Near-surface information determination method and system, electronic equipment and medium

Abstract

The invention relates to the technical field of oil and gas seismic exploration, and mainly relates to a near-surface information determination method and system, electronic equipment and a medium. Determining a correction amount for correcting the crest time of the reflected wave to the take-off point time by using the dominant frequency of the reflected wave; determining the one-way travel time of the reflected waves when the seismic waves are excited at different depths according to the direct waves of the micro-logging obtained by excitation at different depths and the take-off point time of the reflected waves generated by the corresponding high-speed layer top interface; according to the signal-to-noise ratio of each reflected wave, a harmonic mean value of the reflected waves during one-way travel is determined by adopting a harmonic averaging method, and then the thickness and the average speed of the weathered layer are obtained according to a depth-time and speed function. According to the embodiment of the invention, under the condition that the high-speed layer information is not investigated in the micro-logging information, the accurate and reliable weathered layer data can be conveniently obtained at low cost.

Description

Technical Field

[0001] This application relates to the field of oil and gas seismic exploration technology, and mainly to a method, system, electronic device and medium for determining near-surface information. Background Technology

[0002] In areas with extremely thick weathered layers exhibiting continuous media characteristics near the surface, the weathered layers are characterized by their great thickness and significant variations in the longitudinal and lateral dimensions of the near-surface features. This results in a large amount of micrologging data failing to detect the velocities of high-velocity layers, severely impacting the modeling accuracy of near-surface models and shallow velocity fields.

[0003] When the depth of micrologging is unknown in areas where the high-velocity layer is not determined, the preferred approach to further analyze the near-surface structure is to appropriately increase the drilling depth to attempt to penetrate the top interface of the high-velocity layer and then re-acquire micrologging data. This not only requires increased exploration investment but also faces the challenge of not being able to determine the velocity of the high-velocity layer. Secondly, utilizing the continuous medium characteristics of the weathered layer in this area, the first arrival time of micrologging data from areas where the high-velocity layer velocity is unknown can be used to obtain a velocity-depth function with continuous medium characteristics. A depth value for a specific velocity can then be obtained through time-depth extrapolation. However, the near-surface parameters obtained through extrapolation lack actual data verification, resulting in low reliability. Simultaneously, a near-surface model for this area can be constructed by combining the velocity model derived from tomography with the calibration method of ultra-deep micrologging. However, there are certain errors between the tomographically derived near-surface model and the results of ultra-deep micrologging. Finally, the corresponding near-surface parameters can be obtained using planar interpolation based on qualified micrologging data from areas with thinner weathered layers. However, different interpolation methods yield non-unique near-surface parameter values.

[0004] Therefore, when micrologging data fails to identify high-velocity layers, how to conveniently obtain reliable near-surface data required for subsequent near-surface and shallow-surface velocity field modeling has become an urgent problem to be solved. Summary of the Invention

[0005] One objective of this application is to provide a method for determining near-surface information to solve, or at least partially solve, problems in related technologies. A second objective is to provide a system for determining near-surface information. A third objective is to provide an electronic device. A fourth objective is to provide a medium.

[0006] To achieve the above objectives, the technical solution of this application is as follows:

[0007] A method for determining near-surface information, the method comprising:

[0008] The start time of the reflected wave is determined based on the peak time of the reflected wave in the micro-logging data.

[0009] Based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave, the one-way travel time of the reflected wave is determined.

[0010] Based on the signal-to-noise ratio of the reflected waves from multiple channels, the harmonic mean method is used to determine the harmonic mean of the one-way travel time of the reflected waves from each channel.

[0011] The thickness and average velocity of the weathering layer are determined based on the depth-time function and the harmonic mean.

[0012] Optionally, determining the start time of the reflected wave based on the peak time of the reflected wave in the micrologging data includes:

[0013] The peak time of the reflected wave is obtained from the micro-logging data;

[0014] Based on the peak time, obtain the time window of the reflected wave;

[0015] The dominant frequency of the reflected wave is determined based on the time window.

[0016] Based on the dominant frequency, determine the correction amount required to convert the peak time of the reflected wave to the start time of the reflected wave;

[0017] The take-off point time of the reflected wave is determined based on the peak time of the reflected wave and the correction amount.

[0018] Optionally, determining the correction amount required to convert the peak time of the reflected wave to the start time of the reflected wave based on the dominant frequency includes:

[0019] Obtain a first mapping relationship between the main frequency and the correction amount; the first mapping relationship is determined based on empirical values;

[0020] The correction amount is determined based on the first mapping relationship and the main frequency.

[0021] Optionally, determining the one-way travel time of the reflected wave based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave includes:

[0022] Based on the take-off time and the initial arrival time of the direct wave corresponding to the reflected wave, determine twice the one-way travel time;

[0023] The one-way travel time of the reflected wave is determined based on the twice one-way travel time.

[0024] Optionally, determining the harmonic mean of the one-way travel time of each of the reflected waves using the harmonic mean method based on the signal-to-noise ratio of the multiple channels includes:

[0025] Determine the sum of the signal-to-noise ratios of the multiple reflected waves;

[0026] Determine the ratio of the signal-to-noise ratio of each reflected wave to the one-way travel time of the reflected wave, and calculate the sum of the ratios of each reflected wave.

[0027] The harmonic mean of the one-way travel time of each reflected wave is determined based on the sum of the signal-to-noise ratios and the sum of the ratios.

[0028] Optionally, determining the thickness and average velocity of the weathering layer based on the depth-time function and the harmonic mean includes:

[0029] The depth corresponding to the one-way travel time of the reflected wave is determined based on the harmonic mean and the depth-time function; the depth is the thickness of the weathering layer.

[0030] The average velocity of the weathering layer is determined based on the thickness of the weathering layer and the harmonic mean.

[0031] Optionally, before determining the thickness and average velocity of the weathered layer based on the depth-time function and the harmonic mean, the method further includes:

[0032] Obtain multiple first arrival times of direct waves at different depths from micrologging data;

[0033] Preprocessing is performed on the multiple arrival times;

[0034] Based on the preprocessed arrival times, data is fitted to generate a time-depth function;

[0035] The time-depth function is transformed to obtain the depth-time function.

[0036] A system for determining near-surface information, the system comprising:

[0037] The first determining module is used to determine the start time of the reflected wave based on the peak time of the reflected wave in the micro-logging data.

[0038] The second determining module is used to determine the one-way travel time of the reflected wave based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave.

[0039] The adjustment module is used to determine the harmonic mean of the one-way travel time of each of the reflected waves based on the signal-to-noise ratio of the multiple channels using the harmonic mean method.

[0040] The third determining module is used to determine the thickness and average velocity of the weathering layer based on the depth-time function and the harmonic mean.

[0041] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for determining near-surface information as described above.

[0042] A non-volatile storage medium storing a computer program that, when executed by a processor, implements the method for determining near-surface information as described above.

[0043] The beneficial effects of this application are:

[0044] In this application, the starting point time of the reflected wave is determined based on the peak time of the reflected wave in the micrologging data, reducing the difficulty of obtaining the starting point time of the reflected wave and facilitating the calibration of the recorded arrival time of the reflected wave to the same phase as the arrival time of the direct wave. Based on the starting point time of the reflected wave and the initial arrival time of the corresponding direct wave, the one-way travel time of the reflected wave is determined, allowing for the calculation of the depth of the high-velocity layer top interface. Based on the signal-to-noise ratio of multiple reflected waves at different depths, the harmonic mean method is used to determine the harmonic mean of the one-way travel time of each reflected wave, improving the accuracy of the one-way travel time. The thickness and average velocity of the weathering layer are determined based on the depth-time function and the harmonic mean. Thus, even when the high-velocity layer velocity is not investigated in the micrologging data, accurate and reliable weathering layer data can be obtained cost-effectively and conveniently based on the recorded reflected wave information. This allows for the analysis of the near-surface structure of areas with very thick weathering layers, thereby improving the modeling accuracy of near-surface models and shallow velocity fields. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram illustrating the relationship between the incident wave, reflected wave, transmitted wave, and interface in one embodiment of this application;

[0047] Figure 2 This is a flowchart of a method for determining near-surface information according to an embodiment of this application;

[0048] Figure 3 This is a partially enlarged schematic diagram of the reflected wave described in one embodiment of this application;

[0049] Figure 4 This is a schematic diagram of the peak time and take-off point time of the reflected wave in one embodiment of this application;

[0050] Figure 5 This is a schematic diagram of the one-way travel time of the reflected wave described in one embodiment of this application;

[0051] Figure 6 This is a schematic diagram of the depth-time function described in one embodiment of this application;

[0052] Figure 7a This is a schematic diagram of the time window of the reflected wave described in one embodiment of this application;

[0053] Figure 7b This is a schematic diagram of the frequencies corresponding to each time window described in one embodiment of this application;

[0054] Figure 8 This is a schematic diagram comparing the data determined by this application with the actual data in one embodiment of this application;

[0055] Figure 9 This is a schematic diagram of a near-surface information determination system described in one embodiment of this application.

[0056] Among them, 900 is the data system, 901 is the first determining module, 902 is the second determining module, 903 is the adjustment module, and 904 is the third determining module. Detailed Implementation

[0057] The embodiments of this application will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be understood that the preferred embodiments are only for illustrating this application and are not intended to limit the scope of protection of this application.

[0058] In onshore 2D and 3D seismic exploration, in areas with thick weathered layers exhibiting continuous near-surface media, a large amount of micrologging data exists that fails to reveal the velocities of high-velocity layers. It can be understood that after seismic waves are generated at different depths within the weathered layer, these waves are divided into upward direct waves, which are received by a surface receiver and their reception time recorded; and downward incident waves, which generate reflected waves at the top interface of the high-velocity layer. These reflected waves then propagate upwards and are received by the surface receiver, and their reception time is recorded. If the depth reaches the top interface of the high-velocity layer, the arrival time of the generated direct and reflected waves at the surface receiver coincides; if the depth is below the top interface of the high-velocity layer, no reflected waves are generated.

[0059] Based on the wave impedance difference between the weathering layer and the high-velocity layer, the relationship between the incident wave, reflected wave, and interface is shown in [reference needed]. Figure 1 . Figure 1This is a schematic diagram illustrating the relationship between incident waves, reflected waves, transmitted waves, and interfaces in one embodiment of this application. When seismic waves excited in the high-velocity layer are received by the surface, the surface directly receives the rays generated by the excitation that penetrate various strata. When seismic waves excited in the weathered layer are received by the surface, direct waves reaching the surface and reflected waves are generated after being incident on the top interface of the high-velocity layer. The core technical concept of this application lies in: analyzing the reflected wave information of the top interface of the high-velocity layer recorded in micrologging data where the velocity of the high-velocity layer has not been investigated, calculating the arrival time of the reflected waves from the top interface of the high-velocity layer received by the surface, and then obtaining the thickness and average velocity of the weathered layer section, providing high-precision near-surface data for near-surface and shallow-surface velocity field modeling.

[0060] Specifically, refer to Figure 2 , Figure 2 This is a flowchart of a method for determining near-surface information according to an embodiment of this application. Figure 2 As shown, in one embodiment of this application, the method for determining the near-surface information can be specifically performed according to the following steps:

[0061] Step S101: Determine the start time of the reflected wave based on the peak time of the reflected wave in the micro-logging data.

[0062] Specifically, because the dominant frequency, energy, and signal-to-noise ratio of reflected waves from the high-speed top interface vary at different depths, the waveform of the reflected waves is extremely unstable, making it difficult to accurately pinpoint the starting point of the reflected waves. Therefore, it is challenging to pinpoint the easily identifiable peak time t of the reflected waves. r0 t r1 …t rn Since it is difficult to identify reflected waves from some receiver channels, it is sufficient to pick out the peak time of the reflected wave. The peak time of the reflected wave can be understood as the time when the reflected wave is received by the surface receiver (since the peak of the reflected wave is easily collected, the arrival time of the reflected wave recorded by the surface receiver is the peak time); the take-off point time of the reflected wave can be understood as the actual time when the reflected wave arrives at the surface receiver, which is equivalent to the total time from the incident wave downwards after the seismic wave occurs at a certain depth to the top interface of the high-velocity layer (which acts as the reflecting surface) and the time when the reflected wave travels upwards to the surface.

[0063] Reference Figure 3 and Figure 4 , Figure 3 This is a partially enlarged schematic diagram of the reflected wave described in one embodiment of this application; Figure 4 This is a schematic diagram of the peak time and take-off point time of the reflected wave as described in one embodiment of this application. For example... Figure 3 As indicated by the middle arrow, the reflected wave waveform is unstable. Figure 4The take-off time shown in waveform 2 on the lower middle side cannot be accurately picked up directly due to a certain length of ambiguity, but the peak time can be clearly determined. After picking up the peak time of the reflected wave, the reflected wave can be identified, and then the dominant frequency of the reflected wave can be analyzed. Based on the dominant frequency of the reflected wave, the phase of the picked-up peak time is converted, so that the take-off time of the reflected wave can be determined according to the peak time, so that the recorded arrival time of the reflected wave can be calibrated to the phase of the picked-up direct wave initial arrival time. In this way, the difficulty of data picking is reduced, and the speed and accuracy of data processing are improved.

[0064] Step S102: Determine the one-way travel time of the reflected wave based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave.

[0065] Specifically, the first arrival time of the reflected wave corresponds to the first arrival time of the direct wave, which is the time it takes for the upward direct wave of the same seismic wave, occurring at a certain depth, to be received by a surface receiver; it is also called the first arrival time of micrologging. The one-way travel time of the reflected wave can be understood as the time it takes for the downward incident wave of the seismic wave, occurring at a certain depth (not below the top of the high-velocity layer), to be reflected from the top of the high-velocity layer (which acts as the reflecting surface), to travel upward and be received by a surface receiver (the time it takes for the reflected wave to travel from the top of the high-velocity layer to the surface, i.e., the vertical travel time of the seismic wave through the weathered layer).

[0066] Reference Figure 5 , Figure 5 This is a schematic diagram of the one-way travel time of the reflected wave described in one embodiment of this application. (In conjunction with...) Figure 5 Let the source depth of the k-th reflected wave be Q meters, where Q ≤ the depth of the high-velocity layer top interface. After the seismic wave is generated, the first arrival time of the direct wave corresponding to the k-th reflected wave is t. r (i.e., the time it takes for the direct wave of segment a to reach the ground receiver), the take-off time of the k-th reflected wave is t. rk -τ k (That is, the time it takes for the incident wave of segment b1 plus segment b2 to reach the high-velocity layer top interface, be reflected, and then travel to the surface receiver; where segment b2 is the reflected wave, and the travel time is the one-way travel time of the reflected wave).

[0067] It can be understood that the sum of the initial arrival time and the takeoff point time is twice the time it takes for the wave to travel from the high-velocity layer top interface to the surface receiver (i.e., the one-way travel time of the reflected wave). In this way, the one-way travel time of each reflected wave can be obtained.

[0068] Step S103: Based on the signal-to-noise ratio of the reflected waves in the multiple channels, the harmonic mean method is used to determine the harmonic mean of the one-way travel time of each reflected wave.

[0069] Specifically, the signal-to-noise ratio (SNR) of a reflected wave, which is the ratio of its signal to noise, serves as a quality indicator. A higher SNR indicates a higher quality reflected wave, enabling it to transmit information more accurately. Because the medium varies across different parts of the weathering layer, the transmission paths of each reflected wave at different depths exhibit subtle differences. Therefore, to further calibrate the one-way travel time of the reflected waves, a harmonic mean method is used, employing the SNR of each reflected wave at different depths as weighting coefficients to determine the harmonic mean of the one-way travel time. This adjusts the one-way travel time of the reflected waves, making it more accurate and reliable.

[0070] Step S104: Determine the thickness and average velocity of the weathering layer based on the depth-time function and the harmonic mean.

[0071] Specifically, based on the first arrival time in the micrologging data, a time-depth function model is obtained by data fitting (which can simulate the mapping relationship between the first arrival time and depth of direct waves at different depths of the weathered layer). This first arrival time is the time it takes for the direct wave to reach the surface receiver after the seismic waves at different depths in the micrologging. Based on the time-depth function model, the depth-time function can be further obtained.

[0072] Based on the impedance difference between the weathering layer and the high-velocity layer, and the technical principle governing the relationship between reflected waves, incident waves, and the top interface (reflecting surface) of the high-velocity layer, it is known that if a seismic wave occurs at the top interface of the high-velocity layer, the arrival time of the direct wave is the same as the one-way travel time of the reflected wave. Therefore, after further calibrating the one-way travel time of the reflected wave, substituting the calibrated one-way travel time of the reflected wave into the depth-time function, the depth of the top interface of the high-velocity layer (i.e., the thickness of the weathering layer) can be determined. At this point, knowing the thickness of the weathering layer and the time it takes for the reflected wave to reach the surface receiver from the bottom of the weathering layer (i.e., the top interface of the high-velocity layer) (i.e., the one-way travel time of the reflected wave / the vertical travel time of the seismic wave through the weathering layer section), the average velocity of the seismic wave in the weathering layer can be calculated.

[0073] In this embodiment, the start-up time of the reflected wave is determined based on the peak time of the reflected wave in the micrologging data, reducing the difficulty of obtaining the start-up time of the reflected wave and facilitating the calibration of the recorded arrival time of the reflected wave to the same phase as the arrival time of the direct wave. Based on the start-up time of the reflected wave and the initial arrival time of the corresponding direct wave, the one-way travel time of the reflected wave is determined, allowing the depth of the high-velocity layer top interface to be calculated. Based on the signal-to-noise ratio of multiple reflected waves at different depths, the harmonic mean method is used to determine the harmonic mean of the one-way travel time of each reflected wave, improving the accuracy of the one-way travel time. Based on the depth-time function and the harmonic mean, the thickness and average velocity of the weathering layer are determined. Thus, even when the high-velocity layer velocity is not investigated in the micrologging data, accurate and reliable weathering layer data can be obtained cost-effectively and conveniently based on the recorded reflected wave information. This allows for the analysis of the near-surface structure of areas with very thick weathering layers, thereby improving the modeling accuracy of near-surface models and shallow velocity fields.

[0074] In one feasible implementation, prior to step S104 above, the method for determining the near-surface information further includes the following steps:

[0075] Obtain multiple first arrival times of direct waves at different depths from micrologging data;

[0076] Preprocessing is performed on the multiple arrival times;

[0077] Based on the preprocessed arrival times, data is fitted to generate a time-depth function;

[0078] The time-depth function is transformed to obtain the depth-time function.

[0079] Specifically, the micrologging data records multiple arrival times t. b0 t b1 …t bn Different depths correspond to different first arrival times for direct waves. These first arrival times are preprocessed. A coordinate system is established using time and depth. First arrival times with consistent trends are selected, while those with abnormal trends are filtered out. For example, if the first arrival time fluctuates drastically as the depth increases, these are considered outliers and are filtered out. After preprocessing the first arrival times from the micrologging data, a time-depth function model is obtained, leading to the depth-time function. (Refer to...) Figure 6 , Figure 6 This is a schematic diagram of the depth-time function described in one embodiment of this application.

[0080] For example, the time-depth function is as follows:

[0081]

[0082] In Equation 1:

[0083] t is the one-way travel time of the direct wave at depth h (i.e., the first arrival time of the direct wave at depth h);

[0084] V0 is the initial velocity;

[0085] β is the rate of change factor;

[0086] h represents the depth;

[0087] x is the power exponent;

[0088] t0 is the time delay.

[0089] In this embodiment, the time-depth function characterizes the correspondence between the depth above the high-velocity layer top interface and the first arrival time of the direct wave (upward wave).

[0090] In this way, by utilizing the portion of the first arrival time of direct waves at different depths that is in a stable trend segment, a time-depth function is established, which is then transformed into a depth-time function to eliminate the influence of interference terms and improve the accuracy of the data.

[0091] In one feasible implementation, step S101 above, determining the start time of the reflected wave based on the peak time of the reflected wave in the micro-logging data, may specifically include:

[0092] Step S1011: Obtain the peak time of the reflected wave from the micro-logging data.

[0093] Specifically, this application extends the recording time of micrologging to fully record the information of reflected waves. In related technologies, when acquiring micrologging data, the recording length of micrologging data for which the velocity of high-velocity layers has not been investigated is based on the complete recording of the first arrival time, without considering the appearance time of reflected waves generated by the top interface of the high-velocity layer. Therefore, when using conventional micrologging, by adjusting the recording time of the micrologging, it is ensured that the recording length of the micrologging is greater than the predicted reflection time of the top interface of the high-velocity layer. This allows for the subsequent calculation of near-surface parameters at the survey point using information such as the time, dominant frequency, and signal-to-noise ratio of the reflected waves generated by the top interface of the high-velocity layer, as well as the first arrival time of the micrologging. This achieves the goal of completing surface surveys of thick weathered layers with continuous media properties without or with minimal use of ultra-deep micrologging, thereby improving the modeling accuracy of near-surface and shallow surface velocity fields.

[0094] In micrologging data, the peak time of the reflected wave can be directly obtained, thereby capturing the existence of the corresponding reflected wave. Then, the spectral time window of the reflected wave can be obtained, and information such as the dominant frequency and signal-to-noise ratio can be analyzed.

[0095] Step S1012: Obtain the time window of the reflected wave based on the peak time.

[0096] Specifically, once the peak time of the reflected wave is detected, it can be determined that a reflected wave exists. Based on the identified reflected wave, the time window of the reflected wave can be obtained from the micro-logging data, so that the dominant frequency of the reflected wave can be analyzed based on the acquired time window.

[0097] Step S1013: Determine the dominant frequency of the reflected wave according to the time window.

[0098] Specifically, based on the time window, spectral analysis can be used to further analyze the frequency of reflected waves in each time window, thereby determining the dominant frequency of the reflected waves. In this way, the dominant frequency of reflected waves generated at the high-velocity top interface by seismic waves excited at different depths can be determined.

[0099] The dominant frequency and frequency of seismic waves are important parameters describing the characteristics of seismic waves, and they are of great significance for understanding the behavior of seismic waves and for applications such as seismic exploration.

[0100] The dominant frequency refers to the frequency with the highest energy in the seismic wave spectrum, that is, the frequency corresponding to the spectral maximum. The level of the dominant frequency reflects the degree of energy concentration of the seismic wave and is very important for analyzing the energy distribution of seismic waves and identifying stratigraphic features.

[0101] Frequency is the number of wave vibrations per unit time, usually expressed in Hertz (Hz). Seismic waves have a very wide frequency range, from below 1 Hz to hundreds of Hz or even higher. This frequency range is related to the propagation speed and wavelength of the seismic wave. Specifically, the frequency f can be calculated using the relationship between wave speed C and wavelength λ: f = C / λ. The frequency distribution of seismic waves is influenced by factors such as the medium of the geological strata, porosity, water content, formation pressure, formation temperature, and rock anisotropy. These factors determine the propagation speed and wavelength of seismic waves in the underground medium, thus affecting the frequency distribution of seismic waves.

[0102] Understanding the dominant frequency and frequency distribution of seismic waves is of significant value for seismic exploration, stratigraphic modeling, and earthquake hazard prediction. By analyzing the dominant frequency and frequency distribution of seismic waves, we can better understand the physical properties and structural characteristics of underground rock strata, and thus assess potential earthquake risks.

[0103] Reference Figure 7a and Figure 7b , Figure 7a This is a schematic diagram of the time window of the reflected wave described in one embodiment of this application; Figure 7b This is a frequency diagram corresponding to each time window described in one embodiment of this application. For example... Figure 7a As shown, the multiple black rectangles pointed to by the arrows represent multiple spectral time windows of the reflected wave. Figure 7b The multiple curves in the image represent the frequency analysis results for each time window, with the horizontal axis representing frequency and the vertical axis representing amplitude. After confirming the existence of the reflected wave, multiple time windows of the reflected wave are extracted, and the frequency of the reflected wave is analyzed to obtain the dominant frequency of the reflected wave. This can be understood as follows: Figure 7b As shown, the frequency corresponding to the topmost curve is the dominant frequency of the reflected wave.

[0104] Step S1014: Based on the dominant frequency, determine the correction amount required to convert the peak time of the reflected wave to the starting point time of the reflected wave.

[0105] Specifically, after obtaining the dominant frequency of the reflected wave using spectral analysis, time and phase conversion is performed based on the reflected wave at this frequency to determine the peak time and convert it into the jump point time correction amount.

[0106] In one feasible implementation, step S1014 above, which determines the correction amount required to convert the peak time of the reflected wave to the starting point time of the reflected wave based on the dominant frequency, may specifically include:

[0107] Obtain a first mapping relationship between the main frequency and the correction amount; the first mapping relationship is determined based on empirical values;

[0108] The correction amount is determined based on the first mapping relationship and the main frequency.

[0109] Specifically, based on the first mapping relationship between the dominant frequency of the reflected wave from the high-speed top interface excited at each depth and the correction amount for correcting the peak time of the reflected wave to the starting time of the reflected wave, the correction amount required to convert the peak time of the reflected wave to the starting time of the reflected wave is determined. Equation 2 is an expression for the first mapping relationship. Referring to the following expression, the correction amount required to convert the peak time to the starting time of the reflected wave is calculated based on the dominant frequency of the reflected wave:

[0110] τ k =0.25 / f dk Expression 2

[0111] In Equation 2:

[0112] τ k This is a correction factor used to convert the crest time of the k-th reflected wave into the take-off point time.

[0113] f dk is the dominant frequency of the k-th reflected wave.

[0114] Based on experimental data, an empirical value was determined: when the correction amount is one-quarter of the reciprocal of the dominant frequency of the reflected wave, the accuracy of the start-point time is higher. Thus, the first mapping relationship between the dominant frequency and the correction amount is obtained. Since the first arrival time of the micro-logging (i.e., the time when the direct wave is received by the surface receiver) is recorded based on the start-point time, the arrival time recorded by the reflected wave needs to be adjusted to be in phase with the first arrival time, thereby obtaining a more accurate one-way travel time of the reflected wave.

[0115] In this embodiment, the starting point time of the reflected wave is calibrated by picking the more easily obtainable peak time. In this way, while ensuring the accuracy of the data, the difficulty and cost of data acquisition are reduced, which is conducive to obtaining more reliable weathering layer data.

[0116] Step S1015: Determine the start point time of the reflected wave based on the peak time of the reflected wave and the correction amount.

[0117] Specifically, refer to Figure 4 It can be understood that the peak time is greater than the take-off time of the reflected wave. Therefore, the take-off time of the reflected wave can be obtained by subtracting the required correction amount from the peak time of the reflected wave.

[0118] In this embodiment, the peak time of the reflected wave is obtained from the micrologging data. Based on the peak time, the reflected wave can be identified, thereby obtaining the time window of the reflected wave. Based on the time window of the reflected wave, the dominant frequency of the reflected wave is determined using spectral analysis. Based on the dominant frequency, the correction amount required to convert the peak time of the reflected wave to the starting point time of the reflected wave is determined. Based on the peak time of the reflected wave and the correction amount, the starting point time of the reflected wave can be determined. Since the first arrival time of the direct wave is the starting point time of the acquired direct wave, when calculating the one-way travel time of the reflected wave, the recording time of the reflected wave arriving at the surface receiver is in the same phase as the recording time of the direct wave arriving at the surface receiver, thus improving the accuracy of the data.

[0119] In one feasible implementation, step S102 above, determining the one-way travel time of the reflected wave based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave, includes:

[0120] Based on the take-off time and the initial arrival time of the direct wave corresponding to the reflected wave, determine twice the one-way travel time; based on the twice the one-way travel time, determine the one-way travel time of the reflected wave.

[0121] like Figure 5 As shown, the sum of the takeoff point time and the first arrival time of the direct wave corresponding to the reflected wave is twice the one-way travel time. The one-way travel time of the reflected wave can be calculated using the following expression:

[0122] tk =(t rk -τ k +t bk ) / 2 expression 3

[0123] In Equation 3, t k For the one-way travel time of the k-th reflected wave; t rk τ is the peak time of the k-th reflected wave; k To convert the crest time of the k-th reflected wave into a correction factor for the takeoff point time, (t) rk -τ k ) represents the take-off time of the k-th reflected wave; t bk Let be the initial arrival time of the direct wave corresponding to the k-th reflected wave.

[0124] Thus, based on the arrival time and the starting point time obtained after phase conversion, the one-way travel time of the reflected wave can be easily calculated without the need for ultra-deep micro-logging, thereby determining the thickness of the weathering layer.

[0125] In one feasible implementation, step S103 above, which determines the harmonic mean of the one-way travel time of each reflected wave using the harmonic mean method based on the signal-to-noise ratio of the reflected wave, includes:

[0126] Determine the sum of the signal-to-noise ratios of the multiple reflected waves;

[0127] Determine the ratio of the signal-to-noise ratio of each reflected wave to the one-way travel time of the reflected wave, and calculate the sum of the ratios of each reflected wave.

[0128] The harmonic mean of the one-way travel time of each reflected wave is determined based on the sum of the signal-to-noise ratios and the sum of the ratios.

[0129] Specifically, based on the signal-to-noise ratio of the reflected waves, the harmonic mean method can be used. The harmonic mean of the one-way travel time of each reflected wave can be determined by referring to the following expression.

[0130]

[0131] In Equation 4;

[0132] This is the harmonic mean of the reflected wave during its one-way journey.

[0133] ω k The signal-to-noise ratio weighting coefficient of the k-th reflected wave (i.e., the weight of the k-th reflected wave is its signal-to-noise ratio);

[0134] t k For the one-way travel time of the k-th reflected wave;

[0135] n is the number of channels for receiving the reflected wave.

[0136] Combining with Expression 4 above, the signal-to-noise ratios (SNRs) of each reflected wave are summed to obtain the total SNR of all reflected waves. Then, the SNR of each reflected wave is used as the weighting coefficient for its one-way travel time, and the ratio of each weighting coefficient to its one-way travel time is calculated. The sum of these ratios is then calculated. Finally, the sum of the SNRs is divided by the sum of the ratios to obtain the common harmonic mean of the one-way travel times of all reflected waves.

[0137] In this embodiment, the one-way travel time of the reflected wave is adjusted based on the signal-to-noise ratio of the reflected wave to obtain a more accurate one-way travel time. The harmonic mean obtained after adjusting the one-way travel time of the reflected wave can be used as the reference value. Substituting the depth-time function can improve the reliability of subsequent weathering layer data.

[0138] In one feasible implementation, step S104 above, determining the thickness and average velocity of the weathered layer based on the depth-time function and the harmonic mean, includes:

[0139] The depth corresponding to the one-way travel time of the reflected wave is determined based on the harmonic mean and the depth-time function; the depth is the thickness of the weathering layer.

[0140] The average velocity of the weathering layer is determined based on the thickness of the weathering layer and the harmonic mean.

[0141] Specifically, taking Equation 1 in the above implementation of determining the depth-time function as an example, let... Substitute the adjusted one-way travel time of the reflected wave into this function. This will determine the depth corresponding to when the initial arrival time of the micro-logging is equal to the one-way travel time of the reflected wave. At this point, refer to expression 5:

[0142]

[0143] Equation 5 is another expression of Equation 1. Substituting into Equation 5, we can obtain the initial arrival time as... The depth corresponding to the time is the thickness of the weathered layer at the landmark location of the micro-logging well.

[0144] Refer to expression 6:

[0145] V a =h / t expression 6

[0146] In Equation 6, V a Let h be the average velocity of the weathering layer at a depth of h. Substituting into Equation 6, where h is the corresponding depth, and combining Equation 6, dividing the thickness of the weathered layer by the one-way travel time of the reflected wave yields the average velocity of the weathered layer.

[0147] In this embodiment, reliable weathering layer data can be obtained based on the one-way travel time and depth-time function of the calibrated reflected wave. Thus, reliable weathering layer data can be obtained even when the height layer velocity is not investigated in the micrologging data.

[0148] In this application, based on the peak time of the reflected wave generated by the top interface of the underlying high-velocity layer in microlog data where high-velocity layer information was not investigated, the dominant frequency of the reflected wave is used to determine the correction amount for correcting the peak time of the reflected wave to the starting point time; based on the direct wave from the microlog obtained at different depths and the starting point time of the reflected wave generated by the corresponding high-velocity layer top interface, the one-way travel time of the reflected wave from the high-velocity layer top interface to the surface is determined when seismic waves are excited at different depths; based on the signal-to-noise ratio of each reflected wave, the harmonic mean of the one-way travel time of the reflected wave from the high-velocity layer top interface to the surface is calculated using the harmonic mean method; and then, based on the depth-time function (Equation 5 above) and the weathered layer average velocity function (Equation 6 above), the thickness and average velocity of the weathered layer from the high-velocity layer top interface to the surface can be obtained. Through the embodiments of this application, even when high-velocity layer information is not found in the micrologging data, accurate and reliable weathering layer data can be obtained at low cost and conveniently based on the recorded reflected wave information, so as to analyze the near-surface structure of the thick weathering layer area, thereby improving the modeling accuracy of the near-surface model and the shallow velocity field.

[0149] In one embodiment of this application, taking the 2023 Wuqia 3D near-surface survey and modeling technology research project in the southwestern Tarim Basin piedmont zone as an example, the technical solution of this application is applied as follows:

[0150] 1) Collect and pick the first arrival time of the 70m micrologging, select the first arrival time of the stable trend depth range of 6.3m-50m, and obtain the time-depth function and corresponding model parameters: accurately pick the first arrival time t of the micrologging. b0 t b1 …t bn The arrival times are shown in Table 1 under "Arrival Time t". b The HT function model was established using the initial arrival time of the stable trend segment, and the time-depth function was obtained, i.e., expression 1. The corresponding parameters of the model were obtained by fitting: V0 is 317.3 m / s, β is 1.014, x is 0.2632, and t0 is 13.63.

[0151] 2) Because the dominant frequency, energy, and signal-to-noise ratio of the reflected waves from the high-speed top interface vary at different depths, the waveform of the reflected waves is extremely unstable, making it difficult to accurately pinpoint the starting point of the reflected waves. Therefore, it is challenging to pinpoint the easily identifiable peak time t of the reflected waves. r0 t r1 …t rn The specific peak times are shown in Table 1, "Peak Time t". r "For this item, since it is difficult to identify the reflected waves from some receiving channels, it is sufficient to pick out the peak time of the reflected wave."

[0152] Table 1 Relevant Parameters

[0153]

[0154] 3) Calculate the dominant frequency of each reflected wave, and use Equation 2 to calculate the correction amount τ0, τ1…τ to correct the peak time of the reflected wave to the start time of the reflected wave. n The corresponding correction time is shown in the "Correction Time τ" item in Table 1.

[0155] 4) Based on step 3), and combining the first arrival times of the direct waves corresponding to each reflected wave, use Equation 3 to convert the take-off time of the reflected waves at different depths to the one-way travel time t0, t1…t of the reflected waves received at the surface. n The corresponding one-way travel time of the reflected wave is shown in the "One-way travel time t of reflected wave" item in Table 1.

[0156] 5) Calculate the signal-to-noise ratio of each reflected wave. Using Equation 4, the arrival time of the reflected wave from the high-velocity layer top interface received by the surface is calculated based on the harmonic mean method and the signal-to-noise ratio weighting coefficient. The weighting coefficient values ​​of the reflected waves at a depth of 40-50m are shown in the "weighting coefficient ω" item in Table 1. The calculated reflection time t of the high-velocity layer top interface received by the surface is 136.07m.

[0157] 6) Based on the arrival time t of the high-velocity layer top interface reflected wave received at the surface obtained in step 5) (i.e., when the seismic wave passes vertically through the weathered layer), the thickness of the weathered layer is calculated using the depth-time function, i.e., Equation 5. The thickness of the weathered layer is 103.4 m. The average velocity of the weathered layer is calculated using Equation 6 to be 726.1 m / s.

[0158] The above six steps completed the process of using micrologging data from high-velocity layers that were not conventionally investigated. By combining the first arrival time of the micrologging with the reflected wave information from the top interface of the high-velocity layer, the one-way travel time of the reflected wave from the top interface of the high-velocity layer to the surface was obtained as 136.1 ms. Then, the thickness of the weathering layer was calculated as 103.4 ms and the average velocity of the weathering layer was 726.1 ms using the depth-time function. The values ​​determined by the technical solution of this application are compared with the actual micrologging survey results in Table 2.

[0159] Table 2

[0160]

[0161] Reference Figure 8 , Figure 8 This is a schematic diagram comparing the data determined by this application with the actual data in one embodiment of this application. Figure 8 As shown in the figure, experiments have demonstrated that the weathering layer data obtained using this application has a smaller error compared to the actual micro-logging survey results, and can conveniently provide highly accurate and reliable data for modeling near-surface models and shallow velocity fields in oil and gas seismic exploration projects.

[0162] Based on the same or similar technical concept as the above embodiments, in one embodiment of this application, a system for determining near-surface information is also provided. (Refer to...) Figure 9 , Figure 9 This is a schematic diagram of the framework of a near-surface information determination system described in one embodiment of this application. For example... Figure 9 As shown, the near-surface information determination system 900 includes:

[0163] The first determining module 901 is used to determine the start time of the reflected wave based on the peak time of the reflected wave in the micro-logging data.

[0164] The second determining module 902 is used to determine the one-way travel time of the reflected wave based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave.

[0165] The adjustment module 903 is used to determine the harmonic mean of the one-way travel time of each of the reflected waves based on the signal-to-noise ratio of the multiple channels of reflected waves using the harmonic mean method.

[0166] The third determining module 904 is used to determine the thickness and average velocity of the weathering layer based on the depth-time function and the harmonic mean.

[0167] In this embodiment, the start-up time of the reflected wave is determined based on the peak time of the reflected wave in the micrologging data, reducing the difficulty of obtaining the start-up time of the reflected wave and facilitating the calibration of the recorded arrival time of the reflected wave to the same phase as the arrival time of the direct wave. Based on the start-up time and the initial arrival time of the corresponding direct wave, the one-way travel time of the reflected wave is determined, allowing for the calculation of the depth of the high-velocity layer top interface. Based on the signal-to-noise ratio of multiple reflected waves at different depths, the harmonic mean method is used to determine the harmonic mean of the one-way travel time of each reflected wave, improving the accuracy of the one-way travel time. Based on the depth-time function and the harmonic mean, the thickness and average velocity of the weathering layer are determined. Thus, even when the high-velocity layer velocity is not investigated in the micrologging data, accurate and reliable weathering layer data can be obtained cost-effectively and conveniently based on the recorded reflected wave information. This allows for the analysis of the near-surface structure of areas with very thick weathering layers, thereby improving the modeling accuracy of near-surface models and shallow velocity fields.

[0168] This application contains a limited description of the system embodiments; for details, please refer to the above method embodiments, which will not be repeated here.

[0169] In one embodiment of this application, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the above-described method for determining near-surface information.

[0170] In one embodiment of this application, a non-volatile storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, it implements the method for determining near-surface information as described in the above embodiments.

[0171] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0172] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0173] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0174] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0175] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0176] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0177] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0178] The above provides a detailed description of the method, system, electronic device, and medium for determining near-surface information. Specific examples have been used to illustrate the principles and embodiments of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in specific embodiments and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for determining near-surface information, characterized in that, The method includes: The start time of the reflected wave is determined based on the peak time of the reflected wave in the micro-logging data. Based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave, the one-way travel time of the reflected wave is determined. Based on the signal-to-noise ratio of the reflected waves from multiple channels, the harmonic mean method is used to determine the harmonic mean of the one-way travel time of the reflected waves from each channel. The thickness and average velocity of the weathering layer are determined based on the depth-time function and the harmonic mean.

2. The method according to claim 1, characterized in that, The step of determining the start time of the reflected wave based on the peak time of the reflected wave in the micro-logging data includes: The peak time of the reflected wave is obtained from the micro-logging data; Based on the peak time, obtain the time window of the reflected wave; The dominant frequency of the reflected wave is determined based on the time window. Based on the dominant frequency, determine the correction amount required to convert the peak time of the reflected wave to the start time of the reflected wave; The take-off point time of the reflected wave is determined based on the peak time of the reflected wave and the correction amount.

3. The method according to claim 2, characterized in that, The step of determining the correction amount required to convert the peak time of the reflected wave to the starting point time of the reflected wave based on the dominant frequency includes: Obtain a first mapping relationship between the main frequency and the correction amount; the first mapping relationship is determined based on empirical values; The correction amount is determined based on the first mapping relationship and the main frequency.

4. The method according to claim 1, characterized in that, Determining the one-way travel time of the reflected wave based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave includes: Based on the take-off time and the initial arrival time of the direct wave corresponding to the reflected wave, determine twice the one-way travel time; The one-way travel time of the reflected wave is determined based on the twice one-way travel time.

5. The method according to claim 1, characterized in that, The step of determining the harmonic mean of the one-way travel time of each of the reflected waves using the harmonic mean method based on the signal-to-noise ratio of the multiple channels includes: Determine the sum of the signal-to-noise ratios of the multiple reflected waves; Determine the ratio of the signal-to-noise ratio of each reflected wave to the one-way travel time of the reflected wave, and calculate the sum of the ratios of each reflected wave. The harmonic mean of the one-way travel time of each reflected wave is determined based on the sum of the signal-to-noise ratios and the sum of the ratios.

6. The method according to claim 1, characterized in that, The thickness and average velocity of the weathered layer are determined based on the depth-time function and the harmonic mean, including: The depth corresponding to the one-way travel time of the reflected wave is determined based on the harmonic mean and the depth-time function; the depth is the thickness of the weathering layer. The average velocity of the weathering layer is determined based on the thickness of the weathering layer and the harmonic mean.

7. The method according to any one of claims 1-6, characterized in that, Before determining the thickness and average velocity of the weathered layer based on the depth-time function and the harmonic mean, the method further includes: Obtain multiple first arrival times of direct waves at different depths from micrologging data; Preprocessing is performed on the multiple arrival times; Based on the preprocessed arrival times, data is fitted to generate a time-depth function; The time-depth function is transformed to obtain the depth-time function.

8. A system for determining near-surface information, characterized in that, The system includes: The first determining module is used to determine the start time of the reflected wave based on the peak time of the reflected wave in the micro-logging data. The second determining module is used to determine the one-way travel time of the reflected wave based on the take-off point time and the initial arrival time of the direct wave corresponding to the reflected wave. The adjustment module is used to determine the harmonic mean of the one-way travel time of each of the reflected waves based on the signal-to-noise ratio of the multiple channels using the harmonic mean method. The third determining module is used to determine the thickness and average velocity of the weathering layer based on the depth-time function and the harmonic mean.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method for determining near-surface information as described in any one of claims 1-7.

10. A non-volatile storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the method for determining near-surface information as described in any one of claims 1-7.

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