Time-depth conversion method and system for marine seismic acquisition imaging

Abstract

The present application relates to the technical field of geophysical exploration and marine engineering geological survey, and provides a time-depth conversion method and system for offshore seismic acquisition imaging. The time-depth conversion method for offshore seismic acquisition imaging comprises synchronously acquiring seismic data of a submarine tunnel line position and preprocessing the seismic data; based on the preprocessed seismic data, combining regional geological priori and drilling data, a multi-scale velocity field combining a macroscopic layered velocity model and a microscopic lateral variable velocity model is constructed; based on the multi-scale velocity field, a time domain seismic profile is converted into a seismic depth domain profile; transient electromagnetic apparent resistivity data are introduced to calculate corrected seismic velocity and thereby re-perform time-depth conversion to obtain seismic depth domain profile imaging; combining a complex spectrum correction method and a drilling data error verification method, the seismic depth domain profile imaging is optimized. The present application can realize efficient and accurate time-depth conversion of offshore complex geological structures and adverse geological bodies.

Description

Technical Field

[0001] This invention relates to the field of geophysical exploration and marine engineering geological exploration technology, and in particular to a time-depth conversion method and system for marine seismic acquisition and imaging. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Seismic exploration is the most crucial geophysical method in submarine tunnel geological investigation. It acquires seismic wave propagation signals in underground strata to invert stratigraphic structure and lithological information. However, raw seismic exploration data is presented in the time domain (i.e., the relationship between seismic wave travel time and signal intensity), while submarine tunnel construction requires a well-defined depth-domain geological model (i.e., the actual burial of stratigraphic interfaces and geological bodies). Currently, commonly used time-depth conversion methods in marine seismic exploration mainly include simple time-depth conversion methods based on uniform velocity models, tomographic inversion velocity modeling methods, and well-seismic combined time-depth conversion methods. However, these methods have significant limitations in the context of fine-grained submarine tunnel exploration. (1) Traditional methods often use fixed velocity models or layered average velocity models, which do not fully consider the lateral non-uniformity and vertical gradual change characteristics of the seafloor strata. Traditional time-depth conversion methods use fixed velocity integration or simple interpolation, which can easily lead to "stretching distortion" or "compression distortion" of shallow strata in the depth domain. This makes the boundaries of shallow adverse geological bodies such as water-rich layers and shallow gas layers, which pose a great threat to tunnel construction, blurred or even missed, bringing great safety hazards to the construction of the tunnel portal section. (2) Although the well-seismic combination method can calibrate the velocity model through borehole data and improve the conversion accuracy, offshore borehole construction faces many limitations. Existing methods mostly process seismic data independently, while seismic waves are sensitive to strata lithology interfaces and structural morphology, but have a weak ability to identify electrical anomalies such as water-bearing bodies and fractured zones. Transient electromagnetic (TEM) methods are a geophysical approach that is highly sensitive to low-resistivity bodies (water-rich layers, fracture zones, etc.). In marine exploration, they can quickly delineate low-resistivity anomaly zones. However, current technologies have not effectively integrated them with seismic time-depth conversion, which means that seismic velocity models cannot specifically correct the velocity parameters of electrical anomaly zones, thus affecting the reliability of depth models. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a time-depth conversion method and system for marine seismic acquisition and imaging, which can achieve efficient and accurate time-depth conversion for complex geological structures and adverse geological bodies at sea.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of the present invention provides a time-depth conversion method for marine seismic acquisition imaging.

[0006] In one or more embodiments, a time-depth conversion method for marine seismic acquisition imaging is provided, comprising: Simultaneously acquire seismic data on the alignment of the submarine tunnel and preprocess it; Based on preprocessed seismic data, combined with regional geological priors and borehole data, a multi-scale velocity field combining a macroscopic layered velocity model and a microscopic lateral velocity variation model is constructed. Based on the multi-scale velocity field, the time-domain seismic profile is converted into a seismic depth-domain profile; Transient electromagnetic apparent resistivity data is introduced to calculate and correct earthquake velocity, and time-depth conversion is performed again accordingly to obtain earthquake depth domain profile imaging. By combining complex spectrum correction methods and borehole data error verification methods, seismic depth domain profile imaging is optimized.

[0007] As one implementation method, in the process of constructing a multi-scale velocity field, a combination of tomographic inversion and waveform inversion is used to optimize the velocity parameters layer by layer; the macroscopic layered velocity model and the microscopic transverse speed variation model are weighted and fused to obtain the multi-scale velocity field.

[0008] As one implementation method, in the process of constructing the macroscopic layered velocity model, based on the geometric ray theory of seismic wave travel time, the velocity model is iteratively updated by minimizing the residual between the observed travel time and the model's calculated travel time.

[0009] As one implementation method, in the process of constructing the microscopic lateral velocity variation model, based on the wave equation, the complete waveform information of the seismic wave is used to finely characterize the lateral velocity variation by minimizing the difference between the observed waveform and the simulated waveform.

[0010] As one implementation method, based on a multi-scale velocity field, a time-domain seismic profile is converted into a depth-domain profile using a time-varying effective velocity integral formula.

[0011] As one implementation method, the process of introducing transient electromagnetic apparent resistivity data to calculate and correct seismic velocities and then re-converting the time to depth to obtain seismic depth domain profile imaging is as follows: The transient electromagnetic apparent resistivity profile is spatially registered with the seismic depth domain profile. The conductivity of each grid point in the low-resistivity anomaly zone is extracted, and the corrected seismic velocity is calculated point by point. The boundary of the anomaly zone is smoothly transitioned, and the time-depth conversion is performed again using the corrected seismic velocity to obtain the seismic depth domain profile image.

[0012] As one implementation method, a complex spectrum correction method is adopted, and an appropriate correction factor is selected according to the size of the geological body to improve the resolution of the seismic depth domain profile imaging. Borehole data is used to verify the error and ensure that the positioning error of the low-resistivity body and the structural interface error are within the corresponding error range, thus obtaining the optimized seismic depth domain profile imaging.

[0013] A second aspect of the present invention provides a time-depth conversion system for marine seismic acquisition and imaging.

[0014] In one or more embodiments, a time-depth conversion system for marine seismic acquisition imaging includes: The data acquisition and preprocessing module is used to synchronously acquire seismic data of the submarine tunnel alignment and preprocess it. The multi-scale velocity field construction module is used to construct a multi-scale velocity field that combines a macroscopic layered velocity model and a microscopic lateral velocity variation model based on preprocessed seismic data and regional geological priors and borehole data. The initial time-depth conversion module is used to convert time-domain seismic profiles into seismic depth-domain profiles based on multi-scale velocity fields. The depth domain profile imaging module is used to import transient electromagnetic apparent resistivity data to calculate and correct seismic velocity and perform time-depth conversion accordingly to obtain seismic depth domain profile imaging. The depth domain profile imaging optimization module is used to optimize seismic depth domain profile imaging by combining complex spectrum correction methods and borehole data error verification methods.

[0015] A third aspect of the present invention provides a computer-readable storage medium.

[0016] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the time-depth conversion method for marine seismic acquisition imaging as described above.

[0017] A fourth aspect of the present invention provides an electronic device.

[0018] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the time-depth conversion method for marine seismic acquisition imaging as described above.

[0019] Compared with the prior art, the beneficial effects of the present invention are: This invention constructs a multi-scale velocity model based on marine seismic data, combining macroscopic layered and microscopic lateral velocity variations. It balances overall rationality with local adaptability, performs high-fidelity conversion from the seismic time domain to the depth domain, integrates transient electromagnetic data for electrical constraint correction, and optimizes the velocity parameters of adverse geological bodies. Through complex spectrum correction and borehole verification, it improves imaging resolution and reliability, solving problems such as inaccurate velocity models, low shallow resolution, and reliance on boreholes in traditional time-depth conversion methods. It achieves high-precision, intelligent time-depth conversion with less borehole dependence, reducing positioning errors of low-resistivity bodies and structural interface errors. It is particularly suitable for complex geological structure detection in the early stages of submarine tunnel construction, enabling intelligent and high-fidelity conversion from seismic time domain data to geological depth domain models. This provides high-precision geological data for submarine tunnel construction design, risk warning, and on-site construction guidance. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a flowchart of a time-depth conversion method for marine seismic acquisition and imaging according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the time-depth conversion system for marine seismic acquisition and imaging according to an embodiment of the present invention; Figure 3 This is a schematic diagram of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] As the background technology indicates, the commonly used time-depth conversion methods in current marine seismic exploration mainly include the simple time-depth conversion method based on a uniform velocity model, the tomographic inversion velocity modeling method, and the well-seismic combined time-depth conversion method. However, these methods have significant limitations in the scenario of fine exploration of submarine tunnels: Insufficient accuracy of velocity models makes them unsuitable for the complex geological conditions of submarine tunnels: Traditional methods often employ fixed velocity models or layered average velocity models, failing to adequately consider the lateral non-uniformity and vertical gradual variation of submarine strata. For example, when a submarine tunnel traverses a fault fracture zone, the velocity within the fracture zone is only 60%-80% of that of the surrounding rock. Traditional layered models cannot characterize such local velocity abrupt changes, resulting in a systematic error of 5-10m in the converted depth model. This fails to meet the accuracy requirements for geological body positioning during tunnel construction (typically requiring an error ≤3m).

[0026] Shallow strata have low resolution and weak ability to identify adverse geological bodies: Seismic wave velocities in seafloor surface sediments (silt, silt layers) are generally low (1200-1800 m / s) and vary drastically laterally (velocity differences between adjacent points on the same survey line can reach over 300 m / s). Traditional time-depth conversion methods use fixed velocity integration or simple interpolation, which easily leads to "stretching distortion" or "compression distortion" in the depth domain of shallow strata. This results in blurred boundaries of shallow adverse geological bodies such as water-rich layers and shallow gas, which pose a significant threat to tunnel construction, and may even lead to their omission, posing a great safety hazard to tunnel portal construction.

[0027] Relying on borehole data, exploration costs are high and applicability is limited: Although the combined well-seismic method can calibrate velocity models and improve conversion accuracy through borehole data, offshore drilling faces many limitations. On the one hand, offshore drilling requires specialized drilling vessels, with drilling costs reaching several thousand yuan per meter and a single-hole construction cycle of 10-15 days. For a survey line of tens of kilometers of submarine tunnels, the cost of deploying boreholes across the entire area is extremely high. On the other hand, the sparse distribution of boreholes (usually one borehole every 5-10 kilometers) makes it difficult to cover the complex geological sections of the entire tunnel, resulting in "blind spots" in velocity calibration and making it impossible to achieve high-precision time-depth conversion across the entire area.

[0028] The lack of integration of multi-source data presents a weakness in identifying electrical anomalies: Existing methods often process seismic data independently, while seismic waves are sensitive to stratigraphic lithology interfaces and structural morphology, but have a weak ability to identify electrical anomalies such as aquifers and fractured zones. Transient electromagnetic (TEM) methods, as a geophysical tool highly sensitive to low-resistivity bodies (aquifers, fractured zones, etc.), can quickly delineate low-resistivity anomaly zones in marine exploration. However, current technologies do not effectively integrate TEM with seismic time-depth conversion, resulting in seismic velocity models being unable to specifically correct velocity parameters for electrical anomaly zones, thus affecting the reliability of depth models.

[0029] Transient electromagnetic methods and seismic wave methods each have unique advantages in submarine tunnel exploration and are significantly complementary: The core advantages of transient electromagnetic methods are: (1) Extremely high sensitivity to low-resistivity geological bodies: The electrical conductivity of adverse geological bodies such as water-rich layers and fractured zones is usually 5-10 times that of normal strata. By observing the attenuation process of electromagnetic induction signals, the TEM method can accurately identify the spatial distribution range of such low-resistivity anomalies, with an apparent resistivity resolution of up to 0.1Ω. m, can quickly delineate water-rich risk areas on the tunnel path; (2) low operating cost and high coverage efficiency: TEM equipment is small in size and light in weight (the weight of a single set of equipment is ≤50kg), and does not require large operating vessels. It can be towed by small speedboats. The daily coverage length of the survey line can reach 20-30 kilometers, which is 3-5 times the coverage efficiency of seismic exploration, and can greatly reduce the exploration cycle and cost; (3) virtual wave field imaging capability: by performing wave field transformation processing on TEM data, electromagnetic signals can be converted into a virtual wave field similar to seismic waves, which has a certain ability to characterize the stratigraphic interface and provides supplementary interface information for seismic time-depth conversion.

[0030] The core advantages of the seismic wave method are: (1) High resolution and strong structural characterization ability: The vertical resolution of seismic waves (especially high-frequency seismic waves with a main frequency ≥100Hz) can reach 1-3m, and the lateral resolution can reach 5-10m. It can clearly characterize the attitude (strike, dip, dip angle) and spatial continuity of the strata and fault fracture zones. It is currently the only exploration method that can accurately describe the fine structure of the strata along the tunnel path; (2) Rich lithological and fluid information: The amplitude, frequency, phase and other parameters of seismic waves are closely related to the lithology (sandstone, mudstone, bedrock), porosity and fluid type (water, gas). Through wave impedance inversion, attribute analysis and other technologies, the physical and mechanical parameters of the strata can be further obtained, providing a direct basis for the design of tunnel construction parameters; (3) Mature technical system: After decades of development, seismic exploration has formed a complete technical system from data acquisition, preprocessing, inversion modeling to interpretation. The data processing process is standardized and highly automated, and the reliability of the results has been verified by a large number of engineering projects.

[0031] However, the TEM method has low vertical resolution (typically ≥5m), making it difficult to accurately characterize the burial depth of stratigraphic interfaces; while the seismic wave method lacks sensitivity in identifying low-resistivity anomalies and is easily affected by the non-uniformity of stratigraphic velocity. Therefore, there is an urgent need for a time-depth conversion technology that combines the advantages of both methods, enabling intelligent and high-fidelity conversion of time-domain seismic data to depth-domain geological models with minimal or no drilling, thus meeting the high-precision requirements of submarine tunnel construction exploration.

[0032] Figure 1 A schematic diagram of the time-depth conversion method for marine seismic acquisition and imaging according to an embodiment of the present invention is provided. Based on... Figure 1The time-depth conversion method for marine seismic acquisition and imaging in this embodiment may include the following steps: Step 1: Synchronously acquire seismic data of the submarine tunnel alignment and preprocess it.

[0033] Based on the geological background and exploration needs of the target exploration area (such as the site of a submarine tunnel), a joint acquisition mode of "single-channel seismic as the main method and multi-channel seismic as the auxiliary method" is adopted to ensure that the data covers the needs of shallow and deep strata exploration, laying the foundation for subsequent processing.

[0034] Acquisition equipment: Comprehensive oceanographic survey vessel, equipped with a single-channel seismic acquisition system (towed cable length 50-80m), a 48-channel multichannel seismic acquisition system (channel spacing 3.125m, towed cable length 150-200m), an electric spark source (energy 500-1000J, adjusted according to stratum depth) and a high-precision positioning system (RTK-GPS, positioning accuracy ≤0.5m).

[0035] Survey line layout: The main survey line is laid out along the design axis of the seabed tunnel, with the length of the survey line consistent with the length of the tunnel axis and the line spacing controlled at 10m; in key sections such as tunnel entrances and exits and known structural fracture zones, connecting survey lines perpendicular to the main survey line are added, with a spacing of 500m between the connecting survey lines, forming a grid-like observation system of "main survey line + connecting survey line".

[0036] Acquisition parameters: Single-channel seismic data is acquired using a "one shot, one beamline" method with a shot spacing of 2-5m, focusing on shallow strata (0-50m depth); multi-channel seismic data is acquired using "intensified acquisition" with a shot spacing of 2m and a channel spacing of 2m, focusing on deep strata (50-200m depth); seismic wave travel time, amplitude, frequency data, and auxiliary data such as acquisition location, water depth, and seabed topography are recorded simultaneously.

[0037] The preprocessing aims to "improve the signal-to-noise ratio, suppress interference, and retain effective signals," and employs targeted processing algorithms. Multiple wave suppression: The Radon transform method is used, and based on the travel time difference between the primary and secondary waves, the primary and secondary waves are separated by slope filtering, with a suppression ratio of ≥80%; Linear noise suppression: Using FK (frequency-wavenumber) filtering technology, the wavenumber characteristics of linear noise are identified, and a band-stop filter is designed to attenuate the linear noise energy by ≥60%; Signal enhancement: Adaptive gain control (AGC) algorithm is used to compensate for the gain of weak signals in deep layers; spectrum equalization technology is used to broaden the effective frequency band of seismic signals (10-200Hz). Data quality control: The signal-to-noise ratio of the preprocessed data is improved by ≥40%, the effective signal amplitude distortion is ≤5%, and the travel time error is ≤0.1ms.

[0038] Step 2: Based on the preprocessed seismic data, combined with regional geological priors and borehole data, construct a multi-scale velocity field that combines a macroscopic layered velocity model and a microscopic lateral velocity variation model.

[0039] This embodiment constructs a "macroscopic layered velocity model + microscopic lateral speed variation model" to balance the regional rationality and local precision of the velocity field.

[0040] Specifically, in the process of constructing the multi-scale velocity field, a combination of tomographic inversion and waveform inversion is used to optimize the velocity parameters layer by layer; the macroscopic layered velocity model and the microscopic transverse speed variation model are weighted and fused to obtain the multi-scale velocity field.

[0041] Initial model construction: Based on prior regional geological information (geological survey report, borehole data from adjacent areas, regional stratigraphic columnar section), the stratigraphic lithological sequence, average velocity range of each layer, and structural development characteristics are clarified, and 3-5 main stratigraphic units are delineated. Combining data from 3-5 boreholes, the longitudinal wave velocity of the core is obtained through laboratory ultrasonic testing (test accuracy ±10 m / s), and the initial model velocity parameters are preliminarily corrected. For example, initial velocity values ​​are: silty clay 1300 m / s, silt layer 1900 m / s, sandstone 2100 m / s, and granite 3200 m / s.

[0042] Macroscopic velocity model optimization (tomographic inversion): In the process of constructing the macroscopic layered velocity model, based on the geometric ray theory of seismic wave travel time, the velocity model is iteratively updated by minimizing the residual between the observed travel time and the model's calculated travel time.

[0043] The objective function for tomographic inversion is:

[0044] in, N The number of seismic rays; For the first The observation of a ray during travel; For the first A ray in the velocity model Calculating travel time in the context of travel time; For L2 regularization terms; This is the smoothing coefficient (range 0.01-0.1).

[0045] The inversion uses the Algebraic Reconstruction Technique (ART), with an initial iteration step size of 0.1. Iteration stops when the root mean square (RMS) of the travel time residual is ≤0.2ms, and the number of iterations is 10-15.

[0046] In the process of constructing the microscopic lateral velocity variation model, based on the wave equation, the complete waveform information of seismic waves is used to finely characterize the lateral velocity variation by minimizing the difference between the observed waveform and the simulated waveform.

[0047] Microscopic velocity model optimization (full waveform inversion): Based on the wave equation, and utilizing the complete waveform information of seismic waves, the lateral velocity variation is finely characterized by minimizing the difference between the observed and simulated waveforms. The objective function for full waveform inversion is:

[0048] in, For the first Time series of observed seismic waveforms; For velocity-based models Simulated earthquake waveforms; T The duration of the waveform data.

[0049] The inversion adopts a "multi-scale inversion" strategy, first using low-frequency signals (10-30Hz) to update the large-scale velocity structure, and then gradually introducing mid-to-high frequency signals (30-100Hz); the number of iterations is 20-30, and the final waveform fitting error is ≤10%.

[0050] A weighted average method was used to integrate macroscopic and microscopic velocity models: for deep layers (≥200m), the macroscopic model was the primary model (weight 0.7), and the microscopic model was secondary (weight 0.3); for shallow layers (≤200m) and tectonic fracture zones, the microscopic model was the primary model (weight 0.8), and the macroscopic model was secondary (weight 0.2). The final model mesh accuracy reached 5m×5m×2m.

[0051] Step 3: Based on the multi-scale velocity field, convert the time-domain seismic profile into a seismic depth-domain profile.

[0052] Based on the multi-scale velocity field, the time-domain seismic profile is converted into the depth-domain profile using the time-varying effective velocity integral formula, thus achieving a precise mapping from the time domain to the depth domain.

[0053] When seismic waves propagate in non-homogeneous strata, the two-way travel time T With stratum depth H The relationship is:

[0054] in, It is a time-varying effective velocity function, obtained by dynamic interpolation from a multi-scale velocity model.

[0055] Construction of time-varying effective velocity function: Using cubic spline interpolation, a continuous velocity spatial distribution function is constructed based on the grid node velocity values ​​of the multi-scale velocity model. v (x,z); Seismic wave travel time is established using ray tracing technology. t The correspondence with depth z is z=f( t (This converts the spatial velocity function into a time-varying velocity function.) v eff ( t )= v (x,f( t The interpolation step size is 0.1ms, and the speed interpolation error is ≤5m / s.

[0056] Numerical integration calculation: Discrete calculations are performed using the trapezoidal numerical integration method:

[0057] Where, n= T / Δ t This represents the number of discrete sampling points. k=0,1,...,n; Δt=0.1ms is the integration step size; numerical integration error ≤0.1m.

[0058] Picking up two-way travel time one track at a time, one phase axis at a time T ; Calculate the time-varying effective velocity function point by point v eff (t); The depth H corresponding to each travel time is calculated by numerical integration to generate a depth domain seismic profile; The depth domain profile is then smoothed laterally (smoothing window 3×3 grid).

[0059] Step 4: Introduce transient electromagnetic apparent resistivity data to calculate the corrected seismic velocity and perform time-depth conversion again to obtain seismic depth domain profile imaging.

[0060] Transient electromagnetic (TEM) data is introduced for electrical constraint correction, and velocity parameters in the low-resistivity anomaly region are specifically optimized: Acquisition equipment: towed TEM system, transmitting coil side length 5m, receiving coil side length 3m, transmitting frequency 10-1000Hz, observation time window 0.1-10ms, sampling rate 0.01ms; the survey line layout completely coincides with the seismic survey line.

[0061] Data preprocessing: Baseline correction and wavelet denoising were performed on the raw TEM data; the apparent resistivity profile ρ was calculated using OCCAM inversion. s (x,z), inversion depth range 0-500m, inversion error ≤10%; set apparent resistivity threshold. ρ th (Typically 50Ω) m), delineate the low-resistivity anomaly region.

[0062] Establishment of the empirical relationship between conductivity and velocity: Based on laboratory test data of common strata in submarine tunnels, an empirical relationship between electrical conductivity and seismic velocity was established:

[0063] in, v σ0 represents the background formation velocity; σ0 represents the background formation conductivity. k The empirical coefficients (0.05-0.08 for sandstone, 0.08-0.10 for mudstone, and 0.03-0.05 for fractured zones) are calibrated using borehole data, with an error ≤0.01.

[0064] Speed ​​correction formula and process: Correction formula:

[0065] in, The corrected speed; The velocity values ​​are from the pre-correction seismic velocity model; σ(x,z) is the formation conductivity obtained from TEM inversion.

[0066] The process of introducing transient electromagnetic apparent resistivity data to calculate and correct seismic velocity, and then re-converting the time to depth to obtain seismic depth domain profile imaging is as follows: Spatially register the transient electromagnetic apparent resistivity profile with the seismic depth domain profile, extract the conductivity of each grid point in the low resistivity anomaly zone, calculate the corrected seismic velocity point by point, perform a smooth transition on the boundary of the anomaly zone (e.g., a transition zone width of 5m), and use the corrected seismic velocity to perform time-depth conversion again to obtain the seismic depth domain profile image.

[0067] Step 5: Optimize seismic depth domain profile imaging by combining complex spectrum correction method and borehole data error verification method.

[0068] The complex spectrum correction method is adopted, and the corresponding correction factor is selected according to the size of the geological body to improve the resolution of the seismic depth domain profile imaging. The borehole data is used to verify the error and ensure that the positioning error of the low resistivity body and the structural interface error are within the corresponding error range, thus obtaining the optimized seismic depth domain profile imaging.

[0069] Specifically, the correction factor is selected based on the geological body scale: When the geological body scale L < 20m, a correction factor is used. iω 2 Enhance high-frequency components (≥100Hz). When the geological body scale L ≥ 20m, a correction factor is used. iωEnhance mid-frequency components (30-100Hz).

[0070] The complex spectrum F(x,z) is obtained by performing a Fourier transform on the depth-domain seismic signal S(x,z). ω )=A( ω )*e i (ω) The corrected complex spectrum is used as the correction factor, and the corrected depth domain signal S is obtained through inverse Fourier transform. corr (x,z); After optimization, the clarity of the boundary of small geological bodies is improved by ≥40%, and the imaging resolution reaches 1-2m.

[0071] Drilling data verification: Select 7-10 borehole data points (depth ≥ 300m) to verify the following indicators: Low-resistivity body positioning error ≤ 5m; Interface construction error ≤3m; The relative error of the velocity model is ≤5%.

[0072] If the error exceeds the threshold, return to adjust the empirical coefficient k or return to optimize the speed model, and iterate until the requirements are met.

[0073] Final model output: Integrating the corrected depth domain profile, velocity model, and TEM low resistivity anomaly interpretation results, a geological depth domain model of the submarine tunnel is generated; the model format includes depth domain seismic profile (SEGY format), velocity model (grid data format), and geological interpretation results (CAD format).

[0074] like Figure 2 As shown, the time-depth conversion system for marine seismic acquisition and imaging provided in this embodiment of the invention can be implemented in software. The time-depth conversion system for marine seismic acquisition and imaging includes the following software modules: data acquisition and preprocessing module 201, multi-scale velocity field construction module 202, preliminary time-depth conversion module 203, depth domain profile imaging module 204, and depth domain profile imaging optimization module 205.

[0075] The following section describes the functions of each software module in the time-depth conversion system used for marine seismic acquisition and imaging: The data acquisition and preprocessing module 201 is used to synchronously acquire seismic data of the submarine tunnel alignment and preprocess it. Multiscale velocity field construction module 202 is used to construct a multiscale velocity field that combines a macroscopic layered velocity model and a microscopic lateral velocity variation model based on preprocessed seismic data and combined with regional geological priors and borehole data. The preliminary time-depth conversion module 203 is used to convert time-domain seismic profiles into seismic depth-domain profiles based on multi-scale velocity fields. The depth domain profile imaging module 204 is used to introduce transient electromagnetic apparent resistivity data to calculate and correct the seismic velocity and perform time-depth conversion again to obtain seismic depth domain profile imaging. The depth domain profile imaging optimization module 205 is used to optimize seismic depth domain profile imaging by combining complex spectrum correction method and borehole data error verification method.

[0076] It should be noted that each module in the time-depth conversion system for marine seismic acquisition and imaging in this embodiment corresponds one-to-one with each step in the time-depth conversion method for marine seismic acquisition and imaging in the above embodiment, and their specific implementation processes are the same, so they will not be repeated here.

[0077] The structure of the electronic device according to an embodiment of the present invention will be described in detail below. Figure 3 This is a schematic diagram of the composition structure of an electronic device provided in an embodiment of the present invention. It can be understood that... Figure 3 The diagram shows only an exemplary structure of the electronic device, not the entire structure. Some or all of the structures shown may be implemented as needed.

[0078] The electronic device provided in this embodiment of the invention includes: at least one processor 301, a memory 302, a user interface 303, and at least one network interface 304. Various components in the time-depth conversion system for marine seismic acquisition and imaging are coupled together via a bus system 305. It is understood that the bus system 305 is used to realize communication between these components. In addition to a data bus, the bus system 305 also includes a power bus, a control bus, and a status signal bus. However, for clarity, in... Figure 3 The general designated all buses as Bus System 305.

[0079] The user interface 303 may include a monitor, keyboard, mouse, trackball, click wheel, buttons, touchpad, or touch screen.

[0080] It is understood that memory 302 can be volatile memory or non-volatile memory, or both. In this embodiment of the invention, memory 302 is capable of storing data to support the operation of the terminal. Examples of this data include any computer programs used to operate on the terminal, such as operating systems and applications. The operating system includes various system programs, such as framework layers, core library layers, driver layers, etc., used to implement various basic services and handle hardware-based tasks. Applications can include various applications.

[0081] In some embodiments, the time-depth conversion system for marine seismic acquisition and imaging provided in this invention can be implemented using a combination of hardware and software. As an example, the time-depth conversion system for marine seismic acquisition and imaging provided in this invention can be a processor in the form of a hardware decoding processor, programmed to execute the time-depth conversion method for marine seismic acquisition and imaging provided in this invention. For example, the processor in the form of a hardware decoding processor can employ one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic components.

[0082] As an example, processor 301 can be an integrated circuit chip with signal processing capabilities, such as a general-purpose processor, a digital signal processor (DSP), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., wherein the general-purpose processor can be a microprocessor or any conventional processor, etc.

[0083] As an example of the hardware implementation of the time-depth conversion system for marine seismic acquisition and imaging provided in this embodiment of the invention, the device provided in this embodiment of the invention can be directly executed by a processor 301 in the form of a hardware decoding processor. For example, it can be executed by one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic components to implement the time-depth conversion method for marine seismic acquisition and imaging provided in this embodiment of the invention.

[0084] The memory 302 in this embodiment of the invention is used to store various types of data to support the operation of the time-depth conversion system for marine seismic acquisition and imaging, or to store data for execution. Figure 1The program code for the method shown. Examples of this data include: any executable instructions for operation on a time-depth conversion system for marine seismic acquisition imaging, such as executable instructions that can be included in the executable instructions to implement the time-depth conversion method for marine seismic acquisition imaging according to embodiments of the present invention.

[0085] Specifically, according to embodiments of this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program including functions for executing... Figure 1 The program code for the method shown. In such an embodiment, the computer program can be downloaded and installed from a network via a communication component, and / or installed from a removable medium. When the computer program is executed by the central processing unit, it performs the various functions defined in the apparatus of this application.

[0086] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0087] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A time-depth conversion method for marine seismic acquisition and imaging, characterized in that, include: Simultaneously acquire seismic data on the alignment of the submarine tunnel and preprocess it; Based on preprocessed seismic data, combined with regional geological priors and borehole data, a multi-scale velocity field combining a macroscopic layered velocity model and a microscopic lateral velocity variation model is constructed. Based on the multi-scale velocity field, the time-domain seismic profile is converted into a seismic depth-domain profile; Transient electromagnetic apparent resistivity data is introduced to calculate and correct earthquake velocity, and time-depth conversion is performed again accordingly to obtain earthquake depth domain profile imaging. By combining complex spectrum correction methods and borehole data error verification methods, seismic depth domain profile imaging is optimized.

2. The time-depth conversion method for marine seismic acquisition and imaging as described in claim 1, characterized in that, In constructing the multi-scale velocity field, a combination of tomographic inversion and waveform inversion is used to optimize the velocity parameters layer by layer. The macroscopic layered velocity model and the microscopic transverse speed variation model are weighted and fused to obtain the multi-scale velocity field.

3. The time-depth conversion method for marine seismic acquisition and imaging as described in claim 1, characterized in that, In the process of constructing the macroscopic layered velocity model, based on the geometric ray theory of seismic wave travel time, the velocity model is iteratively updated by minimizing the residual between the observed travel time and the model's calculated travel time.

4. The time-depth conversion method for marine seismic acquisition and imaging as described in claim 1, characterized in that, In the process of constructing the microscopic lateral velocity variation model, based on the wave equation, the complete waveform information of seismic waves is used to finely characterize the lateral velocity variation by minimizing the difference between the observed waveform and the simulated waveform.

5. The time-depth conversion method for marine seismic acquisition and imaging as described in claim 1, characterized in that, Based on the multi-scale velocity field, the time-domain seismic profile is converted into a depth-domain profile using the time-varying effective velocity integral formula.

6. The time-depth conversion method for marine seismic acquisition and imaging as described in claim 1, characterized in that, The process of introducing transient electromagnetic apparent resistivity data to calculate and correct seismic velocity, and then re-converting the time to depth to obtain seismic depth domain profile imaging is as follows: The transient electromagnetic apparent resistivity profile is spatially registered with the seismic depth domain profile. The conductivity of each grid point in the low-resistivity anomaly zone is extracted, and the corrected seismic velocity is calculated point by point. The boundary of the anomaly zone is smoothly transitioned, and the time-depth conversion is performed again using the corrected seismic velocity to obtain the seismic depth domain profile image.

7. The time-depth conversion method for marine seismic acquisition and imaging as described in claim 1, characterized in that, The complex spectrum correction method is adopted, and the corresponding correction factor is selected according to the size of the geological body to improve the resolution of the seismic depth domain profile imaging. The borehole data is used to verify the error and ensure that the positioning error of the low resistivity body and the structural interface error are within the corresponding error range, thus obtaining the optimized seismic depth domain profile imaging.

8. A time-depth conversion system for marine seismic acquisition and imaging, characterized in that, The time-depth conversion method for marine seismic acquisition and imaging based on any one of claims 1-7 includes: The data acquisition and preprocessing module is used to synchronously acquire seismic data of the submarine tunnel alignment and preprocess it. The multi-scale velocity field construction module is used to construct a multi-scale velocity field that combines a macroscopic layered velocity model and a microscopic lateral velocity variation model based on preprocessed seismic data and regional geological priors and borehole data. The initial time-depth conversion module is used to convert time-domain seismic profiles into seismic depth-domain profiles based on multi-scale velocity fields. The depth domain profile imaging module is used to import transient electromagnetic apparent resistivity data to calculate and correct seismic velocity and perform time-depth conversion accordingly to obtain seismic depth domain profile imaging. The depth domain profile imaging optimization module is used to optimize seismic depth domain profile imaging by combining complex spectrum correction methods and borehole data error verification methods.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the time-depth conversion method for marine seismic acquisition imaging as described in any one of claims 1-7.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the time-depth conversion method for marine seismic acquisition and imaging as described in any one of claims 1-7.

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