CN106168678A - A kind of crack is propagated separation method and the system of shear wave - Google Patents

Abstract

The present invention provides a method and system for separating shear waves propagating in cracks. The acquisition coordinate system is rotated according to a set angle. If the rotation angle of the acquisition coordinate system is the polarization azimuth of the fast wave, the acquisition coordinate system will be aligned with the natural coordinates. Department of coincidence. If the rotation angle of the collection coordinate system is β, the rotated radial component R(t) is the slow wave component, and the transverse component T(t) is the fast wave component. At this time, the energy ratio of the fast and slow wave components is the energy ratio of the measured radial component R(t) and transverse component T(t), and this ratio should be equal to the tangent of the fracture strike azimuth. Based on the above relationship, this program analyzes whether the energy ratio of the radial component R(t) and the transverse component T(t) obtained after rotating the acquisition coordinate system is equal to the tangent of the rotation angle. When the two are equal, then The rotation angle can be regarded as the polarization azimuth angle of the fast wave. The above scheme of the present invention has a simple analysis and calculation process, and is consistent with existing theories and has high accuracy.

Description

A method and system for separating shear waves propagating in a crack

technical field

The invention relates to the technical field of seismic exploration, in particular to a separation method and system for shear waves propagating in cracks.

Background technique

When a shear wave propagates in a cracked anisotropic medium, the polarization direction of the incident shear wave changes and splits into two independent shear waves whose polarization directions are perpendicular to each other. The two shear waves propagate with different amplitudes and velocities, among which the shear wave parallel to the fracture direction is faster, called the fast wave, represented by S1 _; the shear wave perpendicular to the fracture direction is slower, called the slow wave, represented by S ₂ said. As shown in Fig. ₂ , the fracture azimuth coordinate system determined by the direction of fast wave S1 and slow wave S2 is called the natural coordinate system, which is composed of a single _- point longitudinal wave source and a three-component (X, Y, Z) detector. system is the acquisition coordinate system. Usually there is an unknown angle between the acquisition coordinate system and the natural coordinate system, that is, the azimuth of the fracture strike. Since the polarization azimuth of the fast wave is the same as the azimuth of the fracture direction, the direction of the fracture can be accurately predicted as long as the polarization azimuth of the fast wave is obtained and the fast and slow waves are separated. Therefore, accurate separation of fast and slow waves is the key to judging the orientation of existing fractures, but there is no fast and slow wave separation method with high accuracy in the prior art that can be put into practical application.

Contents of the invention

The technical problem to be solved by the present invention is that the accuracy of the fast and slow wave separation method of the fracture propagating shear wave in the prior art is low.

In order to solve the above technical problems, the present invention provides the following technical solutions:

A method for separating shear waves propagating in a crack, comprising the steps of:

Rotate the acquisition coordinate system, and its rotation angle is the angle α in the counterclockwise direction;

Based on the rotated acquisition coordinate system, the radial component R(t) and transverse component T(t) of the shear wave are collected, where t is the propagation time of the shear wave in the crack;

Obtain the energy ratio G of the collected radial component R(t) and transverse component T(t);

Judging whether the rotation angle α satisfies tg(90°-α)=G;

If not satisfied, the step of returning to the rotating acquisition coordinate system after adjusting the rotation angle α;

If it is satisfied, the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) are obtained:

S ₁ (t)=R(t)cosβ-T(t)sinβ; S ₂ (t)=R(t)sinβ+T(t)cosβ;

Among them, β=90°-α, S ₁ (t) and S ₂ (t) respectively represent the corresponding propagation distance of the fast wave component and the slow wave component when the propagation time is t;

According to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t), it is judged whether the fast wave component S ₁ (t) arrives at a specific position before the slow wave component S ₂ (t);

If yes, determine that β is the polarization azimuth angle of the fast wave; otherwise, adjust the rotation angle α and return to the step of rotating the acquisition coordinate system.

Preferably, the above-mentioned method for separating shear waves propagating in cracks further includes the following steps:

According to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t), the propagation time difference between the fast wave component and the slow wave component is obtained.

Preferably, the above-mentioned method for separating shear waves propagating in cracks further includes the following steps:

The amplitudes of the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) are corrected according to the polarization azimuth angle β of the fast wave.

Preferably, in the separation method of the shear wave propagating in the above-mentioned crack, the polarization azimuth angle of the fast wave corrects the amplitude of the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) In the step, the correction process is carried out according to the numerical simulation method to obtain:

The corrected fast wave component expression: S ₀₁ (t) = S ₁ (t)/cosβ;

The corrected slow wave component expression: S ₀₂ (t)=S ₂ (t)/sinβ.

Based on the same inventive concept, the present invention also provides a shear wave separation system propagating in cracks, including:

The rotation unit rotates the acquisition coordinate system, and its rotation angle is the angle α in the counterclockwise direction;

The acquisition unit, based on the rotated acquisition coordinate system, acquires the radial component R(t) and the transverse component T(t) of the shear wave, where t is the propagation time of the shear wave in the crack;

The data acquisition unit acquires the energy ratio G of the collected radial component R(t) and transverse component T(t);

The first judging unit judges whether the rotation angle α satisfies tg(90°-α)=G;

The processing unit, when the determination result of the determination unit is yes, obtains the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t): S ₁ (t)=R(t)cosβ-T (t)sinβ; S ₂ (t)=R(t)sinβ+T(t)cosβ; where, β=90°-α, S ₁ (t) and S ₂ (t) represent fast wave component and slow wave component respectively The wave component corresponds to the propagation distance when the propagation time is t;

The second judging unit judges whether the fast wave component S ₁ (t) arrives at a specific position earlier than the slow wave component S ₂ (t) according to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t);

The rotation unit rotates the acquisition coordinate system after adjusting the rotation angle α when the determination result of the determination unit is negative;

The rotation unit rotates the acquisition coordinate system after adjusting the rotation angle α when the judgment result of the first judgment unit or the judgment result of the second judgment unit is No;

The processing unit, when the judgment result of the second judging unit is yes, judges that β is the polarization azimuth angle of the fast wave, and S ₁ (t)=R(t)cosβ-T(t)sinβ is the separated Fast wave expression, S ₂ (t)=R(t) sinβ+T(t)cosβ is the separated slow wave expression.

Preferably, in the above-mentioned shear wave separation system propagating in the crack, the data acquisition unit is also used to obtain the fast wave component and the slow wave component according to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) Poor propagation time.

Preferably, the above-mentioned shear wave separation system propagating in the fracture further includes:

The correction unit corrects the amplitudes of the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) according to the polarization azimuth angle β of the fast wave.

Preferably, in the above-mentioned shear wave separation system propagating in the crack, the correction unit performs correction processing according to a numerical simulation method to obtain a corrected fast wave component expression: S ₀₁ (t)=S ₁ (t)/cosβ; The corrected slow wave component expression: S ₀₂ (t)=S ₂ (t)/sinβ.

The technical solution provided by the present invention, compared with the prior art, at least has the following beneficial effects:

(1) In the method and system for separating shear waves propagating in cracks according to the present invention, the acquisition coordinate system is rotated according to the set angle, if the rotation angle of the acquisition coordinate system is the polarization azimuth of the fast wave (i.e. the azimuth of the direction of the crack). ), the acquisition coordinate system will coincide with the natural coordinate system. According to the existing knowledge, it can be deduced that if the rotation angle of the acquisition coordinate system is β, then the rotated radial component R(t) is the slow wave component, and the transverse component T(t) is the fast wave component. At this time, the energy ratio of the fast and slow wave components is the energy ratio of the measured radial component R(t) and transverse component T(t), and this ratio should be equal to the tangent of the complementary angle of the fracture strike azimuth. This program is based on the above relationship as a theoretical basis, and analyzes whether the energy ratio of the radial component R(t) and the transverse component T(t) obtained after rotating the acquisition coordinate system is equal to the tangent of the complementary angle of the rotation angle, when the two are equal , then the rotation angle can be regarded as the polarization azimuth angle of the fast wave (that is, the azimuth angle of the crack strike). The above scheme of the present invention has a simple analysis and calculation process, and is consistent with existing theories and has high accuracy.

(2) The separation method and system of shear waves propagating in the cracks of the present invention consider that different angles may have the same tangent value, so when judging the tangent value of the residual angle of the rotation angle and the energy ratio of the radial component and the transverse component are equal , further judge the propagation relationship between the fast wave and the slow wave according to the obtained results. Since the propagation speed of the fast wave is faster than that of the slow wave, the relationship between time and position can be obtained according to the expression of the fast wave function and the expression of the slow wave function. If it is true that the fast wave arrives at a specific position before the slow wave, it can be considered that The obtained result is accurate, otherwise the result is inaccurate, and the accuracy of the separation result can be further guaranteed through this step.

(3) The separation method and system of the shear wave propagating in the crack of the present invention also includes the step of correcting the amplitude of the fast wave component and the slow wave component, and correcting the amplitude of the fast wave and the slow wave by a numerical simulation method, More accurate fast wave components incident and polarized along the direction of the slit and slow wave components incident and polarized perpendicular to the direction of the slit can be obtained.

Description of drawings

Fig. 1 is the flow chart of the separation method of propagating shear wave in the fracture described in one embodiment of the present invention;

Fig. 2 is a schematic diagram of the angular relationship between the acquisition coordinate system and the fast and slow waves;

Figure 3 is the crack discriminant curve;

Fig. 4A, 4B are the result discriminant curves of the crack strike azimuth angle according to one embodiment of the present invention;

Figures 5A-5D are graphs showing the transformation of the shear wave curve from X, Y components to R, T components, S ₁ , S ₂ components, S ₀₁ , S ₀₂ components in turn according to an embodiment of the present invention;

Fig. 6 is a functional block diagram of a method for separating shear waves propagating in a crack according to an embodiment of the invention;

Fig. 7 is a schematic diagram of a coal seam geological model described in an embodiment of the present invention;

Fig. 8A is the radial component record of the wave field of the model shown in Fig. 7;

Fig. 8B is the record of the transverse component of the wave field of the model shown in Fig. 7;

Fig. 8C is the record of the Z-direction component of the wave field of the model shown in Fig. 7;

9A and 9B are schematic diagrams of azimuth angle superposition of CCP gathers.

The reference signs therein are:

1-rotation unit, 2-acquisition unit, 3-data acquisition unit, 4-first judgment unit, 5-processing unit, 6-second judgment unit, 7-correction unit.

detailed description

Example 1

This embodiment provides a method for separating shear waves propagating in a crack, as shown in Figure 1, comprising the following steps:

S ₁ : rotate the acquisition coordinate system, the rotation angle is α, and the rotation angle is based on the counterclockwise direction. In this step, there is no specific requirement for the rotation direction of the acquisition coordinate system, but the final rotation angle is based on the counterclockwise direction. For example, it can be rotated 240° clockwise, and the final rotation angle is 120° counterclockwise. Then the rotation angle is 120°. As another measurement method, it can be considered that the clockwise rotation angle is negative and the counterclockwise rotation angle is positive. For example, if the clockwise rotation is 30°, it can be considered as -30° counterclockwise rotation.

S2: Based on the rotated collection coordinate system, collect the radial component R(t) and transverse component T(t) of the shear wave, where t is the propagation time of the shear wave in the fracture. In this step, the geophone in the prior art can be utilized, and the X(t) component and the Y(t) component can be detected according to the geophone, and can be further obtained according to the X(t) component and the Y(t) component of the geophone. Radial component R(t) and transverse component T(t): R(t)=X(t)cosα-Y(t)sinα; T(t)=X(t)sinα+Y(t)cosα.

S3: Obtain the energy ratio G of the collected radial component R(t) and transverse component T(t).

S4: Judging whether the rotation angle α satisfies tg(90°-α)=G; if not, proceed to step S8; if satisfied, proceed to step S5.

S5: Obtain the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t): S ₁ (t)=R(t)cosβ-T(t)sinβ; S ₂ (t)=R( t)sinβ+T(t)cosβ; wherein, β=90°-α, S ₁ (t) and S ₂ (t) respectively represent the corresponding propagation distances of the fast wave component and the slow wave component when the propagation time is t.

S6: According to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t), judge whether the fast wave component S ₁ (t) arrives at a specific position before the slow wave component S ₂ (t); if so, enter Step S7, otherwise go to step S8.

S7: Determining that β is the polarization azimuth of the fast wave, S ₁ (t)=R(t)cosβ-T(t)sinβ is the expression of the separated fast wave, S ₂ (t)=R(t)sinβ+ T(t)cosβ is the separated slow wave expression.

S8: Return to step S1 after adjusting the rotation angle α.

The above results are deduced in detail below in conjunction with the accompanying drawings. In order to quantitatively describe the relationship between the fast and slow waves after shear wave splitting and the shear wave before splitting, the acquisition coordinate system in Fig. 2 is used as a reference for illustration. The angle between the direction of the crack and the direction of the measuring line is β, and the transmission energy loss is ignored in this embodiment. When the shear wave is vertically upward, assuming that its particle vibration direction is parallel to the direction of the measuring line, the displacement at time t is S, and enters the vertical After the fractured formation, the split fast wave S ₁ and slow wave S ₂ can be expressed by formula (1):

Obviously, the actual recorded X and Y components are:

It is not difficult to find from Figure 1 that if the XOY coordinate system is rotated counterclockwise by an angle of 90°-β, the component R after rotation is a slow wave, and the component T is a fast wave. The expressions of the components X _R and Y _R after rotation are:

It can be verified that:

Assuming that the rotation angle is 90°-α, the expressions of the components R and T after rotation are:

Combining the formulas (1)-(5), the expressions related to the components R and T are arranged to obtain:

From this you can get:

When α=β, if only the energy of fast and slow waves is considered, and the energy ratio G of component R and component T is calculated, then:

Equation (8) shows that when the acquisition coordinate system is rotated to the natural coordinate system, the energy ratio of the rotated seismic wave is equal to the tangent of the complementary angle of the rotation angle. Azimuth, that is, the azimuth angle of the fracture direction.

In the above scheme of this embodiment, the collection coordinate system is rotated according to the set angle. If the rotation angle of the collection coordinate system is the polarization azimuth angle of the fast wave (that is, the azimuth angle of the crack direction), the collection coordinate system will be different from the natural coordinate system. coincide. According to the existing knowledge, it can be deduced that if the rotation angle of the acquisition coordinate system is β, then the rotated radial component R(t) is the slow wave component, and the transverse component T(t) is the fast wave component. At this time, the energy ratio of the fast and slow wave components is the energy ratio of the measured radial component R(t) and transverse component T(t), and this ratio should be equal to the tangent of the fracture strike azimuth. This program is based on the above relationship as a theoretical basis, and analyzes whether the energy ratio of the radial component R(t) and the transverse component T(t) obtained after rotating the acquisition coordinate system is equal to the tangent of the complementary angle of the rotation angle, when the two are equal , then the rotation angle can be regarded as the polarization azimuth angle of the fast wave (that is, the azimuth angle of the crack strike). The above scheme of this embodiment has a simple analysis and calculation process, and is consistent with existing theories with high accuracy.

In the actual calculation process, a series of β values are used to convert the component R and the component T, and the corresponding energy ratio G and tangent value are calculated corresponding to each β value, forming two curves of G(β) and tgβ, which are called The discriminant curve is shown in Figure 3. The β value at the intersection of the two curves is the azimuth of the formation fracture, that is, the polarization azimuth of the fast wave.

It can also be seen from the figure that when using the above method to detect the crack orientation, there are two solutions 30° and 120° in the entire range of 0-180°. In order to judge the correctness of the solution, a numerical simulation study was carried out. Figure 4A shows the fast and slow wave propagation curves when the azimuth of the fracture strike is 30°. Through comparative analysis, it can be seen that the fast wave S ₁ arrives at a specific position earlier than the slow wave S ₂ . Figure 4B shows the fast and slow wave propagation curves when the azimuth of the fracture strike is 120°. Through comparative analysis, it can be seen that the fast wave S ₁ arrives at a specific position later than the slow wave S ₂ . Obviously the result of rotating 30° is correct, and the result of 120° is incorrect.

Further preferably, the above-mentioned method of this embodiment also includes the following steps:

S9: According to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t), obtain the propagation time difference between the fast wave component and the slow wave component.

As shown in Figure 4A, once the propagation curves of the fast wave and the slow wave are determined, it is easy to obtain the propagation time difference between the fast wave and the slow wave, as shown in Figure 4, the propagation time difference between the two is 6s.

Further preferably, the above-mentioned method of this embodiment also includes the following steps:

S10: Perform correction processing on the amplitudes of the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) according to the polarization azimuth angle β of the fast wave. Correction processing is carried out according to the numerical simulation method to obtain: the expression of the fast wave component after correction: S ₀₁ (t)=S ₁ (t)/cosβ; the expression of the slow wave component after correction: S ₀₂ (t)=S ₂ (t)/sinβ.

The amplitudes of the fast-wave component and the slow-wave component obtained by using the two-dimensional two-component rotation method are related to the offset azimuth, and the final desired amplitude of the fast wave incident and polarized along the crack azimuth and the slow wave incident and polarized perpendicular to the crack It only depends on the strength of the source and has nothing to do with the orientation of the shot inspection. Using the numerical simulation method to study, it is found that the amplitude recovery correction of the S ₁ (t) and S ₂ (t) components according to the above formula can be calculated for the fast wave S ₀₁ (t) incident and polarized along the direction of the crack and the incident direction perpendicular to the crack. and polarized slow wave S ₀₂ (t). The conversion process of the shear wave components described above in this embodiment can be obtained intuitively according to the curves shown in FIG. 5A to FIG. 5D .

Example 2

This embodiment provides a shear wave separation system propagating in a crack, as shown in Figure 6, including:

Rotation unit 1, which rotates the acquisition coordinate system, and its rotation angle is the angle α in the counterclockwise direction;

Acquisition unit 2, based on the rotated acquisition coordinate system, acquires the radial component R(t) and transverse component T(t) of the shear wave, where t is the propagation time of the shear wave in the crack;

A data acquisition unit 3, which acquires the energy ratio G of the collected radial component R(t) and transverse component T(t);

The first judging unit 4 judges whether the rotation angle α satisfies tg(90°-α)=R;

The processing unit 5, when the determination result of the determination unit 4 is yes, obtains the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t): S ₁ (t)=R(t)cosβ -T(t)sinβ; S ₂ (t)=R(t)sinβ+T(t)cosβ; where, β=90°-α, S ₁ (t) and S ₂ (t) respectively represent fast wave components And the slow wave component corresponds to the propagation distance when the propagation time is t.

The second judging unit 6 judges whether the fast wave component S ₁ (t) arrives at a specific position earlier than the slow wave component S ₂ (t) according to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) ;

The rotation unit 1, when the judgment result of the first judgment unit 4 or the judgment result of the second judgment unit 6 is No, adjusts the rotation angle α and then rotates the acquisition coordinate system;

The processing unit 5, when the determination result of the second determination unit 6 is yes, determines that β is the polarization azimuth angle of the fast wave, and S ₁ (t)=R(t)cosβ-T(t)sinβ is the separation After the fast wave expression, S ₂ (t)=R(t) sinβ+T(t)cosβ is the separated slow wave expression. The above scheme of this embodiment considers that different angles may have the same tangent value, so when judging that the tangent value of the complementary angle of rotation is equal to the energy ratio of the radial component and the transverse component, the fast wave and the slow wave are further analyzed according to the obtained results. Determine the wave propagation relationship. Since the propagation speed of the fast wave is faster than that of the slow wave, the relationship between the propagation time and the propagation distance of the two can be obtained according to the fast wave expression and the slow wave expression. If the fast wave arrives at a specific position before the slow wave, then It can be considered that the obtained result is accurate, otherwise the result is inaccurate, and this step can further ensure the accuracy of the separation result.

Further, the data acquisition unit 3 is further configured to obtain the propagation time difference between the fast wave component and the slow wave component according to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t). Once the propagation curves of the fast and slow waves are determined, it is easy to obtain the difference in travel times of the fast and slow waves.

As shown in Figure 1, as a more preferred solution, the above-mentioned system also includes: a correction unit 7, which corrects the fast wave component S ₁ (t) and the slow wave component S ₂ (t) according to the polarization azimuth angle β of the fast wave ) The amplitude of the expression of ) is corrected. Correction processing is carried out according to the numerical simulation method, and the corrected fast wave component expression is obtained: S ₀₁ (t)=S ₁ (t)/cosβ; the corrected slow wave component expression is: S ₀₂ (t)=S ₂ ( t)/sinβ.

In the above scheme of this embodiment, the collection coordinate system is rotated according to the set angle. If the rotation angle of the collection coordinate system is the polarization azimuth angle of the fast wave (that is, the azimuth angle of the crack direction), the collection coordinate system will be different from the natural coordinate system. coincide. According to the existing knowledge, it can be deduced that if the rotation angle of the acquisition coordinate system is β, then the rotated radial component R(t) is the slow wave component, and the transverse component T(t) is the fast wave component. At this time, the energy ratio of the fast and slow wave components is the energy ratio of the measured radial component R(t) and transverse component T(t), and this ratio should be equal to the tangent of the complementary angle of the fracture strike azimuth. This program is based on the above relationship as a theoretical basis, and analyzes whether the energy ratio of the radial component R(t) and the transverse component T(t) obtained after rotating the acquisition coordinate system is equal to the tangent of the complementary angle of the rotation angle, when the two are equal , then the rotation angle can be regarded as the polarization azimuth angle of the fast wave (that is, the azimuth angle of the crack strike). The above scheme of this embodiment has a simple analysis and calculation process, and is consistent with existing theories with high accuracy.

Example 3

This embodiment provides an identification mark for the orientation of coal seam fissures. In order to establish the change relationship between the coal seam conversion wave field and the coal seam fissures, a forward modeling simulation is performed on the coal seam fissure model. The coal seam geological model is shown in Figure 7. All strata are horizontally layered, and the coal seam fractures are vertical fissures parallel to each other, and the direction is parallel to the Y axis. The parameters corresponding to each layer are shown in Table 1.

Table 1 Physical property parameters of coal seam geological model

Excited at point O, received on a circular survey line with point O as the center and radius r (r=1400m in the model), the azimuth angle θ of the crack is calculated from the X axis (that is, the direction of true north), and the model is calculated using the reflectivity method The wave field is selected as the wavelet of 60Hz Recke wavelet, and the wave field records shown in Figure 8A-8C are obtained.

From the wave field records, as shown in Figures 8A and 8B, when the converted shear wave passes through the coal seam, different splitting occurs according to the relative relationship between the incident azimuth and the fracture direction: when the incident direction is perpendicular to the fracture direction (that is, the azimuth angle 0°), the travel time of the shear wave on the radial component R is the longest, the amplitude on the transverse component T is zero, and only slow waves are generated; The travel time of the shear wave is the shortest, the amplitude of the transverse component T is zero, and only the fast wave is generated; in other directions, two kinds of waves, the fast shear wave and the slow shear wave, can be observed. The lengthening of the path through the coal seam becomes larger. When the incident azimuth and the fracture direction are at an angle of 45° (or 225°), the amplitude of the transverse component T reaches the maximum. Every 90° of the incident azimuth, the phase of the transverse component T occurs 180° reverse.

As shown in Figure 8C, when the longitudinal wave passes through the coal seam, the azimuth of the velocity also changes: when the incident azimuth is parallel to the direction of the fracture, the velocity is fast and the amplitude is strong, and when it is vertical, the velocity is slow and the amplitude is weak. This azimuthal anisotropy feature can only be clearly observed at far offsets.

According to the characteristics of the converted wave field of the coal seam, the identification mark of the coal seam fracture azimuth can be obtained, that is, the angle that satisfies the shortest travel time of the radial component R shear wave and the zero amplitude of the transverse component T is the coal seam fast wave polarization azimuth.

In the three-dimensional three-component seismic data acquisition, each track in the common conversion point gather has different offset azimuth angles, and thus has different included angles with the fracture strike, resulting in the amplitude of the radial component and transverse component corresponding to each track and phase changes accordingly. For a common conversion point gather (i.e. CCP gather), the superposition results of the radial component and transverse component at different azimuth angles can be formed, as shown in Fig. 9, there are 36 traces in the radial component and transverse It is the superposition result of each track within a specific azimuth angle range, the first track represents the superposition of all the channels with azimuth angles within the range of 0° to 10°, and the second track represents the azimuth angles of all shots within the range of 11° to 20° The superposition of each channel, and so on.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

While preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once the basic inventive concept is appreciated. Therefore, it is intended that the appended claims be construed to cover the preferred embodiment as well as all changes and modifications which fall within the scope of the invention.

Claims (8)

1. A separation method for propagating shear waves in a fissure, characterized in that it may further comprise the steps: Rotate the acquisition coordinate system, and its rotation angle is the angle α in the counterclockwise direction; Based on the rotated acquisition coordinate system, the radial component R(t) and transverse component T(t) of the shear wave are collected, where t is the propagation time of the shear wave in the crack; Obtain the energy ratio G of the collected radial component R(t) and transverse component T(t); Judging whether the rotation angle α satisfies tg(90°-α)=G; If not satisfied, the step of returning to the rotating acquisition coordinate system after adjusting the rotation angle α; If it is satisfied, the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) are obtained: S ₁ (t)=R(t)cosβ-T(t)sinβ; S ₂ (t)=R(t)sinβ+T(t)cosβ; Among them, β=90°-α, S ₁ (t) and S ₂ (t) respectively represent the corresponding propagation distance of the fast wave component and the slow wave component when the propagation time is t; According to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t), it is judged whether the fast wave component S ₁ (t) arrives at a specific position before the slow wave component S ₂ (t); If so, it is determined that β is the polarization azimuth of the fast wave, S ₁ (t)=R(t)cosβ-T(t)sinβ is the expression of the separated fast wave, S ₂ (t)=R(t)sinβ+ T(t)cosβ is the separated slow wave expression; otherwise, adjust the rotation angle α and return to the step of rotating the acquisition coordinate system. 2. the separation method of propagating shear wave in the crack according to claim 1, is characterized in that, also comprises the steps: According to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t), the propagation time difference between the fast wave component and the slow wave component is obtained. 3. the separation method of propagating shear wave in the crack according to claim 1, is characterized in that, also comprises the steps: The amplitudes of the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) are corrected according to the polarization azimuth angle β of the fast wave. 4. the separation method of propagating shear wave in the crack according to claim 3, is characterized in that: In the step of correcting the amplitude of the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t), the polarization azimuth angle of the fast wave is corrected according to the numerical simulation method to obtain: The corrected fast wave component expression: S ₀₁ (t) = S ₁ (t)/cosβ; The corrected slow wave component expression: S ₀₂ (t)=S ₂ (t)/sinβ. 5. A shear wave separation system propagating in a crack, characterized in that it comprises: The rotation unit rotates the acquisition coordinate system, and its rotation angle is the angle α in the counterclockwise direction; The acquisition unit, based on the rotated acquisition coordinate system, acquires the radial component R(t) and the transverse component T(t) of the shear wave, where t is the propagation time of the shear wave in the crack; The data acquisition unit acquires the energy ratio G of the collected radial component R(t) and transverse component T(t); The first judging unit judges whether the rotation angle α satisfies tg(90°-α)=G; The processing unit, when the determination result of the determination unit is yes, obtains the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t): S ₁ (t)=R(t)cosβ-T (t)sinβ; S ₂ (t)=R(t)sinβ+T(t)cosβ; where, β=90°-α, S ₁ (t) and S ₂ (t) represent fast wave component and slow wave component respectively The wave component corresponds to the propagation distance when the propagation time is t; The second judging unit judges whether the fast wave component S ₁ (t) arrives at a specific position earlier than the slow wave component S ₂ (t) according to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t); The rotation unit rotates the acquisition coordinate system after adjusting the rotation angle α when the judgment result of the first judgment unit or the judgment result of the second judgment unit is No; The processing unit, when the judgment result of the second judging unit is yes, judges that β is the polarization azimuth angle of the fast wave, and S ₁ (t)=R(t)cosβ-T(t)sinβ is the separated Fast wave expression, S ₂ (t)=R(t) sinβ+T(t)cosβ is the separated slow wave expression. 6. The shear wave separation system propagating in the crack according to claim 5, characterized in that: The data acquisition unit is further configured to obtain the propagation time difference between the fast wave component and the slow wave component according to the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t). 7. The shear wave separation system propagating in the fracture according to claim 5, further comprising: The correction unit corrects the amplitudes of the expressions of the fast wave component S ₁ (t) and the slow wave component S ₂ (t) according to the polarization azimuth angle β of the fast wave. 8. The shear wave separation system propagating in the fracture according to claim 7, characterized in that: The correction unit performs correction processing according to the numerical simulation method to obtain the corrected fast wave component expression: S ₀₁ (t)=S ₁ (t)/cosβ; the corrected slow wave component expression: S ₀₂ (t )=S ₂ (t)/sinβ.