Method and device for determining speed spectrum, and computer device
By correcting the depth of reflection points and determining the energy distribution in the exploration area, the problem of low accuracy of velocity spectrum in seismic data was solved, improving the accuracy of velocity spectrum in subsurface media and the interpretability of seismic data.
Patent Information
- Application Number
- CN202411906573.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2026-06-23
Smart Images
Figure CN122260462A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of seismic exploration technology, and in particular to a method, apparatus, and computer device for determining velocity spectrum. Background Technology
[0002] In the field of seismic exploration technology, velocity spectrum can reflect the relationship between the energy and wave velocity of seismic waves. By obtaining the velocity spectrum corresponding to the seismic data of the exploration area, we can understand the lithological changes of the underground structure in the exploration area and provide a basis for comprehensive geological interpretation and stratigraphic research.
[0003] In related technologies, common imaging point gathers corresponding to velocity fields at different offsets are determined using seismic data, and the velocity spectrum is determined using the energy distribution within these gathers. The offset refers to the horizontal distance between the seismic source (or excitation point) and the geophone (or geophone array) receiving the seismic wave signal. However, in exploration areas with complex surface or subsurface structures, the accuracy of the velocity field obtained at the offset is poor, resulting in a less accurate velocity spectrum derived from the offset velocity field, which affects the interpretation of seismic data and exploration efficiency. Summary of the Invention
[0004] This application provides a method, apparatus, and computer device for determining velocity spectra, which improves the accuracy and precision of velocity spectra, thereby enhancing the interpretability of seismic data. The technical solution is as follows:
[0005] On one hand, embodiments of this application provide a method for determining a velocity spectrum, the method comprising:
[0006] Seismic data of the exploration area is acquired, and an initial layer velocity field in the depth domain is determined based on the seismic data. The initial layer velocity field in the depth domain characterizes the initial velocity distribution of subsurface media layers at different depths in the exploration area.
[0007] A reference scanning layer is determined in the underground medium layer, and the scanning parameters corresponding to the reference scanning layer are obtained. The scanning parameters are used to generate the scanning velocity field of the reference scanning layer. Based on the scanning velocity field, a common imaging point offset gather and a depth offset profile are determined. The common imaging point offset gather includes data of multiple reflection points. The reflection points have an initial depth. The depth offset profile is used to determine the velocity information of the reflection points in the underground medium layer.
[0008] The common imaging point offset gather and the depth offset profile are processed to obtain the depth correction parameters of the reflection point. The initial depth of the reflection point is corrected using the depth correction parameters to obtain the reference depth of the reflection point.
[0009] The energy distribution of the reflection point located at the reference depth is determined, the velocity spectrum of the reference scanning layer is determined using the energy distribution of the reflection point, and the velocity spectrum of the subsurface medium layer in the exploration area is determined using the velocity spectrum of the reference scanning layer.
[0010] On the other hand, embodiments of this application provide a velocity spectrum determination apparatus, the apparatus comprising:
[0011] The acquisition module is used to acquire seismic data of the exploration area and determine the initial layer velocity field in the depth domain based on the seismic data. The initial layer velocity field in the depth domain characterizes the initial velocity distribution of the subsurface medium layers at different depths in the exploration area.
[0012] The determination module is used to determine a reference scanning layer in the underground medium layer, obtain scanning parameters corresponding to the reference scanning layer, generate a scanning velocity field of the reference scanning layer using the scanning parameters, and determine a common imaging point offset gather and a depth offset profile based on the scanning velocity field. The common imaging point offset gather includes multiple reflection points, each reflection point has an initial depth, and the depth offset profile is used to determine the velocity information of the reflection points in the underground medium layer.
[0013] The correction module is used to process the common imaging point offset gather and the depth offset profile to obtain the depth correction parameters of the reflection point, and use the depth correction parameters to correct the initial depth of the reflection point to obtain the reference depth of the reflection point.
[0014] The determining module is further configured to determine the energy distribution of the reflection point located at the reference depth, use the energy distribution of the reflection point to determine the velocity spectrum of the reference scanning layer, and use the velocity spectrum of the reference scanning layer to determine the velocity spectrum of the subsurface medium layer in the exploration area.
[0015] In one possible implementation, the common imaging point offset channel set includes multiple offset channels arranged sequentially, each offset channel corresponding to at least one reflection point. The correction module is used to determine the tilt angle of the reflection point based on the common imaging point offset channel set corresponding to the reflection point and the depth offset profile; and to determine the depth correction parameters based on the tilt angle of the reflection point and a reference distance, wherein the reference distance is the horizontal distance between the offset channel where the reflection point is located and the central offset channel in the depth offset profile, and the central offset channel is the middle offset channel in the sequentially arranged offset channels.
[0016] In one possible implementation, the correction module is configured to acquire scanning information, the scanning information including a scanning window used for scanning in the depth offset profile; determine multiple scanning lines passing through the reflection point based on the common imaging point offset gather corresponding to the reflection point and the scanning information, each scanning line having a scanning tilt angle; determine a reference line segment based on the scanning window and the multiple scanning lines, the reference line segment being a line segment of the multiple scanning lines located within the scanning window; calculate the similarity of sampling points with different offset distances on any reference line segment, and determine the scanning tilt angle of the reference line segment corresponding to the maximum similarity as the tilt angle of the reflection point.
[0017] In one possible implementation, the reference scanning layer includes multiple reflection points, and the common imaging point offset set of the reflection points includes multiple offset channels. The determining module is configured to acquire a first energy value of each offset channel in the common imaging point offset set corresponding to the reflection point; determine a second energy value of the common imaging point offset set corresponding to the reflection point based on the first energy value; determine a first energy distribution of the reference scanning layer based on the second energy value; determine the energy distribution of the scanning velocity field corresponding to the reflection point based on the first energy value; determine a second energy distribution of the reference scanning layer using the energy distribution of the scanning velocity field; and determine the velocity spectrum of the reference scanning layer based on the first energy distribution and the second energy distribution.
[0018] In one possible implementation, the offset channel includes multiple sampling points, and the determining module is further configured to obtain a first amplitude of the sampling points in the offset channel; perform a linear transformation on the first amplitude to obtain a second amplitude of the sampling points; and determine the first energy value using the first amplitude, the second amplitude, and the number of sampling points in the offset channel.
[0019] In one possible implementation, the acquisition module is used to process the seismic data to obtain a time-domain velocity field and a time-domain migration profile. The time-domain velocity field characterizes the distribution of the propagation velocity of seismic waves at different locations and time points in the exploration area, and the time-domain migration profile characterizes the migration of reflection points at different times. Based on the time-domain velocity field and the time-domain migration profile, the initial layer velocity field in the depth domain is determined.
[0020] In one possible implementation, the acquisition module is further configured to preprocess the seismic data to obtain preprocessed seismic data, wherein the preprocessing includes at least one of denoising processing, consistency processing, or deconvolution processing; perform velocity analysis on the preprocessed seismic data in the time domain to obtain the time domain velocity field; and perform pre-stack time migration processing on the time domain velocity field to obtain the time domain migration profile.
[0021] In one possible implementation, the acquisition module is used to perform stratigraphic interpretation on the time-domain migration profile to obtain the distribution information of the subsurface medium layers in the exploration area; based on the distribution information of the subsurface medium layers, an initial velocity model is constructed, and the information of the time-domain velocity field and the seismic data are input into the initial velocity model to obtain the initial layer velocity field in the depth domain.
[0022] On the other hand, embodiments of this application provide a computer device, the computer device including a processor and a memory, the memory storing at least one piece of program code, the at least one piece of program code being loaded and executed by the processor, so that the computer device implements any of the above-described methods for determining the velocity spectrum.
[0023] On the other hand, a computer-readable storage medium is also provided, wherein at least one piece of program code is stored in the computer-readable storage medium, the at least one piece of program code being loaded and executed by a processor to enable a computer to implement any of the above-described methods for determining the velocity spectrum.
[0024] On the other hand, a computer program or computer program product is also provided, wherein the computer program or computer program product stores at least one computer instruction, which is loaded and executed by a processor to enable the computer to implement any of the above-mentioned methods for determining the velocity spectrum.
[0025] The technical solution provided in this application has at least the following beneficial effects:
[0026] This application determines the depth correction parameters for reflection points using common imaging point migration gathers and depth migration profiles. Correcting the initial depth of reflection points using these parameters improves the accuracy of the reflection point depth, thereby enhancing the accuracy of the determined dip angle. Using the corrected depth of the reflection points, i.e., the reference depth, to determine the energy distribution, and calculating the velocity spectrum based on this energy distribution, improves the accuracy and precision of the velocity spectrum of the subsurface medium in the exploration area, thus enhancing the interpretability of seismic data in subsequent processes. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 This is a schematic diagram illustrating the implementation environment of a velocity spectrum determination method provided in an embodiment of this application;
[0029] Figure 2 This is a flowchart of a method for determining a velocity spectrum provided in an embodiment of this application;
[0030] Figure 3 This is a schematic diagram illustrating the determination of common imaging point offset gathers and depth offset profiles provided in an embodiment of this application;
[0031] Figure 4 This is a schematic diagram of a common imaging point offset gather determination reference line segment under different scanning parameters provided in an embodiment of this application;
[0032] Figure 5 This is a schematic diagram of the velocity spectrum distribution of a reference scan layer before correction, provided in an embodiment of this application.
[0033] Figure 6 This is a schematic diagram of the velocity spectrum distribution of a corrected reference scan layer provided in an embodiment of this application;
[0034] Figure 7 This is a schematic diagram comparing the accuracy of the velocity spectrum of a corrected reference scan layer with that of the reference scan layer before correction, according to an embodiment of this application.
[0035] Figure 8 This is a schematic diagram of a velocity spectrum determination device provided in an embodiment of this application;
[0036] Figure 9 This is a schematic diagram of the structure of a server provided in an embodiment of this application. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.
[0038] It should be noted that the terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.
[0039] Figure 1 This is a schematic diagram illustrating the implementation environment of a velocity spectrum determination method provided in this application embodiment, such as... Figure 1 As shown, the implementation environment includes: seismic source 101, detector 102, and server 103.
[0040] Seismic source 101 and geophone 102 are distributed throughout the exploration area to collect seismic data within the area. Seismic source 101 can be located at the shot point, and geophone 102 can be located at the detection point (geophone point). The locations of the shot point and geophone point are determined according to the size of the exploration area and geological conditions to ensure that seismic waves can cover the entire exploration area.
[0041] The seismic source 101 is used to generate seismic waves at the shot point. By controlling the parameters of the seismic source 101, it can generate seismic waves that propagate in any direction. The geophone 102 is used to collect the particle vibration at the geophone point to obtain seismic data.
[0042] When seismic waves propagate to the detection point and cause the particles to vibrate, the particles leave their equilibrium positions and complete three-dimensional spatial vibration. After the seismic waves pass through the detection point, the particles return to their original equilibrium positions. The geophone 102 can record the three-dimensional spatial vibration of the particles induced by the seismic wave field. For example, the geophone 102 samples the vibration of the particles at sampling time intervals to obtain seismic data, and then sends the seismic data to the server 103. The number of seismic sources 101 and geophones 102 can be one or more. If there are multiple seismic sources 101 and geophones 102, they can also be arranged in a certain manner.
[0043] Server 103 processes the received seismic data to obtain the velocity spectrum of the subsurface medium layers in the exploration area. Data processing may include, but is not limited to, filtering, denoising, and overlay processing to improve the quality of the seismic data. Seismic images are generated using techniques such as migration imaging to guide practical applications such as oil and gas exploration and development, and geological hazard assessment.
[0044] This application provides a method for determining a velocity spectrum, which can be applied to the above-mentioned... Figure 1 The implementation environment is shown. For example, the method can be implemented by... Figure 1 The seismic source 101, detector 102, and server 103 interact and execute commands. For example... Figure 2 As shown, the method includes the following steps 201 to 204.
[0045] In step 201, seismic data of the exploration area is acquired, and the initial layer velocity field in the depth domain is determined based on the seismic data. The initial layer velocity field in the depth domain characterizes the initial velocity distribution of the subsurface medium layers at different depths in the exploration area.
[0046] In an exemplary embodiment of this application, multiple shot points and detection points (geothermal points) are distributed in the exploration area. Shot points are points used to generate seismic waves during seismic exploration. These seismic waves can be P-waves. During seismic exploration operations, seismic waves are generated by releasing energy at shot points (such as through explosive detonation or controlled source vibration). Detector points are points used to receive seismic wave signals and are typically located on the ground or seabed. Detector points can be equipped with geophones to collect vibration information of particles at their location, i.e., seismic data.
[0047] Seismic data can include data from multiple seismic traces. A seismic trace refers to the vibration (particle displacement, displacement velocity, or displacement acceleration) generated by a single excitation received at any receiver point (single or combined) on the Earth's surface or underground. The seismic signal is continuously acquired by a geophone at the receiver point. In other words, a seismic trace is a one-dimensional seismic signal trace that spatially records the process of seismic waves from the shot point to the receiver point.
[0048] After acquiring seismic data, it can be preprocessed to obtain preprocessed seismic data. Preprocessing includes at least one of denoising, consistency processing, or deconvolution processing.
[0049] During seismic data acquisition, environmental noise and instrument noise are present. After acquiring the seismic data, denoising processing can be performed to retain the valid seismic signals. Denoising methods include, but are not limited to, filtering methods, sparse transform methods, and deep learning-based methods.
[0050] Consistency processing is primarily used to improve the consistency of seismic data across different gathers, eliminating inconsistencies caused by factors such as acquisition conditions and instrument differences. Consistency processing can include amplitude consistency processing and phase consistency processing, among others.
[0051] Deconvolution is primarily used to compress the effective seismic wavelet in seismic traces, shortening its propagation time to improve temporal resolution. Furthermore, deconvolution can improve the consistency of the effective seismic wavelet, enhancing the superposition effect in subsequent processes and strengthening the continuity of phase axes. Commonly used deconvolution methods include predictive deconvolution and surface-consistent deconvolution.
[0052] It should be noted that the preprocessing method for seismic data in this application is illustrative only, and other preprocessing methods may also be included, such as static correction processing. The preprocessing method for seismic data can be set based on actual exploration needs, and this application does not limit it.
[0053] After preprocessing the seismic data, the initial layer velocity field in the depth domain can be determined based on the preprocessed seismic data. The process of determining the initial layer velocity field in the depth domain based on the preprocessed seismic data includes steps 2011 and 2012.
[0054] In step 2011, the seismic data is processed to obtain a time-domain velocity field and a time-domain migration profile. The time-domain velocity field characterizes the distribution of the propagation velocity of seismic waves at different locations and time points in the exploration area, and the time-domain migration profile characterizes the migration of reflection points at different times.
[0055] In an exemplary embodiment of this application, the preprocessed seismic data is subjected to velocity analysis in the time domain to obtain a time-domain velocity field; the time-domain velocity field is then subjected to pre-stack time migration processing to obtain a time-domain migration profile.
[0056] For example, the time range for velocity scanning is determined based on the exploration target and geological characteristics. Scanning parameters are set, including scan step size and velocity range. Velocity scanning software or algorithms are then used to scan the preprocessed seismic data based on these parameters. That is, by changing the velocity values, changes in characteristics such as travel time and amplitude of seismic waves are observed to determine the seismic wave velocity. Based on the velocity scanning results, velocity values at different time points are preliminarily determined. Based on these time points and velocity values, a time-domain velocity field of the subsurface medium layer can be constructed.
[0057] After obtaining the time-domain velocity field, pre-stack time migration processing can be performed on the time-domain velocity field to obtain a time-domain migration profile. For example, a migration velocity model is constructed using geological modeling techniques based on the time-domain velocity field. The migration velocity model describes the velocity distribution of the subsurface media layers. Preprocessed seismic data and the time-domain velocity field data are input into the migration imaging system. The seismic data may include, but is not limited to, the amplitude, phase, and frequency of seismic waves. The migration algorithm in the migration imaging system performs migration processing on the seismic data to obtain the time-domain migration profile, which characterizes the migration of reflection points at different times.
[0058] This application embodiment improves the signal-to-noise ratio of seismic data by preprocessing it, making the effective signal more prominent and reducing noise interference. It also eliminates inconsistencies between different gathers of seismic data, improves the overall quality and stability of the data, and is beneficial to the accuracy and reliability of subsequent processing results.
[0059] Furthermore, accurate velocity field information can be obtained through time-domain velocity analysis, providing a reliable velocity model for subsequent migration imaging. This helps ensure the accuracy and realism of the migration imaging results. Pre-stack time migration processing can fully utilize information such as amplitude, phase, and frequency of seismic data to perform seismic imaging, thereby better reflecting the true morphology and structural characteristics of the subsurface media layers.
[0060] In step 2012, the initial layer velocity field in the depth domain is determined based on the time-domain velocity field and the time-domain offset profile.
[0061] In an exemplary embodiment of this application, the process of determining the initial layer velocity field in the depth domain may include: interpreting the time-domain migration profile to obtain the distribution information of the subsurface medium layers in the exploration area; constructing an initial velocity model based on the distribution information of the subsurface medium layers; and inputting the information of the time-domain velocity field and seismic data into the initial velocity model to obtain the initial layer velocity field in the depth domain.
[0062] For example, various seismic wave reflections are identified on the time-domain migration profile. The positions of the reflections are continuously marked on the time-domain migration profile, either manually or automatically, thereby obtaining a series of continuous stratigraphic interfaces. By tracing the reflections, the structure of the underground strata, i.e., the distribution information of the underground medium layers in the exploration area, can be determined.
[0063] A velocity model can be constructed based on the distribution information of underground media layers. This velocity model is an initial velocity model. The model parameters include, but are not limited to, the number of media layers, the preset velocity of each media layer, and the thickness of each media layer. The number of media layers and the thickness of each media layer can be obtained based on the structure of the underground strata. The preset velocity of each media layer is preset based on geological survey data and the propagation characteristics of seismic waves. For example, the preset velocity can be set based on factors such as geological structure, lithological characteristics, and sedimentary environment.
[0064] A velocity model is used to convert the time-domain velocity field and time-domain migration profile into a time-depth field. This involves transforming the time-domain velocity and migration information into the depth-domain velocity and migration information, and then using this depth-domain information to construct an initial layer velocity field. This initial layer velocity field in the depth domain describes the distribution of seismic wave propagation velocities at different depths within the exploration area. The velocity model can convert the time-domain velocity field into the depth-domain velocity field using the Dix formula or by inversion.
[0065] Optionally, seismic data may also include well data, and a depth-domain velocity field can be created using well curve data. For example, well curve data is collected during drilling operations; this data typically includes various physical parameters that vary with depth, such as depth and velocity parameters. Based on seismic data and geological information, stratigraphic interpretation is performed. A three-dimensional geological structural model is constructed based on the stratigraphic interpretation results. The velocity and depth parameters from the well curves are interpolated into the entire structural model to obtain a continuous velocity distribution. Based on the velocity distribution and the structural model, an initial depth-domain initial layer velocity field is generated.
[0066] In step 202, a reference scanning layer is determined in the subsurface medium layer, and the scanning parameters corresponding to the reference scanning layer are obtained. The scanning velocity field of the reference scanning layer is generated using the scanning parameters. Based on the scanning velocity field, the common imaging point offset gather and the depth offset profile are determined. The common imaging point offset gather includes data of multiple reflection points. The reflection points have an initial depth. The depth offset profile is used to determine the velocity information of the reflection points in the subsurface medium layer.
[0067] In an exemplary embodiment of this application, the subsurface medium layer in the exploration area may include multiple layers, and any layer among the subsurface medium layers can be selected as a reference scanning layer. The reference scanning layer is the layer whose velocity spectrum is to be determined. For example, the subsurface medium layers in the exploration area can be used sequentially from shallowest to deepest as reference scanning layers.
[0068] Scanning parameters can include the scan step size and the scan area. The initial velocity distribution of the reference scan layer can be determined using the initial layer velocity field in the depth domain, and the velocity distribution of the scan velocity field can be determined using the scan step size. For example, if the initial velocity distribution of the reference scan layer is V0 and the scan step size is ΔV, a scan velocity field can be generated in the scan area based on the initial velocity distribution V0 and the scan step size ΔV. For example, the velocity distributions of the scan velocity field could be V0-2ΔV, V0-ΔV, V0, V0+ΔV, and V0+2ΔV.
[0069] Depth migration calculations are performed on different scanning velocity fields to obtain depth migration profiles and common imaging point migration gathers. For example, the Kirchhoff migration algorithm, which is an integral form based on the wave equation, is used to convert seismic data from the time domain to the depth domain by calculating the energy distribution of seismic waves at different migration locations and times, thereby obtaining common imaging point migration gathers and depth migration profiles.
[0070] Figure 3 This is a schematic diagram of determining common imaging point offset gathers and depth offset profiles provided in an embodiment of this application. Figure 3(a) includes a reference scan layer. The velocity of the reference scan layer is scanned using scan parameters, resulting in multiple scan velocity fields; that is, multiple scan velocity fields are contained along the scan direction. Pre-stack depth migration is calculated on the offset stacked profile of the scan velocity fields to obtain... Figure 3 (b) Common imaging point offset gathers corresponding to different scanning velocity fields.
[0071] In step 203, the common imaging point offset gather and depth offset profile are processed to obtain the depth correction parameters of the reflection point. The initial depth of the reflection point is corrected using the depth correction parameters to obtain the reference depth of the reflection point.
[0072] In an exemplary embodiment of this application, the common imaging point offset channel set includes multiple offset channels arranged sequentially, and each offset channel corresponds to at least one reflection point. The process of obtaining the depth correction parameters of the reflection point may include: determining the tilt angle of the reflection point based on the common imaging point offset channel set corresponding to the reflection point and the depth offset profile; determining the depth correction parameters based on the tilt angle of the reflection point and a reference distance, wherein the reference distance is the horizontal distance between the offset channel where the reflection point is located and the central offset channel in the depth offset profile, and the central offset channel is the middle offset channel in the sequentially arranged offset channels.
[0073] For example, the process of determining the tilt angle of a reflection point may include: acquiring scanning information, including a scanning window used for scanning in a depth offset profile; determining multiple scan lines passing through the reflection point based on the common imaging point offset gather corresponding to the reflection point and the scanning information, wherein each scan line has a scanning tilt angle; determining a reference line segment based on the scanning window and the multiple scan lines, wherein the reference line segment is a line segment of the multiple scan lines located within the scanning window; calculating the similarity of sampling points with different offset distances on any reference line segment, and determining the scanning tilt angle of the reference line segment corresponding to the maximum similarity as the tilt angle of the reflection point.
[0074] In an exemplary embodiment of this application, a scanning window is defined within the depth migration profile. The scanning window is a region with a certain depth range, used to limit the search range of the scanning lines. For example, the shape of the scanning window can be rectangular, and its size and position can be adjusted according to the structure and characteristics of the subsurface medium. After determining the scanning window, other scanning parameters, such as scanning step size and scanning range, can also be set. These parameters will determine the distribution and density of the scanning lines in the depth migration profile.
[0075] For example, determine the offset set corresponding to the same common imaging point in the entire offset set. Figure 4 This is a schematic diagram illustrating the determination of a reference line segment for common imaging point offset gathers under different scanning parameters, provided in an embodiment of this application. For example... Figure 4As shown, the scan line can be a straight line passing through the reflection point P. Based on exploration requirements or the accuracy requirements of seismic data, multiple scan lines can be generated. Each scan line has a certain scanning inclination angle, the magnitude of which can be determined based on the scan window. The portion of each scan line located within the scan window is defined as a reference line segment.
[0076] Multiple sampling points are determined in the reference line segment, and the first similarity of the multiple sampling points in any reference line segment is calculated. The first similarity semb1 can be calculated based on formula (1).
[0077]
[0078] In the above formula (1), n represents the number of sampling points in the scanning window, amp j This represents the amplitude value at the j-th sampling point.
[0079] The higher the value of the first similarity score (semb1), the higher the similarity between the reference line segment and the in-phase axis where the reflection point is located in the depth offset profile. Therefore, the scanning tilt angle of the reference line segment corresponding to the maximum value of the first similarity score (semb1) is determined as the tilt angle of the reflection point.
[0080] In an exemplary embodiment of this application, a reference distance can also be determined based on a depth offset profile. The depth offset profile includes multiple offset channels arranged in sequence. The reference distance is the horizontal distance between the offset channel where the reflection point is located and the central offset channel in the depth offset profile. Then, the depth correction parameter is the product of the reference distance and the tangent of the inclination angle of the reflection point.
[0081] The depth of the reflection point is corrected using depth correction parameters to obtain the reference depth of the reflection point. The reference depth z of the reflection point. ij It can be calculated using formula (2).
[0082] z ij =z 0i +dx ij *tanθ i Formula (2)
[0083] In the above formula (2), z 0i dx represents the depth of the reflection point before correction. ij For reference distance, θ i Let be the tilt angle of the i-th reflection point, where i = [1, ncip], ncip is the number of reflection points contained in the reference scan layer, and j = [1, nv], nv is the number of scan velocity fields corresponding to the reference scan layer.
[0084] In this embodiment, depth correction parameters are obtained by using the common imaging point offset gather and the depth offset profile. By using the depth correction parameters to correct the depth of the reflection point, the accuracy of the reflection point depth can be improved, thereby improving the accuracy of the determined reflection point tilt angle.
[0085] In step 204, the energy distribution of the reflection point located at the reference depth is determined, the velocity spectrum of the reference scanning layer is determined using the energy distribution of the reflection point, and the velocity spectrum of the underground medium layer in the exploration area is determined using the velocity spectrum of the reference scanning layer.
[0086] In an exemplary embodiment of this application, the reference scanning layer includes multiple reflection points, the common imaging point offset channel set of the reflection points includes multiple offset channels, and the process of determining the energy distribution of the reflection points located at the reference depth includes steps 2041 to 2044.
[0087] In step 2041, the first energy value of each offset channel in the common imaging point offset channel set corresponding to the reflection point is obtained, and the second energy value of the common imaging point offset channel set corresponding to the reflection point is determined based on the first energy value.
[0088] For example, each offset channel includes multiple sampling points. The process of determining the first energy value of each offset channel in the common imaging point offset channel set corresponding to the reflection point may include: obtaining the first amplitude of the sampling point in the offset channel; performing a linear transformation on the first amplitude to obtain the second amplitude of the sampling point; and determining the first energy value using the first amplitude, the second amplitude, and the number of sampling points in the offset channel.
[0089] For example, for any sampling point in the offset channel, the first amplitude of the sampling point is Ar. Using a linear transformation of the signal, the first amplitude Ar is converted into a second amplitude Ai, then the energy value of the sampling point is... The energy values of the sampling points at different offsets are summed to obtain the second energy value of the common imaging point offset gather corresponding to the reflection point.
[0090] In step 2042, the first energy distribution of the reference scan layer is determined based on the second energy value.
[0091] In an exemplary embodiment of this application, the first energy distribution can be Where ntrace is the number of offset traces in the common imaging point offset trace set corresponding to the reference scan layer. E is the second energy value. i,j Let be the energy value of the sampling point under the j-th scanning velocity field corresponding to the i-th co-imaging point. Where i = [1, ncip], ncip is the number of co-imaging points, and j = [1, nv], nv is the number of scanning velocity fields.
[0092] In step 2043, the energy distribution of the scanning velocity field corresponding to the reflection point is determined based on the first energy value, and the second energy distribution of the reference scanning layer is determined using the energy distribution of the scanning velocity field.
[0093] For example, the energy distribution of the scanning velocity field corresponding to the reflection point is E i,j (trace[k]), the second energy distribution is For detailed explanations of each parameter, please refer to step 2042, which will not be repeated here.
[0094] In step 2044, the velocity spectrum of the reference scan layer is determined based on the first energy distribution and the second energy distribution.
[0095] For example, the velocity spectrum e of the j-th scanning velocity field corresponding to the i-th common imaging point i,j It can be calculated using formula (3).
[0096]
[0097] The velocity spectra of the scanning velocity field corresponding to each common imaging point are summarized to obtain the velocity spectrum of the common imaging point. The velocity spectra of the common imaging points of the reference scanning layer are summarized to obtain the velocity spectrum of the reference scanning layer. The velocity spectra of the reference scanning layer are arranged based on depth to obtain the velocity spectrum of the subsurface medium layer in the exploration area.
[0098] Figure 5 This is a schematic diagram of the velocity spectrum distribution of a reference scan layer before correction, provided in an embodiment of this application. Figure 6 This is a schematic diagram of the velocity spectrum distribution of a corrected reference scanning layer provided in an embodiment of this application. Figure 7 This is a schematic diagram comparing the accuracy of the velocity spectrum of a corrected reference scan layer with that of the uncorrected reference scan layer, according to an embodiment of this application. Figures 5 to 7 As shown, comparing the velocity spectrum of the reference scanning layer before correction (also known as the traditional velocity spectrum) and the velocity spectrum of the reference scanning layer after correction (also known as the tilt-constrained velocity spectrum), it can be seen that the focusing degree, lateral stability and consistency of the velocity spectrum of the reference scanning layer after correction are significantly improved, which is conducive to improving the velocity pickup progress.
[0099] For example, in Figure 7In the study, when the lateral average velocity error is 4%, the percentage root mean square amplitude of velocity picking based on the velocity spectrum of the reference scan layer before correction (traditional velocity spectrum) and the velocity spectrum of the reference scan layer after correction (tilt-constrained velocity spectrum) are 98.7% and 96.2%, respectively, indicating an improvement in velocity picking accuracy of approximately 2%. Furthermore, in terms of velocity determination efficiency, since the velocity spectrum of the corrected reference scan layer is calculated as a superimposed profile in the velocity dimension, the number of data channels processed is less, which can improve computational efficiency to some extent.
[0100] This application determines the depth correction parameters for reflection points using common imaging point migration gathers and depth migration profiles. Correcting the initial depth of reflection points using these parameters improves the accuracy of the reflection point depth, thereby enhancing the accuracy of the determined dip angle. Using the corrected depth of the reflection points, i.e., the reference depth, to determine the energy distribution, and calculating the velocity spectrum based on this energy distribution, improves the accuracy and precision of the velocity spectrum of the subsurface medium in the exploration area, thus enhancing the interpretability of seismic data in subsequent processes.
[0101] This application also provides a device for determining a velocity spectrum. Figure 8 This is a schematic diagram of a velocity spectrum determination device provided in an embodiment of this application, as shown below. Figure 8 As shown, the device includes:
[0102] The acquisition module 801 is used to acquire seismic data of the exploration area and determine the initial layer velocity field in the depth domain based on the seismic data. The initial layer velocity field in the depth domain characterizes the initial velocity distribution of the subsurface medium layers at different depths in the exploration area.
[0103] The determination module 802 is used to determine a reference scanning layer in the underground medium layer, obtain the scanning parameters corresponding to the reference scanning layer, generate a scanning velocity field of the reference scanning layer using the scanning parameters, and determine a common imaging point offset gather and a depth offset profile based on the scanning velocity field. The common imaging point offset gather includes multiple reflection points, each with an initial depth. The depth offset profile is used to determine the velocity information of the reflection points in the underground medium layer.
[0104] The correction module 803 is used to process the common imaging point offset gather and the depth offset profile to obtain the depth correction parameters of the reflection point. The initial depth of the reflection point is corrected using the depth correction parameters to obtain the reference depth of the reflection point.
[0105] The determination module 802 is also used to determine the energy distribution of the reflection point located at the reference depth, use the energy distribution of the reflection point to determine the velocity spectrum of the reference scanning layer, and use the velocity spectrum of the reference scanning layer to determine the velocity spectrum of the underground medium layer in the exploration area.
[0106] In one possible implementation, the common imaging point offset channel set contains multiple offset channels arranged sequentially, and each offset channel corresponds to at least one reflection point. The correction module 803 is used to determine the tilt angle of the reflection point based on the common imaging point offset channel set corresponding to the reflection point and the depth offset profile; and to determine the depth correction parameters based on the tilt angle of the reflection point and the reference distance, where the reference distance is the horizontal distance between the offset channel where the reflection point is located and the central offset channel in the depth offset profile, and the central offset channel is the middle offset channel in the sequentially arranged offset channels.
[0107] In one possible implementation, the correction module 803 is used to acquire scanning information, including a scanning window used for scanning in a depth offset profile; determine multiple scanning lines passing through the reflection point based on the common imaging point offset gather corresponding to the reflection point and the scanning information, each scanning line having a scanning tilt angle; determine a reference line segment based on the scanning window and the multiple scanning lines, the reference line segment being the line segment of the multiple scanning lines located within the scanning window; calculate the similarity of sampling points with different offset distances on any reference line segment, and determine the scanning tilt angle of the reference line segment corresponding to the maximum similarity as the tilt angle of the reflection point.
[0108] In one possible implementation, the reference scanning layer includes multiple reflection points, and the common imaging point offset set of the reflection points includes multiple offset channels. The determining module 802 is used to obtain a first energy value of each offset channel in the common imaging point offset set corresponding to the reflection point, determine a second energy value of the common imaging point offset set corresponding to the reflection point based on the first energy value, determine a first energy distribution of the reference scanning layer based on the second energy value, determine the energy distribution of the scanning velocity field corresponding to the reflection point based on the first energy value, determine the second energy distribution of the reference scanning layer using the energy distribution of the scanning velocity field, and determine the velocity spectrum of the reference scanning layer based on the first energy distribution and the second energy distribution.
[0109] In one possible implementation, the offset channel includes multiple sampling points. The determination module 802 is further used to obtain the first amplitude of the sampling points in the offset channel; to perform a linear transformation on the first amplitude to obtain the second amplitude of the sampling points; and to determine the first energy value using the first amplitude, the second amplitude, and the number of sampling points in the offset channel.
[0110] In one possible implementation, module 801 is used to process seismic data to obtain a time-domain velocity field and a time-domain migration profile. The time-domain velocity field characterizes the distribution of the propagation velocity of seismic waves at different locations and time points in the exploration area, and the time-domain migration profile characterizes the migration of reflection points at different times. The initial layer velocity field in the depth domain is determined based on the time-domain velocity field and the time-domain migration profile.
[0111] In one possible implementation, the acquisition module 801 is further configured to preprocess the seismic data to obtain preprocessed seismic data. The preprocessing includes at least one of denoising, consistency processing, or deconvolution processing. The preprocessed seismic data is then subjected to velocity analysis in the time domain to obtain a time-domain velocity field. The time-domain velocity field is then subjected to pre-stack time migration processing to obtain a time-domain migration profile.
[0112] In one possible implementation, module 801 is used to perform stratigraphic interpretation on the time-domain migration profile to obtain the distribution information of the subsurface medium layers in the exploration area; based on the distribution information of the subsurface medium layers, an initial velocity model is constructed, and the information of the time-domain velocity field and seismic data are input into the initial velocity model to obtain the initial layer velocity field in the depth domain.
[0113] This application determines the depth correction parameters for reflection points using common imaging point migration gathers and depth migration profiles. Correcting the initial depth of reflection points using these parameters improves the accuracy of the reflection point depth, thereby enhancing the accuracy of the determined dip angle. Using the corrected depth of the reflection points, i.e., the reference depth, to determine the energy distribution, and calculating the velocity spectrum based on this energy distribution, improves the accuracy and precision of the velocity spectrum of the subsurface medium in the exploration area, thus enhancing the interpretability of seismic data in subsequent processes.
[0114] It should be understood that the above-described apparatus is only illustrated by the division of the functional modules described above when implementing its functions. In practical applications, the functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the apparatus and method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process can be found in the method embodiments, which will not be repeated here.
[0115] Figure 9 This is a schematic diagram of the server structure provided in the embodiments of this application. The server 900 can vary considerably due to different configurations or performance. It may include one or more processors 901 and one or more memories 902. The one or more memories 902 store at least one line of program code, which is loaded and executed by the one or more processors 901 to implement the velocity spectrum determination method provided in the various method embodiments described above. Of course, the server 900 may also have wired or wireless network interfaces, a keyboard, and input / output interfaces for input and output. The server 900 may also include other components for implementing device functions, which will not be elaborated here.
[0116] In an exemplary embodiment, a computer-readable storage medium is also provided, which stores at least one piece of program code that is loaded and executed by a processor to enable a computer to implement any of the above-described methods for determining the velocity spectrum.
[0117] Optionally, the aforementioned computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), magnetic tape, floppy disk, and optical data storage device, etc.
[0118] In an exemplary embodiment, a computer program or computer program product is also provided, which stores at least one computer instruction, which is loaded and executed by a processor to enable the computer to implement any of the above-described methods for determining the velocity spectrum.
[0119] It should be noted that all information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, stored data, displayed data, etc.), and signals involved in this application have been authorized by the user or fully authorized by all parties, and the collection, use, and processing of related data must comply with the relevant laws, regulations, and standards of the relevant countries and regions. For example, the seismic data, correction parameters, and velocity spectra involved in this application were obtained with full authorization.
[0120] It should be understood that "multiple" as used in this article refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0121] The above description is merely an exemplary embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.
Claims
1. A method for determining a velocity spectrum, characterized in that, The method includes: Seismic data of the exploration area is acquired, and an initial layer velocity field in the depth domain is determined based on the seismic data. The initial layer velocity field in the depth domain characterizes the initial velocity distribution of subsurface media layers at different depths in the exploration area. A reference scanning layer is determined in the underground medium layer, and the scanning parameters corresponding to the reference scanning layer are obtained. The scanning parameters are used to generate the scanning velocity field of the reference scanning layer. Based on the scanning velocity field, a common imaging point offset gather and a depth offset profile are determined. The common imaging point offset gather includes data of multiple reflection points. The reflection points have an initial depth. The depth offset profile is used to determine the velocity information of the reflection points in the underground medium layer. The common imaging point offset gather and the depth offset profile are processed to obtain the depth correction parameters of the reflection point. The initial depth of the reflection point is corrected using the depth correction parameters to obtain the reference depth of the reflection point. The energy distribution of the reflection point located at the reference depth is determined, the velocity spectrum of the reference scanning layer is determined using the energy distribution of the reflection point, and the velocity spectrum of the subsurface medium layer in the exploration area is determined using the velocity spectrum of the reference scanning layer.
2. The method according to claim 1, characterized in that, The common imaging point offset channel set contains multiple offset channels, which are arranged sequentially and each offset channel corresponds to at least one reflection point. The process of processing the common imaging point offset channel set and the depth offset profile to obtain the depth correction parameters for the reflection point includes: The tilt angle of the reflection point is determined based on the common imaging point offset gather and the depth offset profile corresponding to the reflection point. The depth correction parameters are determined based on the tilt angle of the reflection point and the reference distance. The reference distance is the horizontal distance between the offset channel where the reflection point is located and the central offset channel in the depth offset profile. The central offset channel is the offset channel in the middle of the sequentially arranged offset channels.
3. The method according to claim 2, characterized in that, Determining the tilt angle of the reflection point based on the common imaging point offset gather corresponding to the reflection point and the depth offset profile includes: Acquire scanning information, the scanning information including a scanning window, the scanning window being used to perform scanning in the depth offset profile; Based on the common imaging point offset gather corresponding to the reflection point and the scanning information, multiple scan lines passing through the reflection point are determined, and each scan line has a scanning tilt angle. A reference line segment is determined based on the scanning window and the multiple scanning lines, wherein the reference line segment is the line segment of the multiple scanning lines located within the scanning window; Calculate the similarity of sampling points with different offsets on any reference line segment, and determine the scanning tilt angle of the reference line segment corresponding to the maximum similarity as the tilt angle of the reflection point.
4. The method according to claim 1, characterized in that, The reference scanning layer includes multiple reflection points, and the common imaging point offset gather of the reflection points includes multiple offset channels. Determining the energy distribution of the reflection points located at the reference depth and using the energy distribution of the reflection points to determine the velocity spectrum of the reference scanning layer includes: Obtain the first energy value of each offset channel in the common imaging point offset channel set corresponding to the reflection point, and determine the second energy value of the common imaging point offset channel set corresponding to the reflection point based on the first energy value; The first energy distribution of the reference scan layer is determined based on the second energy value; Based on the first energy value, the energy distribution of the scanning velocity field corresponding to the reflection point is determined, and the energy distribution of the scanning velocity field is used to determine the second energy distribution of the reference scanning layer. The velocity spectrum of the reference scan layer is determined based on the first energy distribution and the second energy distribution.
5. The method according to claim 4, characterized in that, The offset channel includes multiple sampling points. Before obtaining the first energy value of each offset channel in the common imaging point offset channel set corresponding to the reflection point, the method further includes: Obtain the first amplitude of the sampling point in the offset channel; A linear transformation is performed on the first amplitude to obtain the second amplitude of the sampling point; The first energy value is determined using the first amplitude, the second amplitude, and the number of sampling points in the offset channel.
6. The method according to any one of claims 1 to 5, characterized in that, Determining the initial layer velocity field in the depth domain based on the seismic data includes: The seismic data is processed to obtain a time-domain velocity field and a time-domain migration profile. The time-domain velocity field characterizes the distribution of the propagation velocity of seismic waves at different locations and time points in the exploration area, and the time-domain migration profile characterizes the migration of reflection points at different times. The initial layer velocity field in the depth domain is determined based on the time-domain velocity field and the time-domain offset profile.
7. The method according to claim 6, characterized in that, Before processing the seismic data to obtain the time-domain velocity field and time-domain migration profile, the process further includes: The seismic data is preprocessed to obtain preprocessed seismic data. The preprocessing includes at least one of denoising, consistency processing, or deconvolution processing. The process of processing the seismic data to obtain the time-domain velocity field and time-domain migration profile includes: The preprocessed seismic data is subjected to velocity analysis in the time domain to obtain the time-domain velocity field. The time-domain velocity field is subjected to pre-stack time migration processing to obtain the time-domain migration profile.
8. The method according to claim 6, characterized in that, Determining the initial layer velocity field in the depth domain based on the time-domain velocity field and the time-domain offset profile includes: The stratigraphic interpretation of the time-domain offset profile yields the distribution information of the subsurface media layers in the exploration area. An initial velocity model is constructed based on the distribution information of the underground medium layer. The information of the time-domain velocity field and the seismic data are input into the initial velocity model to obtain the initial layer velocity field in the depth domain.
9. A device for determining a velocity spectrum, characterized in that, The device includes: The acquisition module is used to acquire seismic data of the exploration area and determine the initial layer velocity field in the depth domain based on the seismic data. The initial layer velocity field in the depth domain characterizes the initial velocity distribution of the subsurface medium layers at different depths in the exploration area. The determination module is used to determine a reference scanning layer in the underground medium layer, obtain scanning parameters corresponding to the reference scanning layer, generate a scanning velocity field of the reference scanning layer using the scanning parameters, and determine a common imaging point offset gather and a depth offset profile based on the scanning velocity field. The common imaging point offset gather includes multiple reflection points, each reflection point has an initial depth, and the depth offset profile is used to determine the velocity information of the reflection points in the underground medium layer. The correction module is used to process the common imaging point offset gather and the depth offset profile to obtain the depth correction parameters of the reflection point, and use the depth correction parameters to correct the initial depth of the reflection point to obtain the reference depth of the reflection point. The determining module is further configured to determine the energy distribution of the reflection point located at the reference depth, use the energy distribution of the reflection point to determine the velocity spectrum of the reference scanning layer, and use the velocity spectrum of the reference scanning layer to determine the velocity spectrum of the subsurface medium layer in the exploration area.
10. A computer device, characterized in that, The computer device includes a processor and a memory, the memory storing at least one piece of program code, the at least one piece of program code being loaded and executed by the processor to enable the computer device to implement the method for determining the velocity spectrum as described in any one of claims 1 to 8.