A wave equation common imaging point gather generation method, device, equipment and medium

Abstract

This disclosure relates to the field of seismic imaging technology, and particularly to a method, apparatus, device, and medium for generating common imaging point gathers for wave equations. The method includes: identifying a source wavelet based on a selected source location; synthesizing the return wavefield of a single-channel seismic record corresponding to a geophone based on the forward propagation wavefield of the source wavelet and a pre-determined linear filter; synthesizing a single-channel seismic image corresponding to the single-channel seismic record using the return wavefield and the forward propagation wavefield; calculating the offset distance corresponding to each single-channel seismic image; classifying the single-channel seismic images according to the offset distance; and superimposing the classified single-channel seismic images to obtain an offset common imaging point gather; performing amplitude processing on the offset common imaging point gathers; and determining the amplitude-processed offset imaging point gathers as the common imaging point gathers for wave equations. This disclosure can improve the efficiency of common imaging point gather generation.

Description

Technical Field

[0001] This disclosure relates to the field of seismic imaging technology, and in particular to a method, apparatus, device, and medium for generating common imaging point gathers for wave equations. Background Technology

[0002] In the field of geophysical exploration, especially in seismic exploration, the generation of common imaging point gathers plays a crucial role in accurately revealing underground geological structures, conducting geological interpretation, and subsequent resource exploration (such as the search for oil and natural gas). By analyzing common imaging point gathers, key information such as interfaces between different underground strata and geological structures can be obtained, providing a strong basis for relevant decision-making.

[0003] Conventional wave equation methods simultaneously migrate / return data at the full offset, but do not generate offset common imaging point gathers during this process. Instead, they generate response gathers by multiple offset migrations at different offsets. This leads to a computational cost that increases exponentially with the number of migrations, making it impractical in real-world production and resulting in low efficiency in generating common imaging point gathers. Summary of the Invention

[0004] This disclosure provides a method, apparatus, device, and medium for generating common imaging point gathers for wave equations, in order to solve the problem of low efficiency in generating common imaging point gathers.

[0005] Firstly, this disclosure provides a method for generating common imaging point gathers for wave equations, including:

[0006] Identify the source wavelet based on the pre-selected source location, and synthesize the return wavelet of the single-channel seismic record corresponding to the detector based on the forward propagation wavefield of the source wavelet and the pre-determined linear filter.

[0007] The single-channel seismic image corresponding to the single-channel seismic record is synthesized by combining the back propagation wavefield and the forward propagation wavefield corresponding to the single-channel seismic record.

[0008] Calculate the offset distance corresponding to each single-track seismic image, classify the single-track seismic images according to the offset distance, and stack the classified single-track seismic images to obtain the offset common imaging point gather.

[0009] The offset common imaging point gather is subjected to amplitude processing, and the amplitude-processed offset imaging point gather is determined as the common imaging point gather of the wave equation.

[0010] In some embodiments, identifying the source wavelet based on a pre-selected source location includes:

[0011] The location of the detector is determined based on the pre-selected location of the seismic source;

[0012] Seismic waves are generated at the hypocenter location, and seismic signals after the seismic waves are generated are received at the detector location;

[0013] The first arrival time of the seismic wave is identified based on the seismic signal, the first arrival wave data is extracted based on the first arrival time, and the first arrival wave data is determined as the source wavelet.

[0014] In some embodiments, the step of synthesizing the return wavefield of the single-channel seismic record corresponding to the detector based on the forward propagation wavefield of the source wavelet and a predetermined linear filter includes:

[0015] Based on the predetermined filter coefficients of the linear filter and the forward propagation wavefield of the source wavelet, the detector synthesizes the initial return wavefield, where the return formula for the initial return wavefield is:

[0016]

[0017] in, x is the location of the earthquake source. s Excitation, at detector position x r The received seismic record feedback, the wavefield value at model spatial location x at time t, U f (x,x′ s =x r ,t-τ(i)) represents the earthquake source at x r The value of the propagating wave field excited at point x at spatial location x after a time delay t-τ(i), where n is the maximum wave field propagation time step, w(i) is the filter coefficient at the i-th wave field propagation time step, and τ(i) is the time delay at the i-th wave field propagation time step.

[0018] The initial propagation wavefield is optimized by a preset least squares matching error algorithm until the least squares matching error reaches a preset matching error threshold.

[0019] When the least squares matching error reaches the preset matching error threshold, the optimized initial return wavefield is used as the return wavefield of the single-channel seismic record corresponding to the detector.

[0020] In some embodiments, optimizing the initial propagation wavefield using a preset least-squares matching error algorithm includes:

[0021] The least-squares matching error between the source wavelet and filter coefficients corresponding to the initial returned wavefield and the pre-acquired actual seismic record is calculated using the following preset least-squares matching error algorithm:

[0022]

[0023] Where φ(w) is the least squares matching error under filter coefficient w, d is the actual earthquake record, w(i) is the filter coefficient under the i-th wavefield propagation time step, f(τ(i)) is the source wavelet after time delay τ(i), and n is the maximum wavefield propagation time step.

[0024] The filter coefficients are adjusted according to the least squares matching error, and the adjusted filter coefficients are updated in the least squares matching error algorithm to obtain the least squares matching error update value.

[0025] When the least squares matching error update value reaches the preset matching error threshold, the adjusted filter coefficients are updated into the synthesis formula of the initial return wave field to obtain the optimized return wave field.

[0026] In some embodiments, the step of synthesizing a single-channel seismic image corresponding to a single-channel seismic record by combining the propagating wavefield and the forward propagating wavefield corresponding to the single-channel seismic record includes:

[0027] According to a pre-set imaging condition processing operator, the propagating wavefield and the forward propagating wavefield corresponding to the single-channel seismic record are synthesized into a single-channel seismic image, wherein the synthesis formula for the single-channel seismic image is:

[0028]

[0029] in, At the epicenter location x s Excitation, at detector position x r The single-channel seismic image synthesized at the model's spatial location x during the received seismic record transmission process, where A is the imaging condition processing operator, and U... f (x,x s ,τ(i)) is the earthquake source at x s A forward propagating wave field excited at location x in the model space, with a propagation time of τ(i). x is the location of the earthquake source. s Excitation, at detector position x r The received earthquake record is transmitted back, and the back propagated wavefield is located at position x in the model space after a time delay of t-τ(i), where n is the maximum wavefield propagation time step.

[0030] In some embodiments, calculating the offset corresponding to each of the single-channel seismic images includes:

[0031] Obtain the target source location and target detector location for each single-channel seismic image;

[0032] Calculate the offset between the target seismic source location and the target geophone location one by one, wherein the offset calculation formula is:

[0033]

[0034] in, Single-channel seismic imaging The corresponding offset distance, x s Let x be the location of the target seismic source. r The target detector position is indicated.

[0035] In some embodiments, the step of stacking the classified single-channel seismic images to obtain the offset common imaging point gather includes:

[0036] Extract the seismic imaging dataset corresponding to the classified single-channel seismic images;

[0037] Extract the depth domain corresponding to each single-channel seismic image from the seismic imaging dataset;

[0038] Each single-track seismic image in the seismic imaging dataset is depth-stacked according to the depth domain, and the stacked seismic imaging dataset is used as an offset common imaging point gather.

[0039] Secondly, this disclosure provides a wave equation common imaging point gather generation device, comprising:

[0040] The return wave field generation module is used to identify the source wavelet according to the pre-selected source location, and synthesize the return wave field of the single-channel seismic record corresponding to the detector based on the forward propagation wave field of the source wavelet and the pre-determined linear filter.

[0041] A single-channel seismic imaging synthesis module is used to synthesize a single-channel seismic image corresponding to the single-channel seismic record by means of the backpropagation wavefield and the forward propagation wavefield corresponding to the single-channel seismic record.

[0042] The offset common imaging point gather stacking module is used to calculate the offset corresponding to each single-track seismic image, classify the single-track seismic images according to the offset, and stack the classified single-track seismic images to obtain the offset common imaging point gather.

[0043] The common imaging point gather generation module is used to perform amplitude processing on the offset common imaging point gather and determine the amplitude-processed offset imaging point gather as the common imaging point gather of the wave equation.

[0044] Thirdly, this disclosure provides a computer device including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the wave equation common imaging point gather generation method described above.

[0045] Fourthly, this disclosure provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the wave equation common imaging point gather generation method described above.

[0046] This disclosure provides a method, apparatus, device, and medium for generating common imaging point gathers for wave equations. It identifies the source wavelet based on the source location, synthesizes the return wavefield of the single-channel seismic record corresponding to the detector based on the forward propagation wavefield of the source wavelet and a pre-determined linear filter, synthesizes the single-channel seismic image corresponding to the single-channel seismic record using the return wavefield and the forward propagation wavefield corresponding to the single-channel seismic record, calculates the offset distance corresponding to each single-channel seismic image, classifies the single-channel seismic images according to the offset distance, and superimposes the classified single-channel seismic images to obtain offset common imaging point gathers. It then performs amplitude processing on the offset common imaging point gathers and determines the amplitude-processed offset imaging point gathers as the common imaging point gathers for the wave equation. This solves the problem that computational costs increase exponentially with the number of offsets, making it unbearable in actual production, and improves the efficiency of common imaging point gather generation.

[0047] 1. Technical Features: Based on the principle of wave field superposition, a linear filter is calculated at the selected seismic source location. The wave field returned by the detector is synthesized according to the forward modeling wave field of the seismic source wavelet. The technical effect is to solve the problem of inaccurate wave field caused by the difference between the theoretical model and the actual seismic record during the synthesis of the returned wave field.

[0048] 2. Technical Features: Based on the imaging conditions derived from cross-correlation calculations, single-channel seismic imaging is synthesized by using the propagation wavefield of each seismic record and the forward propagation wavefield of the corresponding shot. The technical effect is to solve the problem that traditional imaging methods cannot make full use of the inherent correlation between the forward and return wavefields to accurately construct single-channel seismic imaging, resulting in low imaging resolution and unclear characterization of complex geological structures.

[0049] 3. The technical feature calculates the offset distance corresponding to each single-channel seismic image and superimposes images with similar offset distances to synthesize a common offset imaging point gather. The technical effect is to solve the problems of scattered single-channel seismic imaging information, difficulty in grasping the overall picture of underground geological structure, and ineffective comprehensive utilization of imaging features under different offset distances. Attached Figure Description

[0050] The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings:

[0051] Figure 1 A flowchart illustrating a method for generating common imaging point gathers for wave equations provided in this embodiment of the present disclosure;

[0052] Figure 2A schematic diagram illustrating the size of the work area provided in this embodiment of the disclosure;

[0053] Figure 3 A schematic diagram illustrating the distribution of shot point positions and offset distances provided in the embodiments of this disclosure;

[0054] Figure 4a A schematic diagram of amplitude variation of a linear filter provided in an embodiment of this disclosure;

[0055] Figure 4b A schematic diagram showing the comparison between synthetic records and actual seismic records provided in the embodiments of this disclosure;

[0056] Figure 4c A schematic diagram of the synthesized wave field provided in an embodiment of this disclosure;

[0057] Figure 4d A schematic diagram of the target wave field provided in an embodiment of this disclosure;

[0058] Figure 5 A schematic diagram of a synthesized offset co-imaging point gather provided in an embodiment of this disclosure;

[0059] Figure 6 This is a functional block diagram of a wave equation common imaging point gather generation device provided in an embodiment of the present disclosure.

[0060] In the accompanying drawings, the same parts are referred to by the same reference numerals, and the drawings are not drawn to scale. Detailed Implementation

[0061] To enable those skilled in the art to better understand the technical solutions of this disclosure, and to fully understand and implement the process of how this disclosure applies technical means to solve technical problems and achieve corresponding technical effects, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. The embodiments of this disclosure and the various features within them can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort should fall within the protection scope of this disclosure.

[0062] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0063] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0064] Example 1

[0065] Figure 1 This is a schematic flowchart illustrating a method for generating common imaging point gathers for wave equations, provided in an embodiment of this disclosure. Figure 1 As shown, a method for generating common imaging point gathers for wave equations includes:

[0066] S1. Identify the source wavelet based on the pre-selected source location, and synthesize the return wavelet of the single-channel seismic record corresponding to the detector based on the forward propagation wavefield of the source wavelet and the pre-determined linear filter.

[0067] In this embodiment of the invention, the source wavelet is the most basic seismic wave signal generated by the source in seismic exploration. It is the initial waveform of the seismic wave that has not been affected by the complex propagation of the underground medium. It is like the most primitive ground wave pattern generated when the vibrating device first strikes the ground. This primitive wave will propagate to the surroundings and underground, forming a forward propagation wave field.

[0068] In this embodiment of the invention, identifying the source wavelet based on the pre-selected source location includes:

[0069] The location of the detector is determined based on the pre-selected location of the seismic source;

[0070] Seismic waves are generated at the hypocenter location, and seismic signals after the seismic waves are generated are received at the detector location;

[0071] The first arrival time of the seismic wave is identified based on the seismic signal, the first arrival wave data is extracted based on the first arrival time, and the first arrival wave data is determined as the source wavelet.

[0072] In detail, each pre-defined source location has a corresponding geophone location. When a seismic wave is generated at the source location, the geophone records the seismic signal that changes over time. The seismic signal includes information about the source wavelet after propagation, reflection, and refraction through the underground medium. The first arrival time of the seismic wave, i.e. the time when the seismic wave first arrives at the geophone, can be identified from the seismic signal recorded by the geophone. The first arrival time of the seismic wave can be determined by looking for sudden amplitude changes based on the waveform of the seismic signal. Based on the first arrival time, the data of the first arrival wave portion can be extracted from the seismic signal. The first arrival wave data is the part of the seismic wave that propagates directly from the source to the geophone and contains the content closest to the original information of the source wavelet. Thus, the source wavelet corresponding to a single seismic record can be determined based on the source location and the geophone location.

[0073] Furthermore, based on the principle of wave field superposition, a linear filter is calculated at the selected source location, and the detector return wave field is synthesized according to the forward wave field of the source wavelet.

[0074] In this embodiment of the invention, the back-propagating wave field refers to the wave field that the seismic wave, triggered by the seismic source, propagates through the underground medium (including reflection, refraction, etc.) and then propagates back to the detector position. The back-propagating wave field carries information about the underground geological structure because the wave interacts with different underground media during propagation, and the changes in its waveform, amplitude, phase, and other characteristics reflect the properties and structure of the underground medium.

[0075] In this embodiment of the invention, the step of synthesizing the return wavefield of the single-channel seismic record corresponding to the detector based on the forward propagation wavefield of the source wavelet and a pre-determined linear filter includes:

[0076] Based on the predetermined filter coefficients of the linear filter and the forward propagation wavefield of the source wavelet, the detector synthesizes the initial return wavefield, where the return formula for the initial return wavefield is:

[0077]

[0078] in, x is the location of the earthquake source. s Excitation, at detector position x r The received seismic record feedback, the wavefield value at model spatial location x at time t, U f (x,x′ s =x r ,t-τ(i)) represents the earthquake source at x rThe value of the propagating wave field excited at point x at spatial location x after a time delay t-τ(i), where n is the maximum wave field propagation time step, w(i) is the filter coefficient at the i-th wave field propagation time step, and τ(i) is the time delay at the i-th wave field propagation time step.

[0079] The initial propagation wavefield is optimized by a preset least squares matching error algorithm until the least squares matching error reaches a preset matching error threshold.

[0080] When the least squares matching error reaches the preset matching error threshold, the optimized initial return wavefield is used as the return wavefield of the single-channel seismic record corresponding to the detector.

[0081] In detail, the forward propagation wavefield of the source wavelet is the wavefield propagating outward from the source. The return wavefield of the detector is synthesized based on the forward propagation wavefield and the filter coefficients of the linear filter. In the return formula, τ(i) considers the time delay during wave propagation. Different i correspond to different delay conditions. n is the maximum wavefield propagation time step, which represents the upper limit of all possible time delay conditions. The filter coefficients are equivalent to weighting the forward propagation wavefield under different delay conditions. By weighting and summing the forward propagation wavefields with different time delays, the initial return wavefield is synthesized.

[0082] For example, suppose n = 3, t = 5 seconds, when i = 0, τ(0) = 1 second, w(0) = 0.2, U f (x,x ′ s =x r Assuming the value of ,5-1) is A1 (this value is obtained by calculation or measurement of the forward propagation wave field at the corresponding time and position), then the contribution of this term to the initial return propagation wave field is 0.2×A1; when i=1, τ(1)=2 seconds, w(1)=0.3, U f (x,x ′ s =x r Assuming the value of ,5-2) is A2, the contribution is 0.3×A2; when i=2, τ(2)=3 seconds, w(2)=0.4, U f (x,x ′ s =x r If the value of (5-3) is A3, then the contribution is 0.4 × A3. Finally, by adding these terms together, we obtain... The initial value is the composite value of the initial return wave field at position x at t=5 seconds.

[0083] Specifically, after synthesizing the initial return wavefield, it needs to be optimized. The least squares matching error algorithm is a method to measure the difference between the synthesized wavefield and the actual (or desired) wavefield. Its basic idea is to calculate the difference between the synthesized wavefield and the target wavefield (e.g., the real return wavefield obtained through other high-precision measurement methods), and then adjust parameters such as filter coefficients to minimize this difference. When the least squares matching error reaches a preset matching error threshold, it indicates that the synthesized return wavefield is sufficiently close to the real (or desired) return wavefield. At this point, the optimized initial return wavefield is used as the return wavefield of the single-channel seismic record corresponding to the geophone. This final return wavefield can be used for subsequent seismic data processing and analysis.

[0084] Furthermore, based on the imaging conditions derived from cross-correlation calculations, a single-channel seismic image is synthesized by using the propagation wavefield of each seismic record and the forward propagation wavefield of the corresponding shot.

[0085] S2. The single-channel seismic image corresponding to the single-channel seismic record is synthesized by combining the propagating wavefield and the forward propagating wavefield corresponding to the single-channel seismic record.

[0086] In this embodiment of the invention, the single-channel seismic imaging refers to the image representation of the underground geological structure generated using data from a single seismic channel (a channel of seismic wave information excited by a single source and received by a single detector). It only reflects the detection results of the underground geological structure based on the seismic wave information along the path from a specific source location to a specific detector location.

[0087] In this embodiment of the invention, the step of synthesizing a single-channel seismic image corresponding to a single-channel seismic record by combining the propagating wavefield and the forward propagating wavefield corresponding to the single-channel seismic record includes:

[0088] According to a pre-set imaging condition processing operator, the propagating wavefield and the forward propagating wavefield corresponding to the single-channel seismic record are synthesized into a single-channel seismic image, wherein the synthesis formula for the single-channel seismic image is:

[0089]

[0090] in, At the epicenter location x s Excitation, at detector position x r The single-channel seismic image synthesized at the model's spatial location x during the received seismic record transmission process, where A is the imaging condition processing operator, and U... f (x,x s ,τ(i)) is the earthquake source at x s A forward propagating wave field excited at location x in the model space, with a propagation time of τ(i). x is the location of the earthquake source. sExcitation, at detector position x r The received earthquake record is transmitted back, and the back propagated wavefield is located at position x in the model space after a time delay of t-τ(i), where n is the maximum wavefield propagation time step.

[0091] In detail, the synthesis formula for single-channel seismic imaging is based on wavefield interactions to construct single-channel seismic images. This can be represented as a specific location x underground from a specific earthquake source x. s To a specific detector x r Geological structures along the path are imaged, and the imaging condition processing operator A plays a role in adjusting and controlling the imaging results. It can be set according to different geological conditions, exploration objectives, or data processing requirements. For example, it may involve operations such as normalizing the wave field amplitude and correcting for the influence of different media on wave propagation, so that the synthesized seismic image is more consistent with the actual physical meaning. f (x,x s τ(i) describes the state of a seismic wave as it travels from the epicenter to a spatial location x after a time interval τ(i). This includes physical characteristics such as wave amplitude and phase. Different values ​​represent the wave's state at different times as it reaches that location. The final image is constructed by considering multiple wavefield conditions at different times. It reflects the wavefield situation of seismic waves after propagation and reflection through the underground medium and their return to the location. It also contains rich information on underground geological structures. Based on the imaging conditions derived from cross-correlation calculations, a single-channel seismic image is synthesized by using the return wavefield of each seismic record and the forward wavefield of the corresponding shot of that seismic record.

[0092] For example, assuming n=3, for single-channel seismic imaging synthesis at model spatial location x, when i=1, τ(1)=0.5 seconds, U f (x,x s The amplitude of the wave (0.5) is assumed to be A1, and the phase is... (Only amplitude and phase are considered here) Assuming the amplitude is B1 and the phase is θ1, the value of this term can be viewed as a complex multiplication (considering both amplitude and phase). The amplitude part of the result is A1 × B1, and the phase part is... When i = 2, τ(2) = 1 second, U f (x,x s The amplitude of ,1) is assumed to be A2, and the phase is The amplitude is assumed to be B2 and the phase to be θ2. The above complex multiplication operation is performed to obtain the corresponding result. When i = 3, τ(1) = 1.5 seconds is calculated similarly. Finally, the three corresponding results are added together and multiplied by the imaging condition processing operator to obtain the single-channel seismic image at the location.

[0093] Furthermore, in order to generate common imaging point gathers for the wave equation, it is necessary to calculate the offset corresponding to each single-track seismic image, analyze the offset, and thus generate accurate common imaging point gathers.

[0094] S3. Calculate the offset distance corresponding to each single-channel seismic image, classify the single-channel seismic images according to the offset distance, and superimpose the classified single-channel seismic images to obtain the offset common imaging point gather.

[0095] In this embodiment of the invention, the offset distance refers to the distance that a seismic wave travels from the source in the horizontal direction to the detector. Different offset distances mean that the seismic wave undergoes different reflection, refraction and scattering processes underground, because when the seismic wave propagates underground, it will interact with the underground geological structure at different angles and paths as the offset distance changes.

[0096] In this embodiment of the invention, calculating the offset corresponding to each single-channel seismic image includes:

[0097] Obtain the target source location and target detector location for each single-channel seismic image;

[0098] Calculate the offset between the target seismic source location and the target geophone location one by one, wherein the offset calculation formula is:

[0099]

[0100] in, Single-channel seismic imaging The corresponding offset distance, x s Let x be the location of the target seismic source. r The target detector position is indicated.

[0101] In detail, each single-channel seismic image has a corresponding target hypocenter location and target geophone location. In actual seismic exploration, the hypocenter location is the artificially designated location for generating seismic waves, and the geophone location is the placement of the instrument used to receive seismic waves propagating through the subsurface medium. These locations are marked with corresponding coordinates during data recording or processing. By reading these coordinates, the target hypocenter location x corresponding to each single-channel seismic image can be obtained. s and target detector position x r This allows for the calculation of the horizontal distance between the target seismic source location and the target geophone location.

[0102] Specifically, each single-channel seismic record has an offset distance corresponding to the source location and detector location. To group single-channel seismic images with similar offset distances together, the offset distance is usually set based on factors such as the size of the exploration area, the complexity of the geological structure, and the desired level of detail in the geological information. For example, offset distance ranges can be set to 0-100 meters, 100-200 meters, 200-300 meters, etc. The specific range and intervals should be flexibly determined based on the actual situation. Then, it is compared with the pre-set offset distance range, and the single-channel seismic images are assigned to the corresponding range category. For example, if a single-channel seismic image has a calculated offset distance of 80 meters, it will be classified into the category corresponding to the 0-100 meter offset distance range; if another single-channel seismic image has an offset distance of 150 meters, it will be classified into the 100-200 meter category.

[0103] Furthermore, after classifying and grouping single-channel seismic images with similar offsets, in order to enhance the display effect of geological features, data within the same group can be overlaid to improve the display effect of geological features.

[0104] In this embodiment of the invention, the offset common imaging point gather refers to a set of seismic images obtained by stacking single-channel seismic images with similar offsets according to the depth domain. It is an important achievement in seismic exploration data processing, which integrates information from multiple single-channel seismic images within the same offset range.

[0105] In this embodiment of the invention, the step of stacking the classified single-track seismic images to obtain the offset common imaging point gather includes:

[0106] Extract the seismic imaging dataset corresponding to the classified single-channel seismic images;

[0107] Extract the depth domain corresponding to each single-channel seismic image from the seismic imaging dataset;

[0108] Each single-track seismic image in the seismic imaging dataset is depth-stacked according to the depth domain, and the stacked seismic imaging dataset is used as an offset common imaging point gather.

[0109] In detail, after classifying single-channel seismic images according to offset, a dataset is extracted from the single-channel seismic images in each category (i.e., the category corresponding to each offset interval). The seismic imaging dataset contains all single-channel seismic imaging information within a specific offset interval. This information may include various data related to seismic imaging, such as the amplitude, phase, and time of seismic waves. Each single-channel seismic image has a corresponding depth domain, which refers to the range of information at different depths underground reflected by the seismic image. Then, according to the extracted depth domain, each single-channel seismic image in the same category of seismic imaging dataset is depth-stacked. For example, for the imaging information at 200 meters underground in the depth domain, the values ​​(such as amplitude values) corresponding to this depth of all single-channel seismic images are added together. Through such depth stacking, the single-channel seismic imaging information at each depth position is integrated together to obtain a new seismic imaging dataset, which is the offset common imaging point gather.

[0110] Furthermore, in order to restore as much as possible the original amplitude characteristics of seismic waves that have changed due to various factors during underground propagation, it is necessary to eliminate or correct amplitude changes caused by non-geological factors, so that the amplitude of the final offset co-imaging point gather can truly reflect the changes in physical parameters such as the reflection coefficient and scattering characteristics of the underground geological structure.

[0111] S4. Perform amplitude processing on the offset common imaging point gather, and determine the amplitude-processed offset imaging point gather as the common imaging point gather of the wave equation.

[0112] In this embodiment of the invention, the offset co-imaging point gather integrates multiple single-channel seismic imaging information to reveal the overall picture of the underground geological structure and to perform geological interpretation. If the amplitude cannot accurately reflect the underground information, it will lead to incorrect judgment of the underground geological structure. Therefore, the offset co-imaging point gather needs to be amplitude preserved in order to fully restore the geological information contained in the amplitude.

[0113] In this embodiment of the invention, the amplitude processing of the offset common imaging point gather includes:

[0114] The length of the seismic wave propagation path is determined based on each offset in the offset common imaging point gather;

[0115] Calculate the geometric diffusion factor based on the length of the seismic wave propagation path;

[0116] The amplitude of each offset in the offset co-imaging point gather is corrected by the geometric diffusion factor to obtain the amplitude-processed offset co-imaging point gather.

[0117] In detail, in the offset co-imaging point gather, each offset corresponds to a specific seismic wave propagation path. The offset is the horizontal distance between the source and the detector, but the actual seismic wave propagation path is three-dimensional and affected by underground geological structures. The propagation path length can be accurately determined using ray tracing technology. Furthermore, seismic waves undergo geometric diffusion during propagation, causing energy to disperse in space and thus attenuating the amplitude. According to wave theory, in a homogeneous medium, for spherical waves, the geometric diffusion factor is related to the propagation distance. Therefore, the geometric diffusion factor can be expressed as the reciprocal of the seismic wave propagation path length. After obtaining the geometric diffusion factor, it is used to correct the amplitude of each offset in the offset co-imaging point gather. All amplitude data corresponding to each offset are corrected to compensate for the amplitude attenuation caused by geometric diffusion, thereby obtaining the amplitude-processed offset co-imaging point gather.

[0118] Furthermore, after amplitude processing, the amplitude information of the offset imaging point gather has been restored to a state that can accurately reflect the underground geological structure to a certain extent. At this time, the characteristics of seismic wave propagation and reflection presented by it are more consistent with the physical process described by the wave equation. Therefore, the offset imaging point gather after amplitude processing is determined as the wave equation amplitude-preserving surface offset gather.

[0119] Example 2

[0120] Based on the above embodiments, the optimization of the initial return wavefield using a preset least-squares matching error algorithm includes:

[0121] The least-squares matching error between the source wavelet and filter coefficients corresponding to the initial returned wavefield and the pre-acquired actual seismic record is calculated using the following preset least-squares matching error algorithm:

[0122]

[0123] Where φ(w) is the least squares matching error under filter coefficient w, d is the actual earthquake record, w(i) is the filter coefficient under the i-th wavefield propagation time step, f(τ(i)) is the source wavelet after time delay τ(i), and n is the maximum wavefield propagation time step.

[0124] The filter coefficients are adjusted according to the least squares matching error, and the adjusted filter coefficients are updated in the least squares matching error algorithm to obtain the least squares matching error update value.

[0125] When the least squares matching error update value reaches the preset matching error threshold, the adjusted filter coefficients are updated into the synthesis formula of the initial return wave field to obtain the optimized return wave field.

[0126] In detail, the least squares matching error algorithm is used to measure the degree of difference between the synthesized initial return wavefield and the actual seismic record. d is the actual seismic record, which is the seismic wave signal actually recorded by the detector during actual seismic exploration. This is a reference standard, and it is hoped that the synthesized return wavefield will be as close as possible to this actual record. The least squares matching error is obtained by comparing the actual seismic record with the single-channel seismic record of the source wavelet. Then, based on the calculated least squares matching error, the filter coefficients need to be adjusted to find a set of filter coefficients that minimizes the least squares matching error.

[0127] Specifically, the filter coefficients can be adjusted by gradient descent. The coefficients are updated based on the gradient of the filter coefficients using the least squares matching error algorithm. By controlling the step size of each update, the filter coefficients are changed in the direction that reduces the error. The adjusted filter coefficients are then updated in the least squares matching error algorithm, and φ(w) is recalculated to obtain the updated least squares matching error value. This process is repeated continuously, with the error recalculated after each update of the filter coefficients to observe whether the error is decreasing. When the updated least squares matching error value reaches the preset matching error threshold, it indicates that a suitable set of filter coefficients has been found, making the synthesized return wavefield sufficiently close to the actual seismic record. The adjusted filter coefficients are then updated in the synthesis formula of the initial return wavefield. Because the filter coefficients have been optimized, the return wavefield calculated using this updated formula is the optimized return wavefield. This optimized return wavefield can better match the actual seismic record, thus more accurately reflecting relevant information such as underground geological structures.

[0128] Example 3

[0129] Based on the above embodiments, the amplitude processing of the offset common imaging point gather further includes:

[0130] Calculate the root mean square amplitude corresponding to each offset in the offset common imaging point gather;

[0131] The scaling factor is determined based on the root mean square amplitude and the pre-acquired target root mean square amplitude.

[0132] The amplitude of the offset common imaging point gather is preservatively processed according to the scaling factor to obtain the amplitude-preserved offset common imaging point gather.

[0133] In detail, the root-mean-square (RMS) amplitude is a statistical measure of the intensity of a seismic signal. For each offset in the offset common imaging point gather, the root-mean-square amplitude is calculated. The magnitude of the root-mean-square amplitude reflects the relative strength of the seismic wave energy at that offset. Different offsets correspond to different root-mean-square amplitudes, which may be due to factors such as geometric diffusion, absorption attenuation, and changes in underground geological structures during the propagation of seismic waves. Calculating the root-mean-square amplitude provides the basic data for subsequent amplitude normalization and amplitude preservation processing.

[0134] Specifically, the target root mean square amplitude is a pre-set reference value, which is usually determined based on the geological conditions of the entire seismic exploration area, data processing objectives, or empirical values. The scaling factor is a coefficient used to adjust the amplitude of the seismic trace at each offset. The scaling factor is obtained by comparing the target root mean square amplitude with the root mean square amplitude. According to the calculated scaling factor, the amplitude of the seismic trace at each offset corresponding to the offset common imaging point gather is processed to make the overall intensity of the seismic trace amplitude at different offsets more consistent, while retaining the geological structure information contained in the amplitude. After the scaling factor is adjusted, the reflected wave amplitude at different offsets, after geometric diffusion correction and other processing, can better reflect the geological characteristics such as the reflection coefficient of the underground strata interface, thus obtaining an amplitude-preserving offset common imaging point gather.

[0135] Example 4

[0136] Based on the above embodiments, this embodiment provides an application example.

[0137] The method of this invention was tested using actual land data. For example... Figure 2 The diagram shows the size of the work area, which is 27km horizontally, 12km vertically, and 10km deep, with an offset range of 0-6km. Figure 2 The black dots represent the locations of the shot points; some areas have higher density, while others have lower density. The background color is gray, indicating the area where data was collected. Figure 3 The diagram shows the distribution of shot point positions and offsets, illustrating the correspondence between offsets and shot point positions. The curve represents all data, showing the distribution of all collected data at different offsets. The black bar chart represents the data used, showing the distribution of the actual data used in the data processing at different offsets. The data volume is lowest when the offset is 0, and increases and then decreases as the offset increases, reaching a peak at the middle offset. Figure 4aThe diagram shown illustrates the amplitude variation of a linear filter, illustrating how the filter's amplitude changes over time, thus revealing the characteristics of the linear filter's amplitude variation. Figure 4b The diagram shows a comparison between synthetic and actual seismic records. The solid black line represents the amplitude variation of the seismic record over time, while the dashed black line represents the amplitude variation of the synthetic record over time. It can be seen that the amplitude variations in the seismic record and the synthetic record are basically consistent. Figure 4c The diagram shown illustrates the relationship between depth and horizontal distance, displaying that different depths correspond to different horizontal distances. Figure 4d The diagram shown illustrates the target wavefield, representing the relationship between depth and horizontal distance. It displays that different depths correspond to different horizontal distances. Figure 4c and Figure 4d The comparison shows that the characteristics of the synthesized wavefield and the target wavefield are basically the same; for example... Figure 5 The diagram shows a composite offset common imaging point gather, representing the reflected waves formed after seismic waves are reflected at different interfaces in the underground medium. It shows the correspondence between different depths and offsets, and then the common imaging point gather is superimposed according to different depths.

[0138] Example 5

[0139] like Figure 6 As shown in the figure, this embodiment also provides a functional block diagram of a wave equation common imaging point gather generation device.

[0140] The wave equation common imaging point gather generation device 100 described in this embodiment can be installed in an electronic device. Depending on the functions implemented, the wave equation common imaging point gather generation device 100 may include a return wavefield generation module 101, a single-channel seismic imaging synthesis module 102, an offset common imaging point gather stacking module 103, and a common imaging point gather generation module 104. The module described in this invention can also be called a unit, referring to a series of computer program segments that can be executed by the processor of an electronic device and can perform a fixed function, stored in the memory of the electronic device.

[0141] In this embodiment, the functions of each module / unit are as follows:

[0142] The return wave field generation module 101 is used to identify the source wavelet according to the pre-selected source location, and synthesize the return wave field of the single-channel seismic record corresponding to the detector according to the forward propagation wave field of the source wavelet and the pre-determined linear filter.

[0143] The single-channel seismic imaging synthesis module 102 is used to synthesize the single-channel seismic image corresponding to the single-channel seismic record by means of the backpropagation wavefield and the forward propagation wavefield corresponding to the single-channel seismic record.

[0144] The offset common imaging point gather stacking module 103 is used to calculate the offset corresponding to each single-channel seismic image, classify the single-channel seismic images according to the offset, and stack the classified single-channel seismic images to obtain the offset common imaging point gather.

[0145] The common imaging point gather generation module 104 is used to perform amplitude processing on the offset common imaging point gather, and to determine the amplitude-processed offset imaging point gather as the common imaging point gather of the wave equation.

[0146] In detail, each module in the wave equation common imaging point gather generation device 100 described in the embodiments of the present invention adopts the same technical means as the wave equation common imaging point gather generation method described in Embodiments 1 to 4, and can produce the same technical effect, which will not be repeated here.

[0147] Example 6

[0148] Based on the above embodiments, this embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in the above embodiments.

[0149] In some embodiments of this example, a computer-readable storage medium is provided, on which a computer program is stored, characterized in that the computer program, when executed by a processor, implements the steps of the method described in the above embodiments.

[0150] In some embodiments of this example, a computer program product is provided, including a computer program / instructions, characterized in that the computer program, when executed by a processor, implements the steps of the method described in the above embodiments.

[0151] The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor, or other electronic component, for executing the methods in the above embodiments.

[0152] Computer-readable storage media can be implemented by any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media may include, but are not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, and computer storage media (e.g., hard disks, floppy disks, solid-state drives, removable disks, CD-ROMs, DVD-ROMs, Blu-ray discs, etc.).

[0153] Computer-readable storage media may also store at least one computer-executable program / instruction, such as computer-readable instructions. Computer-readable storage media include, but are not limited to, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Computer-readable storage media may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions stored on the computer-readable storage medium, the various methods described above can be performed.

[0154] In addition, the computer device may include (but is not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (e.g., keyboard, mouse, speakers, etc.).

[0155] The processor can communicate with external devices via the I / O bus through wired or wireless networks.

[0156] In one embodiment, the at least one computer-executable instruction may also be compiled into or comprise a software product / computer program product, wherein one or more computer-executable instructions are executed by a processor to perform the steps of the various functions and / or methods in the embodiments described herein.

[0157] In the embodiments provided in this disclosure, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0158] It should be noted that, in this disclosure, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element limited by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0159] While the embodiments disclosed herein are as described above, the foregoing content is merely for the purpose of facilitating understanding of this disclosure and is not intended to limit this disclosure. Any person skilled in the art to which this disclosure pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope of this disclosure; however, the scope of patent protection of this disclosure shall still be determined by the scope defined in the appended claims.

Claims

1. A method for generating common imaging point gathers for wave equations, characterized in that, include: Identify the source wavelet based on the pre-selected source location, and synthesize the return wavelet of the single-channel seismic record corresponding to the detector based on the forward propagation wavefield of the source wavelet and the pre-determined linear filter. The single-channel seismic image corresponding to the single-channel seismic record is synthesized by combining the back propagation wavefield and the forward propagation wavefield corresponding to the single-channel seismic record. Calculate the offset distance corresponding to each single-track seismic image, classify the single-track seismic images according to the offset distance, and stack the classified single-track seismic images to obtain the offset common imaging point gather. The offset common imaging point gather is subjected to amplitude processing, and the amplitude-processed offset imaging point gather is determined as the common imaging point gather of the wave equation.

2. The wave equation common imaging point gather generation method according to claim 1, characterized in that, The process of identifying the source wavelet based on the pre-selected source location includes: The location of the detector is determined based on the pre-selected location of the seismic source; Seismic waves are generated at the hypocenter location, and seismic signals after the seismic waves are generated are received at the detector location; The first arrival time of the seismic wave is identified based on the seismic signal, the first arrival wave data is extracted based on the first arrival time, and the first arrival wave data is determined as the source wavelet.

3. The wave equation common imaging point gather generation method according to claim 1, characterized in that, The method of synthesizing the return wavefield of the single-channel seismic record corresponding to the detector based on the forward propagation wavefield of the source wavelet and a pre-determined linear filter includes: Based on the predetermined filter coefficients of the linear filter and the forward propagation wavefield of the source wavelet, the detector synthesizes the initial return wavefield, where the return formula for the initial return wavefield is: in, x is the location of the earthquake source. s Excitation, at detector position x r The received seismic record feedback, the wavefield value at model spatial location x at time t, U f (x,x′ s =x r ,t-τ(i)) represents the earthquake source at x r The value of the propagating wave field excited at point x at spatial location x after a time delay t-τ(i), where n is the maximum wave field propagation time step, w(i) is the filter coefficient at the i-th wave field propagation time step, and τ(i) is the time delay at the i-th wave field propagation time step. The initial propagation wavefield is optimized by a preset least squares matching error algorithm until the least squares matching error reaches a preset matching error threshold. When the least squares matching error reaches the preset matching error threshold, the optimized initial return wavefield is used as the return wavefield of the single-channel seismic record corresponding to the detector.

4. The wave equation common imaging point gather generation method according to claim 3, characterized in that, The optimization of the initial propagation wavefield using a preset least-squares matching error algorithm includes: The least-squares matching error between the source wavelet and filter coefficients corresponding to the initial returned wavefield and the pre-acquired actual seismic record is calculated using the following preset least-squares matching error algorithm: Where φ(w) is the least squares matching error under filter coefficient w, d is the actual earthquake record, w(i) is the filter coefficient under the i-th wavefield propagation time step, f(τ(i)) is the source wavelet after time delay τ(i), and n is the maximum wavefield propagation time step. The filter coefficients are adjusted according to the least squares matching error, and the adjusted filter coefficients are updated in the least squares matching error algorithm to obtain the least squares matching error update value. When the least squares matching error update value reaches the preset matching error threshold, the adjusted filter coefficients are updated into the synthesis formula of the initial return wave field to obtain the optimized return wave field.

5. The wave equation common imaging point gather generation method according to claim 1, characterized in that, The process of synthesizing a single-channel seismic image corresponding to a single-channel seismic record from the propagating wavefield and the forward propagating wavefield corresponding to the single-channel seismic record includes: According to a pre-set imaging condition processing operator, the propagating wavefield and the forward propagating wavefield corresponding to the single-channel seismic record are synthesized into a single-channel seismic image, wherein the synthesis formula for the single-channel seismic image is: in, At the epicenter location x s Excitation, at detector position x r The single-channel seismic image synthesized at the model's spatial location x during the received seismic record transmission process, where A is the imaging condition processing operator, and U... f (x,x s ,τ(i)) is the earthquake source at x s A forward propagating wave field excited at location x in the model space, with a propagation time of τ(i). x is the location of the earthquake source. s Excitation, at detector position x r The received earthquake record is transmitted back, and the back propagated wavefield is located at position x in the model space after a time delay of t-τ(i), where n is the maximum wavefield propagation time step.

6. The method for generating common imaging point gathers for the wave equation according to claim 1, characterized in that, The calculation of the offset corresponding to each of the single-channel seismic images includes: Obtain the target source location and target detector location for each single-channel seismic image; Calculate the offset between the target seismic source location and the target geophone location one by one, wherein the offset calculation formula is: in, Single-channel seismic imaging The corresponding offset distance, x s Let x be the location of the target seismic source. r The target detector position is indicated.

7. The wave equation common imaging point gather generation method according to claim 1, characterized in that, The process of stacking the classified single-channel seismic images to obtain the offset common imaging point gather includes: Extract the seismic imaging dataset corresponding to the classified single-channel seismic images; Extract the depth domain corresponding to each single-channel seismic image from the seismic imaging dataset; Each single-track seismic image in the seismic imaging dataset is depth-stacked according to the depth domain, and the stacked seismic imaging dataset is used as an offset common imaging point gather.

8. A device for generating common imaging point gathers for wave equations, characterized in that, include: The return wave field generation module is used to identify the source wavelet according to the pre-selected source location, and synthesize the return wave field of the single-channel seismic record corresponding to the detector based on the forward propagation wave field of the source wavelet and the pre-determined linear filter. A single-channel seismic imaging synthesis module is used to synthesize a single-channel seismic image corresponding to the single-channel seismic record by means of the backpropagation wavefield and the forward propagation wavefield corresponding to the single-channel seismic record. The offset common imaging point gather stacking module is used to calculate the offset corresponding to each single-track seismic image, classify the single-track seismic images according to the offset, and stack the classified single-track seismic images to obtain the offset common imaging point gather. The common imaging point gather generation module is used to perform amplitude processing on the offset common imaging point gather and determine the amplitude-processed offset imaging point gather as the common imaging point gather of the wave equation.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the wave equation common imaging point gather generation method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the wave equation common imaging point gather generation method according to any one of claims 1 to 7.

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