An acoustic wave vector reverse time migration imaging method without the influence of reflection angles

Abstract

The present invention belongs to the field of exploration geophysics, and discloses a sonic vector reverse time migration imaging method without the influence of reflection angle, which comprises the following steps: presetting a seismic wavelet and an initial velocity model, and realizing the forward extrapolation of the sonic wave field by using the first-order acoustic wave equation to obtain the sonic source wave field; according to the observed seismic data and the preset initial velocity model, realizing the backward extrapolation of the sonic wave field by using the first-order acoustic wave equation to obtain the sonic receiver wave field; based on the sonic source wave field and the sonic receiver wave field, determining the imaging angle by using the constructed imaging angle extraction function based on the energy norm; and performing imaging by using the constructed dot product cross-correlation imaging condition without the influence of reflection angle to obtain a scalar imaging result without the influence of reflection angle. The method disclosed by the present invention can eliminate the polarity inversion problem caused by the imaging angle in the sonic vector dot product imaging condition, improve the polarity consistency of the sonic imaging isophase axis, and thus guarantee the accuracy of geological structure imaging in a complex environment.

Description

Technical Field

[0001] The present invention belongs to the field of exploration geophysics, and particularly relates to an acoustic vector reverse time migration imaging method without the influence of reflection angle. Background Art

[0002] The acoustic vector reverse time migration imaging method extends the wave field based on the two-way wave equation, has no dip limitation, can accurately image complex structural areas, and shows excellent performance in improving the imaging quality of complex media. Different from the acoustic reverse time migration method, the acoustic vector reverse time migration method can comprehensively utilize the spatial information of the acoustic particle vibration velocity vector to provide an imaging result with richer information for subsequent geological interpretation and other work. However, when extracting the scalar imaging result from the vector seismic wave field based on the dot product cross-correlation imaging condition, affected by the imaging angle coefficient term introduced by the dot product operation, when the incident angle is , there will be a problem of polarity reversal of the imaging in-phase axis different from the reflection coefficient. Then, to a certain extent, this abnormal polarity reversal problem will interfere with the coherence of the imaging in-phase axis during data stacking, making it difficult to serve subsequent geological interpretation and other work. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides an acoustic vector reverse time migration imaging method without the influence of reflection angle to eliminate imaging errors such as polarity reversal caused by the imaging angle at the imaging point and obtain an accurate scalar imaging result representing the reflection coefficient.

[0004] To achieve the above object, the technical solution of the present invention is as follows:

[0005] An acoustic vector reverse time migration imaging method without the influence of reflection angle includes the following steps:

[0006] Step 1: Predetermine a seismic wavelet and an initial velocity model, and use the first-order acoustic wave equation to construct an acoustic wave field forward vector continuation operator to realize the forward extrapolation of the acoustic wave field and obtain the acoustic source wave field;

[0007] Step 2: According to the observed seismic data and the predetermined initial velocity model, use the first-order acoustic wave equation to construct an acoustic wave field reverse vector continuation operator to realize the reverse extrapolation of the acoustic wave field and obtain the acoustic receiver wave field;

[0008] Step 3: Based on the acoustic source wave field and the acoustic receiver wave field at the same imaging time, use the constructed imaging angle extraction function based on the energy norm to determine the imaging angle;

[0009] Step 4: Based on the determined imaging angle, use the constructed dot product cross-correlation imaging condition without the influence of reflection angle for imaging to obtain a scalar imaging result without the influence of reflection angle.

[0010] In the above solution, Step 1 is specifically as follows: Predetermine a seismic wavelet and an initial velocity model . Use the first-order acoustic wave equation to construct an acoustic wavefield forward vector continuation operator, including the acoustic confining pressure wavefield and the acoustic particle velocity vector wavefield at the source end, to achieve the forward extrapolation of the acoustic wavefield, obtain the acoustic source wavefield, and store it on the hard disk. The constructed acoustic wavefield forward vector continuation operator is as follows:

[0011] ;

[0012] where the superscripts and represent integer time points, and are half-time nodes, , represents the number of discrete points corresponding to the total time of the seismic record, represents the time sampling interval, and respectively represent and the acoustic confining pressure fields at the source end at times represents the acoustic particle velocity vector, and respectively represent the x-direction and z-direction components of the particle velocity vector, and respectively represent and the x-direction component of the acoustic particle velocity vector field at the source end at times and respectively represent and the z-direction component of the acoustic particle velocity vector field at the source end at times is the boundary absorption coefficient, in the target area in the boundary absorption area , is the thickness of the absorption layer, represents the density parameter model of the background velocity field, represents the velocity model of the background velocity field, and respectively represent the spatial derivatives in the x and z directions, represents the source wavelet, represents the seismic wavelet function, represents the source spatial attenuation function.

[0013] In the above solution, Step 2 is specifically as follows: According to the observed seismic data and a pre-given initial velocity model , use the first-order acoustic wave equation to construct an acoustic wave field reverse vector continuation operator, including the acoustic confining pressure wave field and the acoustic particle vibration velocity vector wave field at the receiver end, realize the reverse extrapolation of the acoustic wave field, and obtain the acoustic receiver wave field; the constructed acoustic wave field reverse vector continuation operator is as follows:

[0014] ;

[0015] where the subscript represents the acoustic wave field index at the receiver end, and respectively represent and the x-direction component of the acoustic particle vibration velocity vector field at the receiver end at times and respectively represent and the z-direction component of the acoustic particle vibration velocity vector field at the receiver end at times represents the pre-given seismic record vector field at time where represents the seismic record component along the direction at time represents the pre-given seismic record component along the direction at time represents the burial depth at the time of seismic record acquisition, and respectively represent and the acoustic confining pressure fields at the source end at times

[0016] In the above scheme, in step 3, the constructed imaging angle extraction function based on the energy norm is:

[0017] ;

[0018] where represents the imaging angle determined based on the energy norm at the corresponding imaging time , represents the acoustic wave propagation velocity of the initial velocity model, represents the acoustic wave stress field at the source end at the corresponding imaging time , represents the acoustic wave stress field at the receiver end at the corresponding imaging time , " " represents the dot product operation, " " represents the gradient operation, and the superscript "." represents the time derivative.

[0019] In the above solution, step 4 is specifically as follows: At each imaging moment, based on the imaging angle determined in step 3 , the acoustic particle vibration velocity vector field stored in step 1 and the acoustic particle vibration velocity vector field at the detector end in step 2 , use the constructed dot product cross-correlation imaging condition without the influence of the reflection angle for imaging to obtain the scalar imaging result without the influence of the reflection angle at the current imaging moment; superimpose all shot gathers at all imaging moments to obtain the final scalar imaging result without polarity reversal; the constructed dot product cross-correlation imaging condition without the influence of the reflection angle is:

[0020] ;

[0021] Where represents the acoustic dot product cross-correlation imaging condition without the influence of the reflection angle, represents the particle vibration velocity vector field at the source end, represents the particle vibration velocity vector field at the detector end, represents the source end coordinate index, represents the detector end coordinate index, represents the imaging time index, represents the shot gather index, represents the acoustic stress field at the source end, represents the acoustic stress field at the detector end, " " represents the dot product operation, " " represents the gradient operation, and the superscript "." represents the time derivative.

[0022] Through the above technical solution, an acoustic vector reverse time migration imaging method without the influence of the reflection angle provided by the present invention has the following beneficial effects:

[0023] The present invention first uses the first-order acoustic wave equation in the time domain to construct the source wave field and the detector wave field. Subsequently, using the time derivative field and the spatial derivative field of the confining pressure field at the source end and the confining pressure field at the detector end, an imaging reflection angle extraction function at the imaging point at all imaging moments is derived based on the acoustic energy norm. Finally, based on the time consistency principle and the extracted imaging reflection angle information, an acoustic dot product cross-correlation imaging condition without the influence of the reflection angle is constructed, realizing the elimination of the polarity reversal problem affected by the imaging angle and extracting scalar imaging information with effectively maintained amplitude and phase information.

[0024] In the conventional acoustic wave vector imaging method, the present invention derives the imaging angle data at the imaging point by means of the spatial and temporal information of the acoustic wave confining pressure scalar field based on the energy norm, so as to eliminate the polarity inversion error introduced by the reflection angle during dot product cross-correlation imaging, thereby ensuring the in-phase axis polarity consistency of the scalar imaging results extracted from the vector data, and providing a certain guarantee for the accuracy of geological structure imaging under complex geological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0026] Figure 1 is a schematic flow chart of an acoustic wave vector reverse time migration imaging method without the influence of reflection angle disclosed by the present invention;

[0027] Figure 2 is a schematic diagram of calculating the imaging angle by the energy norm at the imaging point at a certain imaging moment;

[0028] Figure 3 Pre-given source wavelet;

[0029] Figure 4 Pre-given initial acoustic wave velocity;

[0030] Figure 5 Pre-given seismic acoustic pressure record;

[0031] Figure 6 is the source end signal propagating forward at time ; (a) is the acoustic pressure wave field, (b) is the x-direction component of the acoustic pressure particle vibration velocity vector field, and (c) is the z-direction component of the acoustic pressure particle vibration velocity vector field;

[0032] Figure 7 is the detector end signal propagating backward at time ; (a) is the acoustic pressure wave field, (b) is the x-direction component of the acoustic pressure particle vibration velocity vector field, and (c) is the z-direction component of the acoustic pressure particle vibration velocity vector field;

[0033] Figure 8 is the imaging angle distribution information determined by the imaging angle extraction function at time ;

[0034] Figure 9 is the result extracted by using the acoustic pressure particle vibration velocity vector field at time ; (a) is the dot product imaging result; (b) is the dot product imaging result without the influence of reflection angle;

[0035] Figure 10The single-shot result extracted by using the acoustic particle vibration velocity vector field; (a) is the dot product imaging result; (b) is the dot product imaging result without the influence of the reflection angle;

[0036] Figure 11 It is a comparison diagram of the reflection results between the single-shot dot product imaging result and the dot product cross-correlation imaging result without the influence of the reflection angle at z = 1800m. Specific implementation manner

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0038] The present invention provides an acoustic vector reverse time migration imaging method without the influence of the reflection angle, as Figure 1 shown, including the following steps:

[0039] Step 1, preset the seismic wavelet and the initial velocity model, use the first-order acoustic wave equation to construct the forward vector continuation operator of the acoustic wave field, realize the forward extrapolation of the acoustic wave field, and obtain the acoustic source wave field.

[0040] Specifically as follows:

[0041] Preset the seismic wavelet and the initial velocity model , use the first-order acoustic wave equation to construct the forward vector continuation operator of the acoustic wave field, including the acoustic confining pressure wave field and the acoustic particle vibration velocity vector wave field at the source end, realize the forward extrapolation of the acoustic wave field, obtain the acoustic source wave field, and store it on the hard disk; the constructed forward vector continuation operator of the acoustic wave field is as follows:

[0042] ;

[0043] Among them, the superscripts and represent the integral time points, and are the half-time nodes, , represents the number of discrete points corresponding to the total time of the seismic record, represents the time sampling interval, and respectively represent and the acoustic confining pressure fields at the source end at the times, the subscript s represents the index of the acoustic wave field at the source end, and respectively represent the x-direction and z-direction components of the particle vibration velocity vector, and respectively represent and The x - component of the acoustic particle vibration velocity vector field at the source end at a certain moment, and respectively represent and the z - component of the acoustic particle vibration velocity vector field at the source end at a certain moment, is the boundary absorption coefficient, which is in the target area , , is the thickness of the absorption layer, represents the density parameter model of the background velocity field, represents the velocity model of the background velocity field, and respectively represent the spatial derivatives in the x and z directions, represents the source wavelet, represents the seismic wavelet function, represents the source spatial attenuation function.

[0044] Step 2: According to the observed seismic data and the pre - given initial velocity model, use the first - order acoustic wave equation to construct the reverse vector continuation operator of the acoustic wave field, realize the reverse extrapolation of the acoustic wave field, and obtain the acoustic wave detector wave field.

[0045] Specifically: According to the observed seismic data and the pre - given initial velocity model , use the first - order acoustic wave equation to construct the reverse vector continuation operator of the acoustic wave field, including the acoustic wave confining pressure wave field and the acoustic particle vibration velocity vector wave field at the detector end, realize the reverse extrapolation of the acoustic wave field, and obtain the acoustic wave detector wave field; the constructed reverse vector continuation operator of the acoustic wave field is as follows:

[0046] ;

[0047] where the subscript represents the index of the acoustic wave field at the detector end, and respectively represent and the x - component of the acoustic particle vibration velocity vector field at the detector end at a certain moment, and respectively represent and the z - component of the acoustic particle vibration velocity vector field at the detector end at a certain moment, represents the pre - given seismic record vector field at a certain moment, where of represents the seismic record component along direction, represents along The seismic recording component in the direction, represents the burial depth at the time of seismic recording acquisition, and respectively represent and the acoustic confining pressure field at the source end at the moment of the earthquake.

[0048] Step 3: Based on the acoustic source wave field and the acoustic detector wave field at the same imaging moment, use the constructed imaging angle extraction function based on the energy norm to determine the imaging angle .

[0049] Specifically as follows:

[0050] At each imaging moment , based on the acoustic confining pressure wave field at the source end stored in Step 1 and the acoustic confining pressure wave field at the detector end obtained in Step 2, use the constructed imaging angle extraction function based on the energy norm to determine the imaging angle . The constructed imaging angle extraction function based on the energy norm is:

[0051] ;

[0052] wherein, represents the imaging angle determined based on the energy norm at the corresponding imaging moment , represents the acoustic wave propagation speed of the initial velocity model, represents the acoustic source stress field at the corresponding imaging moment , represents the acoustic detector stress field at the corresponding imaging moment , " " represents the dot product operation, " " represents the gradient operation, and the superscript "." represents the time derivative.

[0053] Specifically, in the embodiments of the present invention, the imaging angle extraction function is derived in the frequency domain using the plane wave theory.

[0054] Under the plane wave assumption condition, the incident acoustic wave pressure field at the source end in the frequency domain is expressed as:

[0055] ;

[0056] wherein, is the incident acoustic source stress field at the source end, represents the amplitude of the incident acoustic source stress at the source end, represents the wave number vector of the incident acoustic wave at the source end, i.e., the propagation direction of the incident acoustic wave (as shown in Figure 2 ), represents the coordinate index, represents the frequency, denotes time, where the wavenumber vector satisfies , denotes the acoustic wave propagation velocity of the initial velocity model.

[0057] Similarly, under the plane wave assumption, the acoustic pressure field of the incident acoustic wave at the detector end in the frequency domain is expressed as:

[0058] ;

[0059] where is the stress field of the reflected acoustic wave at the detector end, denotes the stress amplitude of the reflected acoustic wave at the detector end, denotes the wavenumber vector of the reflected acoustic wave at the detector end, i.e., the propagation direction of the reflected acoustic wave (as shown in Figure 2 ), and its wavenumber vector satisfies .

[0060] At a certain imaging moment, the spatial derivative of the acoustic pressure of the incident acoustic wave satisfies , and the time derivative satisfies , the spatial derivative of the acoustic pressure of the reflected acoustic wave satisfies , and the time derivative satisfies .

[0061] According to the energy norm expression , the energy expression in the frequency domain can be derived as:

[0062] ;

[0063] Since the wavenumber of the incident acoustic wave satisfies and the wavenumber of the reflected acoustic wave satisfies , then . Where denotes the reflection angle of the incident acoustic wave and the reflected acoustic wave, is the imaging angle at the current imaging moment, which satisfies . Substituting the acoustic wave wavenumber into the energy norm expression is expressed as:

[0064] ;

[0065] Through the energy norm expression, we can easily find that in the energy norm, the potential energy part related to the spatial derivative and the kinetic energy part related to the time derivative have only the difference in the weighting coefficients. Therefore, starting from the energy norm, we construct an imaging angle extraction function:

[0066] ;

[0067] In the time - space domain, at a certain imaging moment the imaging angle extraction function can be expressed as:

[0068] ;

[0069] Wherein, is the imaging angle determined based on the energy norm at a certain imaging time Based on the energy norm.

[0070] Step 4: Based on the determined imaging angle, use the constructed dot product cross-correlation imaging condition without the influence of the reflection angle to perform imaging, and obtain a scalar imaging result without the influence of the reflection angle.

[0071] Specifically: At each imaging time, based on the imaging angle determined in Step 3 , the acoustic particle vibration velocity vector field stored at the source end in Step 1 and the acoustic particle vibration velocity vector field at the receiver end in Step 2 , use the constructed dot product cross-correlation imaging condition without the influence of the reflection angle to perform imaging, and obtain a scalar imaging result without the influence of the reflection angle at the current imaging time; superimpose all the shot gathers at all imaging times to obtain a final scalar imaging result without polarity inversion; the constructed dot product cross-correlation imaging condition without the influence of the reflection angle is:

[0072] ;

[0073] Wherein, represents the dot product cross-correlation imaging condition of acoustic waves without the influence of the reflection angle, represents the acoustic particle vibration velocity vector field at the source end, represents the acoustic particle vibration velocity vector field at the receiver end, represents the source end coordinate index, represents the receiver end coordinate index, represents the imaging time index, represents the shot gather index, represents the acoustic stress field at the source end, represents the acoustic stress field at the receiver end, " " represents the dot product operation, " " represents the gradient operation, and the superscript "." represents the time derivative.

[0074] Specifically, taking a simple flat layer model as an example, a seismic wavelet generated by an air gun at sea as shown in Figure 3 , an initial velocity model as shown in , and a seismic acoustic pressure record as shown in Figure 4 are given in advance. The source end vector wave field is obtained by performing vector wave field extrapolation along the forward time, and the receiver end vector wave field is obtained by performing vector wave field extrapolation along the reverse time. Among them, in (a) is Figure 5 , and (a) in Figure 6 is The sound pressure field of the wave field at the source end at a certain moment, Figure 6 In (b) is The x - component of the acoustic particle vibration velocity vector field of the wave field at the source end at a certain moment, Figure 6 In (c) is The z - component of the acoustic particle vibration velocity vector field of the wave field at the source end at a certain moment, Figure 7 In (a) is The sound pressure field of the wave field at the detector end at a certain moment, Figure 7 In (b) is The x - component of the particle vibration velocity vector field of the wave field at the detector end at a certain moment, Figure 7 In (c) is The z - component of the particle vibration velocity vector field of the wave field at the detector end at a certain moment. It can be found that the wave fronts of the source wave field and the detector wave field are inconsistent, and the information carried by different components in the vector field is inconsistent.

[0075] Preset inspection points and use them as imaging times , According to the preset imaging time Store the acoustic source wave field and the acoustic detector wave field to the hard disk. For each shot At each imaging time, the imaging angle distribution information at the current imaging moment can be determined using the imaging angle extraction function based on the energy norm. Figure 8 Is The imaging angle distribution information determined by the imaging angle extraction function at a certain moment. Figure 9 In (a) is The dot - product imaging result extracted by using the acoustic particle vibration velocity vector field at a certain moment. Figure 9 In (b) is The dot - product imaging result without the influence of the reflection angle extracted by using the acoustic particle vibration velocity vector field at a certain moment. It can be found that the imaging angle distribution information at different positions is different, and when the imaging angle is not specific, that is When, the difference between the dot - product imaging result extracted by using the acoustic particle vibration velocity and the dot - product imaging result without the influence of the reflection angle is not obvious.

[0076] Superimpose the imaging results of all preset inspection points to obtain the single - shot reverse - time migration imaging result. Figure 10 In (a) is the single - shot dot - product imaging result extracted by using the acoustic particle vibration velocity vector field; Figure 10 In (b) is the single - shot dot - product imaging result without the influence of the reflection angle extracted by using the acoustic particle vibration velocity vector field. By comparison, it is found that at the incident angle of That is , Distance At this point, the dot product imaging results gradually exhibit polarity reversal, but the dot product imaging results without the influence of the reflection angle do not show polarity reversal. To further illustrate the imaging results, the dot product imaging results and the dot product imaging results without the influence of the reflection angle are extracted at a depth of z = 1800 m for ballistic comparison. Figure 11 It is a comparison chart of the reflection results of the single-shot dot product imaging results and the dot product cross-correlation imaging results without the influence of the reflection angle at z = 1800 m. The comparison results show that there is a polarity reversal problem in the dot product imaging results without the influence of the reflection angle, but there is also a polarity reversal problem in the dot product imaging results. The acoustic vector reverse time migration method without the influence of the reflection angle can eliminate the polarity reversal problem introduced by the reflection angle, effectively maintain the polarity of the isophase axis under different offset conditions, reduce the dependence of the imaging method on the offset and the incident angle, and improve the imaging accuracy of the vector reverse time migration method in complex environments.

[0077] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for acoustic wave vector reverse time migration imaging without reflection angle influence, characterized in that: The steps include: Step 1: Given the seismic wavelet and initial velocity model in advance, the acoustic wave field forward vector extension operator is constructed using the first-order acoustic wave equation to realize the forward extrapolation of the acoustic wave field and obtain the acoustic source wave field; Step 2: Based on the observed seismic data and the pre-given initial velocity model, the first-order acoustic wave equation is used to construct the acoustic wave field reverse vector extension operator to realize the reverse extrapolation of the acoustic wave field and obtain the acoustic wave detection wave field; Step 3, based on the acoustic source wave field and the acoustic detection wave field at the same imaging time, the imaging angle is determined by using the energy norm-based imaging angle extraction function; Step 4, based on the determined imaging angle, imaging is performed using the constructed dot product cross-correlation imaging condition without the influence of the reflection angle to obtain a scalar imaging result without the influence of the reflection angle; In step 3, the energy norm-based imaging angle extraction function is constructed as: ； in, Indicates the corresponding imaging time Based on the imaging angle determined by the energy norm, represents the sound wave propagation speed of the initial velocity model, Indicates the corresponding imaging time The acoustic stress field at the source end is Indicates the corresponding imaging time Acoustic stress field at the detector end, " " represents the dot product operation, " ” indicates the gradient operation, and the superscript “.” indicates the time derivative.

2. The method for acoustic wave vector reverse time migration imaging without reflection angle influence according to claim 1, characterized in that: Step 1 is as follows: given the seismic wavelet and the initial velocity model , using the first-order acoustic wave equation to construct the acoustic wave field forward vector extension operator, including the acoustic wave confining pressure wave field at the source end and the acoustic wave particle vibration velocity vector wave field, to achieve the forward extrapolation of the acoustic wave field, obtain the acoustic wave source wave field, and store it in the hard disk; the constructed acoustic wave field forward vector extension operator is as follows: ； Among them, the superscript and Indicates the whole time point, and is a half-time node, , represents the number of discrete points corresponding to the total time of earthquake records, represents the time sampling interval, and Respectively and The acoustic wave confining pressure field at the source end at time t, the subscript s represents the acoustic wave field index at the source end, represents the velocity vector of the acoustic wave particle vibration, and They represent the x-direction and z-direction components of the particle vibration velocity vector, respectively. and Respectively and The x-direction component of the velocity vector field of the acoustic wave particle at the source end at time, and Respectively and The z-component of the velocity vector field of the acoustic wave particle at the source end at time, is the boundary absorption coefficient, in the target area , in the boundary absorption region , , is the total number of absorbing layers, represents the background velocity field density parameter model, represents the sound wave propagation speed of the initial velocity model, and denote the spatial derivatives in the x and z directions respectively, represents the source wavelet, represents the earthquake wavelet function, represents the spatial attenuation function of the earthquake source.

3. The method for acoustic wave vector reverse time migration imaging without reflection angle influence according to claim 1, characterized in that: Step 2 is as follows: Based on the observed earthquake data And the pre-given initial velocity model , the first-order acoustic wave equation is used to construct the reverse vector extension operator of the acoustic wave field, including the acoustic wave confining pressure wave field and the acoustic wave particle vibration velocity vector wave field at the detection end, to realize the reverse extrapolation of the acoustic wave field and obtain the acoustic wave detection wave field; the constructed acoustic wave field reverse vector extension operator is as follows: ； Among them, the subscript Indicates the acoustic wave field index of the detector end. and Respectively and The x-direction component of the velocity vector field of the acoustic wave particle vibration at the detector end at time, and Respectively and The z-component of the velocity vector field of the acoustic wave particle vibration at the detector end at time, Indicates a given The vector field of earthquake records at time Indicates a given Time along The seismic record component of the direction, Indicates a given Time along The seismic record component of the direction, Indicates the buried depth when the seismic record was collected. and Respectively and The acoustic wave pressure field at the detector end at all times; represents the time sampling interval, is the boundary absorption coefficient, in the target area , in the boundary absorption region , , is the total number of absorbing layers, represents the background velocity field density parameter model, represents the sound wave propagation speed of the initial velocity model, and denote the spatial derivatives in the x and z directions respectively.

4. The method for acoustic wave vector reverse time migration imaging without reflection angle influence according to claim 1, characterized in that: Step 4 is as follows: At each imaging moment, based on the imaging angle determined in step 3 , the acoustic wave particle vibration velocity vector field at the source end stored in step 1 and the velocity vector field of the acoustic wave particle vibration at the detection end in step 2 , use the constructed dot product cross-correlation imaging condition without the influence of reflection angle to perform imaging, and obtain the scalar imaging result without the influence of reflection angle at the current imaging moment; superimpose all the shot gathers at all imaging moments to obtain the final scalar imaging result without polarity inversion; the constructed dot product cross-correlation imaging condition without the influence of reflection angle is: ； in, represents the acoustic wave dot product cross-correlation imaging condition without the influence of reflection angle, represents the vibration velocity vector field of the particle at the source end, represents the vibration velocity vector field of the particle at the detection end, represents the acoustic wave field index at the source end, Indicates the acoustic wave field index of the detector end. represents the imaging time index, represents the shot gather index, represents the acoustic wave stress field at the source end, represents the acoustic stress field at the detection end, " " represents the dot product operation, " " represents the gradient operation, and the superscript ". " represents the time derivative. Represents the sound wave propagation speed of the initial velocity model.

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