present application;

[0053] Figure 5 is a schematic diagram of SxRx, SxRy, SyRx and SyRy four components in a case of 90-degree change of a fracture direction provided by an embodiment of the present application;

[0054] Figure 6 is a schematic diagram of SxRx, SxRy, SyRx and SyRy four components in a case of 120-degree change of a fracture direction provided by an embodiment of the present application;

[0055] Figure 7 is a schematic diagram of SrRr, SrRt, StRr and StRt four components in a case of 0-degree change of a fracture direction provided by an embodiment of the present application;

[0056] Figure 8 is a schematic diagram of SrRr, SrRt, StRr and StRt four components in a case of 30-degree change of a fracture direction provided by an embodiment of the present application;

[0057] Figure 9 is a schematic diagram of SrRr, SrRt, StRr and StRt four components in a case of 90-degree change of a fracture direction provided by an embodiment of the present application;

[0058] Figure 10 is a schematic diagram of SrRr, SrRt, StRr and StRt four components in a case of 120-degree change of a fracture direction provided by an embodiment of the present application;

[0059] Figure 11 is a schematic diagram of Ss1Rs1, Ss1Rs2, Ss2Rs1 and Ss2Rs2 four components in a case of 0-degree change of a fracture direction provided by an embodiment of the present application;

[0060] Figure 12is a schematic diagram of four components of Ss1Rs1, Ss1Rs2, Ss2Rs1 and Ss2Rs2 in the case of a 30-degree change in the fracture direction, provided by an embodiment of the present application;

[0061] Figure 13 is a schematic diagram of four components of Ss1Rs1, Ss1Rs2, Ss2Rs1 and Ss2Rs2 in the case of a 90-degree change in the fracture direction, provided by an embodiment of the present application;

[0062] Figure 14 is a schematic diagram of four components of Ss1Rs1, Ss1Rs2, Ss2Rs1 and Ss2Rs2 in the case of a 120-degree change in the fracture direction, provided by an embodiment of the present application;

[0063] Figure 15 is a schematic diagram of a pure transverse wave four-component single shot before pre-stack fast-slow pure transverse wave separation, provided by an embodiment of the present application;

[0064] Figure 16 is a schematic diagram of a pure transverse wave four-component single shot after pre-stack fast-slow pure transverse wave separation, provided by an embodiment of the present application;

[0065] Figure 17 is a schematic diagram of a velocity spectrum and a large gather before pre-stack fast-slow wave separation, provided by an embodiment of the present application;

[0066] Figure 18 is a schematic diagram of a velocity spectrum and a large gather after pre-stack fast-slow wave separation, provided by an embodiment of the present application;

[0067] Figure 19 is a schematic diagram of a pre-stack time migration profile before pre-stack fast-slow wave separation, provided by an embodiment of the present application;

[0068] Figure 20 is a schematic diagram of a pre-stack time migration profile after pre-stack fast-slow wave separation, provided by an embodiment of the present application;

[0069] Figure 21 is a schematic diagram of a structure of a pre-stack fast-slow pure transverse wave separation device, provided by an embodiment of the present application;

[0070] Figure 22 is a schematic diagram of a structure of a computer device, provided by an embodiment of the present application. DETAILED DESCRIPTION

[0071] In order to make the purpose, technical scheme and advantages of the present application more clear, the following will make a further detailed description of the embodiments of the present application in combination with the drawings.

[0072] Figure 1 is a flowchart of a pre-stack fast-slow pure transverse wave separation method, provided by an embodiment of the present application, please refer to Figure 1The method can be applied to a computer device, and the method comprises:

[0073] 101. Obtain first observed pre-stack pure shear wave four-component seismic data.

[0074] 102. Rotate the source excitation direction and the horizontal component receiver direction corresponding to the first observed pre-stack pure shear wave four-component seismic data to obtain second observed pre-stack pure shear wave four-component seismic data, the direction corresponding to the second observed pre-stack pure shear wave four-component seismic data comprising: along the direction of the shot-gather line and perpendicular to the direction of the shot-gather line.

[0075] 103. Perform azimuthal stacking or azimuthal migration stacking on the second observed pre-stack pure shear wave four-component seismic data to obtain second observed azimuthal stacking pure shear wave four-component seismic data.

[0076] 104. Obtain an initial crack direction based on the shear wave splitting characteristics of the second observed azimuthal stacking pure shear wave four-component seismic data, and limit the crack direction of the pure shear wave splitting analysis method according to the initial crack direction to obtain a target crack direction.

[0077] 105. Based on the target crack direction, separate the fast and slow shear waves of the second observed azimuthal stacking pure shear wave four-component seismic data to obtain azimuthal stacking and fast-slow shear wave separation pure shear wave four-component seismic data, and stack the azimuthal data to obtain post-stack fast-slow shear wave separation four-component seismic data.

[0078] 106. Based on the judgment matrix X, judge whether the target crack direction changes with depth, if the two sub-diagonal components in the post-stack fast-slow shear wave separation four-component seismic data do not exist effective signals, and the time difference of the slow shear wave component relative to the fast shear wave component increases with depth, the target crack direction does not change with depth.

[0079] X = D 1h R2 -1 D2R2D 1h

[0080] In the judgment matrix X, θ1 and θ2 are the first preset crack direction and the second preset crack direction respectively, and the crack positions corresponding to the first preset crack direction and the second preset crack direction are from shallow to deep.

[0081]

[0082]

[0083]

[0084] 107. Under the condition that θ 2 = θ 1, based on the target fracture direction, the first kind of observed prestack pure shear wave four-component seismic data or the second kind of observed prestack pure shear wave four-component seismic data is subjected to fast and slow shear wave separation.

[0085] The technical scheme provided by the embodiments of the present application rotates the direction corresponding to the first kind of observed prestack pure shear wave four-component seismic data, and then performs azimuth-dependent stacking or azimuth-dependent migration stacking to form the second kind of observed azimuth-dependent stacking pure shear wave four-component seismic data which is convenient for analyzing shear wave splitting characteristics, obtains an initial fracture direction according to the shear wave splitting characteristics shown by the data, limits the shear wave splitting analysis according to the range of the initial fracture direction to obtain a target fracture direction, performs fast and slow shear wave separation on the second kind of observed azimuth-dependent stacking pure shear wave four-component seismic data according to the target fracture direction, obtains azimuth-dependent stacking and fast and slow shear wave separation pure shear wave four-component seismic data, stacks the azimuth-dependent data to obtain poststack fast and slow shear wave separation four-component seismic data, and judges whether the target fracture direction changes with depth in combination with a judgment matrix. Under the condition that the target fracture direction does not change with depth, based on the target fracture direction, the first kind of observed prestack pure shear wave four-component seismic data or the second kind of observed prestack pure shear wave four-component seismic data is subjected to fast and slow shear wave separation. In the technical scheme, the accuracy of fast and slow wave separation is improved by performing prestack fast and slow pure shear wave separation on the shear wave data, the prestack migration calculation amount of the two components of seismic data other than the fast and slow shear waves is reduced, and the velocities of the fast shear wave and the slow shear wave can be adjusted subsequently.

[0086] In a possible implementation manner, after the second kind of observed prestack pure shear wave four-component seismic data is subjected to azimuth-dependent stacking or azimuth-dependent migration stacking to obtain the second kind of observed azimuth-dependent stacking pure shear wave four-component seismic data, the method further includes:

[0087] The second kind of observed azimuth-dependent stacking pure shear wave four-component seismic data is subjected to pass-through to form the second kind of observed azimuth-dependent stacking pure shear wave four-component seismic data in the form of a large common gather.

[0088] In a possible implementation manner, based on the target fracture direction, the first kind of observed prestack pure shear wave four-component seismic data or the second kind of observed prestack pure shear wave four-component seismic data is subjected to fast and slow shear wave separation, including:

[0089] The corresponding index is selected to perform prestack seismic trace matching on the first kind of observed prestack pure shear wave four-component seismic data or the second kind of observed prestack pure shear wave four-component seismic data, and fast and slow shear wave separation is performed after the matching to obtain the separated fast shear wave and slow shear wave.

[0090] In a possible implementation manner, after the fast and slow transverse wave separation is performed on the first or second observed pre-stack pure transverse wave four-component seismic data based on the target crack direction, the method further includes:

[0091] adjusting the separated fast transverse wave velocity and slow transverse wave velocity.

[0092] In a possible implementation manner, the method further includes:

[0093] In the case of θ2≠θ1, the fast and slow transverse wave separation is performed on the second observed pre-stack pure transverse wave four-component seismic data by using the layer-by-layer pre-stack transverse wave splitting correction.

[0094] All the optional technical solutions described above can be combined to form optional embodiments of the present application, and will not be repeated here.

[0095] Figure 2 is a flowchart of a pre-stack fast and slow pure transverse wave separation method provided by an embodiment of the present application, please refer to Figure 2 The method can be applied to a computer device, and the method includes:

[0096] 201. Obtain first observed pre-stack pure transverse wave four-component seismic data.

[0097] The direction corresponding to the first observed pure transverse wave four-component seismic data, that is, the excitation direction and the receiving direction, includes the direction along the survey line and the direction perpendicular to the survey line. Specifically, the transverse wave source is excited once in the parallel survey line direction and the perpendicular survey line direction respectively, and the two horizontal components of the geophone are placed in parallel with the survey line and the perpendicular survey line for receiving, to obtain original four-component seismic records, which are referred to as the first observed pre-stack pure transverse wave four-component seismic data in the present application. The data in this step can be referred to as Figures 3-6 .

[0098] 202. Rotate the source excitation direction and the horizontal component receiving direction of the geophone corresponding to the first observed pre-stack pure transverse wave four-component seismic data to obtain second observed pre-stack pure transverse wave four-component seismic data, the direction corresponding to the second observed pre-stack pure transverse wave four-component seismic data including the direction along the shot-receiver line and the direction perpendicular to the shot-receiver line.

[0099] The shot point is a place for exciting seismic waves in seismic field work, and the shot-receiver line is a line connecting the shot point and the geophone.

[0100] In this step, the excitation direction and the receiving direction of the transverse wave four-component seismic data are rotated to the shot-receiver line direction and the perpendicular direction thereof by using the alford rotation formula (see formula 1).

[0101] The data in this step can be referred to asFigures 7-10 .

[0102]

[0103]

[0104] wherein, SrRr, SrRt, StRr, StRt are pure shear wave four components along the direction of the shot-gather and its vertical observation, which is called second kind of observed pre-stack pure shear wave four component seismic data in the application;

[0105] SxRx, SxRy, SyRx, SyRy are pure shear wave four components along the direction of the survey line and its vertical observation, which is called first kind of observed pre-stack pure shear wave four component seismic data in the application;

[0106] θ is the included angle between the direction of the survey line and the shot-gather;

[0107] azimuth is the angle corresponding to the direction of the shot-gather;

[0108] is the angle corresponding to the direction of the survey line;

[0109] 203. The second kind of observed pre-stack pure shear wave four component seismic data is subjected to azimuthal stack or azimuthal migration stack to obtain second kind of observed azimuthal stack pure shear wave four component seismic data.

[0110] In this step, the second kind of observed pre-stack pure shear wave four component seismic data includes SrRr component, SrRt component, StRr component and StRt component, and the second kind of observed pre-stack pure shear wave four component seismic data is subjected to azimuthal stack or azimuthal migration stack.

[0111] 204. The second kind of observed azimuthal stack pure shear wave four component seismic data is subjected to borrowing to form second kind of observed azimuthal stack pure shear wave four component seismic data in the form of large trace gather.

[0112] Since the shear wave data stack data often has the problem of insufficient high signal-to-noise ratio, for this, the embodiment is to each component, each azimuth, each reflection stack seismic trace, through the data along the line number and point number from the adjacent reflection point moving borrowing reuse, forming the large trace gather corresponding to the reflection point, and then the data of the large trace gather is stacked to form 1 trace. The processing process can be directly performed on the stack data to form shear wave stack data (2D) or shear wave azimuthal stack data (3D) with improved signal-to-noise ratio.

[0113] 205. Based on the shear wave splitting characteristics of the second azimuthally stacked pure shear wave four-component seismic data, an initial fracture direction is obtained, and a pure shear wave splitting analysis method is limited in fracture direction according to the initial fracture direction to obtain a target fracture direction.

[0114] wherein the initial fracture direction refers to a rough fracture direction estimated according to the above shear wave splitting characteristics, and the target fracture direction refers to an accurate fracture direction obtained by shear wave splitting analysis. In this step, the fracture direction of the pure shear wave splitting analysis method is constrained by using the shear wave splitting characteristics of the azimuthally stacked data to obtain the underground fracture direction.

[0115] The azimuthally stacked gathers of the SrRt component and the StRr component have effective energy of 0 in the four directions corresponding to the fracture direction and the vertical direction thereof, and the polarities of the adjacent azimuths before and after them are reversed; meanwhile, the SrRr component has the strongest fast shear wave reflection event in the azimuth corresponding to the fracture direction, and has no effective slow shear wave reflection, and has the strongest slow shear wave reflection event in the azimuth corresponding to the vertical fracture, and has no effective fast shear wave reflection; meanwhile, the StRt component has the strongest slow shear wave reflection event in the azimuth corresponding to the fracture direction, and has no effective fast shear wave reflection, and has the strongest fast shear wave reflection event in the azimuth corresponding to the vertical fracture, and has no effective slow shear wave reflection. According to the above characteristics, the fracture direction distribution range is determined (see Figures 7-10 ).

[0116] Data in the advantage time window with high signal-to-noise ratio in the shallow layer is selected for calculation. In this step, the is obtained based on the alford shear wave splitting analysis method and the like. Figures 11-14 .

[0117]

[0118]

[0119] wherein Ss1Rs1, Ss1Rs2, Ss2Rs1, Ss2Rs2 are pure shear wave four-components observed along the fracture direction and the vertical direction thereof, which are referred to as third azimuthally stacked pure shear wave four-component seismic data in the present application;

[0120] SrRr, SrRt, StRr, StRt are pure shear wave four-components observed along the shot-receiver connecting line direction and the vertical direction thereof, which are referred to as second pre-stack pure shear wave four-component seismic data in the present application;

[0121] The included angle between the fracture direction and the shot-receiver connecting line direction;

[0122] is the angle corresponding to the fracture direction;

[0123] azimuth is the angle corresponding to the direction of the shot-hydrophone line.

[0124] 206. Based on the target fracture direction, the second kind of observation azimuthally stacked pure shear wave four-component seismic data is subjected to fast and slow shear wave separation to obtain azimuthally stacked and fast and slow shear wave separated pure shear wave four-component seismic data, and each azimuthal data is stacked to obtain post-stack fast and slow shear wave separated four-component seismic data.

[0125] Wherein, the post-stack fast and slow shear wave separated four-component seismic data is used to determine whether the fracture direction changes with depth. Wherein, the steps of determining whether the fracture direction changes with depth are as follows:

[0126] According to the post-stack fast and slow wave separation of the four-component stacking / migration profile (2D) or the four-component azimuthally stacked / migrated profile (3D) obtained by solving the fracture direction, the four-component data after fast and slow wave separation is obtained. For azimuthally stacked / migrated stacked data, different azimuthal data can also be stacked to generate a four-component total stacking / migration profile. For the target layer in the analysis time window, if the fracture direction is accurately solved, the reflection energy of the two secondary diagonal components Ss1Rs2 and Ss2Rs1 in the time window is eliminated (see Figures 11-14 , the fracture direction of the shallow layer is 150 degrees in four cases, and after fast and slow wave separation according to this direction, the energy of the two secondary diagonal components is eliminated), the imaging of the Ss1Rs1 component and the Ss2Rs2 component is improved. On the basis of the accurate solution of the fracture direction in the shallow layer time window, the following criteria can be applied to determine whether the fracture direction changes with depth:

[0127] Assuming that there are two layers of fractures in the underground, the fracture directions of the first layer and the second layer are θ1 and θ2 respectively, after the fracture direction θ1 of the first layer is solved, the second kind of observation pure shear wave four-component data is rotated to the fracture direction of the first layer and its vertical direction according to formula 2, specifically, θ1 in formula 2 is , the new four-component data is obtained, which is called the third kind of observation azimuthally stacked pure shear wave four-component seismic data in the present application. The third kind of observation azimuthally stacked pure shear wave four-component seismic data can also stack each azimuthal data to obtain post-stack fast and slow shear wave separated four-component seismic data, which is the fracture direction change judgment matrix X.

[0128] 207. Based on the judgment matrix X, it is determined whether the target fracture direction changes with depth.

[0129] X=D 1h R2 -1 D2R2D 1h

[0130] In the judgment matrix X, θ1 and θ2 are the first preset crack direction and the second preset crack direction respectively, and the crack positions corresponding to the first preset crack direction and the second preset crack direction are from shallow to deep;

[0131]

[0132]

[0133]

[0134] If θ2 = θ1, indicates that there is no effective signal on the secondary diagonal line, and the time difference of the fast and slow transverse waves of the second layer crack increases relative to the fast and slow transverse waves of the first layer crack;

[0135] If |θ2-θ1| = 90°, indicates that there is no signal on the secondary diagonal line, and the time difference of the fast and slow transverse waves of the second layer crack decreases relative to the fast and slow transverse waves of the first layer crack;

[0136] In other cases, X is a non-diagonal matrix, and there are reflected signals in the four components (see Figures 11-14 ).

[0137] Whether the crack direction changes with depth can be preliminarily judged by the transverse wave splitting characteristics of the SrRr component, the SrRt component, the StRr component and the StRt component. If the polarity of the SrRt component and the StRr component is reversed, the azimuthal transverse wave splitting characteristics do not change with depth, it is inferred that the crack direction does not change with depth, or the crack direction changes to the orthogonal direction of the upper layer crack, which should be a special case of coincidence (see Figure 7 and Figure 9 ).

[0138] According to the fast and slow wave separation Ss1Rs1 component, Ss1Rs2 component, Ss2Rs1 component and Ss2Rs2 component, the azimuthal stacking section is judged (according to formula 3): when the two secondary diagonal components (Ss1Rs2 and Ss2Rs1) stacking sections appear obvious reflected energy with the increase of depth, it indicates that the crack direction changes with depth (see Figure 12 and Figure 14 ), in detail, when Ss1Rs2 and Ss2Rs1 profiles appear effective reflected energy with the increase of depth and the time difference of the slow transverse wave Ss2Rs2 component relative to the fast transverse wave Ss1Rs1 component increases with depth, the crack direction changes with depth and the crack direction change angle is small (the angle with the shallow crack direction is smaller, see Figure 12) ; when the Ss1Rs2 component and the Ss2Rs1 component have effective reflected energy with the increase of depth and the time difference of the slow transverse wave Ss2Rs2 component relative to the fast transverse wave Ss1Rs1 component decreases with the increase of depth, the fracture direction changes with the change of depth and the fracture direction change angle is large (the vertical angle with the shallow fracture direction is smaller, see Figure 14 ) ; when the Ss1Rs2 and Ss2Rs1 profiles do not have effective reflected energy from shallow to deep and the time difference of the slow transverse wave Ss2Rs2 component relative to the fast transverse wave Ss1Rs1 component increases with the increase of depth, the fracture direction does not change with the change of depth (see Figure 11 ) ; when the Ss1Rs2 and Ss2Rs1 profiles do not have effective reflected energy from shallow to deep and the time difference of the slow transverse wave Ss2Rs2 component relative to the fast transverse wave Ss1Rs1 component decreases with the increase of depth, the fracture direction change is exactly 90 degrees (see Figure 13 ), which is a special case that the deep fracture direction is perpendicular to the shallow fracture direction (see Figures 11-14 ).

[0139] wherein, if two sub-diagonal components in the post-stack fast-slow transverse wave separation four-component seismic data do not have effective signals and the time difference of the slow transverse wave component relative to the fast transverse wave component increases with the increase of depth, the target fracture direction does not change with the change of depth. After determining that the fracture direction does not change with the change of depth, subsequent processing procedures are performed.

[0140] 208. Under the condition that θ2=θ1, based on the target fracture direction, fast-slow transverse wave separation is performed on the first kind of observed pre-stack pure transverse wave four-component seismic data or the second kind of observed pre-stack pure transverse wave four-component seismic data.

[0141] θ2=θ1 indicates that the fracture direction does not change with the change of depth, and the data in this step can be referred to as Figures 15-20 .

[0142] wherein, Figure 15 is a schematic diagram of a pre-stack fast-slow pure transverse wave separation pre-transverse wave four-component single shot provided by an embodiment of the present application;

[0143] Figure 16 is a schematic diagram of a post-stack fast-slow pure transverse wave separation post-transverse wave four-component single shot provided by an embodiment of the present application;

[0144] Figure 17 is a schematic diagram of a pre-stack fast-slow wave separation pre-velocity spectrum and large trace gather provided by an embodiment of the present application, in which the upper left is the SrRr component and the lower left is the StRt component.

[0145] Figure 18 is a schematic diagram of a post-stack fast-slow wave separation post-velocity spectrum and large trace gather provided by an embodiment of the present application, in which the upper right is the fast transverse wave Ss1Rs1 and the lower right is the slow transverse wave Ss2Rs2.

[0146] Figure 19 is a schematic diagram of a pre-stack fast-slow wave separation pre-stack time migration profile provided by an embodiment of the present application, in which the left is the SrRr component and the right is the StRt component.

[0147] Figure 20 is another schematic diagram of a pre-stack fast-slow wave separation pre-stack time migration profile provided by an embodiment of the present application, in which the left is the Ss1Rs1 fast shear wave and the right is the Ss2Rs2 slow shear wave.

[0148] The first kind of observed pure shear wave four-component seismic data or the second kind of observed pure shear wave four-component seismic data is subjected to pre-stack seismic trace matching by selecting a proper index, and after the matching, fast and slow shear wave separation is performed to obtain the separated fast and slow shear waves.

[0149] Specifically, the sought fracture direction is moderately smoothed, and the above smoothed fracture direction is used for pre-stack fast and slow pure shear wave separation. First, the four-component pre-stack shear wave data is subjected to seismic trace matching according to the trace head of the shot and the receiver, the four-component seismic traces from the same shot and the same receiver are matched, the corresponding fracture direction is read according to the reflection point where the trace is located, and pre-stack fast and slow shear wave separation is performed according to the alookford rotation formula.

[0150] The fast shear wave velocity and the slow shear wave velocity are respectively explained, the fast shear wave Ss1Rs1 is subjected to dynamic correction stacking or pre-stack migration imaging according to the accurate fast shear wave velocity, and the slow shear wave Ss2Rs2 is subjected to dynamic correction stacking or pre-stack migration imaging according to the accurate slow shear wave velocity. The Ss1Rs2 component and the Ss2Rs1 component after the fast and slow wave separation do not have effective reflection energy, and subsequent processing is not necessary. In this way, the migration calculation amount of two components is saved.

[0151] 209. The separated fast shear wave velocity and the slow shear wave velocity are adjusted.

[0152] In this step, the separated fast and slow shear wave velocities are adjusted, and pre-stack migration or other subsequent processing interpretation work is respectively performed.

[0153] 210. Under the condition that θ2≠θ1, the second kind of observed pre-stack pure shear wave four-component seismic data is subjected to fast and slow shear wave separation by using layer-by-layer pre-stack shear wave splitting correction.

[0154] θ2≠θ1 indicates that the fracture direction changes with depth, and in this step, the shear wave splitting correction cooperates with the aforementioned pre-stack fast and slow wave separation method to realize that data with different fracture directions can be processed.

[0155] All the above optional technical solutions can be combined in any manner to form optional embodiments of the present application, and will not be described one by one here.

[0156] The technical scheme provided by the embodiments of the present application rotates the direction corresponding to the first kind of observed pre-stack pure shear wave four-component seismic data, and then performs azimuthal stacking or azimuthal migration stacking to form second kind of observed azimuthal stacking pure shear wave four-component seismic data which is convenient for analyzing shear wave splitting characteristics, obtains an initial crack direction according to the shear wave splitting characteristics shown by the data, limits the crack direction for shear wave splitting analysis according to the initial crack direction range to obtain a target crack direction, separates fast and slow shear waves from the second kind of observed azimuthal stacking pure shear wave four-component seismic data according to the target crack direction to obtain azimuthal stacking and fast and slow shear wave separation pure shear wave four-component seismic data, stacks each azimuthal data to obtain post-stack fast and slow shear wave separation four-component seismic data, and judges whether the target crack direction changes with depth in combination with a judgment matrix, and separates fast and slow shear waves from the first kind of observed pre-stack pure shear wave four-component seismic data or the second kind of observed pre-stack pure shear wave four-component seismic data based on the target crack direction under the condition that the target crack direction does not change with depth. In the technical scheme, the pre-stack fast and slow pure shear wave separation of the shear wave data improves the accuracy of fast and slow wave separation, and can reduce the pre-stack migration calculation amount of the two-component seismic data other than the fast shear wave and the slow shear wave, and at the same time, facilitates subsequent adjustment of the velocity of the fast shear wave and the velocity of the slow shear wave.

[0157] In the technical scheme, if the underground crack direction does not change with depth, the fast and slow wave separation processing is realized by rotating the data, which is relatively simple in process, and because the processing does not have to perform time difference correction on the data, more amplitude-preserved imaging results can be obtained. The fast and slow wave separation processing is generally performed on stacked or partially stacked data. When there is a significant difference between the velocities of the fast shear wave and the slow shear wave, in order to obtain more accurate imaging results, it is necessary to separate the pre-stack shear wave data, and the fast shear wave pre-stack data and the slow shear wave pre-stack data can be separately interpreted in velocity, and then respectively perform moveout stacking processing or pre-stack migration imaging processing according to the respective velocities.

[0158] Figure 21 is a structural schematic diagram of a pre-stack fast and slow pure shear wave separation device provided by the embodiments of the present application, please refer to Figure 21 The device comprises:

[0159] The data acquisition module 2101 is configured to acquire the first kind of observed pre-stack pure shear wave four-component seismic data.

[0160] The rotation module 2102 is configured to rotate a source excitation direction corresponding to the first kind of observed pre-stack pure transverse wave four-component seismic data and a horizontal component receiving direction of a receiver, to obtain second kind of observed pre-stack pure transverse wave four-component seismic data, wherein the direction corresponding to the second kind of observed pre-stack pure transverse wave four-component seismic data comprises a direction along a shot-receiver line and a direction perpendicular to the direction along the shot-receiver line.

[0161] The azimuthal stack module 2103 is configured to perform azimuthal stack or azimuthal migration stack on the second kind of observed pre-stack pure transverse wave four-component seismic data, to obtain second kind of observed azimuthal stack pure transverse wave four-component seismic data.

[0162] The fracture direction acquisition module 2104 is configured to acquire an initial fracture direction based on a transverse wave splitting feature of the second kind of observed azimuthal stack pure transverse wave four-component seismic data, and limit a fracture direction of a pure transverse wave splitting analysis device according to the initial fracture direction, to acquire a target fracture direction.

[0163] The post-stack fast and slow transverse wave separation module 2105 is configured to perform fast and slow transverse wave separation on the second kind of observed azimuthal stack pure transverse wave four-component seismic data based on the target fracture direction, to obtain azimuthal stack and fast and slow transverse wave separation pure transverse wave four-component seismic data, and stack azimuthal data to obtain post-stack fast and slow transverse wave separation four-component seismic data.

[0164] The fracture direction judgment module 2106 is configured to judge, based on a judgment matrix X, whether the target fracture direction changes with depth, wherein if two sub-diagonal components in the post-stack fast and slow transverse wave separation four-component seismic data do not exist effective signals, and a time difference of a slow transverse wave component relative to a fast transverse wave component increases with depth, the target fracture direction does not change with depth.

[0165] X=D 1h R2 -1 D2R2D 1h

[0166] In the judgment matrix X, θ1 and θ2 are respectively a first preset fracture direction and a second preset fracture direction, and the fracture positions corresponding to the first preset fracture direction and the second preset fracture direction are from shallow to deep.

[0167]

[0168]

[0169]

[0170] The pre-stack fast-slow pure transverse wave separation module 2107 is configured to separate fast and slow transverse waves based on the target fracture direction under the condition that θ2=θ1, and separate the first or second observed pre-stack pure transverse wave four-component seismic data.

[0171] In a possible implementation, the azimuthal separation stack module 2103 is further configured to:

[0172] The second observed azimuthal separation stack pure transverse wave four-component seismic data is formed in the form of a large common gather by using a channel.

[0173] In a possible implementation, the pre-stack fast-slow pure transverse wave separation module 2107 is configured to:

[0174] The corresponding index is selected to perform pre-stack seismic trace matching on the first or second observed pre-stack pure transverse wave four-component seismic data, and then fast and slow transverse waves are separated to obtain separated fast and slow transverse waves.

[0175] In a possible implementation, the device further includes a speed adjustment module configured to:

[0176] The speed of the separated fast and slow transverse waves is adjusted.

[0177] In a possible implementation, the pre-stack fast-slow pure transverse wave separation module 2107 is further configured to:

[0178] Under the condition that θ2≠θ1, the second observed pre-stack pure transverse wave four-component seismic data is separated into fast and slow transverse waves by using layer-by-layer pre-stack transverse wave splitting correction.

[0179] The technical scheme provided by the embodiments of the present application is to rotate the direction corresponding to the first observed pre-stack pure shear wave four-component seismic data, and then perform azimuthal stacking or azimuthal migration stacking to form second observed azimuthal stacking pure shear wave four-component seismic data which is convenient for analyzing shear wave splitting characteristics, obtain an initial crack direction according to the shear wave splitting characteristics shown by the data, limit the crack direction for shear wave splitting analysis according to the initial crack direction range to obtain a target crack direction, separate fast and slow shear waves from the second observed azimuthal stacking pure shear wave four-component seismic data according to the target crack direction to obtain azimuthal stacking and fast and slow shear wave separation pure shear wave four-component seismic data, stack the azimuthal data to obtain post-stack fast and slow shear wave separation four-component seismic data, combine a judgment matrix to judge whether the target crack direction changes with depth, and separate fast and slow shear waves from the first observed pre-stack pure shear wave four-component seismic data or the second observed pre-stack pure shear wave four-component seismic data based on the target crack direction under the condition that the target crack direction does not change with depth. In the technical scheme, the pre-stack fast and slow pure shear wave separation of the shear wave data improves the accuracy of fast and slow wave separation, and reduces the pre-stack migration calculation amount of the two-component seismic data other than the fast and slow shear waves, and at the same time, it is convenient for subsequent adjustment of the velocity of the fast shear wave and the velocity of the slow shear wave.

[0180] Figure 22 FIG. 1 is a structural schematic diagram of a computer device provided by an embodiment of the present application. The computer device 2200 can have great differences due to different configurations or performances, and can include one or more processors (central processing units, CPUs) 2201 and one or more memories 2202, wherein the memory 2202 stores at least one program code, the at least one program code is loaded and executed by the processor 2201 to implement the pre-stack fast and slow pure shear wave separation method provided by each method embodiment. Of course, the computer device can also have a wired or wireless network interface, a keyboard, and an input and output interface, and other components for realizing the functions of the device, which will not be described here.

[0181] In some embodiments, the computer program related to the embodiments of the present application can be deployed on one computer device for execution, or on multiple computer devices located in one place for execution, or on multiple computer devices distributed in multiple places and interconnected through a communication network for execution. The multiple computer devices distributed in multiple places and interconnected through a communication network can constitute a blockchain system.

[0182] In the example embodiment, a computer readable storage medium, such as a memory including program code executable by a processor in a computer device to perform the pre-stack fast and slow pure shear wave separation method in the above embodiment, is also provided. For example, the computer readable storage medium can be a Read-Only Memory (ROM), a Random Access Memory (RAM), a Compact Disc Read-Only Memory (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, etc.

[0183] Those of ordinary skill in the art can understand that all or part of the steps of the above embodiments can be completed by hardware or by programs instructing relevant hardware, and the above programs can be stored in a computer readable storage medium, such as a Read-Only Memory, a magnetic disk or an optical disk, etc.

[0184] The above is only an optional embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for separating fast and slow pure shear waves before stacking, characterized in that, The method includes: Acquire the first type of pre-stack pure shear wave four-component seismic data; By rotating the source excitation direction and the detector horizontal component receiving direction corresponding to the first type of pre-stack pure shear wave four-component seismic data, a second type of pre-stack pure shear wave four-component seismic data is obtained. The directions corresponding to the second type of pre-stack pure shear wave four-component seismic data include: along the shot-detector line and perpendicular to the shot-detector line. The second type of observation pre-stack pure shear wave four-component seismic data is stacked by azimuth or by azimuth migration to obtain the second type of observation azimuth stacked pure shear wave four-component seismic data. Based on the shear wave splitting characteristics of the second type of observational azimuth superimposed pure shear wave four-component seismic data, the initial fracture direction is obtained, and the pure shear wave splitting analysis method is constrained according to the initial fracture direction to obtain the target fracture direction. Based on the target crack direction, the second type of observation azimuth stacked pure shear wave four-component seismic data is subjected to fast and slow shear wave separation to obtain azimuth stacked and fast and slow shear wave separated pure shear wave four-component seismic data. The data from each azimuth are stacked to obtain post-stacked fast and slow shear wave separated four-component seismic data. Based on the judgment matrix X, it is determined whether the direction of the target crack changes with depth. If there are no effective signals in the two sub-diagonal components of the post-stack fast and slow shear wave separated four-component seismic data, and the time difference between the slow shear wave component and the fast shear wave component increases with depth, the direction of the target crack does not change with depth. In the judgment matrix X, and The first preset crack direction and the second preset crack direction are respectively, and the crack positions corresponding to the first preset crack direction and the second preset crack direction are from shallow to deep; ； ； ； in, Indicates angular velocity, This represents the time difference between the fast and slow shear waves corresponding to the first layer of cracks. The time difference between the fast and slow shear waves corresponding to the second layer of cracks is indicated. The first preset crack direction is the crack direction corresponding to the first layer of cracks, and the second preset crack direction is the crack direction corresponding to the second layer of cracks. exist Under the condition of the target fracture direction, fast and slow shear wave separation is performed on the first type of pre-stack pure shear wave four-component seismic data or the second type of pre-stack pure shear wave four-component seismic data.

2. The method according to claim 1, characterized in that, After performing azimuth-separated stacking or azimuth-migrating stacking on the second type of pre-stack pure SW wave four-component seismic data to obtain the second type of azimuth-stacked pure SW wave four-component seismic data, the method further includes: The second type of observational azimuth-stacked pure shear wave four-component seismic data is borrowed to form a large set of the second type of observational azimuth-stacked pure shear wave four-component seismic data.

3. The method according to claim 1, characterized in that, The step of separating fast and slow shear waves in either the first type of pre-stack pure shear wave four-component seismic data or the second type of pre-stack pure shear wave four-component seismic data based on the target fracture direction includes: Select the corresponding index to perform pre-stack seismic trace matching on either the first type of observation pre-stack pure S-wave four-component seismic data or the second type of observation pre-stack pure S-wave four-component seismic data. After matching, perform fast and slow S-wave separation to obtain the separated fast and slow S-waves.

4. The method according to claim 1, characterized in that, After performing fast and slow shear wave separation on the first type of pre-stack pure shear wave four-component seismic data or the second type of pre-stack pure shear wave four-component seismic data based on the target fracture direction, the method further includes: Adjust the velocity of the fast shear wave and the velocity of the slow shear wave after separation.

5. The method according to claim 1, characterized in that, The method further includes: exist Under these conditions, fast and slow shear waves are separated from the second type of observed pre-stack pure shear wave four-component seismic data by employing layer-by-layer pre-stack shear wave splitting correction.

6. A pre-stack fast and slow pure shear wave separation device, characterized in that, The device includes: The data acquisition module is used to acquire the first type of pre-stack pure shear wave four-component seismic data. The rotation module is used to rotate the source excitation direction and the detector horizontal component receiving direction corresponding to the first type of pre-stack pure shear wave four-component seismic data to obtain the second type of pre-stack pure shear wave four-component seismic data. The direction corresponding to the second type of pre-stack pure shear wave four-component seismic data includes: along the shot-detector line and perpendicular to the shot-detector line. The azimuth stacking module is used to perform azimuth stacking or azimuth migration stacking on the second type of pre-stack pure shear wave four-component seismic data to obtain the second type of azimuth stacked pure shear wave four-component seismic data. The crack direction acquisition module is used to obtain the initial crack direction based on the shear wave splitting characteristics of the second type of observation azimuth superimposed pure shear wave four-component seismic data, and to restrict the crack direction of the pure shear wave splitting analysis device according to the initial crack direction to obtain the target crack direction. The post-stack fast and slow shear wave separation module is used to perform fast and slow shear wave separation on the second type of observation azimuth stacked pure shear wave four-component seismic data based on the target crack direction, to obtain azimuth stacked and fast and slow shear wave separated pure shear wave four-component seismic data, and to stack the data in each azimuth direction to obtain post-stack fast and slow shear wave separated four-component seismic data. The crack direction determination module is used to determine whether the target crack direction changes with depth based on the determination matrix X. If there are no effective signals in the two sub-diagonal components of the post-stack fast and slow shear wave separated four-component seismic data, and the time difference between the slow shear wave component and the fast shear wave component increases with depth, the target crack direction does not change with depth. In the judgment matrix X, and The first preset crack direction and the second preset crack direction are respectively, and the crack positions corresponding to the first preset crack direction and the second preset crack direction are from shallow to deep; ； ； ； in, Indicates angular velocity, The time difference between the fast and slow shear waves corresponding to the first layer of cracks. The time difference between the fast and slow shear waves corresponding to the second layer of cracks is indicated. The first preset crack direction is the crack direction corresponding to the first layer of cracks, and the second preset crack direction is the crack direction corresponding to the second layer of cracks. Pre-stack fast and slow pure shear wave separation module, used for... Under the condition of the target fracture direction, fast and slow shear wave separation is performed on the first type of pre-stack pure shear wave four-component seismic data or the second type of pre-stack pure shear wave four-component seismic data.

7. The apparatus according to claim 6, characterized in that, The azimuth overlay module is also used for: The second type of observational azimuth-stacked pure shear wave four-component seismic data is borrowed to form a large set of the second type of observational azimuth-stacked pure shear wave four-component seismic data.

8. The apparatus according to claim 6, characterized in that, The pre-stack fast and slow pure shear wave separation module is used for: Select the corresponding index to perform pre-stack seismic trace matching on either the first type of observation pre-stack pure S-wave four-component seismic data or the second type of observation pre-stack pure S-wave four-component seismic data. After matching, perform fast and slow S-wave separation to obtain the separated fast and slow S-waves.

9. The apparatus according to claim 6, characterized in that, The device further includes: a speed control module, used for: Adjust the velocity of the fast shear wave and the velocity of the slow shear wave after separation.

10. The apparatus according to claim 6, characterized in that, The pre-stack fast and slow pure shear wave separation module is also used for: exist Under these conditions, fast and slow shear waves are separated from the second type of observed pre-stack pure shear wave four-component seismic data by employing layer-by-layer pre-stack shear wave splitting correction.

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