A method for constructing velocity structure model based on mixed source surface waves

Abstract

The present application relates to a method for constructing a velocity structure model based on a hybrid surface wave, and belongs to the technical field of surface structure investigation in petroleum geophysical exploration. The method comprises: exciting active surface waves through a vibration excitation device; obtaining vibration information of active surface waves and passive surface waves through detectors arranged on both sides of a shot point; using a computer device to determine the dispersion points of the active surface waves and passive surface waves based on the vibration information, and fitting them to obtain a comprehensive dispersion curve, inverting the comprehensive dispersion curve to obtain a vertical velocity distribution structure; obtaining a shear wave time-depth curve based on the vertical velocity distribution structure, interpreting the shear wave time-depth curve, and obtaining a shear wave velocity structure model at the shot point. The above method has low requirements for equipment, a simple construction method, and high data processing efficiency. It can quickly establish a three-layer near-surface velocity structure model of a low-velocity layer, a reduced-velocity layer, and a high-velocity layer that are of interest in oil and gas seismic exploration.

Description

Technical Field

[0001] The present application relates to a surface structure investigation technology for petroleum geophysical exploration, and in particular to a method for constructing a velocity structure model based on mixed-source surface waves. Background Art

[0002] In oil and gas seismic exploration, near-surface anomalies, such as faults in rock formations, can affect the accurate imaging of deep underground rock formations and reservoirs. To accurately image these anomalies, the effects of near-surface anomalies must be eliminated. Therefore, an accurate velocity structure model is needed to correct for these anomalies.

[0003] In related technologies, micro-logging and small-refraction methods are used to establish a near-surface velocity structure model. The micro-logging method uses explosives to excite seismic waves in a vertical well 10 to 20 meters deep, and deploys detectors near the wellhead. The time it takes for the seismic waves to propagate from the source to the detector is measured by the detector, that is, the travel time of the direct wave is measured, and then the velocity structure model is established; the small-refraction method uses a vibration excitation device to excite seismic waves, and deploys detectors on a straight line of about 100 meters where the excitation device is located. The time it takes for the refracted wave of the seismic wave to reach the detector is measured by the detector, that is, the first arrival time of the refracted wave, and then the velocity structure model is established.

[0004] However, oil and gas seismic exploration operations often require passing through urban areas and riverbanks. These areas are home to numerous railways, highways, airports, and water networks, making it difficult to drill wells and use explosives to stimulate seismic waves. Furthermore, the abundance of human activity significantly interferes with refracted waves. Therefore, it is difficult to establish velocity structure models in these areas using conventional micro-well logging and small-refraction methods. Summary of the Invention

[0005] This application provides a method for constructing a velocity structure model based on hybrid source surface waves. This method has low equipment requirements, simple construction methods, and high data processing efficiency. It can rapidly establish a three-layer near-surface velocity structure model consisting of a low-velocity layer, a reduced-velocity layer, and a high-velocity layer in areas where micro-well logging and small-refraction operations are inconvenient during oil and gas seismic exploration. The technical solution of this application is as follows.

[0006] According to a first aspect of an embodiment of the present application, a surface structure investigation method is provided, the method comprising:

[0007] By using a vibration excitation device, a transient excitation is applied to the ground at a first distance from the shot point to obtain an active source surface wave. The shot point is the location corresponding to the velocity structure model to be constructed.

[0008] performing detection within a first time period using a first geophone disposed within a second distance on both sides of the shot point to obtain first vibration information, and determining a frequency dispersion point of the active surface wave based on the first vibration information, wherein the first time period is a time period from a time point when a transient excitation is applied to the ground to a first time point, and the first vibration information indicates a vibration signal within the first time period;

[0009] performing detection within a second time period using the first geophone and a second geophone positioned a second distance away from the shot point to obtain second vibration information, and determining a frequency dispersion point of a passive surface wave based on the second vibration information, wherein the second time period is a time period from the first time point to the second time point, the passive surface wave indicates ambient noise, and the second vibration information indicates a vibration signal within the second time period;

[0010] Using the cubic spline interpolation method, the dispersion points of the active and passive surface waves are fitted to obtain a comprehensive dispersion curve. This comprehensive dispersion curve is then inverted to obtain the vertical velocity distribution structure at the shot point. This velocity vertical distribution structure indicates the corresponding relationship between the propagation velocity of the shear wave in each preset stratum and the depth of each preset stratum.

[0011] Based on the vertical velocity distribution structure, a shear wave time-depth curve is obtained. Based on the shear wave time-depth curve, a first velocity structure model at the shot point is obtained. The shear wave time-depth curve indicates the correspondence between the time for the shear wave to propagate from the ground to the depth of each preset stratum and the depth of each preset stratum. The first velocity structure model is the velocity structure model of the shear wave at the shot point.

[0012] In one possible implementation, the vibration excitation device and the arrangement direction of the multiple detectors indicate the main propagation direction of the ambient noise at the shot point.

[0013] In one possible implementation, the track spacing between two adjacent first detectors is smaller than the track spacing between two adjacent second detectors.

[0014] In one possible implementation, determining the frequency dispersion point of the active surface wave based on the first vibration information includes:

[0015] Performing dispersion analysis on the first vibration information to obtain a dispersion spectrum of the active surface wave;

[0016] The dispersion point of the active surface wave is picked out from the dispersion spectrum of the active surface wave.

[0017] In one possible implementation, determining the frequency dispersion point of the passive surface wave based on the second vibration information includes:

[0018] Preprocessing the second vibration information corresponding to each detector to obtain third vibration information corresponding to each detector;

[0019] performing cross-correlation calculations on the third vibration information corresponding to any geophone and the third vibration information corresponding to other geophones to obtain a plurality of cross-correlation functions, sorting the plurality of cross-correlation functions based on the distance between the two geophones involved in the cross-correlation calculations, and obtaining multi-channel transient mode pseudo-surface wave data based on the plurality of cross-correlation functions;

[0020] The dispersion analysis of the pseudo-surface wave data in the multi-channel transient mode is performed to obtain the dispersion spectrum of the passive surface wave, and the dispersion points of the passive surface wave are picked out from the dispersion spectrum.

[0021] In one possible implementation, obtaining multi-channel transient mode pseudo-surface wave data based on multiple cross-correlation functions includes:

[0022] averaging the correlation values ​​of a target cross-correlation function at each positive delay and the corresponding correlation values ​​at each negative delay to obtain a plurality of average values, where the target cross-correlation function is any cross-correlation function;

[0023] Multiple average values ​​are superimposed to obtain pseudo-surface wave data of transient mode.

[0024] The above process can be expressed by the following formula:

[0025]

[0026] In the above formula, t is the positive delay of the cross-correlation function, τ is the maximum delay of the cross-correlation function, G k is the kth pseudo-surface wave data, G k (t) is the correlation value of the k-th cross-correlation function at positive delay, G k (-t) is the correlation value of the k-th cross-correlation function at negative delay.

[0027] In one possible implementation, obtaining a shear wave time-depth curve based on the vertical velocity distribution structure includes:

[0028] Based on the propagation speed of the shear wave in each preset stratum and the depth of each preset stratum, the time for the shear wave to propagate from the ground to the depth of each preset stratum is obtained. Based on the time for the shear wave to propagate from the ground to the depth of each preset stratum and the depth of each preset stratum, the shear wave time-depth curve is obtained.

[0029] The above process can be expressed by the following formula:

[0030]

[0031] In the above formula, i indicates a preset stratum, j indicates the jth preset stratum starting from the ground, N indicates the number of preset strata, h indicates the thickness of each preset stratum, and v irepresents the propagation velocity of shear waves in the i-th preset layer, t j It represents the time it takes for a shear wave to propagate from the ground to the depth of the j-th preset stratum, that is, the vertical travel time of the shear wave from the ground to different depths of h meters, 2h meters, ..., Nh meters underground.

[0032] In one possible implementation, obtaining a first velocity structure model at a shot point based on a shear wave time-depth curve includes:

[0033] Fitting the shear wave time-depth curve with multiple straight lines of different slopes to obtain intersections of the multiple straight lines with the shear wave time-depth curve, wherein any straight line has a unique intersection with the shear wave time-depth curve;

[0034] Based on the depths corresponding to the intersections of multiple straight lines with the shear wave time-depth curve, the near-surface at the shot point is divided into multiple strata, and a first velocity structure model at the shot point is obtained. The slope of the straight line indicates the propagation velocity of the shear wave in the stratum corresponding to the straight line.

[0035] In one possible implementation, the method further includes:

[0036] Based on the first velocity structure model and the ratio of the propagation velocities of shear waves and longitudinal waves on the near surface within the shot point target range, a second velocity structure model is obtained, which is the velocity structure model of the longitudinal wave at the shot point.

[0037] According to a second aspect of an embodiment of the present application, a surface wave acquisition and observation system is provided, the surface wave acquisition and observation system comprising a vibration excitation device and a plurality of geophones;

[0038] The vibration excitation device is used to apply transient excitation to the ground at a first distance from a shot point to obtain an active source surface wave. The shot point is the position corresponding to the velocity structure model to be constructed.

[0039] The first detector is used to:

[0040] Performing detection within a first time period to obtain first vibration information, the first time period being a time period from a time point when a transient excitation is applied to the ground to a first time point, the first vibration information indicating a vibration signal within the first time period;

[0041] Performing detection within a second time period to obtain second vibration information, the second time period being a time period from the first time point to the second time point, the second vibration information indicating a vibration signal within the second time period;

[0042] The second detector is used to perform detection in a second time period to obtain second vibration information;

[0043] Among them, the arrangement direction of the vibration excitation device and multiple detectors indicates the main propagation direction of the ambient noise at the shot point, the first detector is arranged within the second distance on both sides of the shot point, and the second detector is arranged outside the second distance on both sides of the shot point. The track spacing between two adjacent first detectors is smaller than the track spacing between two adjacent second detectors.

[0044] According to a third aspect of an embodiment of the present application, a computer device is provided, the computer device comprising:

[0045] one or more processors;

[0046] a memory for storing program codes executable by the processor;

[0047] The processor is configured to execute the program code to implement the above-mentioned surface structure investigation method.

[0048] According to a fourth aspect of an embodiment of the present application, a computer-readable storage medium is provided, which includes: when the program code in the computer-readable storage medium is executed by a processor of a computer device, the computer device is enabled to execute the above-mentioned method for constructing a velocity structure model based on hybrid source surface waves.

[0049] According to a fifth aspect of an embodiment of the present application, a computer program product is provided, comprising one or more instructions, which are executed by one or more processors of a computer device, so that the computer device can execute the above-mentioned method for constructing a velocity structure model based on hybrid source surface waves.

[0050] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application.

[0051] In the above method, pseudo-surface wave data is obtained based on the vibration signal detected by the detector. This pseudo-surface wave data is processed as the vibration information of the passive surface wave to obtain the dispersion spectrum of the passive surface wave. The dispersion points of the active and passive surface waves are then integrated to obtain a comprehensive dispersion curve. This comprehensive dispersion curve is inverted to obtain the vertical velocity distribution structure of the shear wave, and then the shear wave time-depth curve is obtained. The shear wave time-depth curve is interpreted according to conventional micro-logging methods to obtain a velocity structure model. The above method has low equipment requirements, simple construction methods, high data processing efficiency, and the established near-surface shear wave vertical velocity structure is accurate. It can quickly establish a near-surface three-layer velocity structure model in areas where micro-logging and small refraction construction are not convenient during oil and gas seismic exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application, and do not constitute an improper limitation on the present application.

[0053] Figure 1 This is a structural diagram of a surface wave acquisition and observation system provided in an embodiment of the present application;

[0054] Figure 2 This is a flow chart of a method for constructing a velocity structure model based on mixed-source surface waves provided in an embodiment of the present application;

[0055] Figure 3 is a schematic diagram of a surface wave acquisition and observation system provided in an embodiment of the present application;

[0056] Figure 4 This is a schematic diagram of a surface wave collection and observation system deployed on the side of a road provided in an embodiment of the present application;

[0057] Figure 5 Schematic diagram of a vibration signal of an active surface wave provided in an embodiment of the present application;

[0058] Figure 6 Schematic diagram of a dispersion spectrum of an active surface wave provided in an embodiment of the present application;

[0059] Figure 7 is a schematic diagram of a vibration signal of a passive surface wave provided in an embodiment of the present application;

[0060] Figure 8 is a schematic diagram of a cross-correlation spectrum provided in an embodiment of the present application;

[0061] Figure 9 Schematic diagram of a dispersion spectrum of a passive surface wave provided in an embodiment of the present application;

[0062] Figure 10 is a schematic diagram of a comprehensive dispersion curve provided in an embodiment of the present application;

[0063] Figure 11 is a schematic diagram of a vertical velocity distribution structure provided in an embodiment of the present application;

[0064] Figure 12 is a schematic diagram of a shear wave time-depth curve provided in an embodiment of the present application;

[0065] Figure 13 is a schematic diagram of a shear wave velocity structure model provided in an embodiment of the present application;

[0066] Figure 14 This is a structural block diagram of a terminal provided in an embodiment of the present application;

[0067] Figure 15 This is a structural block diagram of a server provided in an embodiment of the present application. DETAILED DESCRIPTION

[0068] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0069] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of methods and systems consistent with certain aspects of the present application, as detailed in the appended claims.

[0070] In this application, the terms "first," "second," and the like are used to distinguish identical or similar items having substantially the same role and function. It should be understood that "first," "second," and "nth" do not have a logical or temporal dependency, nor do they limit the quantity or execution order. It should also be understood that although the following description uses the terms "first," "second," and the like to describe various elements, these elements should not be limited by these terms.

[0071] These terms are only used to distinguish one element from another.For example, without departing from the scope of the various examples, a first predetermined formation can be referred to as a second predetermined formation, and similarly, a second predetermined formation can also be referred to as a first predetermined formation.

[0072] Here, "at least one" means one or more. For example, at least one predetermined stratum can be one predetermined stratum, two predetermined stratums, three predetermined stratums, or any other integer greater than one. And "plurality" means two or more. For example, multiple predetermined strata can be two predetermined strata, three predetermined strata, or any other integer greater than two.

[0073] The implementation environment of the embodiments of the present application is introduced below.

[0074] Figure 11 is a schematic structural diagram of a surface roll acquisition and observation system provided in an embodiment of the present application. The surface roll acquisition and observation system includes a vibration excitation device 101 and multiple geophones 102, wherein the multiple geophones include a first geophone 1021 and a second geophone 1022. The central axis of the surface roll observation system passes through the shot point and is along the main propagation direction of the ambient noise. The vibration excitation device 101 and the multiple geophones 102 are arranged along the central axis of the surface roll observation system. That is, the arrangement direction of the vibration excitation device 101 and the multiple geophones 102 indicates the main propagation direction of the ambient noise at the shot point. The first geophone 1021 is arranged within a second distance on both sides of the shot point, and the second geophone 1022 is arranged outside the second distance on both sides of the shot point. The trace spacing between two adjacent first geophones 1021 is smaller than the trace spacing between two adjacent second geophones 1022. For example, if the second distance is 15 meters, the track spacing between two adjacent detectors arranged within 15 meters from the shot point is 1 meter, and the track spacing between two adjacent detectors arranged outside 15 meters from the shot point is 2 meters.

[0075] In some embodiments, due to the limitations of terrain conditions, the vibration excitation equipment and multiple detectors in the surface wave acquisition and observation system cannot be arranged along the main propagation direction of the environmental noise, that is, they cannot be arranged in a straight line. At this time, the central axis of the surface wave acquisition and observation system should be ensured to be along the main propagation direction of the environmental noise. The distance that each detector deviates from the central axis is determined according to the terrain conditions. The principle is to be as close to the central axis as possible.

[0076] The vibration excitation device 101 is used to apply a transient excitation to the ground at a first distance from a shot point to generate active surface waves. The shot point is the location corresponding to the velocity structure model to be constructed. The first detector 1021 is used to perform detection within a first time period and a second time period to obtain first vibration information and second vibration information. The first time period is the time period from the time the transient excitation is applied to the ground to the first time point, and the second time period is the time period from the first time point to the second time point. The second detector 1022 is used to perform detection within the second time period to obtain second vibration information. The first detector 1021 and the second detector 1022 can continuously detect vibration signals for 30 to 60 minutes.

[0077] The surface roll acquisition and observation system is associated with a computer device. The geophone transmits the detected vibration signal in the form of an electrical signal to the computer device, which then processes the vibration information. In some embodiments, the geophone preprocesses the vibration signal, performing preprocessing, such as filtering and sampling, on the detected vibration signal to obtain preprocessed vibration information. This preprocessed vibration information is then transmitted to the computer device, which then further processes the vibration information. This is not a limitation in the present embodiment.

[0078] In some embodiments, the computer device is a terminal, such as a smart phone, a tablet computer, a laptop computer, a desktop computer, etc., but is not limited to this. The terminal runs a target application, which provides a signal processing function, can convert the received electrical signal into a digital signal, and analyze and visualize the digital signal. For example, the target application is a signal processing application, a programming application, etc., which is not limited to this. In other embodiments, the computer device also includes a server, which is used to provide background services for the terminal, for example, to store the vibration information received by the terminal, and to complete the calculation in the vibration information processing process, and return the calculation results to the terminal, which is displayed by the terminal. The server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides cloud services, cloud databases, cloud computing, cloud storage, network services, cloud communications, middleware services, domain name services, security services, distribution networks (Content Delivery Network, CDN), and basic cloud computing services such as big data and artificial intelligence platforms.

[0079] The implementation environment of the embodiment of the present application is introduced above. The following describes a method for constructing a velocity structure model based on hybrid source surface waves provided by the embodiment of the present application. Figure 2 This is a flow chart of a method for constructing a velocity structure model based on mixed source surface waves provided in an embodiment of the present application. Figure 2 As shown, the method includes the following steps 201 to 209.

[0080] In step 201, a surface wave collection and observation system is deployed along the main propagation direction of the ambient noise at the shot point.

[0081] Among them, with the shot point position designed for oil and gas seismic exploration and acquisition engineering as the center, an approximately linear arrangement of unequally spaced detection points is arranged according to the terrain conditions to form a mixed-source surface wave acquisition and observation system, wherein the shot point refers to the position corresponding to the velocity structure model to be constructed, which is determined according to the requirements of the seismic exploration and acquisition project; environmental noise refers to vibrations generated by activities in the environment, including vibrations generated by human activities, such as vehicle movement, factory machinery operation, human walking, etc., and also includes vibrations generated by animal activities; the main propagation direction of environmental noise refers to the main propagation direction of vibrations generated by human or animal activities. For example, on the side of a road, the main propagation direction of environmental noise is along the direction of the road, and the detectors are arranged along the direction of the road.

[0082] The surface roll acquisition and observation system includes a vibration excitation device and multiple geophones. The layout of the vibration excitation device and the multiple geophones is the same as that of the surface roll acquisition and observation system in the above implementation environment, and will not be repeated here.

[0083] In step 202, a transient excitation is applied to the ground at a first distance from a shot point by a vibration excitation device to obtain an active source surface wave. The shot point is the position corresponding to the velocity structure model to be constructed.

[0084] The vibration excitation device is used to excite transient active surface waves. The vibration excitation device can be a mechanical or manual vibration excitation device, such as a sledgehammer, and is not limited in this embodiment of the present application. Optionally, the value of the first distance ranges from 18 meters to 22 meters. The value of the first distance can be determined experimentally or based on experience in seismic exploration and acquisition projects, and is not limited in this embodiment of the present application. The vibration excitation device can excite active surface waves to the left or right of the shot point, and is not limited in this embodiment of the present application. The active surface wave is a transient Rayleigh surface wave.

[0085] In some embodiments, the first distance is 20 meters, and the vibration excitation device is an iron plate and a 30-pound sledgehammer. An iron plate is placed 20 meters from the shot point and struck once with the 30-pound sledgehammer to apply transient excitation to the ground, generating transient Rayleigh surface waves, also known as active source surface waves.

[0086] In step 203, a first detector arranged within a second distance on both sides of the shot point performs detection within a first time period to obtain first vibration information. The first time period is the time period from the time point when transient excitation is applied to the ground to the first time point. The first vibration information indicates the vibration signal within the first time period.

[0087] Optionally, the second distance ranges from 14 meters to 16 meters. The value of the second distance can be determined experimentally or based on experience in seismic exploration and acquisition projects. In some embodiments, the second distance is 15 meters, which is not limited in this embodiment of the present application. The time point at which the transient excitation is applied to the ground is recorded using a timer at the moment the vibration device applies the excitation to the ground; the first time point is 500 milliseconds from the moment the excitation is applied to the ground, that is, the duration of the first time period is 500 milliseconds; the vibration signal within the first time period is also the vibration signal of the active source surface wave.

[0088] The first detector can continuously detect vibration signals within a first time period. The first detector transmits the vibration signals detected within the first time period to a computer device in the form of an electrical signal. The computer device receives the electrical signal and obtains the first vibration information. In some embodiments, the first detector transmits the detected vibration signals to the computer device in real time in the form of an electrical signal. The computer device receives the electrical signal within the first time period and obtains the first vibration information. This embodiment of the present application is not limited to this.

[0089] In step 204, detection is performed within a second time period by using the first detector and a second detector arranged at a second distance on both sides of the shot point to obtain second vibration information. The second time period is the time period from the first time point to the second time point. The second vibration information indicates the vibration signal within the second time period.

[0090] Optionally, the second time period is in a range of 20 minutes to 30 minutes. The vibration signal in the second time period is also a vibration signal of a passive surface wave.

[0091] It should be noted that the active surface wave excited in step 202 is a transient Rayleigh surface wave. This active surface wave experiences significant amplitude attenuation over a relatively short period of time, making it nearly impossible for the geophone farther from the shot point, i.e., the second geophone, to detect the vibration signal of this active surface wave. However, the vibration caused by ambient noise is continuous, meaning that the passive surface wave is stable and can be detected by each geophone in the surface wave acquisition and observation system. Therefore, the vibration signal detected by the first geophone closer to the shot point during the first time period is the vibration signal of the active surface wave, while the vibration signals detected by each geophone during the second time period are the vibration signals of the passive surface wave, and the second time period is longer than the first time period.

[0092] In step 205 , the computer device determines the frequency dispersion point of the active surface wave based on the first vibration information.

[0093] The active surface wave is composed of surface waves of different frequencies, that is, it includes multiple modes, each corresponding to a frequency. The mode with the highest frequency is the fundamental mode, and the remaining modes are higher-order modes. According to the dispersion characteristics of the active surface wave, each mode corresponds to a different phase velocity. As the propagation distance of the active surface wave increases, the phase difference between the modes gradually increases. By analyzing the first vibration information using the phase shift method, a dispersion spectrum representing the energy distribution of the active surface wave can be obtained. Since the energy of the active surface wave is mainly concentrated in the fundamental mode, multiple frequency-phase velocity pairs can be picked out from the energy-concentrated area of ​​the dispersion spectrum. These are the fundamental dispersion points of the active surface wave.

[0094] The above step 205 includes the following steps 1 and 2.

[0095] In step 1, a dispersion analysis is performed on the first vibration information to obtain a dispersion spectrum of the active surface wave.

[0096] Among them, the dispersion spectrum of the active surface wave is used to represent the energy distribution of the active surface wave.

[0097] It should be noted that, in the above embodiment, the dispersion spectrum of the active surface wave is obtained by the phase shift method, and the dispersion spectrum of the active surface wave can also be obtained by other methods, for example, by any one of the methods such as τ-p transformation, fk transformation, frequency decomposition method and high-resolution linear Radon transformation, etc., and the embodiments of the present application are not limited to this.

[0098] In step 2, the dispersion points of the active surface wave are picked out from the dispersion spectrum of the active surface wave.

[0099] The dispersion points of active surface waves are the frequency-phase velocity pairs in the dispersion spectrum. The terminal application provides an automatic dispersion point picking function. Users can set a target number of dispersion points to be picked. The terminal automatically determines the region in the dispersion spectrum corresponding to the fundamental mode of the active surface wave based on the energy distribution in the dispersion spectrum and then retrieves the target number of frequency-phase velocity pairs from this region.

[0100] In the above embodiments, the dispersion points are picked up by the automatic dispersion point picking function provided by the terminal application. In some embodiments, the active source surface wave is picked up from the dispersion spectrum by manual operation, which is not limited in the embodiments of the present application.

[0101] In step 206 , the computer device determines a frequency dispersion point of a passive surface wave based on the second vibration information, where the passive surface wave indicates environmental noise.

[0102] Among them, the energy of environmental noise propagates to distant places in the form of waves, which include various body waves, but the main form of energy propagation is surface waves, namely the so-called passive source surface waves. The frequency dispersion points of the passive source surface waves can be picked out from the vibration signals of the received passive source surface waves.

[0103] The above step 206 includes the following steps A to C.

[0104] In step A, the second vibration information corresponding to each detector is preprocessed to obtain the third vibration information corresponding to each detector.

[0105] The pre-processing of the second vibration information corresponding to each detector includes removing the average value, removing the trend value, and filtering out the strong pulse interference signal caused by the movement of people.

[0106] In step B, the third vibration information corresponding to any detector is cross-correlated with the third vibration information corresponding to other detectors to obtain multiple cross-correlation functions. The multiple cross-correlation functions are sorted based on the distance between the two detectors involved in the cross-correlation calculation. Based on the multiple cross-correlation functions, multi-channel transient mode pseudo-surface wave data is obtained.

[0107] The process of calculating the cross-correlation between any two third vibration information signals includes delaying one of the third vibration information signals, calculating the inner product of the two third vibration information signals, and integrating the inner product of the two third vibration information signals with respect to the delay time to obtain a function related to the delay time, namely the cross-correlation function. The delay time includes positive and negative delay times. The multiple cross-correlation functions are sorted from smallest to largest according to the distance between any two detectors involved in the cross-correlation calculation.

[0108] Taking any cross-correlation function as an example, the process of obtaining the transient mode pseudo-surface roll data based on the cross-correlation function includes: averaging the correlation values ​​of the target cross-correlation function at each positive delay and the corresponding correlation values ​​at the negative delay to obtain multiple average values; and superimposing the multiple average values ​​to obtain the transient mode pseudo-surface roll data. This process can be expressed by the following formula (1):

[0109]

[0110] In the above formula (1), t is the positive delay of the cross-correlation function, τ is the maximum delay of the cross-correlation function, G k is the kth pseudo-surface wave data, G k (t) is the correlation value of the k-th cross-correlation function at positive delay, G k (-t) is the correlation value of the k-th cross-correlation function at negative delay.

[0111] In step C, dispersion analysis is performed on the pseudo-surface wave data of the multi-channel transient mode to obtain the dispersion spectrum of the passive surface wave, and the dispersion points of the passive surface wave are picked out from the dispersion spectrum of the passive surface wave.

[0112] Here, a pseudo-surface wave data stream is used as vibration information for a passive surface wave. A phase shift method is used to perform dispersion analysis on multiple pseudo-surface wave data streams, thereby obtaining the dispersion spectrum of the passive surface wave. This is done by calculating the dispersion spectrum of the pseudo-surface wave data using the same method for processing multiple transient surface waves. This step C is similar to step 205 and will not be further described.

[0113] The above steps 205 to 206 are described by taking the example of first determining the dispersion point of the active surface wave and then determining the dispersion point of the passive surface wave. In some embodiments, the dispersion point of the passive surface wave is determined first and then the dispersion point of the active surface wave. In other embodiments, the dispersion points of the active surface wave and the dispersion points of the passive surface wave are determined in parallel. This embodiment of the present application is not limited to this.

[0114] Steps 203 and 205 are implemented by first detectors positioned within a second distance on both sides of the shot point, performing detection within a first time period to obtain first vibration information, and determining the dispersion point of the active surface wave based on this first vibration information. In some embodiments, this step may be performed using other methods, which are not limited in this embodiment of the present application.

[0115] Steps 204 and 206 are one implementation method for determining the dispersion point of the passive surface wave based on the second vibration information obtained by performing detection within a second time period using the first geophone and a second geophone positioned a second distance away on either side of the shot point. In some embodiments, this step may be performed using other methods, which are not limited in this embodiment of the present application.

[0116] In step 207, the computer equipment uses the cubic spline interpolation method to fit the dispersion points of the active source surface wave and the dispersion points of the passive source surface wave to obtain a comprehensive dispersion curve, and inverts the comprehensive dispersion curve to obtain the vertical velocity distribution structure at the shot point. The vertical velocity distribution structure indicates the corresponding relationship between the propagation velocity of the shear wave in each preset stratum and the depth of each preset stratum.

[0117] The cubic spline interpolation is used to fit the frequency dispersion points of the active surface wave and the passive surface wave. Of course, the least square method, artificial neural network, support vector machine and other methods can also be used for fitting, which is not limited in the present embodiment.

[0118] The process of inverting the integrated dispersion curve is as follows: the near-surface at the shot point is divided into multiple preset strata, and based on the multiple frequency-phase velocity pairs on the integrated dispersion curve, the corresponding relationship between the propagation velocity of the shear wave in each preset stratum and the depth of each preset stratum is obtained. The integrated dispersion curve can be inverted using thin layers of equal thickness. For example, the thickness of each preset stratum is set to h meters, and the dispersion curve is inverted using a genetic algorithm to obtain the vertical distribution structure of the shear wave velocity at points with a depth interval of h meters near the surface, that is, h~v1, 2h~v2, ..., Nh~v N , where h represents the thickness of each preset formation, v i represents the propagation velocity of the shear wave in the i-th preset stratum, that is, the layer velocity of the shear wave in each preset stratum, and N represents the number of preset strata.

[0119] In the above embodiment, a genetic algorithm is used to invert the comprehensive dispersion curve. Of course, other methods can also be used to invert the comprehensive dispersion curve, such as simulated annealing, differential evolution, Bayesian inversion method, etc., which is not limited in the embodiment of the present application.

[0120] In step 208, the computer device obtains a shear wave time-depth curve based on the vertical velocity distribution structure, where the shear wave time-depth curve indicates the corresponding relationship between the time for the shear wave to propagate from the ground to the depth of each preset stratum and the depth of each preset stratum.

[0121] The process of obtaining the shear wave time-depth curve based on the vertical velocity distribution structure includes: obtaining the time for the shear wave to propagate from the ground to the depth of each preset stratum based on the propagation velocity of the shear wave in each preset stratum and the depth of each preset stratum, that is, obtaining the vertical travel time of the shear wave; and obtaining the shear wave time-depth curve based on the time for the shear wave to propagate from the ground to the depth of each preset stratum and the depth of each preset stratum. This process can be expressed by the following formula (2):

[0122]

[0123] In the above formula (2), i indicates a preset stratum, j indicates the jth preset stratum starting from the ground, N indicates the number of preset strata, h indicates the thickness of each preset stratum, and v i represents the propagation velocity of shear waves in the i-th preset layer, t j It represents the time it takes for a shear wave to propagate from the ground to the depth of the j-th preset stratum, that is, the vertical travel time of the shear wave from the ground to different depths of h meters, 2h meters, ..., Nh meters underground.

[0124] In the above embodiment, the thickness of each preset stratum is the same, that is, a thin layer of equal thickness is used. In some embodiments, the thickness of each preset stratum may be different. In this case, h in formula (2) should be h i , h i represents the thickness of the i-th preset stratum, that is, calculating the vertical travel time of the shear wave from the ground to different depths of h meters, 2h meters, ..., Nh meters underground.

[0125] In step 209 , the computer device obtains a first velocity structure model at the shot point based on the shear wave time-depth curve. The first velocity structure model is a velocity structure model of the shear wave at the shot point.

[0126] Among them, according to the conventional micro-logging curve interpretation method, the near-surface velocity is stratified according to the shear wave time-depth curve, so as to obtain the shear wave velocity structure model of the surface at the shot point position of the oil and gas seismic exploration and acquisition engineering design. The process includes: fitting the shear wave time-depth curve with multiple straight lines with different slopes to obtain the intersection points of multiple straight lines with the shear wave time-depth curve, and any straight line has a unique intersection point with the shear wave time-depth curve; based on the depths corresponding to the intersection points of multiple straight lines with the shear wave time-depth curve, the near-surface at the shot point is divided into multiple strata to obtain the first velocity structure model at the shot point, and the slope of the straight line indicates the propagation velocity of the shear wave in the stratum corresponding to the straight line.

[0127] The above steps 201 to 209 introduce the process of constructing the velocity structure model of the shear wave at the shot point. In some embodiments, after obtaining the velocity structure model of the shear wave, the computer device also obtains the velocity structure model of the longitudinal wave at the shot point based on the first velocity structure model and the ratio of the propagation speeds of the shear wave and the longitudinal wave in the near-surface within the target range of the shot point. That is, the velocity structure model of the shear wave is converted into the velocity structure model of the longitudinal wave using the empirical value of the near-surface longitudinal and shear wave velocity ratio of the work area. This embodiment of the present application is not limited to this.

[0128] Below Figures 3 to 13 As an example, the above steps 201 to 209 are illustrated.

[0129] Figure 3 is a schematic diagram of a surface wave acquisition and observation system provided in an embodiment of the present application, such as Figure 3 As shown in the figure, a nearly linear array of unequally spaced geophones is arranged along the highway, centered on the shot point designed for seismic exploration and acquisition. Geophones within 15 meters to the left and right of the shot point have a trace spacing of approximately 1 meter, while those beyond 15 meters have a trace spacing of approximately 2 meters. A total of 50 geophones are deployed. The geophone farthest from the shot point is designated R1, and the remaining geophones are designated R2, R3, ..., in increasing order of distance from R1. This constitutes a surface roll acquisition and observation system {R1, R2, R3, ..., R49, R50}. The geophones used can continuously record seismic signals for 30 to 60 minutes. The geophones are arranged in the direction of the primary propagation of ambient noise. Figure 4 This is a schematic diagram of a surface wave collection and observation system deployed on the side of a road provided in an embodiment of the present application.

[0130] Place an iron plate 20 meters away from the shot point and strike it once with a 30-pound sledgehammer to apply transient excitation to the ground, generating a transient Rayleigh surface wave. Based on the striking time, a detector within 15 meters of the shot point detects the vibration signal within 500 milliseconds to obtain the vibration information of the active source surface wave, such as Figure 5 As shown, Figure 5 This is a schematic diagram of a vibration signal of an active surface wave provided by an embodiment of the present application. The dispersion spectrum of the active surface wave is calculated using the phase shift method, and the dispersion points of the active surface wave are picked out, such as Figure 6 As shown, Figure 6 This is a schematic diagram of a dispersion spectrum of an active surface wave provided by an embodiment of the present application. The dispersion spectrum has frequency as the horizontal axis and the phase velocity of the active surface wave as the vertical axis. Figure 6 The white dots in the middle are the picked-out dispersion points of the active surface waves.

[0131] After the hammer strikes, each detector continuously detects the vibration signal within 20 minutes. Figure 7 As shown, Figure 7 This is a schematic diagram of a vibration signal of a passive surface wave provided by an embodiment of the present application. The 50 channels of vibration information received are pre-processed by removing the average value, removing the trend value, and filtering out the strong pulse interference caused by people moving around. The cross-correlation calculation is performed between each channel of data, and the values ​​on both sides of the cross-correlation results of all channels at time zero are summed and averaged according to formula (1). The channels are arranged in order from small to large according to the distance between the two channels involved in the cross-correlation calculation to obtain the pseudo-surface wave data of the multi-channel transient mode, as shown in the figure. Figure 8 As shown, Figure 8 This is a schematic diagram of a cross-correlation spectrum provided by an embodiment of the present application. The dispersion spectrum of passive surface waves is calculated using the phase shift method according to the method of processing multi-channel transient surface waves for multi-channel pseudo-surface wave data, as shown in FIG. Figure 9 As shown, Figure 9 is a schematic diagram of a dispersion spectrum of a passive surface wave provided in an embodiment of the present application. Figure 9 The horizontal axis is frequency, and the vertical axis is the phase velocity of the passive surface wave propagation. Figure 9 The white points in the figure are the dispersion points of passive surface waves picked up manually.

[0132] The active and passive surface wave dispersion points are fitted using cubic spline interpolation to obtain the comprehensive dispersion curve, such as Figure 10 As shown, Figure 10 This is a schematic diagram of a comprehensive dispersion curve provided in the embodiment of the present application. After the formation is divided into thin layers of equal thickness, the dispersion curve is inverted to obtain a Figure 11 The vertical distribution structure of shear wave velocity is shown in Figure 11 This is a schematic diagram of a velocity vertical distribution structure provided by the embodiment of the present application. According to the above formula (2), the comprehensive dispersion curve is converted into a shear wave time-depth curve, such as Figure 12 As shown, Figure 12 This is a schematic diagram of a shear wave time-depth curve provided in an embodiment of the present application. According to the micro-logging curve interpretation method, the shear wave time-depth curve is fitted with straight lines of different slopes. Each straight line has a unique intersection with the shear wave time-depth curve. The depths corresponding to two adjacent intersections are divided into one layer. That is, the points on the same straight line in the curve are divided into one layer. The slope of the straight line is the shear wave velocity of the formation, thereby obtaining a three-layer velocity structure of the near-surface low-velocity layer, the velocity reduction layer, and the high-velocity layer that is of interest to oil and gas exploration, as shown in FIG. Figure 13 As shown, Figure 13 A schematic diagram of a shear wave velocity structure model provided in an embodiment of the present application, wherein H0, H1 and H2 are the depths corresponding to each near-surface structural layer obtained based on the method for constructing the velocity structure model provided in the present application, and V0, V1, V2 and V3 represent the layer velocities of shear waves in each near-surface structural layer.

[0133] In summary, by deploying a surface wave acquisition and observation system, the vibration signals of active and passive surface waves are detected. Based on the vibration signals detected by the detector, pseudo-surface wave data are obtained, and the pseudo-surface wave data are processed as the vibration information of passive surface waves to obtain the dispersion spectrum of the passive surface waves. Then, the dispersion points of the active and passive surface waves are fitted with cubic spline differences through computer equipment to obtain a comprehensive dispersion curve. The comprehensive dispersion curve is inverted to obtain the vertical velocity distribution structure of the shear wave, and then the shear wave time-depth curve is obtained. According to conventional micro-logging methods, the shear wave time-depth curve is interpreted to obtain a velocity structure model. The above method has low requirements for equipment, simple construction method, high data processing efficiency, and the established near-surface shear wave vertical velocity structure is accurate. It can quickly establish a three-layer near-surface shear wave velocity structure model of low velocity layer, reduced velocity layer and high velocity layer in areas where micro-logging and small refraction construction are not convenient for oil and gas seismic exploration, thereby providing effective near-surface velocity structure information of the work area for subsequent static correction and depth migration imaging of seismic data.

[0134] In an embodiment of the present application, a computer device is also provided, which includes a processor and a memory, wherein the memory is used to store at least one computer program, and the at least one computer program is loaded and executed by the processor to implement the above-mentioned method for constructing a velocity structure model based on hybrid source surface waves.

[0135] Taking computer equipment as the terminal as an example, Figure 14 This is a block diagram of a terminal provided in an embodiment of the present application, see Figure 14 Terminal 1400 may be a smartphone, tablet computer, MP3 player (Moving Picture Experts Group Audio Layer III), MP4 player (Moving Picture Experts Group Audio Layer IV), laptop computer, or desktop computer. Terminal 1400 may also be referred to as user equipment, portable terminal, laptop terminal, desktop terminal, or other similar names.

[0136] Typically, the terminal 1400 includes a processor 1401 and a memory 1402 .

[0137] The processor 1401 may include one or more processing cores, such as a 4-core processor, a 14-core processor, etc. The processor 1401 may be implemented in at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), or PLA (Programmable Logic Array). The processor 1401 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a CPU (Central Processing Unit); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 1401 may be integrated with a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 1401 may also include an AI (Artificial Intelligence) processor, which is used to process computing operations related to machine learning.

[0138] Memory 1402 may include one or more computer-readable storage media, which may be non-transitory. Memory 1402 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory storage devices. In some embodiments, the non-transitory computer-readable storage medium in memory 1402 is used to store at least one program code, which is executed by processor 1401 to implement the terminal execution process in the method for constructing a velocity structure model based on hybrid source surface waves provided in the method embodiments of this application.

[0139] In some embodiments, terminal 1400 may optionally include a peripheral device interface 1403 and at least one peripheral device. Processor 1401, memory 1402, and peripheral device interface 1403 may be connected via a bus or signal lines. Each peripheral device may be connected to peripheral device interface 1403 via a bus, signal lines, or circuit boards. Specifically, the peripheral device may include at least one of a radio frequency circuit 1404, a display screen 1405, a camera assembly 1406, an audio circuit 1407, and a power supply 1408.

[0140] The peripheral device interface 1403 can be used to connect at least one I / O (Input / Output)-related peripheral device to the processor 1401 and the memory 1402. In some embodiments, the processor 1401, the memory 1402, and the peripheral device interface 1403 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor 1401, the memory 1402, and the peripheral device interface 1403 can be implemented on separate chips or circuit boards, which is not limited in this embodiment of the present application.

[0141] RF circuit 1404 is used to receive and transmit RF (Radio Frequency) signals, also known as electromagnetic signals. RF circuit 1404 communicates with communication networks and other communication devices via electromagnetic signals. RF circuit 1404 converts electrical signals into electromagnetic signals for transmission, or converts received electromagnetic signals into electrical signals. In some embodiments, RF circuit 1404 includes: an antenna system, an RF transceiver, one or more amplifiers, a tuner, an oscillator, a digital signal processor, a codec chipset, a user identity module card, and the like. RF circuit 1404 can communicate with other terminals via at least one wireless communication protocol. Such wireless communication protocols include, but are not limited to, metropolitan area networks, various generations of mobile communication networks (2G, 3G, 4G, and 5G), wireless local area networks, and / or WiFi (Wireless Fidelity) networks. In some embodiments, RF circuit 1404 may also include circuits related to NFC (Near Field Communication), which is not limited in this application.

[0142] The display screen 1405 is used to display a UI (User Interface). The UI may include graphics, text, icons, videos, and any combination thereof. When the display screen 1405 is a touch screen display, the display screen 1405 also has the ability to collect touch signals on the surface or above the surface of the display screen 1405. The touch signal can be input as a control signal to the processor 1401 for processing. At this time, the display screen 1405 can also be used to provide virtual buttons and / or virtual keyboards, also known as soft buttons and / or soft keyboards. In some embodiments, there can be one display screen 1405, which is set on the front panel of the terminal 1400; in other embodiments, there can be at least two display screens 1405, which are respectively set on different surfaces of the terminal 1400 or in a folding design; in other embodiments, the display screen 1405 can be a flexible display screen, which is set on the curved surface or folding surface of the terminal 1400. Even more, the display screen 1405 can be set to a non-rectangular irregular shape, that is, a special-shaped screen. The display screen 1405 can be made of materials such as LCD (Liquid Crystal Display) and OLED (Organic Light-Emitting Diode).

[0143] The camera assembly 1406 is used to capture images or videos. In some embodiments, the camera assembly 1406 includes a front camera and a rear camera. Typically, the front camera is set on the front panel of the terminal, and the rear camera is set on the back of the terminal. In some embodiments, there are at least two rear cameras, which are any one of a main camera, a depth of field camera, a wide-angle camera, and a telephoto camera, so as to realize the fusion of the main camera and the depth of field camera to realize the background blur function, the fusion of the main camera and the wide-angle camera to realize panoramic shooting and VR (Virtual Reality) shooting function or other fusion shooting functions. In some embodiments, the camera assembly 1406 may also include a flash. The flash can be a single-color temperature flash or a dual-color temperature flash. A dual-color temperature flash refers to a combination of a warm light flash and a cold light flash, which can be used for light compensation at different color temperatures.

[0144] The audio circuit 1407 may include a microphone and a speaker. The microphone is used to collect sound waves from the user and the environment, and convert the sound waves into electrical signals that are input into the processor 1401 for processing, or input into the radio frequency circuit 1404 to achieve voice communication. For the purpose of stereo sound collection or noise reduction, there may be multiple microphones, each located in different parts of the terminal 1400. The microphone may also be an array microphone or an omnidirectional collection microphone. The speaker is used to convert electrical signals from the processor 1401 or the radio frequency circuit 1404 into sound waves. The speaker may be a traditional thin film speaker or a piezoelectric ceramic speaker. When the speaker is a piezoelectric ceramic speaker, it can not only convert electrical signals into sound waves audible to humans, but also convert electrical signals into sound waves inaudible to humans for purposes such as ranging. In some embodiments, the audio circuit 1407 may also include a headphone jack.

[0145] Power supply 1408 is used to power various components in terminal 1400. Power supply 1408 can be AC ​​power, DC power, a disposable battery, or a rechargeable battery. When power supply 1408 includes a rechargeable battery, the rechargeable battery can support wired charging or wireless charging. The rechargeable battery can also be used to support fast charging technology.

[0146] In some embodiments, the terminal 1400 further includes one or more sensors 1409 , including but not limited to: an acceleration sensor 1410 , a gyroscope sensor 1411 , a pressure sensor 1412 , an optical sensor 1413 , and a proximity sensor 1414 .

[0147] Accelerometer 1410 can detect the magnitude of acceleration along the three coordinate axes of the coordinate system established by terminal 1400. For example, accelerometer 1410 can be used to detect the components of gravity acceleration along the three coordinate axes. Processor 1401 can control display screen 1405 to display user pages in either a landscape or portrait view based on the gravity acceleration signal collected by accelerometer 1410. Accelerometer 1410 can also be used to collect game or user motion data.

[0148] The gyroscope sensor 1411 can detect the orientation and rotation angle of the terminal 1400. It can also work with the accelerometer 1410 to collect the user's 3D movements on the terminal 1400. Based on the data collected by the gyroscope sensor 1411, the processor 1401 can implement the following functions: motion sensing (for example, changing the UI based on the user's tilt), image stabilization during shooting, game control, and inertial navigation.

[0149] The pressure sensor 1412 can be provided on the side frame of the terminal 1400 and / or below the display screen 1405. When the pressure sensor 1412 is provided on the side frame of the terminal 1400, it can detect the user's gripping signal of the terminal 1400, and the processor 1401 can perform left-hand or right-hand recognition or shortcut operations based on the gripping signal collected by the pressure sensor 1412. When the pressure sensor 1412 is provided below the display screen 1405, the processor 1401 controls the operable controls on the UI page based on the user's pressure operation on the display screen 1405. Operable controls include at least one of a button control, a scroll bar control, an icon control, and a menu control.

[0150] Optical sensor 1413 is used to detect ambient light intensity. In one embodiment, processor 1401 can control the display brightness of display screen 1405 based on the ambient light intensity detected by optical sensor 1413. Specifically, when the ambient light intensity is high, the display brightness of display screen 1405 is increased; when the ambient light intensity is low, the display brightness of display screen 1405 is decreased. In another embodiment, processor 1401 can also dynamically adjust the shooting parameters of camera assembly 1406 based on the ambient light intensity detected by optical sensor 1413.

[0151] Proximity sensor 1414, also known as a distance sensor, is typically located on the front panel of terminal 1400. Proximity sensor 1414 is used to detect the distance between the user and the front of terminal 1400. In one embodiment, when proximity sensor 1414 detects that the distance between the user and the front of terminal 1400 is gradually decreasing, processor 1401 controls display screen 1405 to switch from the screen-on state to the screen-off state. When proximity sensor 1414 detects that the distance between the user and the front of terminal 1400 is gradually increasing, processor 1401 controls display screen 1405 to switch from the screen-off state to the screen-on state.

[0152] Those skilled in the art will understand that Figure 14 The structure shown in the figure does not constitute a limitation on the terminal 1400, and the terminal 1400 may include more or fewer components than shown in the figure, or combine certain components, or adopt a different component arrangement.

[0153] Taking the computer device as a server as an example, Figure 15This is a block diagram of the structure of a server provided in an embodiment of the present application. Server 1500 may vary significantly depending on configuration or performance, and may include one or more CPUs (Central Processing Units) 1501 and one or more memories 1502. The one or more memories 1502 store at least one computer program, which is loaded and executed by the one or more processors 1501 to implement the aforementioned method for constructing a velocity structure model based on hybrid source surface waves. Of course, server 1500 may also include components such as a wired or wireless network interface, a keyboard, and input / output interfaces for input and output. Server 1500 may also include other components for implementing device functions, which are not detailed here.

[0154] In an embodiment of the present application, a computer-readable storage medium including program code is also provided, such as memory 1402 including the program code. The program code can be executed by processor 1401 of terminal 1400 to implement the method for constructing a velocity structure model based on hybrid source surface waves. Alternatively, the computer-readable storage medium can be a ROM (Read-Only Memory), RAM (Random Access Memory), CD-ROM (Compact Disc Read-Only Memory), magnetic tape, floppy disk, or optical data storage device.

[0155] In an embodiment of the present application, a computer program product is also provided, comprising one or more instructions, which are executed by one or more processors of a computer device, so that the computer device can execute the above-mentioned method for constructing a velocity structure model based on hybrid source surface waves.

[0156] In some embodiments, the computer program involved in the embodiments of the present application may be deployed and executed on a computer device, or on multiple computer devices located at one location, or on multiple computer devices distributed at multiple locations and interconnected through a communication network. Multiple computer devices distributed at multiple locations and interconnected through a communication network may constitute a blockchain system.

[0157] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0158] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for constructing a velocity structure model based on mixed source surface waves, characterized in that: The method comprises: Applying transient excitation to the ground at a first distance from a shot point by means of a vibration excitation device to obtain an active source surface wave, wherein the shot point is the position corresponding to the velocity structure model to be constructed; performing detection within a first time period using a first geophone disposed within a second distance on both sides of the shot point to obtain first vibration information, and determining a frequency dispersion point of the active surface wave based on the first vibration information, wherein the first time period is a time period from a time point when a transient excitation is applied to the ground to a first time point, and the first vibration information indicates a vibration signal within the first time period; performing detection within a second time period using the first geophone and a second geophone positioned a second distance away from the shot point to obtain second vibration information, and determining a frequency dispersion point of a passive surface wave based on the second vibration information, wherein the second time period is a time period from the first time point to a second time point, the second vibration information indicates a vibration signal within the second time period, and the passive surface wave indicates ambient noise; Using a cubic spline interpolation method, the frequency dispersion points of the active surface wave and the frequency dispersion points of the passive surface wave are fitted to obtain a comprehensive dispersion curve, and the comprehensive dispersion curve is inverted to obtain a vertical velocity distribution structure at the shot point, wherein the vertical velocity distribution structure indicates a corresponding relationship between the propagation velocity of the shear wave in each preset stratum and the depth of each preset stratum; Based on the vertical velocity distribution structure, a shear wave time-depth curve is obtained, and based on the shear wave time-depth curve, a first velocity structure model at the shot point is obtained. The shear wave time-depth curve indicates the correspondence between the time for the shear wave to propagate from the ground to the depth of each of the preset strata and the depth of each of the preset strata. The first velocity structure model is the velocity structure model of the shear wave at the shot point.

2. The method according to claim 1, characterized in that The arrangement direction of the vibration excitation device and the plurality of detectors indicates the main propagation direction of the ambient noise at the shot point.

3. The method according to claim 1, characterized in that The track spacing between two adjacent first detectors is smaller than the track spacing between two adjacent second detectors.

4. The method according to claim 1, wherein The determining, based on the first vibration information, the frequency dispersion point of the active surface wave includes: performing a dispersion analysis on the first vibration information to obtain a dispersion spectrum of the active surface wave; The dispersion points of the active surface wave are picked out from the dispersion spectrum of the active surface wave.

5. The method according to claim 1, wherein The determining of the frequency dispersion point of the passive surface wave based on the second vibration information includes: pre-processing the second vibration information corresponding to each of the detectors to obtain third vibration information corresponding to each of the detectors; performing cross-correlation calculations on the third vibration information corresponding to any one of the geophones with the third vibration information corresponding to the other geophones to obtain a plurality of cross-correlation functions, sorting the plurality of cross-correlation functions based on the distance between the two geophones involved in the cross-correlation calculations, and obtaining multi-channel transient mode pseudo-surface wave data based on the plurality of cross-correlation functions; A dispersion analysis is performed on the pseudo-surface wave data of the multi-channel transient mode to obtain a dispersion spectrum of the passive surface wave, and the dispersion points of the passive surface wave are picked out from the dispersion spectrum of the passive surface wave.

6. The method according to claim 5, characterized in that The step of obtaining multi-channel transient mode pseudo-surface wave data based on the multiple cross-correlation functions includes: averaging the correlation values ​​of a target cross-correlation function at each positive delay and the corresponding correlation values ​​at each negative delay to obtain a plurality of average values, wherein the target cross-correlation function is any cross-correlation function; The multiple average values ​​are superimposed to obtain pseudo-surface wave data of the transient mode.

7. The method according to claim 1, characterized in that The shear wave time-depth curve is obtained based on the vertical velocity distribution structure, including: Based on the propagation speed of the shear wave in each of the preset strata and the depth of each of the preset strata, the time for the shear wave to propagate from the ground to the depth of each of the preset strata is obtained. Based on the time for the shear wave to propagate from the ground to the depth of each of the preset strata and the depth of each of the preset strata, the shear wave time-depth curve is obtained.

8. The method according to claim 1, characterized in that The obtaining of a first velocity structure model at the shot point based on the shear wave time-depth curve includes: Fitting the shear wave time-depth curve with a plurality of straight lines of different slopes to obtain intersections of the plurality of straight lines with the shear wave time-depth curve, wherein any straight line has a unique intersection with the shear wave time-depth curve; Based on the depths corresponding to the intersections of the multiple straight lines and the shear wave time-depth curve, the near-surface at the shot point is divided into multiple strata to obtain a first velocity structure model at the shot point. The slope of the straight line indicates the propagation velocity of the shear wave in the stratum corresponding to the straight line.

9. The method according to claim 1, characterized in that The method further comprises: Based on the first velocity structure model and the ratio of the propagation velocities of shear waves and longitudinal waves on the near surface within the shot point target range, a second velocity structure model is obtained. The second velocity structure model is a velocity structure model of longitudinal waves at the shot point.

10. A surface wave acquisition and observation system, characterized in that: The surface wave acquisition and observation system includes a vibration excitation device and a plurality of geophones; The vibration excitation device is used to apply transient excitation to the ground at a first distance from a shot point to obtain an active source surface wave, wherein the shot point is a position corresponding to the velocity structure model to be constructed; The first detector is used to: Performing detection within a first time period to obtain first vibration information, the first time period being a time period from a time point when a transient excitation is applied to the ground to a first time point, the first vibration information indicating a vibration signal within the first time period; Performing detection within a second time period to obtain second vibration information, where the second time period is a time period from the first time point to a second time point, and the second vibration information indicates a vibration signal within the second time period; a second detector, configured to perform detection within the second time period to obtain the second vibration information; In which, the arrangement direction of the vibration excitation device and the multiple detectors indicates the main propagation direction of the ambient noise at the shot point, the first detector is arranged within the second distance on both sides of the shot point, and the second detector is arranged outside the second distance on both sides of the shot point, and the track spacing between two adjacent first detectors is smaller than the track spacing between two adjacent second detectors.

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