Diffraction wave imaging method and related equipment based on azimuth-time gather

Abstract

The present invention discloses a diffraction wave imaging method based on azimuth-time difference gathers and related equipment, the method comprising: generating an azimuth-time difference gather according to acquired seismic data; detecting the type of diffraction wave based on the azimuth-time difference gathers, the type of diffraction wave being at least one of point diffraction wave generated by a point diffractor, fault diffraction wave generated by a fault line diffractor, and crack diffraction wave generated by a crack line diffractor; imaging the point diffraction wave, fault diffraction wave and / or crack diffraction wave to obtain a corresponding imaging result. In the present invention, the type of diffraction wave is detected based on the azimuth-time difference gathers, and it is determined that the diffraction wave is generated by a point diffractor, a fault line diffractor and / or a crack line diffractor, and imaging results of the point diffraction wave, the fault diffraction wave and / or the crack line diffractor can be obtained, thereby accurately distinguishing the type of diffraction wave, and being able to obtain a clear diffraction wave imaging result.

Description

Technical Field

[0001] The invention relates to the technical field of seismic exploration, and in particular to a diffraction wave imaging method based on azimuth-time difference gathers and related equipment. Background Art

[0002] The current seismic exploration is mainly based on reflected longitudinal wave exploration. In the past few decades, reflection wave exploration based on structural imaging has achieved great success in the detection of large-scale geological bodies. However, reflection wave exploration is limited by the classic Rayleigh resolution criterion. At present, seismic exploration has gradually shifted from structural exploration to lithological exploration and fine exploration. With the development of oil and gas field exploration and development, the detection of some small-scale geological bodies has attracted more and more attention, such as small breakpoints, pinch points, small fault blocks, caves, cracks and other geological bodies with a scale close to or less than one wavelength. Diffraction waves are the seismic responses of these discontinuous geological bodies that are equivalent to the seismic wavelength. Therefore, diffraction wave imaging has a resolution capability that exceeds the Rayleigh criterion of half a wavelength.

[0003] In conventional seismic data processing (NMO (Near Moving Average), stacking, etc.), diffraction waves are often regarded as noise and suppressed because diffraction waves and reflection waves have different kinematic characteristics. In addition, the energy of diffraction waves in seismic data is usually one to two orders of magnitude weaker than that of reflection waves. Even if the diffraction waves and reflection waves are accurately offset and returned to their positions at the same time, they will still be masked by the reflection waves. With the in-depth study of diffraction wave imaging, different diffraction wave imaging methods have been proposed one after another. The core of these methods is to separate the reflection wave field from the diffraction wave field, and then image the diffraction wave field separately.

[0004] Based on the separation and extraction of diffraction wave fields, the commonly used diffraction wave imaging methods can be divided into two types. One is the data domain diffraction wave imaging method, which picks up the relevant diffraction wave event axes based on the precise description of the diffraction wave travel time in the data domain, or uses the difference in the kinematic characteristics of the diffraction wave and the reflection wave to separate the diffraction wave field using methods such as plane wave decomposition and Radon filtering. However, this type of method is very difficult to achieve the correct separation of the two when the reflection wave and the diffraction wave interfere with each other. The other is the offset domain diffraction wave imaging method, which suppresses the reflected wave energy within the Fresnel zone (the wavefront of the spherical wave emitted by the surface point source when it reaches the interface, and the circle formed on the interface by another wavefront that arrives 1 / 4 wavelength earlier is called the first Fresnel zone) through an anti-stable filter or the construction of an offset gather (a collection of seismic traces), thereby achieving diffraction wave imaging. The diffraction wave imaging method based on the dip domain offset gather currently developed is a relatively effective method. In the offset domain dip gather, there is a significant difference in the morphology of the reflected wave and the diffraction wave, and the diffraction wave imaging can be achieved by suppressing the reflected wave energy within the Fresnel zone. However, the diffraction wave imaging methods based on the dip domain offset gather currently developed are mostly two-dimensional methods. In the three-dimensional case, the dip domain Fresnel zone changes with the offset distance and azimuth, and this type of method cannot distinguish the common important three-dimensional diffractor types (holes and other point diffractors). Therefore, the existing technology has the problem that it is difficult to separate the reflected wave and the diffraction wave, and it is impossible to distinguish the specific types of three-dimensional diffractors. Summary of the invention

[0005] The main purpose of the present invention is to provide a diffraction wave imaging method and related equipment based on azimuth-time difference gathers to solve the technical problems existing in the prior art such as the inability to accurately distinguish the specific types of three-dimensional diffracting bodies and the weak energy of diffraction wave imaging.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A diffraction wave imaging method based on azimuth-time difference gathers, comprising:

[0008] Generate azimuth-time difference gathers based on the acquired seismic data;

[0009] Detecting the type of the diffraction wave based on the azimuth-moment gather, the type being at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a fracture diffraction wave generated by a fracture line diffractor;

[0010] The point diffraction wave, the fault diffraction wave and / or the crack diffraction wave are subjected to imaging processing to obtain corresponding imaging results.

[0011] In the diffraction wave imaging method based on azimuth-moment gathers, the azimuth-moment gathers are a collection of all azimuth-moment gathers, and each azimuth-moment gather represents a move gather corresponding to each azimuth;

[0012] The azimuth in the azimuth-time difference gather is the azimuth on the time slice of the two-dimensional dip tangent gather;

[0013] The time difference in the azimuth-time difference gather is the vertical one-way time difference between any point on the event axis of the reflection wave and its corresponding stable phase point in the two-dimensional dip tangent gather.

[0014] In the diffraction wave imaging method based on azimuth-time gathers, generating azimuth-time gathers according to acquired seismic data includes:

[0015] Based on the seismic data, generating dip gathers along the survey line direction and perpendicular to the survey line direction;

[0016] Based on the dip gather, a dip field along the survey line direction and a dip field perpendicular to the survey line direction is obtained, and a preset azimuth-moment gather formula is confirmed according to the dip field;

[0017] Based on the frequency parameters of the seismic data, determining a time difference weight function for cutting off the reflection wave components in the Fresnel zone;

[0018] Based on the time difference weight function and the preset azimuth-time difference gather formula, an azimuth-time difference gather is generated.

[0019] In the diffraction wave imaging method based on the azimuth-move gather, the type of the diffraction wave is detected based on the azimuth-move gather, and the type is at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor, including:

[0020] Determine a correlation coefficient set corresponding to the azimuth-time difference gather, wherein the correlation coefficient set is composed of a correlation coefficient set corresponding to each time depth and azimuth;

[0021] At each time depth, the correlation coefficient of the time difference gather corresponding to each azimuth angle is compared with the preset correlation coefficient;

[0022] If the correlation coefficients of the time difference gathers corresponding to all azimuth angles are greater than the preset correlation coefficients, it is determined that there are point diffraction waves generated by point diffractors in the seismic data;

[0023] If there is a pair of time difference gathers with azimuth angles that differ by 180°, and the absolute values ​​of the correlation coefficients are both greater than the preset correlation coefficients, and the correlation coefficients have different signs, it is determined that there are fault diffraction waves generated by the fault line diffractor in the seismic data;

[0024] If there is a pair of time difference gathers with azimuth angles differing by 180°, and the absolute values ​​of the correlation coefficients are both greater than the preset correlation coefficients, and the correlation coefficients have the same sign, it is determined that there are fracture diffraction waves generated by fracture line diffractors in the seismic data.

[0025] In the diffraction wave imaging method based on azimuth-time gathers, the point diffraction wave, the fault diffraction wave and / or the crack diffraction wave are subjected to imaging processing to obtain corresponding imaging results, including:

[0026] If there is a point diffraction wave, the azimuth-time difference gather is directly superimposed and imaged along the azimuth dimension and the time difference dimension to obtain the imaging result of the point diffraction wave;

[0027] If there is a fault diffraction wave, the azimuth-time difference gather is divided into two azimuth regions according to the azimuth information of the fault strike, and the amplitude values ​​of the two azimuth regions are superimposed along the azimuth dimension and the time difference dimension respectively and then subtracted to obtain the imaging result of the fault diffraction wave;

[0028] If there is a crack diffraction wave, the azimuth-time difference gather is directly superimposed and imaged along the azimuth dimension and the time difference dimension to obtain the imaging result of the crack diffraction wave.

[0029] In the diffraction wave imaging method based on the azimuth-moment gather, the type of the diffraction wave is detected based on the azimuth-moment gather, and the type is at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor, and further includes:

[0030] If it is determined that the diffraction wave is generated by a line diffractor, the azimuth information of the line diffractor is determined, wherein the line diffractor includes: a fault line diffractor and a crack line diffractor.

[0031] In the diffraction wave imaging method based on azimuth-time difference gathers, if it is determined that the diffraction wave is generated by a line diffractor, determining the azimuth information of the line diffractor includes:

[0032] According to the linear diffraction wave generated by the linear diffractor, calculating the azimuth angle of the linear diffraction wave;

[0033] Based on the azimuth, the azimuth information of the fault line diffractor or the crack line diffractor is determined; wherein the azimuth of the line diffracted wave event on the time slice of the azimuth-moment gather is perpendicular to the azimuth information of the line diffractor.

[0034] A diffraction wave imaging system based on azimuth-time difference gathers, comprising:

[0035] An acquisition and generation module is used to generate azimuth-time difference gathers according to the acquired seismic data;

[0036] a detection and determination module, configured to detect the type of the diffraction wave based on the azimuth-moment gather, wherein the type is at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor;

[0037] An imaging module is used to perform imaging processing on the point diffraction wave, the fault diffraction wave and / or the crack diffraction wave to obtain corresponding imaging results.

[0038] A controller, the controller comprising: a memory, a processor, and a diffraction wave imaging program based on azimuth-time difference gathers stored in the memory and executable on the processor, wherein the diffraction wave imaging program based on azimuth-time difference gathers implements the steps of the diffraction wave imaging method based on azimuth-time difference gathers as described above when the diffraction wave imaging program based on azimuth-time difference gathers is executed by the processor.

[0039] A computer-readable storage medium stores a diffraction wave imaging program based on an azimuth-time difference track gather, and when the diffraction wave imaging program based on an azimuth-time difference track gather is executed by a processor, the steps of the diffraction wave imaging method based on an azimuth-time difference track gather as described above are implemented.

[0040] Compared with the prior art, the present invention provides a diffraction wave imaging method based on azimuth-time gathers and related equipment, the diffraction wave imaging method based on azimuth-time gathers comprising: generating azimuth-time gathers according to acquired seismic data; detecting the type of diffraction waves based on the azimuth-time gathers, the type being at least one of point diffraction waves generated by a point diffractor, fault diffraction waves generated by a fault line diffractor, and fracture diffraction waves generated by a fracture line diffractor; imaging the point diffraction waves, the fault diffraction waves and / or the fracture diffraction waves to obtain corresponding imaging results. In the present invention, the type of diffraction wave is detected based on the azimuth-time difference gather, so as to determine whether the diffraction wave is generated by the point diffractor, the fault line diffractor and / or the crack line diffractor, and imaging results of the point diffraction wave, the fault diffraction wave and / or the crack line diffraction wave can be obtained, so as to accurately distinguish the type of diffraction wave and obtain a clear diffraction wave imaging result. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A flowchart of a diffraction wave imaging method based on azimuth-time gathers provided in an embodiment of the present application;

[0042] Figure 2A flowchart of step S100 in a diffraction wave imaging method based on azimuth-time gathers provided in an embodiment of the present application;

[0043] Figure 3 A flowchart of step S200 in a diffraction wave imaging method based on azimuth-time gathers provided in an embodiment of the present application;

[0044] Figure 4 A flowchart of step S300 in a diffraction wave imaging method based on azimuth-time gathers provided in an embodiment of the present application;

[0045] Figure 5 A three-dimensional diffraction model used to generate forward simulation data;

[0046] Figure 6 It is the 2D dip gather (INLINE and CROSSLINE dimensions) at the CDP coordinate (2500, 2500);

[0047] Figure 7 and Figure 8 The time slice at 2.116s of the 2D dip gather at the CDP coordinate (2500, 2500) and the corresponding 2D dip tangent gather;

[0048] Fig. 9 is the azimuth-time gather at (2000, 2000);

[0049] Fig.10 and Fig.11 The time slices of the azimuth-time difference gather at (2000, 2000) without and with the Fresnel zone removed at 0.8s;

[0050] Fig.12 is the azimuth-time gather at (2500, 2500);

[0051] Fig.13 and Fig.14 The time slices of the azimuth-time difference gather at (2500, 2500) without and with the Fresnel zone removed at 2.116s;

[0052] Fig.15 and Fig.16 They are respectively the reflection wave migration section and diffraction wave imaging section of the 3D simulation data at Y coordinate = 2000m;

[0053] Fig.17 and Fig.18 They are respectively the waveform diagrams of the diffraction wave of the upper fault in the diffraction wave imaging section of the 3D simulation data at the Y coordinate = 2000m without and with phase correction;

[0054] Fig.19 A schematic diagram of the structure of a diffraction wave imaging system based on azimuth-time gathers provided in an embodiment of the present application;

[0055] Fig. 20 A schematic diagram of the operating environment of a preferred embodiment of the controller provided in the embodiments of the present application. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0057] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0058] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0059] Most of the methods currently developed for separating reflection waves and diffraction waves based on offset gathers such as dip gathers and then imaging them separately are two-dimensional methods, which cannot distinguish the common important three-dimensional diffractor types. In the three-dimensional case, the types of diffraction waves can be divided into point diffraction waves generated by velocity anomalies such as holes and line diffraction waves generated by line diffractors, and line diffraction waves can be divided into fault line diffraction waves generated by faults and fracture diffraction waves generated by fractures. The distinction between the above diffraction wave types is very important in exploration practice. The identification and study of point diffraction waves generated by velocity anomalies such as holes and fracture line diffraction waves is of great significance to the study of carbonate hole-cavity and fracture-cavity oil and gas reservoirs; and the three-dimensional study of line diffraction waves generated by faults and fractures can extract the azimuth information of line diffractors carried by line diffraction waves generated by faults and fractures. In three-dimensional situations, the Fresnel zone in the dip domain changes with the offset and azimuth, and it is difficult to accurately cut off the reflected wave energy. We can only approximately estimate a larger Fresnel zone at zero offset to cut off the reflected wave energy, which will cause the useful diffraction wave energy to be unable to participate in imaging. These requirements are difficult to achieve using the currently developed diffraction wave imaging technology.

[0060] In order to solve the above-mentioned prior art problems, the present invention provides a diffraction wave imaging method based on azimuth-time difference gathers and related equipment. In the present invention, after pre-stack time migration is performed on seismic data to generate azimuth-time difference gathers, accurate separation of reflection waves and diffraction waves in a three-dimensional situation is achieved, and then the type of diffraction waves is detected based on the azimuth-time difference gathers, so that the type is point diffraction waves generated by point diffractors, fault diffraction waves generated by fault line diffractors, and fracture diffraction waves generated by fracture line diffractors. At least one of the above methods can be used to determine the azimuth information of the line diffractor, and obtain imaging results of the point diffraction wave and / or the line diffraction wave, so as to accurately distinguish point diffraction waves generated by velocity anomalies such as holes and point diffractors such as lithology pinch-out points, broken line diffraction waves generated by faults, and line diffraction waves generated by cracks. When imaging the line diffraction waves caused by line diffractors such as faults and cracks, the strike information of the line diffractors can be extracted. Phase correction can also be achieved in the imaging process of the broken line diffraction waves caused by the faults, thereby enhancing the imaging energy of the broken line diffraction waves.

[0061] The following describes the design of the diffraction wave imaging method based on the azimuth-time difference gather through specific exemplary embodiments. It should be noted that the following embodiments are only used to explain the technical solution of the invention and are not specifically limited:

[0062] See also Figure 1 The present invention provides a diffraction wave imaging method based on azimuth-time difference gathers, comprising:

[0063] Flow chart of the diffraction wave imaging method based on azimuth-time difference gathers, such as Figure 1 As shown, the method comprises the following steps:

[0064] Step S100, generating azimuth-time difference gathers according to the acquired seismic data.

[0065] In the embodiment of the present application, seismic data may refer to common offset data. The azimuth-time difference gather is a collection of all azimuth-time difference gathers, each of which represents the time difference gather corresponding to each azimuth; the azimuth in the azimuth-time difference gather is the azimuth on the time slice of the two-dimensional dip tangent gather; the time difference in the azimuth-time difference gather is the vertical one-way time difference between any point on the phase axis of the reflection wave in the two-dimensional dip tangent gather and its corresponding stable phase point.

[0066] In the embodiment of the present application, the azimuth angle set (the set of plane angles of 0-360 degrees in a plane) is recorded as U = {θ1, θ2, ..., θ n}, the time difference gather corresponding to each element θ in the azimuth set U can be called azimuth-time difference gather. Among them, the value range of θ is [0°, 360°]. In the time difference gather, the horizontal axis is the time difference dimension, which is the vertical one-way time difference between any point on the reflection wave phase axis and its corresponding stable phase point in the two-dimensional inclination tangent value gather, and its vertical axis is the travel time. The value of each point in the time difference gather is the amplitude value at the corresponding time difference and travel time.

[0067] Furthermore, if Figure 2 As shown, step S100, generating an azimuth-time difference gather according to the acquired seismic data, includes the following steps:

[0068] Step S110, generating dip gathers along the survey line direction and perpendicular to the survey line direction based on the seismic data;

[0069] Step S120, based on the dip gather, obtaining the dip field along the survey line direction and the direction perpendicular to the survey line direction, and confirming the preset azimuth-moment gather formula according to the dip field;

[0070] Step S130, determining a time difference weight function for cutting off the reflection wave component in the Fresnel zone based on the frequency parameter of the seismic data;

[0071] In the embodiment of the present application, the time difference is the vertical one-way time difference between any point on the event axis of the reflection wave in the two-dimensional dip tangent gather and its corresponding stable phase point. The Fresnel zone corresponding to the time difference can be estimated using an appropriate frequency (the size of the frequency can be customized). The Fresnel zone boundary corresponding to the time difference is determined based on the main frequency of the seismic recording data or its semi-derivative. The time difference weight function used to cut off the reflection wave component in the Fresnel zone is denoted as w(ζ), and the formula is as follows:

[0072]

[0073] Among them, ζ1 is the main frequency of the semi-derivative of the seismic data, and ζ2 is the threshold for controlling the length of the attenuation band. w(ζ) can also be replaced by the weight function w(T0,ζ) obtained by the time-frequency analysis method, where T0 is the vertical two-way travel time of the seismic migration profile.

[0074] Step S140, based on the time difference weight function and the preset azimuth-time difference gather formula, generate an azimuth-time difference gather (an azimuth-time difference gather with the reflection wave component in the Fresnel band cut off). The azimuth-time difference gather is a collection of all azimuth-time difference gathers after cutting off the Fresnel band, and each azimuth-time difference gather represents the time difference gather corresponding to each azimuth; the azimuth in the azimuth-time difference gather is the azimuth on the time slice of the two-dimensional dip tangent gather; the time difference in the azimuth-time difference gather is the vertical one-way time difference between any point on the phase axis of the reflection wave in the two-dimensional dip tangent gather and its corresponding stable phase point.

[0075] In the embodiment of the present application, the preset azimuth-inclination gather formula is:

[0076]

[0077] Where (x, y, T) is the coordinate of the imaging point; T0 = 2T is the vertical two-way travel time at the imaging point (x, y, T); f m is the semi-derivative of the mth seismic trace; N is the total number of input seismic pre-stack traces; (x s ,y s ) is the shot point coordinate corresponding to the mth seismic trace; (x g ,y g ) is the coordinate of the receiver point corresponding to the mth seismic trace; τ s With τ g are the travel times from the shot point and the receiver point to the imaging point respectively. The azimuth angle θ is the azimuth angle on the time slice of the two-dimensional dip tangent gather, and the azimuth angle θ is any azimuth angle in the azimuth set, which can be expressed as:

[0078]

[0079] in, is the steady phase point corresponding to the time T0 of the two-dimensional dip tangent gather, and is the dip field along the lateral line (INLINE) and the vertical line (CROSSLINE) determined by the human-computer interaction picking method in step S120; (γ x ,γ y ) is the shot point (x s ,y s ), detection point (xg ,y g ) and the travel time-related inclination angle determined by the imaging point (x, y, T), γ x and γ y It can be expressed as:

[0080]

[0081]

[0082] The time difference ζ is the vertical one-way time difference between any point on the event axis of the reflected wave and its corresponding stable phase point in the two-dimensional dip tangent gather, which can be expressed as:

[0083]

[0084] Among them, V rms is the root mean square velocity at the imaging point (x, y, T); l s and l g They are respectively the shot points (x s ,y s ) and detection point (x g ,y g ) is the square of the horizontal distance from the imaging point (x, y, T), which can be expressed as

[0085] l s =(x s -x) 2 +(y s -y) 2 ,

[0086] l g =(x g -x) 2 +(y g -y) 2 .

[0087] Where t is the shot point (x s ,y s ) and detection point (x g ,y g ) relative to the imaging point (x, y, T) and with an inclination of The travel time of the interface can be expressed as:

[0088]

[0089] Among them, r is a distance-related variable, which can be expressed as

[0090]

[0091] The time difference weight function obtained in step S130 is recorded as w(ζ) and used in the above formula to obtain all azimuth time difference gathers in the azimuth set U, that is, all azimuth migration time difference gathers generated by pre-stack time migration in the azimuth set U:

[0092] I(x,y,T0,θ,ζ),θ=θ1,θ2,…,θ n .

[0093] For further information, please refer to Figure 1 , step S200, detecting the type of the diffraction wave based on the azimuth-time difference gather, the type being at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a fracture diffraction wave generated by a fracture line diffractor.

[0094] Specifically, after obtaining the azimuth-time difference gather, by detecting the type of the diffraction wave, it can be determined whether the diffraction wave is a point diffraction wave or a line diffraction wave, and then it can be confirmed that the diffraction wave is at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor.

[0095] Furthermore, if Figure 3 As shown, in step S200, the type of the diffraction wave is detected based on the azimuth-moment gather, and the type is at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor, including:

[0096] Step S210, determining a correlation coefficient set corresponding to the azimuth-time difference gather, wherein the correlation coefficient set is composed of a correlation coefficient set corresponding to each time depth and azimuth;

[0097] Step S220, at each time depth, comparing the correlation coefficient of the time difference gather corresponding to each azimuth with a preset correlation coefficient;

[0098] Step S230, if the correlation coefficients of the time difference gathers corresponding to all azimuth angles are greater than the preset correlation coefficient, it is determined that there are point diffraction waves generated by the point diffractor in the seismic data;

[0099] Step S240, if there is a pair of time difference gathers corresponding to azimuth angles differing by 180°, the absolute values ​​of the correlation coefficients of which are both greater than the preset correlation coefficients, and the correlation coefficients have different signs, it is determined that there are fault diffraction waves generated by the fault line diffractor in the seismic data;

[0100] Step S250: If there is a pair of time difference gathers corresponding to azimuth angles differing by 180°, and the absolute values ​​of the correlation coefficients are both greater than the preset correlation coefficients, and the correlation coefficients have the same sign, it is determined that there are fracture diffraction waves generated by fracture line diffractors in the seismic data.

[0101] In the embodiment of the present application, the flatness of the diffraction wave event axis is described by the correlation coefficient, which can be used as a sign to detect whether the diffraction wave exists. The specific analysis is as follows: the diffraction wave event axis is detected at each time depth at the time difference gather CDP corresponding to each azimuth angle, and the straight diffraction wave event axis can be judged by a ratio (correlation coefficient set, a correlation coefficient set corresponding to each time depth and azimuth angle), and the ratio is recorded as ξ(θ,T0), which is expressed as:

[0102]

[0103] Where θ represents the azimuth in the azimuth time difference gather, and its value range is 0° to 180°. Represents the maximum value (positive or negative) of a CDP in the time window centered on T0 in the i-th track of the time difference gather with an azimuth of θ. When calculating the correlation coefficient, the value interval of i is located on the time difference axis outside the boundary of the Fresnel zone, and a pair of correlation coefficients ξ(θ,T0) and ξ(θ+180°,T0) are calculated simultaneously using the above formula.

[0104] Next, a threshold value (i.e., a preset correlation coefficient) is set to detect whether the relevant diffraction wave event axis exists, for example, the threshold value is 0.8. In an embodiment of the present application, the threshold values ​​for presetting the judgment of point diffraction waves, fault diffraction waves, and crack diffraction waves can be set and modified according to actual conditions. If at each time depth, the correlation coefficients of all azimuth corresponding time difference gathers are greater than 0.8, it is determined that there are point diffraction waves generated by point diffractors such as holes in the seismic data; if there is a pair of azimuth corresponding time difference gathers with an absolute value of correlation coefficients greater than 0.8, and the correlation coefficient values ​​are of different signs, it is determined that there are fault diffraction waves generated by fault line diffractors in the seismic data; if there is a pair of azimuth corresponding time difference gathers with an absolute value of correlation coefficients greater than 0.8, and the correlation coefficient values ​​are of the same sign, it is determined that there are crack diffraction waves generated by crack line diffractors in the seismic data.

[0105] Further, if it is determined that the diffraction wave is generated by a line diffractor, the azimuth information of the line diffractor is determined, wherein the line diffractor includes: a fault line diffractor and a crack line diffractor;

[0106] Specifically, at each time depth, if the correlation coefficients of all azimuth-time difference gathers are greater than the preset correlation coefficient (0.8), it can be determined that the diffraction wave is generated by a fault line diffractor or a crack line diffractor, and according to the following properties of the line diffractor: the azimuth of the event axis of the line diffractor on the time slice of the azimuth-time difference gather is perpendicular to the azimuth information of the line diffractor, the azimuth information of the line diffractor can be further determined.

[0107] Further, if it is determined that the diffraction wave is generated by a linear diffractor, determining the azimuth information of the linear diffractor includes:

[0108] According to the linear diffraction wave generated by the linear diffractor, calculating the azimuth angle of the linear diffraction wave;

[0109] Based on the azimuth, the azimuth information of the fault line diffractor or the crack line diffractor is determined; wherein the azimuth of the line diffracted wave event on the time slice of the azimuth-moment gather is perpendicular to the azimuth information of the line diffractor.

[0110] Specifically, if a pair of correlation coefficients |ξ(θ, T0) and |ξ(θ+180°, T0)| greater than a threshold value is detected, it can be determined that the azimuth angle of the corresponding linear diffractor is θ+90°.

[0111] For further information, please refer to Figure 1 , step S300, performing imaging processing on the point diffraction wave, the fault diffraction wave and / or the crack diffraction wave to obtain corresponding imaging results.

[0112] The embodiment of the present application provides a diffraction wave imaging method based on azimuth-time difference gathers, firstly obtain seismic data, and generate azimuth-time difference gathers based on the seismic data by prestack time migration, then detect the type of diffraction wave based on the azimuth-time difference gathers, determine whether the diffraction wave is generated by a hole, a fault or a crack, and determine the azimuth information of the fault line diffractor and the crack line diffractor. Finally, the point diffraction wave, the fault diffraction wave and / or the crack diffraction wave are imaged to obtain the corresponding imaging result. In the embodiment of the present application, the Fresnel zone of the reflection wave is accurately cut off in the generated azimuth-time difference gathers, and the type of the diffraction wave is detected, and the diffraction wave is imaged based on the type of the diffraction wave. The type of the three-dimensional diffractor can be distinguished, and the azimuth information of the line diffractor such as the fault and the crack can be determined. Phase correction can also be implemented in the imaging process of the broken line diffraction wave generated by the fault to enhance the energy of the broken line diffraction wave imaging.

[0113] For further information, see Figure 4 , step S300, performing imaging processing on the point diffraction wave, the fault diffraction wave and / or the crack diffraction wave to obtain corresponding imaging results, including:

[0114] Step S310, if there is a point diffraction wave, the azimuth-moment gather is directly superimposed and imaged along the azimuth dimension and the move dimension to obtain the diffraction wave imaging result of the hole and other point diffracting bodies;

[0115] Step S320, if there is a fault diffraction wave, the azimuth information of the fault strike divides the azimuth-moment gather into two azimuth regions, and the amplitude values ​​of the two azimuth regions are superimposed along the azimuth dimension and the move dimension and then subtracted, that is, phase correction is performed on the fault diffraction wave to obtain the diffraction wave imaging result of the fault;

[0116] Step S330: If there is a crack diffraction wave, the azimuth-time difference gather is directly superimposed and imaged along the azimuth dimension and the time difference dimension to obtain the crack diffraction wave imaging result.

[0117] In the embodiment of the present application, different types of diffraction waves have different corresponding imaging methods. Specifically, in a three-dimensional case, point diffraction waves and crack diffraction waves do not have opposite phases in the azimuth-time difference gathers. Therefore, if the types of diffraction waves are point diffraction waves and crack diffraction waves, the azimuth-time difference gathers are directly superimposed and imaged along the azimuth dimension and the time difference dimension to obtain the imaging results of the point diffraction waves and the crack diffraction waves; in a three-dimensional case, fault diffraction waves have opposite phases in the azimuth-time difference gathers. Therefore, it is necessary to perform phase correction on them, and the energies of the two regions with opposite phases are superimposed along the azimuth dimension and the time difference dimension respectively, and then subtracted to obtain the imaging results of the fault diffraction waves.

[0118] The embodiment of the present application is specifically described by a three-dimensional diffraction model:

[0119] Figure 5 The 3D diffraction model used to generate forward simulation data has a model background velocity of 2000 m / s and contains two thin layers and two independent diffraction points. Figure 5 The upper middle thin layer is a horizontal layer, and the lower thin layer is an inclined layer with apparent dip angles of 10° and 15° in the xz- and yz-planes, respectively. There is a small fault in the upper thin layer, indicated by a white dotted line, with a fault throw of 10m and a strike of 45°. There is a crack in the lower thin layer, indicated by a white dotted line, with a crack width of 5m and a strike of 60°. The coordinates of the diffraction points indicated by the two black dots are (2000, 2000, 2500) and (3000, 3000, 1500), respectively.

[0120] based on Figure 5The given model simulates seismic data and generates dip gathers along the survey line direction and perpendicular to the survey line direction. Based on the dip gathers along the survey line direction and perpendicular to the survey line direction, the dip field along the survey line direction and perpendicular to the survey line direction is obtained by a human-computer interactive picking method (a self-developed software combined with a manual adjustment method), and the preset azimuth-time difference gather formula is confirmed according to the dip field.

[0121] Figure 6 is the 2D dip gather (INLINE and CROSSLINE dimensions) at the CDP coordinate (2500, 2500). The inclination angles of INLINE and CROSSLINE corresponding to the stable phase point are 10° and 15° respectively, which is consistent with Figure 5 The lower oblique layer in the xz- and yz-planes has the same apparent dip angle. The reflection wave event axis is in a bowl shape, and the reflection wave Fresnel zone is located in the relatively flat part of the reflection wave event axis near the stable phase point of the 2D dip gather, that is, the bottom of the bowl. Figure 4 The vertical one-way time difference between any point on the event axis of the reflection wave and its corresponding stable phase point in the two-dimensional dip tangent gather is the concept of time difference in the azimuth-time difference gather. Therefore, the concept of time difference is directly related to the Fresnel zone of the reflection wave. When the time difference is the main period of the seismic recording data or its semi-derivative, the time difference is the boundary of the Fresnel zone of the reflection wave. Therefore, the Fresnel zone can be conveniently and accurately removed based on the time difference gather.

[0122] Figure 7 and Figure 8 It is the time slice of the 2D dip gather at the CDP coordinate (2500, 2500) and the corresponding 2D dip tangent gather at 2.116s. Figure 7 It is the time slice corresponding to the 2D dip gather, and the linear diffraction wave event axis is characterized by a curve. Figure 8 is the time slice corresponding to the 2D dip tangent gather, and the line diffraction wave event axis is a straight line feature. Figure 7 and Figure 8 It is shown as an ellipse-like shape in the plane rectangular coordinates. This is consistent with the fact that the slope is the tangent of the azimuth in the plane rectangular coordinates, and the azimuth of the time slice corresponding to the 2D dip tangent gather is perpendicular to the direction of the line diffractor. Therefore, in order to obtain the azimuth information of the line diffractor in the diffraction wave imaging process, the azimuth on the time slice of the 2D dip tangent gather is introduced to construct the azimuth-time difference gather. Therefore, the azimuth in the azimuth-time difference gather is the azimuth on the time slice of the 2D dip tangent gather.

[0123] Fig. 9Here ζ is the vertical one-way time difference between any point on the event axis of the reflection wave in the two-dimensional dip tangent gather and its corresponding steady phase point, which is the concept of time difference in the azimuth-time difference gather; the azimuth in the azimuth-time difference gather is the azimuth on the time slice of the two-dimensional dip tangent gather.

[0124] Fig. 9 The azimuth-time gather at (2000, 2000) is generated. In practice, the azimuth-time gather is usually generated with an azimuth interval of 15° or less. Here, for clear display, the azimuth interval is 45°. Figure 5 The small fault and an isolated diffraction point above the model pass through this horizontal position, while the crack below does not pass through this horizontal position. Fig. 9 It can be seen that the reflection wave phase axis presents a very strong upward-sloping curve, and the diffraction wave at the small fault above appears as a pair of straight lines with opposite phases at a pair of azimuths 135° and 315° perpendicular to the 45° strike of the fault. The point diffraction wave generated by the isolated diffraction point appears as a straight line with constant phase at each azimuth of the azimuth-time difference gather. Since the lower crack does not pass through this horizontal position, Fig. 9 No horizontally correlated crack diffraction wave events were observed.

[0125] Fig.10 and Fig.11 The time slices of the azimuth-time difference gather at (2000, 2000) without and with the Fresnel zone removed at 0.8s. Fig.10 and Fig.11 , Fig.11 The reflected waves with strong energy in the upper part of the image are cut off. Therefore, the boundary of the Fresnel zone corresponding to the time difference can be determined based on the main frequency of the seismic recording data or its semi-derivative in the azimuth-time difference gather, which can conveniently and accurately cut off the Fresnel zone, avoiding the difficulty of estimating the Fresnel zone in the 2D dip gather. In the present application process, based on the time difference weight function related to the Fresnel zone and the preset azimuth-time difference gather formula, the azimuth-time difference gather after cutting off the Fresnel zone is generated.

[0126] Fig.12 It is the azimuth-time gather at (2500, 2500), and the azimuth interval is 45°. Figure 5 The small fault above and the crack below in the model all pass through this horizontal position, and there is no isolated diffraction point passing through this horizontal position. Fig.12 The crack diffraction waves in the image appear as a pair of straight lines with the same phase at azimuths of 150° and 330°, which are perpendicular to the 60° strike of the crack.

[0127] Fig.13 and Fig.14The time slices of the azimuth-time difference gather at (2500, 2500) without and with the Fresnel zone removed at 2.116s show a pair of crack diffraction wave event axes with the same phase more clearly.

[0128] Fig.15 and Fig.16 They are respectively the reflection wave migration section and diffraction wave imaging section of the 3D simulation data at Y coordinate = 2000m, Fig.15 This is a conventional reflection wave migration profile, which shows a horizontal thin layer, an inclined thin layer and a very weak isolated diffraction point. Fig.16 The corresponding diffraction wave imaging section shows the fault diffraction point above, the crack diffraction point below and an isolated diffraction point. Fig. 9 and Fig.10 It can be seen that in the time difference gathers corresponding to different azimuths, the point diffraction wave appears as a straight line with constant phase at each azimuth of the azimuth-time difference gathers. Therefore, the existence of point diffraction waves generated by point diffractors such as holes in seismic data can be determined by taking the condition that the correlation coefficient of the time difference gathers corresponding to all azimuths is greater than the preset correlation coefficient. Fig. 9 and Fig.10 It can also be seen that the fault diffraction wave appears as a pair of straight lines with opposite phases in the azimuth perpendicular to the fault strike. Therefore, the existence of fault diffraction waves in seismic data can be determined by using a pair of time difference gathers with azimuths that differ by 180°, whose absolute values ​​of correlation coefficients are greater than the preset correlation coefficients and whose correlation coefficients are of different signs. Fig.12 and Fig.12 It can be seen that the fracture diffraction wave appears as a pair of straight lines with the same phase in the azimuth perpendicular to the fault strike. Therefore, the presence of fracture diffraction waves in seismic data can be determined by the condition that the absolute value of the correlation coefficient of a pair of time difference gathers corresponding to azimuths with a difference of 180° is greater than the preset correlation coefficient and the correlation coefficient values ​​have the same sign. After detecting the type of diffraction wave, the diffraction wave imaging profiles of point diffraction wave, fault diffraction wave and fracture diffraction wave can be obtained separately.

[0129] Fig.17 and Fig.18 They are the waveforms of the diffraction wave imaging section of the 3D simulation data at Y coordinate = 2000m without and with phase correction; the waveform of the Fresnel zone after removal Fig.11 In the image, a pair of straight lines with opposite phases can be clearly seen. Therefore, when imaging the fault diffraction wave, it is not possible to directly stack the imaging along the azimuth dimension and the time difference dimension. It is necessary to consider the phase correction of the fault diffraction wave. After phase correction, the energy of the fault diffraction wave is significantly enhanced.

[0130] The diffraction wave imaging system based on azimuth-time difference gather provided in the embodiment of the present application has the following advantages: 1) Based on the azimuth-time difference gather, the Fresnel zone of the reflection wave can be accurately cut off, which can avoid the difficulty of estimating the three-dimensional Fresnel zone using the dip gather, and conveniently and accurately realize the separation of the reflection wave and the diffraction wave; 2) The embodiment of the present application can accurately distinguish the point diffraction waves caused by velocity anomalies such as fractures and caves, the line diffraction waves caused by the lithology pinch-out points, and the line diffraction waves caused by the faults; 3) Phase correction can be achieved in the imaging process of the line diffraction waves caused by the faults to enhance the energy of the fault imaging; 4) The embodiment of the present application can not only image the line diffraction waves, but also indicate the direction of the faults or cracks, which is convenient for scientific researchers to conduct in-depth research on the faults. In summary, the embodiment of the present application can obtain high-resolution imaging of small-scale non-continuous geological bodies, which is a beneficial supplement to the conventional reflection wave imaging method, and has important application value for the identification and characterization of small faults and the research on carbonate fracture-cavity and hole-cavity oil and gas reservoirs.

[0131] An embodiment of the present application provides a diffraction wave imaging system based on an azimuth-time gather. The diffraction wave imaging system based on an azimuth-time gather is mainly used to execute the diffraction wave imaging method based on an azimuth-time gather provided in the above content. The following is a specific introduction to the diffraction wave imaging system based on an azimuth-time gather provided in an embodiment of the present application.

[0132] Fig.19 The following is a schematic diagram of the structure of a diffraction wave imaging system based on azimuth-time difference gathers provided in an embodiment of the present application. Fig.19 As shown, the diffraction wave imaging system based on azimuth-time difference gather mainly includes: an acquisition generation module 11, a detection determination module 12 and an imaging module 13, wherein:

[0133] The acquisition generation module 11 is used to generate an azimuth-time difference gather based on the acquired seismic data; wherein the azimuth-time difference gather is a collection of all azimuth-time difference gathers after cutting off the Fresnel zone, and each of the azimuth-time difference gathers represents the time difference gather corresponding to each azimuth; the azimuth in the azimuth-time difference gather is the azimuth on the time slice of the two-dimensional dip tangent gather; the time difference in the azimuth-time difference gather is the vertical one-way time difference between any point on the phase axis of the reflection wave in the two-dimensional dip tangent gather and its corresponding stable phase point.

[0134] A detection and determination module 12 is used to detect the type of the diffraction wave based on the azimuth-time difference gather, determine whether the diffraction wave is generated by a hole, a fault or a crack, and determine the azimuth information of the fault and the crack;

[0135] The imaging module 13 is used to image the diffraction wave based on the type of the diffraction wave to obtain a result of diffraction wave imaging.

[0136] The embodiment of the present application provides a diffraction wave imaging system based on azimuth-time difference gathers. First, the seismic data is acquired by using an acquisition generation module 11, and the azimuth-time difference gathers are generated by pre-stack time migration based on the seismic data. Then, the detection and determination module 12 is used to detect the type of diffraction wave based on the azimuth-time difference gathers. The type is at least one of the point diffraction wave generated by the point diffractor, the fault diffraction wave generated by the fault line diffractor, and the fracture diffraction wave generated by the fracture line diffractor. Finally, the imaging module 13 is used to image the point diffraction wave, the fault diffraction wave and / or the fracture diffraction wave to obtain the corresponding imaging result. In the embodiment of the present application, the type of the three-dimensional diffractor can be distinguished by detecting the type of the diffraction wave in the generated azimuth-time difference gathers, and the azimuth information of the line diffractors such as faults and fractures can be determined. Phase correction can also be implemented in the imaging process of the broken line diffraction wave generated by the fault to enhance the energy of the broken line diffraction wave imaging.

[0137] Furthermore, the present invention also provides a controller, which includes a processor 10 , a memory 20 and a display 30 . Fig. 20 Only some of the components of the controller are shown, but it should be understood that implementation of all of the components shown is not required, and more or fewer components may be implemented instead.

[0138] In some embodiments, the memory 20 may be an internal storage module of the controller, such as a hard disk or memory of the controller. In other embodiments, the memory 20 may also be an external storage device of the controller, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), etc. equipped on the controller. Further, the memory 20 may also include both an internal storage module of the controller and an external storage device. The memory 20 is used to store application software and various types of data installed in the controller. The memory 20 may also be used to temporarily store data that has been output or is to be output. In one embodiment, a diffraction wave imaging program 40 based on azimuth-time difference gathers is stored on the memory 20, and the diffraction wave imaging program 40 based on azimuth-time difference gathers can be executed by the processor 10, thereby realizing the diffraction wave imaging method based on azimuth-time difference gathers in the present invention.

[0139] In some embodiments, the processor 10 may be a central processing unit (CPU), a microprocessor or other data processing chip, used to run the program code or process data stored in the memory 20, such as executing the diffraction wave imaging method based on the azimuth-time difference gather.

[0140] In some embodiments, the display 30 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch device, etc. The display 30 is used to display information on the device and to display a visual user interface. The components 10-30 of the device communicate with each other via a system bus.

[0141] In one embodiment, when the processor 10 executes the diffraction wave imaging program 40 based on the azimuth-time gather in the memory 20, the following steps are implemented:

[0142] Generate azimuth-time difference gathers based on the acquired seismic data;

[0143] Detecting the type of the diffraction wave based on the azimuth-moment gather, the type being at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a fracture diffraction wave generated by a fracture line diffractor;

[0144] The point diffraction wave, the fault diffraction wave and / or the crack diffraction wave are subjected to imaging processing to obtain corresponding imaging results.

[0145] The azimuth-time gather is a collection of all azimuth-time gathers, and each azimuth-time gather represents a time gather corresponding to each azimuth;

[0146] The azimuth in the azimuth-time difference gather is the azimuth on the time slice of the two-dimensional dip tangent gather;

[0147] The time difference in the azimuth-time difference gather is the vertical one-way time difference between any point on the event axis of the reflection wave and its corresponding stable phase point in the two-dimensional dip tangent gather.

[0148] The step of generating an azimuth-time gather according to the acquired seismic data specifically includes:

[0149] Based on the seismic data, generating dip gathers along the survey line direction and perpendicular to the survey line direction;

[0150] Based on the dip gather, a dip field along the survey line direction and a dip field perpendicular to the survey line direction is obtained, and a preset azimuth-moment gather formula is confirmed according to the dip field;

[0151] Based on the frequency parameters of the seismic data, determining a time difference weight function for cutting off the reflection wave components in the Fresnel zone;

[0152] Based on the time difference weight function and the preset azimuth-time difference gather formula, an azimuth-time difference gather is generated.

[0153] The step of detecting the type of the diffraction wave based on the azimuth-moment gather, wherein the type is at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor specifically comprises:

[0154] Determine a correlation coefficient set corresponding to the azimuth-time difference gather, wherein the correlation coefficient set is composed of a correlation coefficient set corresponding to each time depth and azimuth;

[0155] At each time depth, the correlation coefficient corresponding to the -time difference gather corresponding to each azimuth angle is compared with the preset correlation coefficient;

[0156] If the correlation coefficients of the time difference gathers corresponding to all azimuth angles are greater than the preset correlation coefficients, it is determined that there are point diffraction waves generated by point diffractors in the seismic data;

[0157] If there is a pair of time difference gathers with azimuth angles that differ by 180°, and the absolute values ​​of the correlation coefficients are both greater than the preset correlation coefficients, and the correlation coefficients have different signs, it is determined that there are fault diffraction waves generated by the fault line diffractor in the seismic data;

[0158] If there is a pair of time difference gathers with azimuth angles that differ by 180°, and the absolute values ​​of the correlation coefficients are both greater than the preset correlation coefficients, and the correlation coefficients have the same sign, it is determined that there are fracture diffraction waves generated by fracture line diffractors in the seismic data;

[0159] If it is determined that the diffraction wave is generated by a linear diffractor, the azimuth information of the linear diffractor is determined.

[0160] The step of performing imaging processing on the point diffraction wave, the fault diffraction wave and / or the crack diffraction wave to obtain corresponding imaging results specifically includes:

[0161] If there is a point diffraction wave, the azimuth-time difference gather is directly superimposed and imaged along the azimuth dimension and the time difference dimension to obtain the imaging result of the point diffraction wave;

[0162] If there is a fault diffraction wave, the azimuth-time difference gather is divided into two azimuth regions according to the azimuth information of the fault strike, and the amplitude values ​​of the two azimuth regions are superimposed along the azimuth dimension and the time difference dimension respectively and then subtracted to obtain the imaging result of the fault diffraction wave;

[0163] If there is a crack diffraction wave, the azimuth-time difference gather is directly superimposed and imaged along the azimuth dimension and the time difference dimension to obtain the imaging result of the crack diffraction wave.

[0164] Wherein, the type of the diffraction wave is detected based on the azimuth-time difference gather, and the type is at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor, and further includes:

[0165] If it is determined that the diffraction wave is generated by a line diffractor, the azimuth information of the line diffractor is determined, wherein the line diffractor includes: a fault line diffractor and a crack line diffractor.

[0166] If it is determined that the diffraction wave is generated by a linear diffractor, determining the azimuth information of the linear diffractor includes:

[0167] According to the linear diffraction wave generated by the linear diffractor, calculating the azimuth angle of the linear diffraction wave;

[0168] Based on the azimuth, the azimuth information of the fault line diffractor or the crack line diffractor is determined; wherein the azimuth of the line diffracted wave event on the time slice of the azimuth-moment gather is perpendicular to the azimuth information of the line diffractor.

[0169] Furthermore, the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a diffraction wave imaging program 40 based on azimuth-time trace gathers, and when the diffraction wave imaging program 40 based on azimuth-time trace gathers is executed by a processor, the steps of the diffraction wave imaging method based on azimuth-time trace gathers as described above are implemented; since the steps of the diffraction wave imaging method based on azimuth-time trace gathers are described in detail above, they will not be repeated here.

[0170] In summary, the present invention provides a diffraction wave imaging method based on azimuth-time gathers and related equipment, and the diffraction wave imaging method based on azimuth-time gathers includes: generating azimuth-time gathers according to acquired seismic data; detecting the type of diffraction waves based on the azimuth-time gathers, the type being at least one of point diffraction waves generated by point diffractors, fault diffraction waves generated by fault line diffractors, and fracture diffraction waves generated by fracture line diffractors; imaging the point diffraction waves, the fault diffraction waves and / or the fracture diffraction waves to obtain corresponding imaging results. In the present invention, the type of diffraction wave is detected based on the azimuth-time difference gather, so as to determine whether the diffraction wave is generated by the point diffractor, the fault line diffractor and / or the crack line diffractor, and imaging results of the point diffraction wave, the fault diffraction wave and / or the crack line diffraction wave can be obtained, so as to accurately distinguish the type of diffraction wave and obtain a clear diffraction wave imaging result.

[0171] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A diffraction wave imaging method based on azimuth-time gathers, characterized in that: include: Generate azimuth-time difference gathers based on the acquired seismic data; The step of generating an azimuth-time gather according to the acquired seismic data comprises: Based on the seismic data, generating dip gathers along the survey line direction and perpendicular to the survey line direction; Based on the dip gather, a dip field along the survey line direction and a dip field perpendicular to the survey line direction is obtained, and a preset azimuth-moment gather formula is confirmed according to the dip field; Based on the frequency parameters of the seismic data, determining a time difference weight function for cutting off the reflection wave components in the Fresnel zone; Generate an azimuth-time gather based on the time difference weight function and the preset azimuth-time gather formula; Detecting the type of the diffraction wave based on the azimuth-moment gather, the type being at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a fracture diffraction wave generated by a fracture line diffractor; The point diffraction wave, the fault diffraction wave and / or the crack diffraction wave are subjected to imaging processing to obtain corresponding imaging results.

2. The diffraction wave imaging method based on azimuth-time gather according to claim 1, characterized in that: The azimuth-time gather is a collection of all azimuth-time gathers, and each azimuth-time gather represents the time gather corresponding to each azimuth; The azimuth in the azimuth-time difference gather is the azimuth on the time slice of the two-dimensional dip tangent gather; The time difference in the azimuth-time difference gather is the vertical one-way time difference between any point on the event axis of the reflection wave and its corresponding stable phase point in the two-dimensional dip tangent gather.

3. The diffraction wave imaging method based on azimuth-time gather according to claim 1, characterized in that: Detecting the type of the diffraction wave based on the azimuth-moment gather, the type being at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor, including: Determine a correlation coefficient set corresponding to the azimuth-time difference gather, wherein the correlation coefficient set is composed of a correlation coefficient set corresponding to each time depth and azimuth; At each time depth, the correlation coefficient of the time difference gather corresponding to each azimuth angle is compared with the preset correlation coefficient; If the correlation coefficients of the time difference gathers corresponding to all azimuth angles are greater than the preset correlation coefficients, it is determined that there are point diffraction waves generated by point diffractors in the seismic data; If there is a pair of time difference gathers with azimuth angles that differ by 180°, and the absolute values ​​of the correlation coefficients are both greater than the preset correlation coefficients, and the correlation coefficients have different signs, it is determined that there are fault diffraction waves generated by the fault line diffractor in the seismic data; If there is a pair of time difference gathers with azimuth angles differing by 180°, and the absolute values ​​of the correlation coefficients are both greater than the preset correlation coefficients, and the correlation coefficients have the same sign, it is determined that there are fracture diffraction waves generated by fracture line diffractors in the seismic data.

4. The diffraction wave imaging method based on azimuth-time gather according to claim 1, characterized in that: Performing imaging processing on the point diffraction wave, the fault diffraction wave and / or the crack diffraction wave to obtain corresponding imaging results includes: If there is a point diffraction wave, the azimuth-time difference gather is directly superimposed and imaged along the azimuth dimension and the time difference dimension to obtain the imaging result of the point diffraction wave; If there is a fault diffraction wave, the azimuth-time difference gather is divided into two azimuth regions according to the azimuth information of the fault strike, and the amplitude values ​​of the two azimuth regions are superimposed along the azimuth dimension and the time difference dimension respectively and then subtracted to obtain the imaging result of the fault diffraction wave; If there is a crack diffraction wave, the azimuth-time difference gather is directly superimposed and imaged along the azimuth dimension and the time difference dimension to obtain the imaging result of the crack diffraction wave.

5. The diffraction wave imaging method based on azimuth-time gather according to claim 1, characterized in that: The type of the diffraction wave is detected based on the azimuth-moment gather, the type being at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor, further comprising: If it is determined that the diffraction wave is generated by a line diffractor, the azimuth information of the line diffractor is determined, wherein the line diffractor includes: a fault line diffractor and a crack line diffractor.

6. The diffraction wave imaging method based on azimuth-time gather according to claim 5, characterized in that: If it is determined that the diffraction wave is generated by a line diffractor, determining the azimuth information of the line diffractor includes: According to the linear diffraction wave generated by the linear diffractor, calculating the azimuth angle of the linear diffraction wave; Based on the azimuth, the azimuth information of the fault line diffractor or the crack line diffractor is determined; wherein the azimuth of the line diffracted wave event on the time slice of the azimuth-moment gather is perpendicular to the azimuth information of the line diffractor.

7. A diffraction wave imaging system based on azimuth-time gathers, characterized in that: include: An acquisition and generation module is used to generate azimuth-time difference gathers according to the acquired seismic data; The step of generating an azimuth-time gather according to the acquired seismic data comprises: Based on the seismic data, generating dip gathers along the survey line direction and perpendicular to the survey line direction; Based on the dip gather, a dip field along the survey line direction and a dip field perpendicular to the survey line direction is obtained, and a preset azimuth-moment gather formula is confirmed according to the dip field; Based on the frequency parameters of the seismic data, determining a time difference weight function for cutting off the reflection wave components in the Fresnel zone; Generate an azimuth-time gather based on the time difference weight function and the preset azimuth-time gather formula; a detection and determination module, configured to detect the type of the diffraction wave based on the azimuth-moment gather, wherein the type is at least one of a point diffraction wave generated by a point diffractor, a fault diffraction wave generated by a fault line diffractor, and a crack diffraction wave generated by a crack line diffractor; An imaging module is used to perform imaging processing on the point diffraction wave, the fault diffraction wave and / or the crack diffraction wave to obtain corresponding imaging results.

8. A controller, characterized in that: The controller includes: a memory, a processor, and a diffraction wave imaging program based on azimuth-time gathers stored in the memory and executable on the processor. When the diffraction wave imaging program based on azimuth-time gathers is executed by the processor, the steps of the diffraction wave imaging method based on azimuth-time gathers as described in any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a diffraction wave imaging program based on azimuth-time trace gathers, and when the diffraction wave imaging program based on azimuth-time trace gathers is executed by a processor, the steps of the diffraction wave imaging method based on azimuth-time trace gathers as described in any one of claims 1 to 6 are implemented.

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