Shallow velocity structure inversion method and device based on deep sea guided waves, electronic equipment and storage medium

Abstract

The invention discloses a shallow velocity structure inversion method and device based on deep sea guided waves, electronic equipment and a storage medium. The method comprises the steps that a first wave field corresponding to a target stratum is determined, the target stratum is a stratum located at the seabed position, and the first wave field is a wave field obtained after first seismic waves received by a first detector and recorded in a first common shot gather are reflected and refracted by the target stratum; carrying out wave field downward continuation on the first wave field from the sea level corresponding to the target stratum to the seabed surface of the target stratum to obtain a second wave field corresponding to the target stratum; extracting a target guided wave from the second wave field; and determining a longitudinal wave velocity structure of the target stratum based on the target guided wave, wherein the frequency dispersion information of the target guided wave is used for constraining the longitudinal wave velocity structure of the target stratum. According to the scheme, the target guided wave corresponding to the target stratum is obtained from the second wave field corresponding to the target stratum, and the resolution of the longitudinal wave velocity structure of the target stratum obtained by inversion of the target guided wave corresponding to the target stratum is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of marine seismic exploration, and particularly to a method, device, electronic device and storage medium for inverting the shallow velocity structure based on deep sea guided waves. Background Art

[0002] With the continuous deepening of marine oil and gas resource exploration, deep sea oil and gas resources have received increasing attention. Most of the future important potential clean energy, natural gas hydrates, are stored in shallow deep sea sediments. Therefore, it is of great significance to use seismic exploration technology to detect deep sea oil and gas resources.

[0003] Inverting the high-resolution P-wave velocity structure in the shallow deep sea is the key to subsequent high-precision seismic imaging of the shallow deep sea. At present, the conventional P-wave velocity modeling method is to invert the P-wave velocity structure of the shallow deep sea by using the travel time information of refracted waves and reflected waves. However, the resolution of the P-wave velocity structure obtained by this velocity modeling method is low, which affects seismic imaging of the shallow deep sea. Summary of the Invention

[0004] The present invention provides a method, device, electronic device and storage medium for inverting the shallow velocity structure based on deep sea guided waves, so as to solve the problem of low resolution of the P-wave velocity structure obtained when inverting the P-wave velocity structure of the deep sea formation.

[0005] According to an aspect of the present invention, there is provided a method for inverting the shallow velocity structure based on deep sea guided waves, the method comprising:

[0006] Determine a first wave field corresponding to a target formation, the target formation being the formation located at the seabed position, the first wave field being the wave field after reflection and refraction of the first seismic wave received by the first geophone recorded in the first common shot gather, the first seismic wave being the seismic wave emitted by the first source towards the target formation, and the first source, the first geophone and the first wave field being all located at the sea level corresponding to the target formation;

[0007] Perform wave field downward continuation of the first wave field from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a second wave field corresponding to the target formation;

[0008] Extract a target guided wave from the second wave field, the target guided wave being a P-wave restricted to propagate in a specific layered structure of the target formation;

[0009] Determine the P-wave velocity structure of the target formation based on the target guided wave, the dispersion information of the target guided wave being used to constrain the P-wave velocity structure of the target formation, and the P-wave velocity structure being used to describe the propagation velocity distribution of seismic P-waves at different depths within the target formation.

[0010] According to another aspect of the present invention, there is provided a shallow velocity structure inversion device based on deep-sea guided waves, the device comprising:

[0011] A first determination module, configured to determine a first wave field corresponding to a target formation, the target formation being a formation located at the seabed position, the first wave field being the wave field after reflection and refraction of a first seismic wave received by a first detector in a first common shot gather, the first seismic wave being a seismic wave emitted by a first source towards the target formation, and the first source, the first detector, and the first wave field being all located at the sea level corresponding to the target formation;

[0012] A wave field continuation module, configured to perform downward wave field continuation of the first wave field from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a second wave field corresponding to the target formation;

[0013] A target guided wave extraction module, configured to extract a target guided wave from the second wave field, the target guided wave being a longitudinal wave restricted to propagate in a specific layered structure of the target formation;

[0014] A second determination module, configured to determine the longitudinal wave velocity structure of the target formation based on the target guided wave, the dispersion information of the target guided wave being used to constrain the longitudinal wave velocity structure of the target formation, and the longitudinal wave velocity structure being used to describe the propagation velocity distribution of seismic longitudinal waves at different depths within the target formation.

[0015] According to another aspect of the present invention, there is provided an electronic device, the electronic device comprising:

[0016] At least one processor; and

[0017] A memory communicatively connected to the at least one processor; wherein,

[0018] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the shallow velocity structure inversion method based on deep-sea guided waves according to any embodiment of the present invention.

[0019] According to another aspect of the present invention, there is provided a computer-readable storage medium storing computer instructions for causing a processor to implement the shallow velocity structure inversion method based on deep-sea guided waves according to any embodiment of the present invention when executed.

[0020] In the technical solution of the embodiment of the present invention, by determining a first wave field corresponding to a target formation, the target formation is a formation located at the seabed position, and the first wave field is the wave field after reflection and refraction of the first seismic wave received by a first geophone recorded in a first common shot gather passing through the target formation; downwardly continuing the first wave field from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a second wave field corresponding to the target formation; extracting a target guided wave from the second wave field, the target guided wave is a longitudinal wave restricted to propagate in a specific layered structure of the target formation, effectively obtaining the target guided wave corresponding to the target formation and improving the quality of the target guided wave, so that the longitudinal wave velocity structure of the target formation can be effectively inverted by using the target guided wave corresponding to the target formation to improve the resolution of the inverted longitudinal wave velocity structure; determining the longitudinal wave velocity structure of the target formation based on the target guided wave, the dispersion information of the target guided wave is used to constrain the longitudinal wave velocity structure of the target formation, and the longitudinal wave velocity structure is used to describe the propagation velocity distribution of seismic longitudinal waves at different depths within the target formation, so as to achieve high-precision seismic imaging of the target formation based on the longitudinal wave velocity structure of the target formation.

[0021] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a flowchart of a method for inverting the shallow velocity structure based on deep-sea guided waves provided by an embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of a first wave field corresponding to a target formation provided by an embodiment of the present invention;

[0025] Figure 3 It is a schematic diagram of a second wave field corresponding to a target formation provided by an embodiment of the present invention;

[0026] Figure 4 It is a flowchart of another method for inverting the shallow velocity structure based on deep-sea guided waves provided by an embodiment of the present invention;

[0027] Figure 5 It is a dispersion spectrogram of the target guided wave of a target formation provided by an embodiment of the present invention;

[0028] Figure 6 Schematic diagram of a shallow velocity structure inversion device based on deep - sea guided waves provided by an embodiment of the present invention;

[0029] Figure 7 Schematic diagram of an electronic device for implementing a shallow velocity structure inversion method based on deep - sea guided waves provided by an embodiment of the present invention. Detailed implementation manners

[0030] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above - mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non - exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0032] Figure 1 Flowchart of a shallow velocity structure inversion method based on deep - sea guided waves provided by an embodiment of the present invention. The embodiments of the present invention are applicable to the case of performing P - wave velocity structure inversion on the formation located at the seabed. This method can be executed by a shallow velocity structure inversion device based on deep - sea guided waves. The device can be implemented in the form of hardware and / or software and can be configured in an electronic device for implementing a shallow velocity structure inversion method based on deep - sea guided waves. As Figure 1 shown, the method specifically includes:

[0033] S101. Determine a first wave field corresponding to a target formation. The target formation is a formation located at the seabed position. The first wave field is the wave field after reflection and refraction of the first seismic wave received by a first geophone in a first common - shot gather through the target formation. The first seismic wave is a seismic wave emitted by a first source towards the target formation. The first source, the first geophone, and the first wave field are all located at the sea level corresponding to the target formation.

[0034] In an embodiment of the present invention, the target formation may refer to a sedimentary layer within a first depth range below the seabed surface. The sea level corresponding to the target formation may refer to the sea level perpendicular to the target formation, and the range of the sea level corresponding to the target formation is consistent with the horizontal range of the target formation. The first seismic source may refer to a seismic source capable of emitting seismic waves towards the target formation, such as an air gun seismic source or a mechanical seismic source. The first geophone may refer to a sensor capable of converting the seismic waves reflected and refracted by the target formation into electrical signals. The first geophone is located at the sea level corresponding to the target formation, such that the wave field received by the first geophone is also at the sea level corresponding to the target formation. The first common shot gather may refer to a set composed of the wave fields received by different first geophones after the first seismic wave emitted by the first seismic source towards the target formation is reflected and refracted by the target formation.

[0035] Exemplarily, a ship equipped with the first seismic source and a seismic streamer may be used as the first exploration ship, and different first geophones are included in the seismic streamer. When the first exploration ship sails to the sea level corresponding to the target formation, the first seismic wave is emitted towards the target formation by the first seismic source configured on the first exploration ship, and the wave fields of the first seismic wave reflected and refracted by the target formation are received by different first geophones included in the seismic streamer configured on the first exploration ship. Furthermore, referring to Figure 2 , by recording the wave field received by the first geophone in the first common shot gather, the first wave field corresponding to the target formation can be obtained.

[0036] As an alternative implementation manner of an embodiment of the present invention, determining the first wave field corresponding to the target formation includes: performing a preset waveform processing on the wave field of the first seismic wave received by the first geophone after being reflected and refracted by the target formation and then recording it in the first common shot gather to obtain the first wave field. The preset waveform processing at least includes: trace equalization and band-pass filtering.

[0037] In an embodiment of the present invention, the wave field of the first seismic wave received by the first geophone after being reflected and refracted by the target formation may be used as the original wave field. Furthermore, trace equalization may refer to performing amplitude processing on the original wave field. Band-pass filtering may refer to allowing the wave field within a specific frequency range in the original wave field to pass through while suppressing the wave fields of other frequencies. Performing the preset waveform processing on the original wave field and then recording the first common shot gather can improve the data quality of the first wave field.

[0038] S102. Downward continue the wave field of the first wave field from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain the second wave field corresponding to the target formation.

[0039] In the embodiments of the present invention, the seabed surface where the target formation is located may refer to the topographic surface of the seabed where the target formation is located. The downward continuation of the wavefield may refer to the process of downward wavefield simulation continuation of the first wavefield corresponding to the target formation actually recorded. The calculation methods adopted for the downward continuation of the wavefield may include one of the integral method, the finite difference method, and the frequency - wavenumber method.

[0040] Referring to Figure 3 , the second wavefield corresponding to the target formation may refer to the simulated wavefield obtained by downward wavefield continuation of the first wavefield corresponding to the target formation to the seabed surface where the target formation is located. Both the simulated source and geophone corresponding to the second wavefield are located on the seabed surface where the target formation is located.

[0041] S103. Extract the target guided wave from the second wavefield, where the target guided wave is a longitudinal wave restricted to propagate in a specific layered structure of the target formation.

[0042] In the embodiments of the present invention, the specific layered structure may refer to the low - velocity layer in the target formation. The target guided wave may refer to the P - guided wave. The target guided wave is formed by the interference and superposition of multiple reflected waves and refracted waves, has a dispersion characteristic, and can be used for inverting the longitudinal wave velocity structure of the target formation.

[0043] Specifically, referring to Figure 3 , based on the frequency characteristics of the target guided wave, the waveform with a sudden change in the second wavefield corresponding to the target formation can be used as the target guided wave, and the target guided wave is separated. Exemplarily, the separation filtering method can be used to separate the target guided wave in the second wavefield corresponding to the target formation. Extracting the target guided wave from the second wavefield corresponding to the target formation can avoid the situation that when the seawater depth corresponding to the target formation exceeds the second depth, since the arrival time of the target guided wave recorded in the first wavefield corresponding to the target formation is later than the reflected wave corresponding to the target formation, the target guided wave is covered by the reflected wave, making it impossible to effectively extract the target guided wave from the first wavefield corresponding to the target formation. Among them, the second depth can be 1000 m.

[0044] As an optional implementation manner of the embodiments of the present invention, extracting the target guided wave from the second wavefield includes: extracting the target guided wave from the second wavefield based on the first time window, where the start time of the first time window is the time when the waveform mutation point appears in the second wavefield, and the window length of the first time window is determined based on the theoretical arrival time of the empirical velocity of the target guided wave.

[0045] In an embodiment of the present invention, the time when a waveform mutation point appears in the second wave field may be the first arrival time of the target guided wave in the second wave field. The theoretical arrival time of the empirical velocity of the target guided wave may refer to the theoretical arrival time of the target guided wave determined based on the guided wave characteristics of the target guided wave and the empirical velocity model. Specifically, based on the first time window, the waveform with mutations can be intercepted from the second wave field corresponding to the target formation to obtain the target guided wave. Exemplarily, referring to Figure 3 , based on the first time window, a dashed box can be determined, and thus the waveform within the dashed box can be extracted to obtain the target guided wave.

[0046] S104. Determine the P-wave velocity structure of the target formation based on the target guided wave. The dispersion information of the target guided wave is used to constrain the P-wave velocity structure of the target formation, and the P-wave velocity structure is used to describe the propagation velocity distribution of seismic P-waves at different depths within the target formation.

[0047] In an embodiment of the present invention, the dispersion information of the target guided wave may refer to the situation where the propagation velocity of the target guided wave changes with frequency. The propagation velocities corresponding to different frequencies of the target guided wave are different, resulting in the waveform diffusion of the target guided wave and forming a dispersion phenomenon. Seismic P-waves may refer to seismic waves in which the vibration direction of the particles is consistent with the propagation direction of the wave. Specifically, the P-wave velocity structure of the target formation can be obtained by performing inversion calculations on the dispersion information of the target guided wave.

[0048] The technical solution of the embodiment of the present invention determines the first wave field corresponding to the target formation, where the target formation is the formation located at the seabed position, and the first wave field is the wave field obtained by reflecting and refracting the first seismic wave received by the first geophone recorded in the first common shot gather through the target formation; the first wave field is wave field downward continued from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain the second wave field corresponding to the target formation; the target guided wave is extracted from the second wave field, and the target guided wave is a P-wave restricted to propagate in a specific layered structure of the target formation, realizing the effective acquisition of the target guided wave corresponding to the target formation and improving the quality of the target guided wave, so that the P-wave velocity structure of the target formation can be effectively inverted using the target guided wave corresponding to the target formation to improve the resolution of the inverted P-wave velocity structure; determine the P-wave velocity structure of the target formation based on the target guided wave, the dispersion information of the target guided wave is used to constrain the P-wave velocity structure of the target formation, and the P-wave velocity structure is used to describe the propagation velocity distribution of seismic P-waves at different depths within the target formation, so as to realize high-precision seismic imaging of the target formation based on the P-wave velocity structure of the target formation.

[0049] Figure 4This is a flowchart of another shallow velocity structure inversion method based on deep - sea guided waves provided by an embodiment of the present invention. The technical solution of this embodiment further optimizes the process of wave - field downward continuation of the first wave - field from the sea level corresponding to the target formation to the seabed surface where the target formation is located in the foregoing embodiment. For the solutions not described in detail in this embodiment, refer to the foregoing embodiment. This embodiment can be combined with various optional solutions in the above - mentioned one or more embodiments. As Figure 4 shown, the method specifically includes:

[0050] S201. Determine the first wave - field corresponding to the target formation. The target formation is the formation located at the seabed position. The first wave - field is the wave - field after reflection and refraction of the first seismic wave received by the first geophone recorded in the first common - shot gather. The first seismic wave is the seismic wave emitted by the first seismic source towards the target formation. The first seismic source, the first geophone, and the first wave - field are all located at the sea level corresponding to the target formation.

[0051] S202. Based on the acoustic wave equation, downward continue the first wave - field from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain the third wave - field corresponding to the target formation. The third wave - field is recorded in the second common - shot gather.

[0052] In the embodiment of the present invention, the acoustic wave equation can refer to the basic equation describing the propagation of seismic waves in the target formation and seawater. Specifically, based on the acoustic wave equation, simulate and calculate the propagation process of the first wave - field corresponding to the target formation in seawater, and realize downward continuation of the first wave - field corresponding to the target formation to the seabed surface where the target formation is located to obtain the third wave - field corresponding to the target formation. The simulated seismic source corresponding to the third wave - field is located at the sea level corresponding to the target formation, and the simulated geophone corresponding to the third wave - field is located at the seabed surface where the target formation is located.

[0053] As an optional implementation manner of the embodiment of the present invention, the acoustic wave equation is expressed as:

[0054]

[0055] where P represents the pressure field, v represents the seawater velocity, and f s represents the source - time function.

[0056] In the embodiment of the present invention, since the velocity in seawater is approximately uniform and there is no lateral variation, the seawater velocity in the acoustic wave equation can be 1500 m / s.

[0057] S203. Sort the third wave - field into the first common - geophone gather to obtain the fourth wave - field corresponding to the target formation.

[0058] Specifically, the first common receiver gather can be set as an empty set, so that the third wavefield recorded in the second common shot gather is rearranged and recorded in the first common receiver gather as the fourth wavefield corresponding to the target formation. Sorting the third wavefield into the first common receiver gather is equivalent to swapping the perspectives of the simulated seismic source and the simulated receiver corresponding to the third wavefield to obtain the fourth wavefield corresponding to the target formation. The simulated seismic source corresponding to the fourth wavefield is located on the seabed surface where the target formation is located, and the simulated receiver corresponding to the fourth wavefield is located at the sea level corresponding to the target formation.

[0059] S204. Based on the acoustic wave equation, the fourth wavefield corresponding to the target formation is downward continued from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain the fifth wavefield corresponding to the target formation, and the fifth wavefield is recorded in the second common receiver gather.

[0060] Specifically, based on the acoustic wave equation, the propagation process of the fourth wavefield corresponding to the target formation in seawater is simulated and calculated to realize the continuation of the fourth wavefield corresponding to the target formation to the seabed surface where the target formation is located, and the fifth wavefield corresponding to the target formation is obtained. The simulated seismic source and receiver corresponding to the fifth wavefield are both located on the seabed surface where the target formation is located.

[0061] S205. Sort the fifth wavefield into the third common shot gather to obtain the second wavefield.

[0062] Specifically, the third common shot gather can be set as an empty set, so that the fifth wavefield recorded in the second common receiver gather is rearranged and recorded in the third common shot gather as the second wavefield corresponding to the target formation. Sorting the fifth wavefield into the third common shot gather is equivalent to swapping the perspectives of the simulated seismic source and the simulated receiver corresponding to the fifth wavefield to obtain the second wavefield corresponding to the target formation.

[0063] S206. Extract the target guided wave from the second wavefield, where the target guided wave is a longitudinal wave restricted to propagate in a specific layered structure of the target formation.

[0064] S207. Determine the longitudinal wave velocity structure of the target formation based on the target guided wave. The dispersion information of the target guided wave is used to constrain the longitudinal wave velocity structure of the target formation, and the longitudinal wave velocity structure is used to describe the propagation velocity distribution of seismic longitudinal waves at different depths within the target formation.

[0065] As an optional implementation manner of the embodiment of the present invention, determining the longitudinal wave velocity structure of the target formation based on the target guided wave includes: determining the dispersion spectrum of the target guided wave, and extracting the first dispersion curve of the target guided wave from the dispersion spectrum of the target guided wave; inverting the longitudinal wave velocity structure of the target formation based on the first dispersion curve of the target guided wave.

[0066] In the embodiment of the present invention, refer to Figure 5, the dispersion spectrum of the target guided wave can refer to the distribution diagram of the phase velocity of the target guided wave varying with frequency formed due to the dispersion phenomenon of the target guided wave. The dispersion spectrum of the target guided wave can be obtained by performing dispersion calculation on the target guided wave. Among them, the methods of dispersion calculation at least include: frequency-domain Bessel function transformation method, phase shift method, slant stack method, and Radon transform method. The first dispersion curve of the target guided wave can refer to the curve of the phase velocity of the target guided wave varying with frequency. Specifically, the first dispersion curve of the target guided wave can be picked up based on the distribution of the energy peaks in the dispersion spectrum of the target guided wave. Furthermore, through numerical simulation calculation, the first dispersion curve of the target guided wave is matched with the longitudinal wave velocity structure of the target formation to realize the inversion of the longitudinal wave velocity structure of the target formation.

[0067] As an alternative implementation manner of the embodiment of the present invention, inverting the longitudinal wave velocity structure of the target formation based on the first dispersion curve of the target guided wave includes the following steps A1 - A4:

[0068] Step A1, establish a first model corresponding to the target formation, and the first model is a one-dimensional layered longitudinal wave velocity model.

[0069] Step A2, determine the second dispersion curve of the target guided wave based on the first model.

[0070] Step A3, if the first dispersion curve does not match the second dispersion curve, then adjust the model parameters of the first model based on the first dispersion curve and the second dispersion curve, and return to execute the operation of determining the second dispersion curve of the target guided wave based on the first model.

[0071] Step A4, if the first dispersion curve matches the second dispersion curve, then describe the longitudinal wave velocity structure of the target formation through the first model.

[0072] In the embodiment of the present invention, the one-dimensional layered longitudinal wave velocity model can refer to a model used to describe the variation of the longitudinal wave velocity of the target formation with depth. The one-dimensional layered initial longitudinal wave velocity model simplifies the target formation into multiple horizontal layers, and each horizontal layer has a uniform longitudinal wave velocity, ignoring the velocity variation of the target formation in the lateral direction and only considering the velocity variation of the target formation in the vertical direction. Furthermore, the second dispersion curve of the target guided wave can be obtained by performing numerical calculation on the first model. For example, the second dispersion curve of the target guided wave is obtained by performing numerical calculation on the first model based on the generalized anti-transmission coefficient method.

[0073] By matching and comparing the first dispersion curve of the target guided wave with the second dispersion curve, if the first dispersion curve does not match the second dispersion curve, the model parameters of the first model can be adjusted based on the first dispersion curve and the second dispersion curve of the target guided wave through the least squares algorithm until the second dispersion curve of the target guided wave determined by the first model matches the first dispersion curve of the target guided wave. Among them, the model parameters of the first model at least include: the longitudinal wave velocity and thickness of each horizontal layer. Furthermore, the longitudinal wave velocity structure of the target formation can be determined by the longitudinal wave velocity and thickness of each horizontal layer in the first model.

[0074] The technical solution of the embodiment of the present invention is to determine the first wave field corresponding to the target formation; based on the acoustic wave equation, the first wave field is extended downward from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain the third wave field corresponding to the target formation; the third wave field is sorted into the first common geophone gather to obtain the fourth wave field corresponding to the target formation; based on the acoustic wave equation, the fourth wave field is extended downward from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain the fifth wave field corresponding to the target formation; the fifth wave field is sorted into the third common shot gather to obtain the second wave field, realizing the downward wave field extension of the first wave field corresponding to the target formation based on the acoustic wave equation to obtain the second wave field corresponding to the target formation, thereby improving the quality and accuracy of the second wave field corresponding to the target formation; extracting the target guided wave from the second wave field; determining the longitudinal wave velocity structure of the target formation based on the target guided wave, so as to realize high-precision seismic imaging of the target formation based on the longitudinal wave velocity structure of the target formation.

[0075] Figure 6 It is a schematic structural diagram of a shallow velocity structure inversion device based on deep-sea guided waves provided by an embodiment of the present invention. The embodiment of the present invention is applicable to the situation of inverting the longitudinal wave velocity structure of a formation located on the seabed, and the device can be implemented in the form of hardware and / or software. As Figure 6 shown, the device specifically includes:

[0076] The first determination module 301 is used to determine the first wave field corresponding to the target formation. The target formation is a formation located at the seabed position. The first wave field is the wave field after reflection and refraction of the first seismic wave received by the first geophone recorded in the first common shot gather. The first seismic wave is a seismic wave emitted by the first seismic source towards the target formation. The first seismic source, the first geophone, and the first wave field are all located at the sea level corresponding to the target formation;

[0077] The wave field extension module 302 is used to perform downward wave field extension of the first wave field from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain the second wave field corresponding to the target formation;

[0078] The target guided wave extraction module 303 is used to extract the target guided wave from the second wave field, where the target guided wave is a longitudinal wave restricted to propagate in a specific layered structure of the target formation;

[0079] The second determination module 304 is used to determine the longitudinal wave velocity structure of the target formation based on the target guided wave. The dispersion information of the target guided wave is used to constrain the longitudinal wave velocity structure of the target formation, and the longitudinal wave velocity structure is used to describe the propagation velocity distribution of seismic longitudinal waves at different depths within the target formation.

[0080] Based on any of the above optional technical solutions, optionally, the first determination module 301 includes: a waveform processing unit. Among them, the waveform processing unit is used to perform preset waveform processing on the wave field after the first seismic wave received by the first geophone is reflected and refracted by the target formation and record it in the first common shot gather to obtain the first wave field. The preset waveform processing at least includes: trace equalization and band-pass filtering.

[0081] Based on any of the above optional technical solutions, optionally, the wave field continuation module 302 includes: a first continuation unit, a first sorting unit, a second continuation unit, and a second sorting unit. Among them, the first continuation unit is used to continue the first wave field downward from the sea level corresponding to the target formation to the seabed surface where the target formation is located based on the acoustic wave equation to obtain the third wave field corresponding to the target formation, and the third wave field is recorded in the second common shot gather; the first sorting unit is used to sort the third wave field into the first common receiver gather to obtain the fourth wave field corresponding to the target formation; the second continuation unit is used to continue the fourth wave field downward from the sea level corresponding to the target formation to the seabed surface where the target formation is located based on the acoustic wave equation to obtain the fifth wave field corresponding to the target formation, and the fifth wave field is recorded in the second common receiver gather; the second sorting unit is used to sort the fifth wave field into the third common shot gather to obtain the second wave field.

[0082] Based on any of the above optional technical solutions, optionally, the acoustic wave equation is expressed as:

[0083]

[0084] Among them, P represents the pressure field, v represents the seawater velocity, and f s represents the source time function.

[0085] Based on any of the above optional technical solutions, optionally, the target guided wave extraction module 303 includes: a guided wave extraction unit. Among them, the guided wave extraction unit is used to extract the target guided wave from the second wave field based on the first time window. The start time of the first time window is the time when a waveform mutation point appears in the second wave field, and the window length of the first time window is determined based on the theoretical arrival time of the empirical velocity of the target guided wave.

[0086] Based on any of the above optional technical solutions, optionally, the second determination module 304 includes: a dispersion curve determination unit and a longitudinal wave velocity structure inversion unit. Among them, the dispersion curve determination unit is used to determine the dispersion spectrum of the target guided wave and extract the first dispersion curve of the target guided wave from the dispersion spectrum of the target guided wave; the longitudinal wave velocity structure inversion unit is used to invert the longitudinal wave velocity structure of the target formation based on the first dispersion curve of the target guided wave.

[0087] Based on any of the above optional technical solutions, optionally, the longitudinal wave velocity structure inversion unit is specifically used for: establishing a first model corresponding to the target formation, where the first model is a one-dimensional layered longitudinal wave velocity model; determining a second dispersion curve of the target guided wave based on the first model; if the first dispersion curve does not match the second dispersion curve, then adjusting the model parameters of the first model based on the first dispersion curve and the second dispersion curve, and returning to execute the operation of determining the second dispersion curve of the target guided wave based on the first model; if the first dispersion curve matches the second dispersion curve, then describing the longitudinal wave velocity structure of the target formation through the first model.

[0088] In the technical solution of the embodiment of the present invention, the first determination module 301 is used to determine a first wave field corresponding to the target formation, where the target formation is a formation located at the seabed position, and the first wave field is the wave field after the first seismic wave received by the first geophone recorded in the first common shot gather is reflected and refracted by the target formation; the wave field continuation module 302 is used to perform downward wave field continuation of the first wave field from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a second wave field corresponding to the target formation; the target guided wave extraction module 303 is used to extract the target guided wave from the second wave field, and the target guided wave is a longitudinal wave restricted to propagate in a specific layered structure of the target formation, which realizes the effective acquisition of the target guided wave corresponding to the target formation and improves the quality of the target guided wave, so that the longitudinal wave velocity structure of the target formation can be effectively inverted by using the target guided wave corresponding to the target formation to improve the resolution of the inverted longitudinal wave velocity structure; the second determination module 304 is used to determine the longitudinal wave velocity structure of the target formation based on the target guided wave, and the dispersion information of the target guided wave is used to constrain the longitudinal wave velocity structure of the target formation, and the longitudinal wave velocity structure is used to describe the propagation velocity distribution of seismic longitudinal waves at different depths in the target formation, so as to realize high-precision seismic imaging of the target formation based on the longitudinal wave velocity structure of the target formation.

[0089] The shallow layer velocity structure inversion device based on deep sea guided waves provided by the embodiment of the present invention can execute the shallow layer velocity structure inversion method based on deep sea guided waves provided by any embodiment of the present invention, and has the corresponding functional modules and beneficial effects for executing the method.

[0090] Figure 7Schematic diagram of a structure of an electronic device for implementing a method for inverting a shallow velocity structure based on deep - sea guided waves provided by an embodiment of the present invention. The electronic device is intended to represent various forms of digital computers, such as, laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as, personal digital processors, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the present invention described herein and / or claimed.

[0091] As Figure 7 shown, the electronic device 10 includes at least one processor 11, and a memory communicatively connected to the at least one processor 11, such as a read - only memory (ROM) 12, a random - access memory (RAM) 13, etc. Among them, the memory stores a computer program executable by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read - only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random - access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. The input / output (I / O) interface 15 is also connected to the bus 14.

[0092] Multiple components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0093] The processor 11 can be various general - purpose and / or special - purpose processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine - learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the method for inverting a shallow velocity structure based on deep - sea guided waves.

[0094] In some embodiments, the method for shallow velocity structure inversion based on deep sea guided waves can be implemented as a computer program tangibly embodied in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the method for shallow velocity structure inversion based on deep sea guided waves described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the method for shallow velocity structure inversion based on deep sea guided waves by any other suitable means (e.g., by means of firmware).

[0095] The various embodiments of the systems and techniques described above in this document can be implemented in digital electronic circuitry, integrated circuit systems, field-programmable gate arrays (FPGA), application specific integrated circuits (ASIC), application specific standard products (ASSP), systems-on-a-chip (SOC), complex programmable logic devices (CPLD), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special-purpose or general-purpose programmable processor that receives data and instructions from a storage system, at least one input device, and at least one output device, and transmits the data and instructions to the storage system, the at least one input device, and the at least one output device.

[0096] The computer programs for implementing the methods of the present invention can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, such that the computer programs, when executed by the processor, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The computer programs can be executed entirely on the machine, partially on the machine, as a stand-alone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0097] In the context of the present invention, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, the computer-readable storage medium can be a machine-readable signal medium. More specific examples of the machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0098] In order to provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the electronic device. Other kinds of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0099] The systems and techniques described herein can be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected to each other by any form or medium of digital data communication (e.g., a communication network). Examples of the communication network include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0100] A computing system may include a client and a server. The client and the server are generally far from each other and usually interact via a communication network. The relationship between the client and the server is created by computer programs running on respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or a cloud host, which is a host product in the cloud computing service system, and solves the defects of difficult management and weak business scalability existing in traditional physical hosts and VPS services.

[0101] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps recited in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0102] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A shallow velocity structure inversion method based on deep-sea guided waves, characterized in that The method includes: Determining a first wavefield corresponding to a target formation, where the target formation is a formation located at the seabed position, the first wavefield is the wavefield after reflection and refraction of a first seismic wave received by a first geophone and recorded in a first common-shot gather, the first seismic wave is a seismic wave emitted by a first source towards the target formation, and the first source, the first geophone, and the first wavefield are all located at the sea level corresponding to the target formation; Performing downward wavefield continuation of the first wavefield from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a second wavefield corresponding to the target formation; Extracting a target guided wave from the second wavefield, where the target guided wave is a longitudinal wave restricted to propagate in a specific layered structure of the target formation; Determining the longitudinal wave velocity structure of the target formation based on the target guided wave, where the dispersion information of the target guided wave is used to constrain the longitudinal wave velocity structure of the target formation, and the longitudinal wave velocity structure is used to describe the propagation velocity distribution of seismic longitudinal waves at different depths within the target formation.

2. The method according to claim 1, wherein Determining the first wavefield corresponding to the target formation includes: Performing a preset waveform processing on the wavefield after reflection and refraction of the first seismic wave received by the first geophone and recording it in the first common-shot gather to obtain the first wavefield, where the preset waveform processing at least includes: trace equalization and band-pass filtering.

3. The method according to claim 1, characterized in that, Performing downward wavefield continuation of the first wavefield from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a second wavefield corresponding to the target formation includes: Based on the acoustic wave equation, performing downward continuation of the first wavefield from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a third wavefield corresponding to the target formation, and the third wavefield is recorded in a second common-shot gather; Sorting the third wavefield into a first common-receiver gather to obtain a fourth wavefield corresponding to the target formation; Based on the acoustic wave equation, performing downward continuation of the fourth wavefield from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a fifth wavefield corresponding to the target formation, and the fifth wavefield is recorded in a second common-receiver gather; Sorting the fifth wavefield into a third common-shot gather to obtain the second wavefield.

4. The method according to claim 3, wherein The acoustic wave equation is expressed as: where P represents the pressure field, v represents the seawater velocity, and f s represents the source time function.

5. The method according to claim 1, characterized in that, Extracting the target guided wave from the second wavefield includes: Extracting the target guided wave from the second wavefield based on a first time window, where the start time of the first time window is the time when a waveform mutation point appears in the second wavefield, and the window length of the first time window is determined based on the theoretical arrival time of the empirical velocity of the target guided wave.

6. The method according to claim 1, wherein Determining the longitudinal wave velocity structure of the target formation based on the target guided wave includes: Determining the dispersion spectrum of the target guided wave and extracting the first dispersion curve of the target guided wave from the dispersion spectrum of the target guided wave; Inverting the longitudinal wave velocity structure of the target formation based on the first dispersion curve of the target guided wave.

7. The method according to claim 6, wherein Inverting the longitudinal wave velocity structure of the target formation based on the first dispersion curve of the target guided wave includes: Establish a first model corresponding to the target formation, where the first model is a one-dimensional layered P-wave velocity model; Determine a second dispersion curve of the target guided wave based on the first model; If the first dispersion curve does not match the second dispersion curve, adjust the model parameters of the first model based on the first dispersion curve and the second dispersion curve, and return to execute the operation of determining the second dispersion curve of the target guided wave based on the first model; If the first dispersion curve matches the second dispersion curve, describe the P-wave velocity structure of the target formation through the first model.

8. An inversion device for shallow velocity structure based on deep-sea guided waves, characterized in that, The device includes: A first determination module for determining a first wave field corresponding to the target formation, where the target formation is a formation located at the seabed position, the first wave field is the wave field after reflection and refraction of the first seismic wave received by the first geophone recorded in the first common shot gather, the first seismic wave is the seismic wave emitted by the first seismic source towards the target formation, and the first seismic source, the first geophone, and the first wave field are all located at the sea level corresponding to the target formation; A wave field continuation module for performing downward wave field continuation of the first wave field from the sea level corresponding to the target formation to the seabed surface where the target formation is located to obtain a second wave field corresponding to the target formation; A target guided wave extraction module for extracting a target guided wave from the second wave field, where the target guided wave is a P-wave restricted to propagate in a specific layered structure of the target formation; A second determination module for determining the P-wave velocity structure of the target formation based on the target guided wave, where the dispersion information of the target guided wave is used to constrain the P-wave velocity structure of the target formation, and the P-wave velocity structure is used to describe the propagation velocity distribution of seismic P-waves at different depths within the target formation.

9. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for inverting the shallow velocity structure based on deep sea guided waves according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing a processor to implement the method for inverting the shallow velocity structure based on deep sea guided waves according to any one of claims 1-7 when executed.

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