A two-dimensional curved wide-line dip-angle domain phase-stable absorption-compensated prestack time migration method

Abstract

The application provides a two-dimensional curved wide-line dip-angle domain stable-phase absorption compensation pre-stack time migration method and relates to the technical field of seismic exploration. After the dip-angle domain Fresnel zone of a target work area is determined, the application generates an inverse Q trace set by taking the Fresnel zone as a constraint, so that the Q value compensation only acts on the most effective signal area of imaging. Moreover, the application corrects the Fresnel zone based on the built equivalent Q value field, so that the width of the Fresnel zone linearly expands with the widening of the effective signal frequency band. In addition, the application performs migration calculation by grouping according to the migration distance under the joint constraint of the corrected Fresnel zone, the equivalent Q value field and the high cut frequency field, so that the noise suppression and absorption compensation are simultaneously completed in the same framework. Therefore, the technical problem that the traditional migration method is difficult to balance the signal-to-noise ratio and imaging resolution when applied in the curved wide-line data processing field is solved.

Description

Technical Field

[0001] This invention relates to the field of seismic exploration technology, and in particular to a two-dimensional flexural width dip domain steady phase absorption compensation pre-stack time migration method. Background Technology

[0002] In oil and gas seismic exploration, two-dimensional curved broadline observation systems are often used in complex surface areas such as loess plateaus and mountains. This technology avoids surface obstacles through flexible survey line layout and increases the coverage by using a broadline system composed of multiple receiver lines, thereby significantly improving the signal-to-noise ratio of the original seismic data while ensuring construction efficiency. However, seismic data processing in these areas faces two challenges: First, the thick near-surface loose layer (such as loess) has a strong viscoelastic absorption effect on seismic waves, leading to wavefield energy attenuation and wavelet dispersion, which severely restricts the imaging resolution of mid-deep and karst reservoirs; Second, the curved observation system results in an irregular, banded distribution of common midpoints (CMPs) and variable azimuth angles of source and receiver rays, making it difficult for traditional migration methods based on the straight-line assumption to achieve a balance between steep-dip structural imaging and migration noise suppression. Summary of the Invention

[0003] The purpose of this invention is to provide a two-dimensional curved line dip-domain steady-state absorption compensation pre-stack time migration method to alleviate the technical problem that traditional migration methods are difficult to balance between signal-to-noise ratio and imaging resolution when applied in the field of curved line data processing.

[0004] In a first aspect, the present invention provides a two-dimensional flexural width line dip domain steady-state absorption compensation pre-stack time migration method, comprising: acquiring two-dimensional flexural width line pre-stack seismic data of a target work area and preprocessing it to obtain standard seismic data, flexural width line CMP centerline, migration velocity field, and stretch cut parameters of CMP point gathers; determining the dip domain Fresnel zone of the target work area based on the standard seismic data, flexural width line CMP centerline, and migration velocity field; generating an inverse Q gather under Fresnel zone constraints based on the dip domain Fresnel zone and standard seismic data, and constructing an equivalent Q-value field and a high-frequency cutoff field of the target work area based on the inverse Q gather; correcting the dip domain Fresnel zone based on the equivalent Q-value field, and performing migration calculations on the standard seismic data according to the migration distance based on the corrected dip domain Fresnel zone, equivalent Q-value field, and high-frequency cutoff field, to obtain the migration results corresponding to each set of migration distances; and determining the imaging profile of the target work area based on the stretch cut parameters and the migration results corresponding to each set of migration distances.

[0005] In an optional implementation, the dip domain Fresnel zone of the target work area is determined based on standard seismic data, the centerline of the curve width line (CMP), and the migration velocity field. This includes: using the migration velocity field, calculating the tangential apparent dip angle contributed by each seismic trace to the imaging point corresponding to each CMP point on the CMP centerline; looping through all seismic traces, performing pre-stack time migration on the standard seismic data, and sorting and arranging the migration results of each seismic trace according to the tangential apparent dip angle to obtain the tangential dip angle gather for each CMP point; picking the Fresnel zone boundary of the imaging point corresponding to the target CMP point based on the tangential dip angle gather of the target CMP point; wherein, the target CMP point represents any one of multiple key CMP points on the CMP centerline; and performing full-work area interpolation and spatial smoothing on the Fresnel zone boundary of the imaging point corresponding to the target CMP point to obtain the dip domain Fresnel zone of the target work area.

[0006] In an optional implementation, based on dip-domain Fresnel zone and standard seismic data, an inverse Q-gather constrained by Fresnel zone is generated, including: obtaining a Q-value scanning range and interval that matches the formation absorption characteristics of the target work area; determining an initial Q-value set based on the Q-value scanning range and interval; sequentially using each Q-value in the initial Q-value set to perform inverse Q-filtering on the data of each seismic trace in the standard seismic data, obtaining the inverse Q-filtering result of each seismic trace at each Q-value; under the constraint of dip-domain Fresnel zone, performing pre-stack time migration calculations on the inverse Q-filtering results of each seismic trace at each Q-value in batches, obtaining an inverse Q-migration profile corresponding to each Q-value; and determining an inverse Q-gather based on all inverse Q-migration profiles.

[0007] In an optional implementation, constructing the equivalent Q-value field and high cutoff frequency field of the target work area based on the inverse Q gather includes: determining multiple equivalent Q analysis windows that match the geological structure of the target work area; calculating the noise level of each equivalent Q analysis window at each Q value, and using a preset noise level threshold to select its candidate Q value set from the initial Q value set for each equivalent Q analysis window; using the maximization of the effective spectral width after compensation as the criterion, combined with a preset imaging quality index, determining the optimal equivalent Q value for each equivalent Q analysis window from its candidate Q value set, and taking the frequency point in the compensation profile corresponding to the optimal Q value that matches the noise threshold as the high cutoff frequency of the window; using the equivalent Q value and high cutoff frequency of each equivalent Q analysis window as nodes, performing full-area interpolation and spatial smoothing processing to obtain the equivalent Q-value field and high cutoff frequency field of the target work area.

[0008] In an optional implementation, the dip-domain Fresnel zone is corrected based on the equivalent Q-value field, including: extracting the Q-value corresponding to a preset key layer in the target work area from the equivalent Q-value field; performing a Fourier transform on the seismic data in the offset profile corresponding to the preset key layer based on the Q-value to determine the first dominant frequency in its superimposed spectrum; obtaining the second dominant frequency in the standard seismic data; and correcting the dip-domain Fresnel zone based on the first and second dominant frequencies to obtain the corrected dip-domain Fresnel zone.

[0009] In an optional implementation, migration calculations are performed on standard seismic data based on the corrected dip-domain Fresnel zone, equivalent Q-value field, and high-frequency cutoff field, including: constructing a stable phase weighting function based on the corrected dip-domain Fresnel zone and the contribution of each seismic trace to the tangential apparent dip angle of the corresponding imaging point at each CMP point; constructing a migration formula for each imaging point at each migration distance based on the stable phase weighting function, equivalent Q-value field, and high-frequency cutoff field; grouping the standard seismic data by migration distance interval, and for each group of migration distance data, iterating through all imaging points, substituting them into the migration formula to perform migration calculations, generating migration results corresponding to each group of migration distances.

[0010] In an optional implementation, the imaging profile of the target work area is determined based on the stretch cut parameters and the offset results corresponding to each set of offset distances, including: arranging the offset results corresponding to each set of offset distances to construct a CRP offset gather; performing stretch cut processing on the CRP offset gather using the stretch cut parameters to obtain the stretched cut CRP offset gather; and weighting and stacking the stretched cut CRP offset gathers along the offset direction to obtain the imaging profile of the target work area.

[0011] Secondly, the present invention provides a two-dimensional flexural width line dip domain steady-state absorption compensation pre-stack time migration device, comprising: an acquisition module for acquiring two-dimensional flexural width line pre-stack seismic data of a target work area and preprocessing it to obtain standard seismic data, flexural width line CMP centerline, migration velocity field, and stretching cut parameters of CMP point gathers; a first determination module for determining the dip domain Fresnel zone of the target work area based on the standard seismic data, flexural width line CMP centerline, and migration velocity field; and a construction module for determining the dip domain Fresnel zone and... Standard seismic data is used to generate inverse Q gathers under Fresnel zone constraints, which are then used to construct the equivalent Q-value field and high-frequency cutoff field of the target work area. A correction and migration module is used to correct the dip-domain Fresnel zone based on the equivalent Q-value field, and then, based on the corrected dip-domain Fresnel zone, equivalent Q-value field, and high-frequency cutoff field, to perform migration calculations on the standard seismic data according to the offset distance, obtaining the migration results corresponding to each set of offset distances. A second determination module is used to determine the imaging profile of the target work area based on the stretching shear parameters and the migration results corresponding to each set of offset distances.

[0012] Thirdly, the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program that can run on the processor, and the processor executes the computer program to implement the two-dimensional bending width line tilt angle domain stable phase absorption compensation pre-stack time migration method as described in any of the foregoing embodiments.

[0013] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions, which, when executed by a processor, implement the two-dimensional bending width line tilt angle domain stable phase absorption compensation pre-stack time migration method described in any of the foregoing embodiments.

[0014] This invention provides a two-dimensional, angular-domain, steady-state absorption compensation pre-stack time migration method. After determining the Fresnel band in the angular domain of the target area, this method generates an inverse Q-gather using this Fresnel band as a constraint. This ensures that Q-compensation only applies to the most effective signal region in the imaging process. Furthermore, the Fresnel band is corrected based on the established equivalent Q-field, causing its width to linearly expand with the effective signal bandwidth. This fully encompasses the high-frequency effective signal recovered by Q-compensation while maintaining precise suppression of migration noise. Finally, migration calculations grouped by offset distance are performed under the joint constraints of the corrected Fresnel band, the equivalent Q-field, and the high-cutoff field, achieving simultaneous completion of noise suppression and absorption compensation within the same framework. In a two-dimensional bend width line observation system, this method achieves closed-loop coupling of Fresnel zone aperture constraint and viscoelastic absorption compensation. This not only suppresses the amplification of migration noise caused by Q compensation, but also avoids the truncation loss of high-frequency signals after compensation due to the fixed aperture. Thus, while maintaining the geometric fidelity of the imaging of steep-angle structures, it simultaneously improves the signal-to-noise ratio and resolution of the imaging profile, alleviating the technical problem of traditional migration methods in achieving a balance between signal-to-noise ratio and imaging resolution when applied in the field of bend width line data processing. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 A flowchart of a two-dimensional curved line dip angle domain steady-phase absorption compensation pre-stack time migration method provided in an embodiment of the present invention; Figure 2 A schematic diagram of CMP point distribution for curve width data provided in an embodiment of the present invention; Figure 3A schematic diagram of a pre-stack time-migrated local imaging profile of conventional commercial software provided in an embodiment of the present invention; Figure 4 A schematic diagram of a local imaging profile of a two-dimensional curved line dip angle domain before phase stacking time migration provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a pre-stack time migration local imaging profile provided by an embodiment of the present invention for phase absorption compensation of a conventional aperture two-dimensional bending width line. Figure 6 A schematic diagram of a local imaging profile of pre-stack time migration provided in an embodiment of the present invention, showing a two-dimensional curved line dip angle domain steady-state absorption compensation. Figure 7 This is a schematic diagram of a local imaging profile spectrum comparison provided in an embodiment of the present invention; Figure 8 A comparison chart of signal-to-noise ratio versus frequency curves provided in this embodiment of the invention; Figure 9 Provided for embodiments of the present invention Figure 3 , 4 Magnified comparison of imaging profile details in images 5 and 6; Figure 10 A functional block diagram of a two-dimensional curved line tilt angle domain stable phase absorption compensation pre-stack time migration device provided in an embodiment of the present invention; Figure 11 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0019] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0020] Example 1 Figure 1A flowchart of a two-dimensional curved line dip angle domain steady-phase absorption compensation pre-stack time migration method provided by an embodiment of the present invention is shown below. Figure 1 As shown, the method specifically includes the following steps: Step S102: Obtain the two-dimensional pre-stack seismic data of the target work area, and preprocess it to obtain standard seismic data, the center line of the CMP (Center for Motion Mass Mapping), the migration velocity field, and the stretching cut parameters of the CMP point gather.

[0021] In this embodiment of the invention, the target seismic area refers to a complex surface area such as the Loess Plateau and mountains. The two-dimensional curved-width pre-stack seismic data refers to the original seismic records with zonal curved CMP distribution characteristics obtained within the target seismic area through non-linear survey line deployment and collaborative acquisition by multiple receiver lines. The purpose of this step is to execute the migration preprocessing workflow for the two-dimensional curved-width pre-stack seismic data.

[0022] After acquiring the two-dimensional bend-width line pre-stack seismic data, preprocessing operations such as CMP point localization, pre-stack denoising, amplitude compensation, and deconvolution need to be performed sequentially. CMP point localization refers to the precise localization of the bend-width line CMP points. First, a virtual CMP centerline is automatically calculated based on the source-receiver coordinates. In sections with significant line curvature, manual intervention is used to adjust the centerline in conjunction with tectonic trends, ensuring that the centerline closely matches the center of the reflected wave scatter points (e.g., the distance between them is less than a distance threshold), thus obtaining the bend-width line CMP centerline and laying a solid geometric foundation for subsequent processing. Pre-stack denoising employs targeted techniques such as FK filtering and coherent noise attenuation to suppress surface waves and random interference while preserving the amplitude and phase information of effective reflected waves. Amplitude compensation performs surface consistency correction to correct energy differences between different receiver lines and offset groups. Deconvolution compresses the wavelet length, improving the longitudinal resolution of the data. After these processing steps, standard seismic data is obtained.

[0023] After obtaining the standard seismic data, velocity analysis can be performed. Specifically, CMP point gathers are first extracted from the standard seismic data at preset CMP point intervals. Conventional dynamic correction velocity picking and spatial smoothing are then applied to the extracted gathers to establish an initial migration velocity field. Subsequently, conventional pre-stack time migration techniques are used for iterative updates, and velocity parameters are optimized by judging the flatness of the phase axis to finally obtain a high-precision migration velocity field (i.e., the migration velocity field in step S102 above). Simultaneously, based on the stretching characteristics of the migration gathers at each CMP point, the wavelet stretching rate at different time depths is statistically analyzed to reasonably determine the stretching cut-off parameters for the CMP point gathers, avoiding invalid energy interference with subsequent processing. This provides accurate velocity parameter support for subsequent steps such as dip gather construction, inverse Q gather generation, and viscoelastic migration travel time calculation. The methods used in the above preprocessing process are all existing technologies in the field; therefore, they will not be described in detail in this embodiment of the invention.

[0024] Step S104: Based on standard seismic data, the centerline of the curve width line (CMP), and the migration velocity field, determine the dip domain Fresnel zone of the target work area.

[0025] Specifically, this step is the core preliminary step in this embodiment of the invention, aiming to provide an accurate and optimal imaging aperture adapted to the geometry of the curved width line for subsequent integrated migration. Its core lies in abandoning the fixed azimuth or orthogonal dip angle definition methods relied upon by traditional straight survey lines or 3D survey areas. Instead, it adopts a direction reference system based on the local tangential of the curved width line CMP centerline, reparameterizing the propagation direction of each seismic data at each imaging point, thereby deriving the tangential apparent dip angle that truly reflects the actual ray path characteristics of the curved width line. Based on this, a gather structure organized by dip angle is generated through pre-stack time migration, and the region with the most concentrated reflected energy and the most stable phase, i.e., the Fresnel zone, is identified as the effective aperture boundary for subsequent imaging. In this embodiment of the invention, the Fresnel zone is not a statically set empirical parameter, but a continuous spatial function dynamically picked from actual data and smoothed by interpolation across the entire survey area. Its boundary changes jointly with the CMP position and time depth, fully characterizing the spatial evolution law of the optimal stacking aperture under the unique banded curvature of the curved width line, i.e., the variable azimuth observation geometry.

[0026] Step S106: Based on dip-domain Fresnel zone and standard seismic data, generate inverse Q gathers under Fresnel zone constraints, and construct the equivalent Q-value field and high cutoff field of the target work area based on the inverse Q gathers.

[0027] Specifically, this step achieves a fundamental shift in the absorption compensation modeling paradigm: upgrading Q-value inversion from traditional full-aperture spectrum analysis to restricted inversion within the effective signal-dominated region. In this embodiment of the invention, the Fresnel zone-constrained inverse Q gather refers to retaining only the energy contribution within the aforementioned Fresnel zone range during the migration calculation after performing inverse Q filtering, forcibly eliminating high-frequency noise components outside the aperture caused by scattering, diffraction, and modeling errors. The resulting set of migration profiles corresponding to different Q hypotheses constitutes a Q-response space with controlled signal-to-noise ratio and clear physical meaning. Within this high-quality response space, by setting reasonable noise tolerance thresholds and imaging quality optimization criteria, the equivalent Q-value and its corresponding high cutoff parameters that can fully compensate for formation absorption attenuation without inducing excessive noise amplification can be determined. Thus, the final constructed equivalent Q-value field and high cutoff field are no longer isolated geological parameter models, but rather a global physical field coupled with the geometric depth of the curved width line observation and inherently consistent with the steady-phase aperture logic, providing a compensation basis with both accuracy and robustness for subsequent fusion migration.

[0028] Step S108: Correct the dip domain Fresnel zone based on the equivalent Q value field, and calculate the migration of the standard seismic data according to the offset based on the corrected dip domain Fresnel zone, equivalent Q value field and high cutoff frequency field, to obtain the migration result corresponding to each set of offsets.

[0029] This step is the core integration of phase shift and Q compensation in the bend width region. Its essence lies in establishing a feedback aperture adaptation mechanism: because Q compensation significantly broadens the effective signal bandwidth and increases the dominant frequency, if the original Fresnel band in the tilt region remains unchanged, some of the recovered high-frequency effective energy will be incorrectly removed, or low signal-to-noise ratio edge energy will be improperly included. Therefore, it is necessary to quantitatively correct the initial Fresnel band boundary based on the spectral characteristic changes (especially the degree of dominant frequency increase) reflected by the equivalent Q value, so that the aperture width dynamically matches the energy distribution characteristics of the compensated signal.

[0030] Next, the corrected dip domain Fresnel band, equivalent Q-value field, and high cutoff field are simultaneously embedded into the Kirchhoff pre-stack time migration integral to form a dip domain steady-state absorption compensation migration operator designed specifically for two-dimensional wavy line observation systems. This operator no longer calls the steady-state module and Q-compensation module separately, but completes noise suppression and wavefield reconstruction simultaneously in a single integration process. Moreover, its calculation process is organized according to the offset distance, taking into account both computational efficiency and physical fidelity, and finally outputs a set of intermediate imaging results with clear offset distance attributes.

[0031] Step S110: Based on the stretching cut parameters and the offset results corresponding to each set of offset distances, determine the imaging profile of the target work area.

[0032] Specifically, in this embodiment of the invention, the output results of each offset group are reorganized into common reflection point (CRP) gathers according to their original acquisition attributes. This organization method inherits the spatial continuity and azimuth sensitivity of the center line of the curve width line (CMP). Then, the previously determined stretching and cutting parameters are applied to perform directional cutting of the time-varying stretching distortion caused by large offsets in the CRP gathers, avoiding the superposition process of invalid energy contamination. Finally, weighted superposition is performed along the offset direction to generate an imaging profile that retains the integrity of the steep diagonal structure imaging and has the synergistic advantages of high signal-to-noise ratio and high resolution.

[0033] This invention provides a two-dimensional, angular-domain, steady-state absorption compensation pre-stack time migration method. After determining the Fresnel band in the angular domain of the target area, this method generates an inverse Q-gather using this Fresnel band as a constraint. This ensures that Q-value compensation only applies to the most effective signal region in the imaging process. Furthermore, the Fresnel band is corrected based on the established equivalent Q-value field, causing its width to linearly expand with the effective signal bandwidth. This fully encompasses the high-frequency effective signal recovered by Q-compensation while maintaining precise suppression of migration noise. Finally, migration calculations grouped by offset distance are performed under the joint constraints of the corrected Fresnel band, the equivalent Q-value field, and the high-cutoff field, achieving simultaneous completion of noise suppression and absorption compensation within the same framework. In a two-dimensional bend width line observation system, this method achieves closed-loop coupling of Fresnel zone aperture constraint and viscoelastic absorption compensation. This not only suppresses the amplification of migration noise caused by Q compensation, but also avoids the truncation loss of high-frequency signals after compensation due to the fixed aperture. Thus, while maintaining the geometric fidelity of the imaging of steep-angle structures, it simultaneously improves the signal-to-noise ratio and resolution of the imaging profile, alleviating the technical problem of traditional migration methods in achieving a balance between signal-to-noise ratio and imaging resolution when applied in the field of bend width line data processing.

[0034] In an optional implementation, step S104 above, based on standard seismic data, the centerline of the curve width line (CMP), and the migration velocity field, determines the dip region Fresnel zone of the target work area, specifically including the following steps: Step S1041: Using the migration velocity field, calculate the tangential dip angle contributed by each seismic trace to the imaging point corresponding to each CMP point on the center line of the curve width line CMP.

[0035] Specifically, first, calculate the tangential azimuth angle of the CMP point on the bend width line. For the i-th CMP point on the center line of the bend width line, its coordinates are... Select the (i-1)th and (i+1)th CMP points adjacent to it, with coordinates as follows: , The azimuth angle is obtained by approximating the tangent direction of the i-th CMP point with the line connecting the two points. for: azimuth Define the current CMP point The local survey line direction at the location solves the problem that the fixed azimuth angle of the straight survey line cannot be adapted to the variable azimuth angle of the curved line, and provides a geometric reference that fits the shape of the survey line for subsequent inclination calculation.

[0036] Next, for each trace in the preprocessed prestack seismic data, the coordinates of the shot point and receiver point are as follows: , Using the offset velocity field established in step S102, for the CMP point Corresponding imaging points ( (Given the vertical one-way travel time of the imaging point), the contribution of the seismic trace to the tangential dip angle at that imaging point can be calculated. , is represented as: ;in, , These represent the travel times from the shot point and the receiver point to the imaging point, respectively. This indicates the superposition velocity of the imaging points. The calculation of the tangential inclination angle incorporates the geometric characteristics of the curved line, avoiding the inclination angle distortion caused by the traditional straight-line surveying line inclination angle formula in the curved-line work area, so that the inclination angle parameter can accurately reflect the adaptation relationship between the propagation direction of the reflected wave and the curvature of the surveying line.

[0037] Step S1042: Loop through all seismic traces, perform pre-stack time migration on the standard seismic data, and sort and arrange the migration results of each seismic trace according to the tangential dip angle to obtain the tangential dip angle gather for each CMP point.

[0038] In this step, pre-stack time migration can be performed using a two-dimensional curved-width line conventional pre-stack time migration, that is, looping through all seismic traces and performing a two-dimensional curved-width line conventional pre-stack time migration according to the tangential dip angle. By setting a fixed interval, the migration results of each seismic trace are sorted and arranged according to dip angle intervals to obtain the dip angle gather along the tangent of the CMP point, as follows: ;in, Represents the i-th CMP point Tangential angle gathers, This indicates the total number of traces used in two-dimensional wavy line seismic data. This represents the semi-derivative of the m-th seismic trace. The generated gathers are distributed tangentially along the CMP, and the phase axis of the reflected waves exhibits a regular downward convex curve shape. Compared with the dip gathers of straight seismic lines, this completely solves the problems of distortion and effective signal dispersion in the data gathers of curved and wide lines.

[0039] Step S1043: Based on the tangential tilt gather of the target CMP point, pick the Fresnel zone boundary of the imaging point corresponding to the target CMP point; wherein, the target CMP point represents any one of the multiple key CMP points on the center line of the curved width line CMP.

[0040] This invention does not specifically limit the selection method of critical CMP points; conventionally, they are considered as a subset of all CMP points within the target work area. Optionally, critical CMP points can be selected by randomly sampling all CMP points, uniformly sampling, or sampling areas with drastic structural changes in the target work area according to a first density, and areas with gentle structural changes in the target work area according to a second density, where the first density is greater than the second density.

[0041] The purpose of this step is to extract the Fresnel zone boundaries of the imaging points corresponding to some CMP points within the target work area. For a target CMP point, to extract the Fresnel zone boundaries of its corresponding imaging points, the steady-state point must first be determined. On the tangential tilt gather, the phase axis of the reflected wave appears as a convex curve, and the tilt angle corresponding to its apex is the steady-state point at that time. The Fresnel zone is located in the relatively flat area around the steady-state point. This can be represented as: ;in, Represents the imaging point The theoretical Fresnel zone has left and right boundaries. This represents the vertical one-way travel time corresponding to the imaging point. Indicates the dominant frequency of earthquake data. Indicates the stable phase point.

[0042] Stable phase points can be automatically identified by calculating the flatness and amplitude ratio indices of the local window of the gather. The flatness index is expressed as: The amplitude ratio index can be expressed as: . Indicates the target CMP point The j-th imaging point The corresponding vertical one-way travel time, Indicating the inclination angle of the i-th channel in the channel set The maximum amplitude value (positive or negative) within a small time window centered on the oscillator. The inclination channel concentration imaging point is represented by The Fresnel zone is the stable phase point, that is, according to Sure . This represents the amplitude value of the j-th imaging point in the i-th channel of the CMP point in the tilt-focused target area. This represents the amplitude value of the offset profile at the j-th imaging point of the target CMP point.

[0043] Therefore, for all imaging points of the cyclic target CMP point, if the imaging points Flatness index Amplitude ratio index If all values ​​are greater than the set threshold (e.g., 0.8), then For imaging points The potential stable phase point angle value. If there are multiple potential stable phase points for the j-th imaging point, then the average of all potential stable phase points is taken as its final stable phase point. Finally, the time-depth sequence of the in-phase axis of the target CMP is obtained. and its corresponding stable phase point sequence , where j=1,2…J, and J represents the total number of imaging points picked up.

[0044] After determining the stable phase point, this embodiment of the invention uses the stable phase point as the starting point and employs a left-right energy search method to pick up its Fresnel zone boundary, ensuring coverage of both reflected and diffracted wave energy. Let... Indicates the inclination angle range , The angle sampling interval of the tangential tilt angle gather (a preset value) is represented, and k is an integer search step size. The imaging point is searched using the following formula. The left and right boundaries of the Fresnel zone in the tilt region: , This represents the interval of inclination in the search that satisfies the above inequality conditions. As the Fresnel zone boundary for stable phase shift, the imaging point is obtained. The left and right boundaries of the Fresnel zone with stable phase shift , The energy search method not only includes reflected wave energy, but also the diffraction wave energy of diffractors such as faults and karst "beads", avoiding the problem of unclear diffractor characterization caused by only retaining reflected waves.

[0045] Step S1044: Perform full-area interpolation and spatial smoothing on the Fresnel zone boundary of the imaging point corresponding to the target CMP point to obtain the tilt domain Fresnel zone of the target area.

[0046] To achieve full and continuous coverage of the Fresnel zone, firstly, the left and right boundaries of the Fresnel zone of the imaging point corresponding to the target CMP point are defined. , , , Linear interpolation is used along the time-depth direction of the seismic data to fill the boundary gaps between sampling points at different times. Secondly, along the curvature path of the CMP (the path determined according to the CMP centerline determined in step S102), the cumulative chord length interpolation method is used to interpolate the Fresnel zone boundary of the imaging points corresponding to the discrete CMP points to all CMP points in the entire work area.

[0047] Specifically, the chord length between adjacent CMP points is (in (where is the coordinate of the i-th CMP point), the cumulative chord length of the i-th CMP point relative to the starting point is . The cumulative chord length is normalized to the interval [0, 1] to obtain the cumulative chord length interpolation parameters. , where N represents the total number of CMPs between two adjacent target CMPs, and i is the local index within the interval (the interval formed by two adjacent target CMPs). The left boundary of the Fresnel band for the imaging point corresponding to the i-th CMP point is calculated based on the normalized parameters. , (in and (These are the left boundaries of the Fresnel bands of two adjacent target CMPs, respectively). Similarly, the right boundary of the Fresnel band of the imaging point corresponding to the i-th CMP point can be calculated. .

[0048] In practice, the planar coordinates of all CMP points along the bend width line can be extracted first. Then, the chord length, cumulative chord length, and normalized parameters can be calculated. Next, the left and right boundaries of the Fresnel zone after time-depth interpolation are used as lateral discrete nodes, and linear interpolation is performed laterally along the bend width line to achieve full coverage of parameters across all CMP points. Spatial smoothing is then applied to the interpolated Fresnel zone boundaries to eliminate abrupt local boundary changes, providing a precise and continuous aperture constraint basis for subsequent phase-steady absorption compensation migration across the entire work area. Since this Fresnel zone is obtained without Q compensation, it defines the effective signal region that contributes most to imaging. In subsequent steps, an inverse Q gather is generated under this aperture constraint, and the Q value is picked up. This can minimize the interference of external aperture noise on the spectral analysis, thereby obtaining a more reliable equivalent Q value estimate.

[0049] In an optional implementation, step S106 above, which generates an inverse Q-gather under Fresnel zone constraints based on dip-domain Fresnel zone and standard seismic data, specifically includes the following steps: Step S1061: Obtain the Q-value scanning range and interval that match the formation absorption characteristics of the target work area.

[0050] Step S1062: Determine the initial set of Q values ​​based on the Q value scanning range and interval.

[0051] Specifically, unlike traditional unconstrained inverse Q gather generation methods, this invention incorporates the aperture constraint of the Fresnel zone in the dip domain into the offset process of the inverse Q filter data, which can significantly suppress high-frequency noise caused by Q compensation. First, based on the absorption characteristics of the strata in the bend-width line work area, a suitable Q-value scanning range (e.g., set by technicians based on experience) and interval are set. Optionally, the scanning range covers 50-500, and 10-15 (exemplary values) scanning nodes are selected at equal intervals of 1 / Q. Then, the reciprocal of each selected scanning node is taken to obtain the corresponding Q, ensuring that the scanning range completely covers the true Q-value distribution of strata at different depths in the work area, avoiding Q-value picking deviations caused by missing scanning intervals.

[0052] For example, setting the range of Q: =50, =500, then the range of 1 / Q is 1 / 50=0.02 and 1 / 500=0.002. We need to take 10 to 15 points at equal intervals between 0.002 and 0.02, and then take the reciprocal of each selected point to obtain the corresponding Q value, thus forming the initial Q value set.

[0053] Step S1063: Inverse Q-filtering is performed on the data of each seismic trace in the standard seismic data using each Q-value in the initial Q-value set in sequence to obtain the inverse Q-filtering result of each seismic trace at each Q-value.

[0054] Specifically, for each seismic trace obtained after preprocessing in step S102, the N preset Q values ​​in the initial Q value set are substituted into the following formula in sequence to perform amplitude attenuation compensation and phase dispersion correction (i.e., inverse Q filtering) on ​​the seismic data corresponding to the trace, so as to restore the high-frequency effective signal, and all filtering results are temporarily stored in memory. ;in, For earthquake channels The result of inverse Q filtering, For earthquake channels The spectrum, Angular frequency, For earthquake channels The frequency of the main character.

[0055] Step S1064: Under the constraint of the dip domain Fresnel zone, perform pre-stack time migration calculations on the inverse Q filtering results of each seismic trace at each Q value in batches to obtain the inverse Q migration profile corresponding to each Q value.

[0056] Step S1065: Determine the inverse Q gather based on all inverse Q offset profiles.

[0057] Finally, for each of the N inverse Q filtering results in memory, pre-stack time migration calculations are performed in batches. The core constraint is to retain only the energy within the Fresnel zone boundary picked up in step S104 at the dip angle, and to remove scattering noise and invalid energy outside the Fresnel zone. This results in a series of inverse Q migration profiles that correspond one-to-one with each Q value. The N inverse Q migration profiles constitute an inverse Q migration set, which completely solves the core problem of inverse Q compensation for synchronous amplification noise.

[0058] In an optional implementation, step S106 above, which involves constructing the equivalent Q-value field and high cutoff frequency field of the target work area based on the inverse Q gather, specifically includes the following steps: Step S1066: Determine multiple equivalent Q analysis windows that match the geological structure of the target work area.

[0059] This invention, based on Fresnel band-constrained inverse Q gathers, employs strategies such as analysis window adaptation, signal-to-noise separation filtering, and multi-index optimization to achieve the coupled and synchronous determination of the equivalent Q value and high cutoff frequency. In this invention, the selection criteria for the equivalent Q analysis window include: lateral coverage of continuous CMP points, temporal inclusion of multiple continuous reflection phase axes, and no crossing of major faults / tectonic zones; densification of the analysis window in sections with significant line curvature to ensure accurate parameter acquisition in curved sections; and window center coinciding with the CMP centerline of the curve width line to conform to the line topology.

[0060] Step S1067: Calculate the noise level of each equivalent Q analysis window at each Q value, and use a preset noise level threshold to select a set of candidate Q values ​​for each equivalent Q analysis window from the initial set of Q values.

[0061] Specifically, for each equivalent Q analysis window, Fourier transform is performed on the seismic data within the migration profile corresponding to each Q value to extract its stacked spectrum and determine the dominant frequency. The maximum frequency corresponding to -20 dB (That is, each Q value corresponds to a set) and ), forming the frequency range for noise level calculation .

[0062] By applying a local second-order polynomial filter within the analysis window to the inverse Q-offset gather generated by Fresnel band constraints, the noise spectrum is obtained. With effective signal spectrum Then, the noise level corresponding to each Q value for each equivalent Q analysis window is calculated based on the following formula: ;in, Indicates the equivalent Q analysis window in The noise level below, Indicates the equivalent Q analysis window in The lower clock speed, Indicates the equivalent Q analysis window in The maximum frequency corresponding to -20 dB is the frequency point that matches the noise threshold.

[0063] Next, a unified acceptable noise level threshold is set for the target work area, and noise levels are filtered out. Q values ​​less than or equal to the threshold are used to form a candidate Q value set. If the candidate set is empty, the threshold can be relaxed appropriately to ensure that subsequent parameter selection has a reasonable basis.

[0064] Step S1068: Based on the maximization of the effective spectral width after compensation, and combined with the preset imaging quality index, determine the optimal equivalent Q value from its candidate Q value set for each equivalent Q analysis window, and take the frequency point in the compensation profile corresponding to the optimal Q value that matches the noise threshold as the high cutoff frequency of the window.

[0065] Specifically, maximizing the effective spectral width focuses on geological resolution, emphasizing the recovery of absorbed and attenuated high-frequency components as much as possible while meeting noise constraints, thereby improving vertical resolution. Preset imaging quality indicators serve as auxiliary criteria to verify the physical consistency of the compensation results. For example, phase axis continuity ensures the integrity of structural distribution; wavelet sidelobe separation reflects the compression effect and vertical resolution of the seismic wavelet; wavelet sidelobe suppression reflects amplitude fidelity; and local signal-to-noise ratio gradient reflects compensation uniformity. The optimal equivalent Q-value is the Pareto optimal solution that simultaneously satisfies the above multi-objective constraints within the candidate Q-value set. The high cutoff frequency is the highest frequency reliably usable within the noise tolerance boundary under the action of this optimal equivalent Q-value; it forms a pair of coupling parameters with the Q-value.

[0066] Step S1069: Using the equivalent Q value and high cutoff frequency of each equivalent Q analysis window as nodes, perform full-area interpolation and spatial smoothing to obtain the equivalent Q value field and high cutoff frequency field of the target work area.

[0067] Specifically, considering the topological characteristics of the curved CMP centerline, a three-dimensional parameter field construction process was adopted, employing time-domain interpolation, lateral cumulative chord length interpolation, and spatial smoothing. Using the discrete equivalent Q-values ​​and high cutoff frequencies determined by each analysis window as nodes, linear interpolation was performed along the time depth direction to form a parameter sequence continuously distributed along the time axis at each CMP point. Lateral interpolation was performed along the curved path of the CMP centerline using the cumulative chord length interpolation method, ensuring the parameter field closely matches the survey line morphology. Spatial smoothing was then applied to the interpolated parameter field to eliminate local parameter abrupt changes, forming a globally continuous equivalent Q-value field and high cutoff frequency field. The cumulative chord length interpolation perfectly adapts to the geometric characteristics of the curved line, avoiding parameter field distortion in the curved segment caused by linear interpolation, and providing accurate global parameter support for subsequent absorption compensation migration.

[0068] This invention achieves the first deep integration of curved-width line stable phase and curved-width line Q-modeling at the methodological logic level by first constraining the inverse Q-gather with Fresnel bands, then picking parameters on the inverse Q-gather, and finally constructing a continuous field using a method adapted to the topology of the curved-width line.

[0069] In an optional implementation, step S108 above, which corrects the Fresnel band in the tilt domain based on the equivalent Q-value field, specifically includes the following steps: Step S1081: Extract the Q value corresponding to the preset key layer in the target work area from the equivalent Q value field.

[0070] Preset key strata refer to specific geological interfaces or reservoir sections that are of decisive significance for seismic exploration, such as the top surface of bedrock, the bottom boundary of major gas-bearing sand bodies, or the central depth of karst development zones. In this embodiment of the invention, the preset key strata are not specifically limited, and users can set them according to their actual needs.

[0071] Step S1082: Based on the Q value corresponding to the preset key layer, perform Fourier transform on the seismic data in the offset profile corresponding to the Q value to determine the first dominant frequency in its superimposed spectrum.

[0072] Referring to the relevant description in step S1067 above, the first main frequency in this step is actually the Q value corresponding to the preset key layer. .

[0073] Step S1083: Obtain the second dominant frequency from the standard seismic data, denoted as... .

[0074] Step S1084: Based on the first and second main frequencies, the tilt domain Fresnel band is corrected to obtain the corrected tilt domain Fresnel band.

[0075] To accommodate the increased dominant frequency and wider effective signal bandwidth of seismic waves after Q-compensation, this embodiment of the invention dynamically adjusts the Fresnel zone boundary in the dip domain to ensure precise matching between the Fresnel zone range and the compensated high-frequency signal. The dominant frequency of the initial pre-stack dataset (i.e., the second dominant frequency) is used as the basis. ) and the target main frequency after Q compensation (i.e., the first main frequency) Using ) as the core parameter, the Fresnel zone boundary of the tilt region picked in step S104 is... The correction is expressed as follows: .in, This represents the Fresnel zone boundary adjusted with Q, that is, the corrected Fresnel zone boundary in the tilt region. When considering the vertical one-way travel of the imaging point, this formula is used to determine the imaging point. When correcting the Fresnel zone boundary, the formula in and That is, substitute the parameters corresponding to the imaging point. , .

[0076] This formula directly corrects the tilt boundary by increasing the main frequency, making the Fresnel band width expand linearly with the effective signal bandwidth. It not only fully encompasses the high-frequency effective signal recovered by Q compensation, but also maintains precise suppression of offset noise. This solves the problem of signal loss or noise residue caused by the mismatch between the fixed Fresnel band and the Q compensation main frequency, and provides precise dynamic aperture constraints for fusion offset.

[0077] In an optional implementation, step S108 above, based on the corrected dip-domain Fresnel zone, equivalent Q-value field, and high-frequency cutoff field, performs offset calculations on the standard seismic data according to the offset distance, specifically including the following steps: Step S1085: Based on the corrected dip domain Fresnel zone and the contribution of each seismic trace to the tangential apparent dip angle of the corresponding imaging point at each CMP point, construct a stable phase weighting function.

[0078] For any seismic trace (shot point S, receiver point G) and imaging point Step S104 calculates the tangential dip angle contributed by each seismic trace to the imaging point. Afterwards, the left and right boundaries of the Fresnel zone are adjusted with Q. In comparison, a stable phase weighting function is constructed: ;in, This indicates the width of the tilt attenuation band (a preset parameter).

[0079] Step S1086: Based on the phase-stabilized weighting function, the equivalent Q-value field, and the high-frequency cutoff field, construct the offset formula for each imaging point at each offset distance.

[0080] Specifically, by fusing the Fresnel zone weighting function of the tilt-domain stable phase shift with the viscoelastic absorption compensation term, the core shift formula of this invention is constructed, achieving simultaneous execution of noise suppression and absorption compensation. The shift formula for each imaging point at each shift distance is expressed as follows: ;in, Represents the imaging point Corresponding offset The offset magnitude, This represents the total number of traces used in the two-dimensional curved-width line stable-phase pre-stack time-migrating seismic data. Angular frequency, To input the main frequency of earthquake data, For high cutoff frequency The corresponding angular frequency, To input seismic traces Fourier transform, This is the equivalent Q value.

[0081] Step S1087: Group the standard seismic data according to the offset interval, and for each group of offset data, loop through all imaging points, substitute them into the offset formula to perform offset calculation, and generate the offset result corresponding to each group of offsets.

[0082] Specifically, firstly, standard seismic data is grouped according to offset intervals, with each group containing seismic traces within the same offset range to improve computational efficiency. For each offset data group, all imaging points are iterated, and the aforementioned migration formula is substituted into the data. Combined with the corrected dip-domain Fresnel bands, equivalent Q-value field, and high-frequency cutoff field, migration calculations are performed to generate migration results corresponding to each offset group. This process achieves deep fusion of Fresnel band-constrained noise suppression and Q-value field-compensated absorption, improving resolution while maintaining the signal-to-noise ratio.

[0083] In an optional implementation, step S110 above, which determines the imaging profile of the target work area based on the stretching excision parameters and the offset results corresponding to each set of offset distances, specifically includes the following steps: Step S1101: Arrange the offset results corresponding to each set of offsets to construct the CRP offset gather.

[0084] Step S1102: Perform stretch cut processing on the CRP offset gather using stretch cut parameters to obtain the stretched cut CRP offset gather.

[0085] Step S1103: The CRP offset gather after stretching and shearing is weighted and superimposed along the offset distance direction to obtain the imaging profile of the target work area.

[0086] This step is a post-processing of the migration results generated in step S108 above. Through the process of common reflection point (CRP) gather generation, stretching and cutting, and stacking, the migration data is transformed into the final imaging profile. The specific technical solution and effects are as follows: First, the migration results with different offsets generated in step S108 are arranged to construct CRP migration gathers. Then, according to the stretching cut parameters determined in step S102, the CRP gathers are stretched and cut to remove gather data with stretching rates exceeding a set threshold, eliminating invalid stretching energy interference. Finally, the stretched and cut CRP migration gathers are weighted and stacked along the offset direction to generate the final imaging profile. Thus, this embodiment of the invention completes the entire process from two-dimensional curved-width line raw seismic data to a high signal-to-noise ratio, high-resolution final imaging profile, realizing a deep synergy and integrated solution for stable phase migration and viscoelastic absorption compensation in the downdip domain of the curved-width line observation system.

[0087] The weights used in weighted stacking can be dynamically weighted with physical meaning based on the signal-to-noise ratio contribution, amplitude consistency, and local structural fit of each offset gather at a specific imaging point. For example, in shallow regions, short offset samples are preferentially enhanced to improve resolution; in deep or steeply dipping regions, the weight of long offset samples is appropriately increased to enhance structural imaging stability. This weighting strategy does not rely on empirical settings but is embedded in the physical consistency framework jointly characterized by the previously constructed equivalent Q-field, high cutoff field, and modified Fresnel band. That is, the weight allocation itself implicitly contains a comprehensive evaluation of absorption compensation effect, aperture fit quality, and noise suppression level.

[0088] The following example, using two-dimensional bend width line data from a loess plateau, illustrates the application effect of the method provided in this embodiment. This data, after undergoing a pre-processing workflow for pre-stack seismic data migration based on two-dimensional bend width lines, has a total data volume of approximately 1.1 GB, a maximum migration distance of 3903 meters, a data sampling interval of 2 milliseconds, and 2501 data sampling points. Figure 2The diagram shows the distribution of CMP points in the bend width line data. It can be seen that the CMP points are not distributed in a traditional straight line, but rather in a continuous curved line along the structural direction of the work area. This reflects the typical characteristics of a two-dimensional bend width line observation system and also places higher demands on the geometric adaptability of subsequent migration imaging. To verify the imaging effect of the method of this invention, four methods were used to image the preprocessed data: conventional pre-stack time migration using commercial software, dip-domain stable-phase pre-stack time migration, conventional aperture absorption-compensated pre-stack time migration, and the dip-domain stable-phase absorption-compensated pre-stack time migration of the two-dimensional bend width line of this invention. The superiority of the method of this invention was verified by comparing the qualitative characteristics and quantitative indicators of the imaging profile.

[0089] Figure 3 This is a schematic diagram of a local imaging profile from pre-stack time migration using conventional commercial software, provided as an embodiment of the present invention. Conventional commercial software employs a fixed aperture scheme based on the assumption of straight survey lines for pre-stack time migration. The aperture parameters only change vertically with time, without any lateral adjustment, and do not consider formation viscoelastic absorption effects or migration noise suppression. Figure 3 The local imaging profile shows that the profile is severely offset by noise, the continuity of the effective reflected wave phase axis is poor, and the mid-to-deep reflected signals are masked by noise, which completely fails to meet the needs of fine exploration in the work area.

[0090] Figure 4 This is a schematic diagram of a local imaging profile of a two-dimensional flexural width line dip-domain steady-phase pre-stack time migration provided in an embodiment of the present invention. After processing with the two-dimensional flexural width line dip-domain steady-phase pre-stack time migration method, the optimal aperture superposition is achieved by constructing the tangential dip angle gather of the flexural width line CMP point and picking the Fresnel zone of the dip angle domain. The migration noise of the imaging profile processed by this method is significantly reduced and the continuity of the effective reflected wave phase axis is greatly improved. However, this method does not consider the viscoelastic absorption effect of the formation and does not perform wavefield energy attenuation and wavelet dispersion compensation. The high-frequency components of the seismic waves are still greatly lost, the profile resolution is insufficient, and it is still difficult to meet the positioning requirements of fine exploration in the work area.

[0091] Figure 5 This invention provides a schematic diagram of a local imaging profile of a two-dimensional curved-width line phase absorption compensation pre-stack time migration using conventional aperture. The method employs a curved-width line reflection seismic data Q-value field modeling approach combined with a conventional migration aperture to achieve absorption compensation during pre-stack time migration. This effectively compensates for wavefield attenuation and dispersion caused by viscoelastic absorption in the loess layer, restoring the high-frequency effective seismic signal. The resolution is significantly improved compared to commercial software and pure steady-state phase migration. However, this method uses the migration aperture of conventional commercial software and does not introduce noise suppression constraints from the dip-domain Fresnel zone. While Q-compensation restores the high-frequency signal, it simultaneously amplifies the scattering noise of the migration operator, significantly increasing the profile background noise. Some weakly reflected effective signals are masked by the amplified noise.

[0092] Figure 6 This invention provides a schematic diagram of a local imaging profile of a two-dimensional bend width line with dip-domain steady-state absorption compensation before stacking time migration. After processing the two-dimensional bend width line data of the Loess Plateau using the method of this invention, a deep fusion of dip-domain steady-state migration and absorption compensation specific to the bend width line is achieved. On the one hand, it inherits the core advantages of dip-domain steady-state pre-stack time migration, constructing a tangential dip angle gather and dynamically adjusting the Fresnel zone boundary with the Q-compensation dominant frequency to achieve precise adaptation of the bend width line's geometric features and efficient suppression of migration noise. On the other hand, it integrates the high-precision equivalent Q-value field modeling technology of conventional aperture absorption compensation pre-stack time migration to complete precise compensation for wavefield energy attenuation and wavelet dispersion. Simultaneously, Fresnel zone constraints avoid the noise amplification problem of Q-compensation. From the qualitative characteristics of the imaging profile, the overall migration noise of the profile is effectively suppressed, the continuity of the effective reflected wave phase axis is significantly improved compared to the previous three methods, the profile signal-to-noise ratio and resolution are synergistically optimized, and the imaging integrity and clarity of fine structures are significantly improved.

[0093] Figure 7 This is a schematic diagram comparing the spectrum of a local imaging profile provided in an embodiment of the present invention. The overall spectrum comparison between the offset profile of commercial software and the steady-phase viscoelastic offset profile in the tilt domain clearly shows from the curve trend that, compared with the conventional offset profile of commercial software, the main frequency of the profile processed by the method of the present invention is increased by more than 10 Hz, the spectral width of the effective signal is simultaneously expanded by more than 10 Hz, and the amplitude attenuation rate of the effective signal at the high-frequency end is significantly slowed down. This indicates that the method of the present invention effectively recovers the high-frequency signal lost by the viscoelastic absorption of the loess layer through absorption compensation of the equivalent Q-value field, and achieves a substantial improvement in imaging resolution.

[0094] Figure 8 The comparison chart of signal-to-noise ratio versus frequency provided in the embodiments of the present invention shows that the method of the present invention effectively suppresses high-frequency noise while restoring high-frequency signals through Fresnel band dynamic adjustment and high cutoff frequency constraint, thus solving the core contradiction of resolution improvement accompanied by signal-to-noise ratio degradation and achieving optimal synergy between the two.

[0095] Figure 9 Provided for embodiments of the present invention Figure 3 , 4 The magnified comparison images of imaging profiles 5 and 6 demonstrate the core effects of this invention. These profiles combine the advantages of high signal-to-noise ratio and high resolution, clearly revealing the "beaded" structural features of the karst reservoir. The development location, longitudinal distribution, and lateral boundaries of the karst caves are precisely depicted. Simultaneously, background noise is effectively suppressed, and the energy characteristics of the effectively reflected waves are clearer, achieving precise imaging of the fine structure of the karst reservoir and fully meeting the needs of fine oil and gas exploration in the Loess Plateau two-dimensional bend-wide line work area.

[0096] In summary, this invention addresses the unique characteristics of two-dimensional curved-width line reflection seismic data by performing a curved-width line-specific global adaptive reconstruction and integrated process fusion on the traditional straight-line / three-dimensional steady-phase absorption compensation fusion technology. This solves the problems of fusion imaging distortion and the inability to synergistically improve signal-to-noise ratio and resolution caused by incompatible geometric frameworks and fragmented processes in existing technologies.

[0097] Specifically, this invention abandons the traditional aperture-unconstrained inverse Q gather generation mode and fixed Fresnel band setting logic, and designs a Fresnel band-constrained inverse Q gather generation scheme. Simultaneously, based on the initial dominant frequency and the target dominant frequency after Q compensation, the Fresnel band is dynamically adjusted, both suppressing noise at the source to improve Q-value pickup accuracy and achieving precise matching between the Fresnel band and high-frequency signals. Furthermore, a dedicated stable-phase absorption compensation fusion offset formula for curved lines is constructed, enabling simultaneous execution of noise suppression and absorption compensation. The stable-phase offset noise suppression logic is integrated into the entire Q-value field modeling process, solving the core problem of the inability to synergistically improve fusion imaging distortion and signal-to-noise ratio resolution.

[0098] Example 2 This invention also provides a two-dimensional bend width line tilt angle domain steady-state absorption compensation pre-stack time migration device. This device is mainly used to execute the two-dimensional bend width line tilt angle domain steady-state absorption compensation pre-stack time migration method provided in Embodiment 1 above. The following is a detailed description of the two-dimensional bend width line tilt angle domain steady-state absorption compensation pre-stack time migration device provided in this invention.

[0099] Figure 10 A functional block diagram of a two-dimensional curved line dip angle domain stable phase absorption compensation pre-stack time migration device provided in an embodiment of the present invention is shown below. Figure 10 As shown, the device mainly includes: an acquisition module 10, a first determination module 20, a construction module 30, a correction and offset module 40, and a second determination module 50, wherein: The acquisition module 10 is used to acquire two-dimensional pre-stack seismic data of the target work area and preprocess it to obtain standard seismic data, the center line of the CMP (Center for Motion Mass Mapping), the migration velocity field, and the stretching cut parameters of the CMP point gather.

[0100] The first determination module 20 is used to determine the dip domain Fresnel zone of the target work area based on standard seismic data, the center line of the curve width line (CMP), and the migration velocity field.

[0101] Module 30 is used to generate inverse Q gathers under Fresnel zone constraints based on dip domain Fresnel zone and standard seismic data, so as to construct the equivalent Q-value field and high cutoff field of the target work area based on the inverse Q gathers.

[0102] The correction and migration module 40 is used to correct the dip domain Fresnel zone based on the equivalent Q value field, and to perform migration calculations on the standard seismic data according to the offset distance based on the corrected dip domain Fresnel zone, equivalent Q value field and high cutoff frequency field, so as to obtain the migration results corresponding to each set of offset distances.

[0103] The second determining module 50 is used to determine the imaging profile of the target work area based on the stretching excision parameters and the offset results corresponding to each set of offset distances.

[0104] This invention provides a two-dimensional, angular-domain, steady-state absorption compensation pre-stack time migration device. After determining the angular-domain Fresnel zone of the target area, the device generates an inverse Q-gather using this Fresnel zone as a constraint. This ensures that Q-value compensation only applies to the most effective signal region for imaging. Furthermore, based on the established equivalent Q-value field, the Fresnel zone is corrected, causing its width to linearly expand with the effective signal bandwidth. This fully encompasses the high-frequency effective signal recovered by Q-compensation while maintaining precise suppression of migration noise. Finally, under the joint constraints of the corrected Fresnel zone, the equivalent Q-value field, and the high-cutoff field, migration calculations are performed grouped by offset distance, achieving simultaneous completion of noise suppression and absorption compensation within the same framework. In the two-dimensional bend width line observation system, this device achieves closed-loop coupling of Fresnel zone aperture constraint and viscoelastic absorption compensation. This not only suppresses the amplification of migration noise caused by Q compensation, but also avoids the truncation loss of high-frequency signals after compensation due to the fixed aperture. Thus, while maintaining the geometric fidelity of the imaging of steep-angle structures, it simultaneously improves the signal-to-noise ratio and resolution of the imaging profile. This alleviates the technical problem of traditional migration methods in the field of bend width line data processing, which is difficult to balance between signal-to-noise ratio and imaging resolution.

[0105] Optionally, the first determining module 20 is specifically used for: Using the migration velocity field, the contribution of each seismic trace to the tangential dip angle of the imaging point corresponding to each CMP point on the center line of the curve width line is calculated.

[0106] All seismic traces are iterated, pre-stack time migration is performed on the standard seismic data, and the migration results of each seismic trace are sorted and arranged according to the tangential dip angle to obtain the tangential dip angle gather for each CMP point.

[0107] Based on the tangential tilt gather of the target CMP point, the Fresnel zone boundary of the imaging point corresponding to the target CMP point is picked; where the target CMP point represents any one of the multiple key CMP points on the center line of the curved width line CMP.

[0108] The Fresnel zone boundary of the imaging point corresponding to the target CMP point is interpolated across the entire imaging area and spatially smoothed to obtain the Fresnel zone in the tilt domain of the target imaging area.

[0109] Optionally, module 30 is specifically used for: Obtain the Q-value scanning range and interval that match the formation absorption characteristics of the target work area.

[0110] The initial set of Q values ​​is determined based on the Q-value scanning range and interval.

[0111] By sequentially using each Q value in the initial Q value set, inverse Q filtering is performed on the data of each seismic trace in the standard seismic data to obtain the inverse Q filtering result of each seismic trace at each Q value.

[0112] Under the constraint of the dip domain Fresnel zone, the inverse Q filtering results of each seismic trace at each Q value are batch-processed with pre-stack time migration calculation to obtain the inverse Q migration profile corresponding to each Q value.

[0113] The inverse Q gather is determined based on all inverse Q offset profiles.

[0114] Optionally, building module 30 is also used for: Determine multiple equivalent Q-analysis windows that match the geological structure of the target work area.

[0115] Calculate the noise level of each equivalent Q analysis window at each Q value, and use a preset noise level threshold to select a set of candidate Q values ​​for each equivalent Q analysis window from the initial set of Q values.

[0116] Based on the criterion of maximizing the effective spectral width after compensation, and combined with the preset imaging quality index, the optimal equivalent Q value is determined from its candidate Q value set for each equivalent Q analysis window, and the frequency point in the compensation profile corresponding to the optimal Q value that matches the noise threshold is taken as the high cutoff frequency of the window.

[0117] Using the equivalent Q value and high cutoff frequency of each equivalent Q analysis window as nodes, interpolation and spatial smoothing are performed across the entire work area to obtain the equivalent Q value field and high cutoff frequency field of the target work area.

[0118] Optionally, the correction and offset module 40 includes: The extraction unit is used to extract the Q value corresponding to the preset key layer in the target work area from the equivalent Q value field.

[0119] The transformation unit is used to perform Fourier transform on the seismic data in the offset profile corresponding to the preset key layer based on the Q value, so as to determine the first dominant frequency in its superimposed spectrum.

[0120] The acquisition unit is used to acquire the second dominant frequency in standard seismic data.

[0121] The correction unit is used to correct the tilt-domain Fresnel band based on the first and second main frequencies to obtain the corrected tilt-domain Fresnel band.

[0122] Optionally, the correction and offset module 40 also includes: The first building unit is used to construct a stable phase weighting function based on the corrected dip domain Fresnel zone and the contribution of each seismic trace to the tangential apparent dip angle of the corresponding imaging point at each CMP point.

[0123] The second building unit is used to construct the offset formula for each imaging point at each offset distance based on the stable phase weighting function, the equivalent Q-value field, and the high cutoff frequency field.

[0124] The migration imaging unit is used to group standard seismic data into offset intervals, and for each offset data group, it iterates through all imaging points, substitutes them into the migration formula to perform migration calculation, and generates the migration result corresponding to each offset.

[0125] Optionally, the second determining module 50 is specifically used for: The offset results corresponding to each offset are arranged to construct the CRP offset gather.

[0126] The CRP offset gather is subjected to stretch cut processing using stretch cut parameters to obtain the stretched cut CRP offset gather.

[0127] The CRP offset gathers after stretching and shearing are weighted and superimposed along the offset direction to obtain the imaging profile of the target work area.

[0128] Example 3 See Figure 11 This invention provides an electronic device, which includes a processor 60, a memory 61, a bus 62, and a communication interface 63. The processor 60, the communication interface 63, and the memory 61 are connected via the bus 62. The processor 60 is used to execute executable modules, such as computer programs, stored in the memory 61.

[0129] The memory 61 may include high-speed random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface 63 (which can be wired or wireless), such as the Internet, wide area network, local area network, metropolitan area network, etc.

[0130] Bus 62 can be an ISA bus, PCI bus, or EISA bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 11 The symbol is represented by a single double-headed arrow, but this does not mean that there is only one bus or one type of bus.

[0131] The memory 61 is used to store programs. After receiving an execution instruction, the processor 60 executes the program. The method executed by the apparatus defined by the process disclosed in any of the foregoing embodiments of the present invention can be applied to the processor 60 or implemented by the processor 60.

[0132] Processor 60 may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by the integrated logic circuitry in the hardware of processor 60 or by instructions in software form. Processor 60 can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in memory 61. Processor 60 reads the information in memory 61 and, in conjunction with its hardware, completes the steps of the above method.

[0133] The computer program product of the two-dimensional bending width line dip angle domain steady phase absorption compensation pre-stack time migration method provided in the embodiments of the present invention includes a computer-readable storage medium storing non-volatile program code executable by a processor. The instructions included in the program code can be used to execute the methods described in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.

[0134] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0135] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0136] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0137] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0138] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0139] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for compensating pre-stack time migration by stable phase absorption in the dip angle domain of a two-dimensional curved line, characterized in that, include: Two-dimensional pre-stack seismic data of the bend width line of the target work area were acquired and preprocessed to obtain standard seismic data, the center line of the bend width line CMP, the migration velocity field and the stretching shear parameters of the CMP point gather; Based on the standard seismic data, the CMP centerline, and the migration velocity field, the dip domain Fresnel zone of the target work area is determined; Based on the dip-domain Fresnel zone and the standard seismic data, an inverse Q gather constrained by the Fresnel zone is generated, and the equivalent Q-value field and high cutoff frequency field of the target work area are constructed based on the inverse Q gather; The dip domain Fresnel zone is corrected based on the equivalent Q-value field, and the standard seismic data is offset according to the offset distance based on the corrected dip domain Fresnel zone, the equivalent Q-value field, and the high cutoff frequency field to obtain the offset result corresponding to each set of offset distances; Based on the stretching and cutting parameters and the offset results corresponding to each set of offset distances, the imaging profile of the target work area is determined; The correction of the Fresnel zone in the tilt region based on the equivalent Q-value field includes: Extract the Q value corresponding to the preset key layer in the target work area from the equivalent Q value field; Based on the Q value corresponding to the preset key layer, a Fourier transform is performed on the seismic data in the offset profile corresponding to the Q value to determine the first dominant frequency in its superimposed spectrum. Obtain the second dominant frequency from the standard seismic data; Based on the first main frequency and the second main frequency, the tilt-domain Fresnel band is modified to obtain the modified tilt-domain Fresnel band.

2. The two-dimensional curved line dip angle domain stable phase absorption compensation pre-stack time migration method according to claim 1, characterized in that, Based on the standard seismic data, the CMP centerline of the bend width line, and the migration velocity field, the dip-domain Fresnel zone of the target work area is determined, including: Using the aforementioned offset velocity field, the contribution of each seismic trace to the tangential dip angle of the imaging point corresponding to each CMP point on the center line of the curve width CMP is calculated; All seismic traces are looped through, and pre-stack time migration is performed on the standard seismic data. The migration results of each seismic trace are sorted and arranged according to the tangential dip angle to obtain the tangential dip angle gather for each CMP point. Based on the tangential tilt gather of the target CMP point, the Fresnel zone boundary of the imaging point corresponding to the target CMP point is picked; wherein, the target CMP point represents any one of the multiple key CMP points on the center line of the curved width line CMP. The Fresnel zone boundary of the imaging point corresponding to the target CMP point is interpolated and spatially smoothed over the entire imaging area to obtain the tilt domain Fresnel zone of the target imaging area.

3. The two-dimensional curved line dip angle domain stable phase absorption compensation pre-stack time migration method according to claim 1, characterized in that, Based on the dip-domain Fresnel zone and the standard seismic data, an inverse Q-gather under Fresnel zone constraints is generated, including: Obtain the Q-value scanning range and interval that match the formation absorption characteristics of the target work area; Based on the Q-value scanning range and interval, an initial set of Q-values ​​is determined; By sequentially using each Q value in the initial Q value set, inverse Q filtering is performed on the data of each seismic trace in the standard seismic data to obtain the inverse Q filtering result of each seismic trace at each Q value; Under the constraint of the dip domain Fresnel zone, the inverse Q filtering results of each seismic trace at each Q value are batch-processed with pre-stack time migration calculation to obtain the inverse Q migration profile corresponding to each Q value; The inverse Q gather is determined based on all inverse Q offset profiles.

4. The two-dimensional curved line dip angle domain stable phase absorption compensation pre-stack time migration method according to claim 3, characterized in that, Constructing the equivalent Q-value field and high cutoff field of the target work area based on the inverse Q gather includes: Determine multiple equivalent Q-analysis windows that match the geological structure of the target work area; Calculate the noise level of each equivalent Q analysis window at each Q value, and use a preset noise level threshold to filter out a set of candidate Q values ​​for each equivalent Q analysis window from the initial set of Q values; Based on the criterion of maximizing the effective spectral width after compensation, and combined with the preset imaging quality index, the optimal equivalent Q value is determined from its candidate Q value set for each equivalent Q analysis window, and the frequency point in the compensation profile corresponding to the optimal Q value that matches the noise threshold is taken as the high cutoff frequency of the window. Using the equivalent Q value and high cutoff frequency of each equivalent Q analysis window as nodes, interpolation and spatial smoothing are performed across the entire work area to obtain the equivalent Q value field and high cutoff frequency field of the target work area.

5. The two-dimensional curved line dip angle domain stable phase absorption compensation pre-stack time migration method according to claim 2, characterized in that, Based on the corrected dip-domain Fresnel zone, the equivalent Q-value field, and the high-frequency cutoff field, the standard seismic data is migrated according to the offset, including: Based on the corrected dip domain Fresnel zone and the contribution of each seismic trace to the tangential apparent dip angle of the corresponding imaging point at each CMP point, a stable phase weighting function is constructed; Based on the phase-stabilizing weighting function, the equivalent Q-value field, and the high-frequency cutoff field, an offset formula for each imaging point at each offset distance is constructed. The standard seismic data is grouped according to offset intervals. For each group of offset data, all imaging points are iterated and the offset calculation is performed by substituting them into the offset formula to generate the offset result corresponding to each group of offsets.

6. The two-dimensional curved line dip angle domain stable phase absorption compensation pre-stack time migration method according to claim 1, characterized in that, Based on the stretching resection parameters and the offset results corresponding to each set of offset distances, the imaging profile of the target work area is determined, including: The offset results corresponding to each set of offsets are arranged to construct a CRP offset gather; The CRP offset gather is subjected to stretching and cutting processing using the stretching and cutting parameters to obtain the stretched and cut CRP offset gather. The CRP offset gathers after stretching and shearing are weighted and superimposed along the offset direction to obtain the imaging profile of the target work area.

7. A two-dimensional curved line dip angle domain stable phase absorption compensation pre-stack time migration device, characterized in that, include: The acquisition module is used to acquire two-dimensional pre-stack seismic data of the bend width line of the target work area and preprocess it to obtain standard seismic data, the center line of the bend width line CMP, the migration velocity field and the stretching cut parameters of the CMP point gather; The first determining module is used to determine the dip domain Fresnel zone of the target work area based on the standard seismic data, the CMP centerline, and the migration velocity field. The construction module is used to generate an inverse Q gather under Fresnel zone constraints based on the dip domain Fresnel zone and the standard seismic data, so as to construct the equivalent Q-value field and high cutoff frequency field of the target work area based on the inverse Q gather; The correction and migration module is used to correct the dip domain Fresnel zone based on the equivalent Q value field, and to perform migration calculation on the standard seismic data according to the migration distance based on the corrected dip domain Fresnel zone, the equivalent Q value field and the high cutoff frequency field, so as to obtain the migration result corresponding to each set of migration distances. The second determining module is used to determine the imaging profile of the target work area based on the stretching resection parameters and the offset results corresponding to each set of offset distances; The correction and offset modules include: Extraction unit, used to extract the Q value corresponding to the preset key layer in the target work area in the equivalent Q value field; The transformation unit is used to perform Fourier transform on the seismic data in the offset profile corresponding to the preset key layer based on the Q value, so as to determine the first dominant frequency in its superimposed spectrum. The acquisition unit is used to acquire the second dominant frequency in the standard seismic data; The correction unit is used to correct the tilt-domain Fresnel band based on the first main frequency and the second main frequency to obtain the corrected tilt-domain Fresnel band.

8. An electronic device comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, characterized in that, When the processor executes the computer program, it implements the two-dimensional bending width line tilt angle domain steady phase absorption compensation pre-stack time migration method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed by a processor, implement the two-dimensional flexural width line dip angle domain stable phase absorption compensation pre-stack time migration method according to any one of claims 1 to 6.

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