Stratum quality factor extraction method and apparatus, and device and storage medium

Abstract

The present invention belongs to the technical field of petroleum seismic exploration data processing. Provided are a stratum quality factor extraction method and apparatus, and a device and a storage medium. The method comprises: extracting first-arrival wave data from VSP well data, and performing velocity stratification on the first-arrival wave data; for each horizon, executing an amplitude curve fitting process, so as to obtain a fitted amplitude curve corresponding to each horizon; using the fitted amplitude curve corresponding to each horizon to determine the amplitude value at the start depth of first-arrival waves in the horizon, and the amplitude value at the end depth of the first-arrival waves in the horizon, and on the basis of the amplitude value at the start depth, the amplitude value at the end depth, and the depth interval and horizon velocity of the horizon, calculating an attenuation factor corresponding to the horizon; and on the basis of the attenuation factor corresponding to the horizon and dominant-frequency information of the horizon, performing calculation to obtain a stratum quality factor of the horizon. In the present invention, multi-point amplitude curve fitting of each horizon is integrated with formulas for accurately calculating an attenuation factor and a Q value, such that the Q-value is extracted at a high accuracy, high stability and high convenience.

Description

Formation quality factor extraction method, device, equipment and storage medium Technical Field

[0001] The present invention belongs to the technical field of seismic data processing, and in particular relates to a formation quality factor extraction method, a formation quality factor extraction device, a device and a machine-readable storage medium. Background Art

[0002] As seismic waves propagate through the Earth's medium, they experience energy loss. This energy loss primarily occurs in three ways. The first is spherical diffusion, where the longer a seismic wave propagates, the weaker its amplitude becomes. This energy loss does not vary with the frequency of the wave, but only with factors such as the propagation distance. It does not cause the frequency of the wave to decrease during propagation. The second type of energy loss is due to friction within the medium. This loss is frequency-dependent, meaning high-frequency seismic waves attenuate quickly while low-frequency waves attenuate slowly, resulting in a decrease in the dominant frequency of the seismic wave with increasing propagation distance. The third type of energy loss is scattering attenuation, which is particularly pronounced in strongly inhomogeneous media but is less of a concern in the predominantly layered Earth. In the field of petroleum seismic exploration data processing, the second type of loss, absorption attenuation, is primarily addressed. To quantitatively characterize the attenuation of seismic waves propagating through a formation, the formation quality factor (FQF) is often used as a quantitative evaluation parameter. In geophysics, the absorption attenuation coefficient is equal to the inverse of the FQF. In typical ground seismic exploration, due to absorption attenuation, the dominant frequency of seismic waves gradually decreases with increasing reflection time (increasing propagation depth), resulting in a gradual decrease in the resolution of deep seismic waves, making it difficult to identify various deep geological formations. In the processing and interpretation of seismic exploration data, two methods are often used to overcome this resolution loss. One is deconvolution, and the other is absorption attenuation compensation. Absorption attenuation compensation is a crucial step in seismic exploration data processing. Obtaining an accurate formation quality factor, or Q value, is crucial. An accurate Q value is the cornerstone of absorption attenuation compensation.

[0003] There are three common approaches for extracting formation quality factors (Q): rock physics testing, surface seismic data, and vertical seismic profile (VSP) well data. The first approach is relatively expensive and scarce (small rock samples are obtained). The second approach suffers from low analysis accuracy and limited reliability due to the overlapping of various reflections, multiple reflections, and multi-layer reflection information. The third approach is currently the most common and effective method for processing seismic exploration data. Currently, methods for extracting Q values ​​from VSP well data often use methods such as peak frequency shift, spectral ratio, and frequency centroid shift. The peak frequency shift method is based on the principle that seismic wave frequency decreases with increasing propagation distance. However, this method has the following drawbacks: 1) The peak frequency is difficult to accurately determine due to the mixing of first arrivals and other waves; 2) Slight changes in peak frequency can result in large, even dramatic, changes in the Q value; and 3) the formula used to calculate Q using the peak frequency shift method is approximate, resulting in significant errors in highly absorbing and attenuating media (i.e., Q values ​​below 20). The spectral ratio method is based on the basic principle that the frequency of the high-frequency band of seismic waves decreases as the propagation distance increases. The ratio on the amplitude spectrum is approximately a linear function. This method has the following shortcomings: 1) Due to the mixing of the first-arrival wave and other waves, the amplitude spectrum changes dramatically with frequency, so a relatively clean amplitude spectrum is required; 2) The approximation of the linear function is, in many cases, quite arbitrary based on the user's experience; 3) Like the approximation of the peak frequency shift method, it has large errors for strongly absorbing and attenuating media (i.e., those with a Q value below 20). The frequency center of gravity shift method is based on the characteristic that the center of gravity of the seismic wave spectrum shifts toward lower frequencies as the propagation distance increases. However, this method has the following shortcomings: 1) It is computationally cumbersome and complex; 2) When the seismic data contains random noise, the method is limited by the selection of the integration frequency band, which makes it less robust. The estimated Q values ​​often vary significantly depending on the selected frequency band; 3) This method is derived under the assumption that the amplitude or energy spectrum of the seismic wave is Gaussian. The actual amplitude spectrum of seismic waves deviates from this assumption, resulting in low Q value accuracy. Figure 1 shows the Q value estimation errors using the peak frequency shift method, the spectral ratio method, and the frequency center of gravity shift method at a velocity of 800 m / s and a frequency of 40 Hz. For Q values ​​below 20, the errors of these Q estimation methods are large, reaching as high as 50% to 70% in extreme cases. In addition, there are cases where the estimated Q value falls below the minimum limit of 6.283.

[0004] Based on the deficiencies of the above-mentioned various algorithms, it is necessary for those skilled in the art to research and implement an effective method for extracting the formation quality factor Q value.

[0005] Summary of the Invention

[0006] The purpose of the embodiments of the present invention is to provide a formation quality factor extraction method, apparatus, device, and storage medium to address one or more of the drawbacks of the peak frequency shift method, spectral ratio method, and frequency center of gravity shift method based on VSP well data proposed in the background art.

[0007] To achieve the above-mentioned object, a first aspect of an embodiment of the present invention provides a method for extracting a formation quality factor, the method comprising:

[0008] Extract first arrival wave data from VSP well data and perform velocity stratification on the first arrival wave data. After velocity stratification, obtain the interval velocity and depth interval of each layer.

[0009] For each layer, the amplitude curve fitting process is performed to obtain the fitting amplitude curve corresponding to each layer;

[0010] The starting depth amplitude value and ending depth amplitude value of the first arrival wave of the layer are determined by using the fitting amplitude curve corresponding to the layer, and the attenuation factor corresponding to the layer is calculated according to the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer and the layer velocity;

[0011] The formation quality factor of the layer is calculated based on the attenuation factor corresponding to the layer and the main frequency information of the layer.

[0012] Optionally, the amplitude curve fitting process is specifically as follows:

[0013] The first-arrival wave data received at the layer is transformed in time-frequency mode to obtain the amplitude value of each acquisition depth in the first-arrival wave data. The amplitude value of the first-arrival wave data in the main frequency single frequency or the narrow band near the main frequency in the frequency domain is curve fitted according to the acquisition depth to obtain the fitting amplitude curve corresponding to the layer.

[0014] Optionally, when obtaining the attenuation factor corresponding to the layer according to the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer, and the layer velocity, the following formula is used for calculation:

[0015] Among them, α represents the attenuation factor, V represents the layer velocity, Indicates the end depth amplitude value, represents the starting depth amplitude value, and Δx represents the depth interval of the layer.

[0016] Optionally, when calculating the formation quality factor of the layer according to the attenuation factor corresponding to the layer and the main frequency information of the layer, the following formula is used for calculation:

[0017] Where Q represents the formation quality factor, α represents the attenuation factor, and W represents the main frequency of the layer.

[0018] Optionally, perform time-frequency transformation on the first arrival wave data received at the layer position to obtain the amplitude values at each acquisition depth in the first arrival wave data, and perform curve fitting on the amplitude values of the first arrival wave data in the main frequency single frequency or narrow band range near the main frequency in the frequency domain according to the acquisition depth to obtain the fitting amplitude curve corresponding to this layer position. Specifically:

[0019] Select the first arrival wave data received at this layer position;

[0020] Perform Fourier transform on the first arrival wave data received at this layer position to obtain the frequency domain expression of the first arrival wave data at each acquisition depth within this layer position;

[0021] For each acquisition depth, determine the amplitude value of the main frequency single frequency of the first arrival wave data in the frequency domain or the average value of each amplitude value within the narrow band range near the main frequency according to the frequency domain expression, and determine the amplitude value of the main frequency corresponding to this acquisition depth as the amplitude value of the main frequency single frequency or this average value. The narrow band range near the main frequency is w0 - Δw to w0 + Δw, where w0 represents the main frequency of the first arrival wave data of this layer position, and Δw > 0;

[0022] Perform curve fitting on the amplitude values of the main frequency corresponding to each acquisition depth according to the acquisition depth to obtain the fitting amplitude curve.

[0023] Optionally, perform curve fitting on the amplitude values of the main frequency corresponding to each acquisition depth in a logarithmic coordinate system according to the acquisition depth.

[0024] Optionally, the value range of Δw is 2 to 5.

[0025] Optionally, when extracting the first arrival wave data from the VSP well data, perform first arrival wave amplitude picking and excision according to the first preset rule. The first preset rule is specifically:

[0026] After picking the peak amplitude time t of the first arrival wave from the VSP well data, move upward according to the peak amplitude time t, and the moving time point is the second positive and negative change time point t1;

[0027] Move downward according to the peak amplitude time t, and the moving time point is the first or second positive and negative change time point t2;

[0028] Set the transition zone according to the time point t1 and the time point t2. The transition zone interval is expressed as taper;

[0029] Set the amplitude of the first arrival wave within t < t1 - taper and t > t2 + taper to 0, keep the amplitude of the first arrival wave within t1 < t < t2 unchanged, multiply the amplitude of the first arrival wave within t1 - taper < t < t1 by the coefficient k1, and multiply the amplitude of the first arrival wave within t2 < t < t2 + taper by the coefficient k2;

[0030] Among them, k1=(t-t1+taper) / taper; k2=(t2-t+taper) / taper.

[0031] A second aspect of an embodiment of the present invention provides a formation quality factor extraction device, comprising:

[0032] First arrival wave extraction module, used to extract first arrival wave data from VSP well data;

[0033] The velocity stratification module is used to perform velocity stratification on the first arrival wave data extracted from the VSP well data. After velocity stratification, the interval velocity and depth interval of each layer are obtained.

[0034] An amplitude curve fitting module is used to perform an amplitude curve fitting process for each layer to obtain a fitting amplitude curve corresponding to each layer;

[0035] The attenuation factor calculation module is used to determine the starting depth amplitude value and the ending depth amplitude value of the first arrival wave of the layer using the fitting amplitude curve corresponding to the layer, and to obtain the attenuation factor corresponding to the layer according to the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer and the layer velocity;

[0036] The formation quality factor calculation module is used to calculate the formation quality factor of the layer according to the attenuation factor corresponding to the layer and the main frequency information of the layer.

[0037] The third aspect of the embodiments of the present invention also provides a device, which includes a memory, a processor, and a computer program stored on the memory and runnable on the processor. When the processor executes the program, it implements the formation quality factor extraction method as described in the first aspect of the embodiments of the present invention.

[0038] A fourth aspect of the embodiments of the present invention further provides a machine-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the formation quality factor extraction method as described in the first aspect of the embodiments of the present invention is implemented.

[0039] It is known that the physical definition of the formation quality factor Q value is the energy attenuation ratio of a single-frequency wave propagating one wavelength (i.e., the relative energy attenuation within a unit wavelength). The traditional spectrum ratio method, peak frequency shift method, and frequency center of gravity shift method mentioned in the background technology often use approximate formulas to facilitate Q value calculation. This approximate formula has a large error when estimating the Q value of a strongly absorbing and attenuating medium. Theoretical calculations show that the error is as high as 50-70%. In addition, when estimating the Q value using methods such as the spectral ratio method and the peak shift method, the estimated Q value may be lower than the minimum limit of 6.283 during the near-surface absorption and attenuation process. This situation often occurs when estimating the near-surface Q value. However, the present invention uses a precise calculation formula based on the physical definition of the Q value, and the error is theoretically 0. At the same time, the traditional spectral ratio method, the peak frequency shift method, and the frequency center of gravity shift method mostly use a point-by-point calculation method for each layer. The Q value calculated for each layer is very sensitive to changes in the data source, which results in an unstable extracted Q value. When calculating the Q value for each layer, the present invention uses a multi-point fitting technical concept to fit the amplitude curve, automatically eliminating large error data in the data source. The Q value obtained by this regression statistics-based method is more robust.

[0040] In summary, the present invention uses VSP well data as the data source for formation quality factor extraction. During the extraction, an accurate Q-value calculation formula and regression statistical method are combined to achieve high-precision, high-stability, and high-convenience Q-value extraction.

[0041] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:

[0043] FIG1 is a schematic diagram showing the error generated by using an approximate formula to estimate the Q value using a conventional Q value extraction method proposed in the background art;

[0044] FIG2 is a schematic flow chart of a formation quality factor extraction method implemented in an embodiment;

[0045] Figure 3 shows the first arrival wave extraction results without clutter removal;

[0046] Figure 4 shows the first arrival wave extraction results when the clutter removal is not precise;

[0047] FIG5 is a diagram showing the first arrival wave extraction result when fine excision is performed based on the first preset rule;

[0048] FIG6 is a schematic diagram of velocity stratification;

[0049] FIG7 is a schematic diagram of the results of amplitude curve fitting;

[0050] FIG8 is a comparison diagram of the formation quality factor obtained in the embodiment and the formation quality factor obtained using the peak frequency shift method. DETAILED DESCRIPTION

[0051] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.

[0052] Referring to FIG2 , an embodiment of the present invention provides a formation quality factor extraction method, which specifically includes the following implementation steps:

[0053] S100. Acquire VSP well data after observation system loading, abnormal amplitude attenuation, and three-component azimuth rotation. Extract first arrival data from the P component data of the VSP well data, and perform velocity stratification on the first arrival data. After velocity stratification, obtain the interval velocity and depth interval of each layer. The depth interval of each layer is the difference between the end depth and the starting depth of the layer.

[0054] 6 , velocity stratification of the first arrival wave data can be performed using a known velocity stratification model or algorithm module in a common embodiment, for example:

[0055] S01. Calculate the interval velocity based on the first arrival wave data. The calculation formula is shown in Equation 1:

[0056] V=(Depth(i)-Depth(i-1)) / (t(i)-t(i-1))(Formula 1);

[0057] Where Depth(i) represents the acquisition depth i, Depth(i-1) represents the acquisition depth i-1, t(i) represents the time when the first arrival wave data is obtained at the acquisition depth i, and t(i-1) represents the time when the first arrival wave data is obtained at the acquisition depth i-1.

[0058] S02. Smoothing the calculated interval velocity.

[0059] S03. Layer the layers based on the smoothed layer velocities to obtain depth intervals for each layer. Layering can be performed using methods such as interactive operations or automatic calculation of layers using intra-layer differences, ordered clustering, and extreme variance clustering. This embodiment does not describe this in detail.

[0060] In addition, when extracting first arrival wave data from the P component data of the VSP well data, the first arrival wave can be intercepted and filtered using the first arrival wave preprocessing method in the conventional embodiment.

[0061] Exemplarily, in a specific embodiment, the following improvements are made to the first arrival wave preprocessing method in the ordinary embodiment, specifically:

[0062] S100. Obtain the VSP well data after being loaded by the observation system, abnormal amplitude attenuation, and three-component azimuth rotation. Extract the first arrival wave data from the P-component data of the VSP well data, and perform velocity layering on the first arrival wave data. After velocity layering, obtain the layer velocity and depth interval of each layer.

[0063] Among them, when extracting the first arrival wave data from the P-component data of the VSP well data, pick up and cut off the first arrival wave amplitude according to the first preset rule, and the first preset rule is a refined first arrival wave waveform intercepting and filtering rule. Specifically, the first preset rule specifically refers to:

[0064] After picking up the first arrival wave peak amplitude time t from the VSP well data, move upward according to the peak amplitude time t, and the moving time point is the second positive and negative change time point t1;

[0065] Move downward according to the peak amplitude time t, and the moving time point is the first or second positive and negative change time point t2;

[0066] Set a transition zone according to the time point t1 and the time point t2, and the transition zone interval is expressed as taper;

[0067] Set the amplitude of the first arrival wave within t < t1 - taper and t > t2 + taper to 0, keep the amplitude of the first arrival wave within t1 < t < t2 unchanged, multiply the amplitude of the first arrival wave within t1 - taper < t < t1 by the coefficient k1, and multiply the amplitude of the first arrival wave within t2 < t < t2 + taper by the coefficient k2;

[0068] Among them, k1 = (t - t1 + taper) / taper; k2 = (t2 - t + taper) / taper.

[0069] Preferably, the value of the above-mentioned taper can be preset to 5 or 10.

[0070] Figures 3 to 5 successively show the first arrival wave extraction result diagrams without clutter removal, the first arrival wave extraction result diagrams obtained by non-precise clutter removal, and the first arrival wave extraction result diagrams obtained by precise removal based on the above first preset rule. Compared with the prior art without clutter removal or non-precise clutter removal, picking up and cutting off the first arrival wave according to the first preset rule filters out the clutter interference in the first arrival wave data and effectively supports the extraction accuracy of the subsequent formation quality factor.

[0071] S200. For each layer, perform an amplitude curve fitting process to obtain the corresponding fitting amplitude curve for each layer.

[0072] The amplitude curve fitting process is as follows:

[0073] S201. Perform time-frequency transformation on the first-arrival wave data received at the layer to obtain the amplitude value of each acquisition depth in the first-arrival wave data, and perform curve fitting on the amplitude value of the first-arrival wave data in the main frequency single frequency or the narrow band range near the main frequency in the frequency domain according to the acquisition depth to obtain the fitting amplitude curve corresponding to the layer.

[0074] For example, in one embodiment, S201 specifically includes the following sub-steps:

[0075] S001. Select the first arrival wave data received at this layer.

[0076] S002. Perform Fourier transform on the first-arrival wave data received at the layer to obtain the frequency domain expression of the first-arrival wave data at each acquisition depth in the layer.

[0077] Among them, the expression of Fourier transform is f(x,t) represents the first arrival wave data received at the layer, and T_max represents the acquisition depth x at each layer. i The maximum time interval for receiving the first arrival wave, w represents the frequency, F(x i , w) represents the frequency domain expression of f(x, t);

[0078] S003. For each acquisition depth, determine the amplitude value of the main frequency of the first arrival wave data in the frequency domain, or the average of the amplitude values ​​in the narrow band near the main frequency, based on the above frequency domain expression. The amplitude value of the main frequency or the average is determined as the main frequency amplitude value corresponding to the acquisition depth. The narrow band near the main frequency is w0-Δw to w0+Δw, where w0 represents the main frequency of the first arrival wave data at this layer, and Δw is greater than 0. Among them, the amplitude values ​​in the narrow band near the main frequency are expressed as A(x i ,w j )=|F(x i ,w j )|,j=1,2,...n,W j It represents a certain frequency in a narrow band around the main frequency, and n represents the number of certain frequencies.

[0079] S004. Perform curve fitting on the main frequency amplitude values ​​corresponding to each acquisition depth according to the acquisition depth to obtain a fitting amplitude curve. The fitting amplitude curve is a minimum error curve obtained based on, for example, the least squares method, and can be expressed as Fitness represents the fitting curve function, that is, the relationship curve between the main frequency amplitude value corresponding to each acquisition depth and the acquisition depth.

[0080] Under the influence of frequency offset, if the amplitude value of the main frequency single frequency is directly selected for amplitude curve fitting, the fitted amplitude curve will be inaccurate. By selecting an effective frequency band centered on the main frequency of the first-arrival wave data (a narrow band near the main frequency) and calculating the mean of the amplitude values ​​in the effective frequency band, the above problem can be overcome, thereby improving the accuracy of the fitted amplitude curve. The value of Δw can be empirically determined according to the specific application scenario. For example, the value range of Δw is preferably 2 to 5, and Δw can be 2 or 5.

[0081] For example, in one embodiment:

[0082] S004. Perform curve fitting on the main frequency amplitude value corresponding to each acquisition depth according to the acquisition depth to obtain a fitting amplitude curve;

[0083] The main frequency amplitude values ​​corresponding to each acquisition depth were curve-fitted in a logarithmic coordinate system according to the acquisition depth. As shown in Figure 7, the main frequency amplitude values ​​corresponding to each acquisition depth decay exponentially with acquisition depth. In the logarithmic coordinate system, the amplitude value and acquisition depth exhibit a very clear linear characteristic. This logarithmic coordinate fitting effectively eliminates amplitude anomalies and improves the accuracy of the amplitude curve fitting.

[0084] S300. Determine the starting depth amplitude value and the ending depth amplitude value of the first arrival wave of the layer using the fitting amplitude curve corresponding to the layer, and calculate the attenuation factor corresponding to the layer based on the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer and the layer velocity.

[0085] For example, in one embodiment, when calculating the attenuation factor corresponding to the layer according to the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer, and the layer velocity, the calculation is performed using Formula 2:

[0086] Among them, α represents the attenuation factor, V represents the layer velocity, Indicates the end depth amplitude value, represents the starting depth amplitude value, and Δx represents the depth interval of the layer.

[0087] S400. Calculate the formation quality factor of the layer according to the attenuation factor corresponding to the layer and the main frequency information of the layer.

[0088] For example, in one embodiment, when calculating the formation quality factor of a layer based on the attenuation factor corresponding to the layer and the main frequency information of the layer, the calculation is performed using Formula 3:

[0089] Where Q represents the formation quality factor, α represents the attenuation factor, and W represents the main frequency of the layer.

[0090] Based on the physical definition of formation quality factor Q value, the calculation formula of formation quality factor Q value is:

[0091] Formula 4 can be equivalent to:

[0092] Formula 5 can be equivalent to:

[0093] Based on the fitted amplitude curve, the attenuation factor is calculated as:

[0094] The formation quality factor extracted by combining the fitted amplitude curve, Equations 2 and 3 is a precise calculation method based on the physical definition of the Q value. Compared with the approximate formula used in traditional extraction methods in the background art, it achieves a theoretical zero error.

[0095] As shown in Figure 8, the AmpFit curve is a schematic diagram of the Q value obtained by the formation quality factor extraction method implemented in this embodiment, and the PeakFreFit curve is a schematic diagram of the Q value obtained by the traditional peak frequency shift method in the background technology. By comparison, it can be seen that the AmpFit curve is more robust.

[0096] On the other hand, the present invention also provides a formation quality factor extraction device, which specifically includes a first-arrival wave extraction module, a velocity stratification module, an amplitude curve fitting module, an attenuation factor calculation module and a formation quality factor calculation module. The velocity stratification module is respectively connected to the first-arrival wave extraction module and the amplitude curve fitting module, and the attenuation factor calculation module is respectively connected to the amplitude curve fitting module and the formation quality factor calculation module.

[0097] Specifically, the first arrival wave extraction module is used to obtain VSP well data after observation system loading, abnormal amplitude attenuation, and three-component azimuth rotation, and extract the first arrival wave data from the P component data of the VSP well data. The velocity stratification module is used to perform velocity stratification on the first arrival wave data extracted from the VSP well data, and after velocity stratification, the interval velocity and depth interval of each layer are obtained. The amplitude curve fitting module is used to perform the amplitude curve fitting process for each layer and obtain the fitting amplitude curve corresponding to each layer. The attenuation factor calculation module is used to use the fitting amplitude curve corresponding to the layer to determine the starting depth amplitude value and ending depth amplitude value of the first arrival wave of the layer, and calculate the attenuation factor corresponding to the layer based on the starting depth amplitude value, ending depth amplitude value, depth interval and interval velocity of the layer. The formation quality factor calculation module is used to calculate the formation quality factor of the layer based on the attenuation factor corresponding to the layer and the main frequency information of the layer.

[0098] Preferably, the amplitude curve fitting process is specifically as follows: performing time-frequency transformation on the first-arrival wave data received at the layer to obtain the amplitude value of each acquisition depth in the first-arrival wave data, and performing curve fitting on the amplitude value of the first-arrival wave data in the main frequency single frequency or the narrow band range near the main frequency in the frequency domain according to the acquisition depth to obtain the fitting amplitude curve corresponding to the layer.

[0099] Preferably, the attenuation factor calculation module uses the following formula to calculate the attenuation factor corresponding to the layer according to the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer and the layer velocity: Among them, α represents the attenuation factor, V represents the layer velocity, Indicates the end depth amplitude value, represents the starting depth amplitude value, and Δx represents the depth interval of the layer.

[0100] Preferably, the formation quality factor calculation module calculates the formation quality factor of the layer according to the attenuation factor corresponding to the layer and the main frequency information of the layer, and uses the following formula for calculation: Where Q represents the formation quality factor, α represents the attenuation factor, and W represents the main frequency of the layer.

[0101] Preferably, when the amplitude curve fitting module executes the amplitude curve fitting process, time-frequency transformation is performed on the first arrival wave data received at the layer to obtain the amplitude value of each acquisition depth in the first arrival wave data, and curve fitting is performed on the amplitude value of the first arrival wave data in the main frequency single frequency or the narrow band range near the main frequency in the frequency domain according to the acquisition depth to obtain the fitting amplitude curve corresponding to the layer. The specific process is as follows:

[0102] Select the first arrival wave data received at this layer;

[0103] Performing Fourier transform on the first arrival wave data received at the layer to obtain the frequency domain expression of the first arrival wave data at each acquisition depth in the layer;

[0104] For each acquisition depth, the amplitude value of the main frequency of the first arrival wave data in the frequency domain, or the average of the amplitude values ​​in the narrow band near the main frequency, is determined according to the frequency domain expression. The amplitude value of the main frequency or the average is determined as the main frequency amplitude value corresponding to the acquisition depth. The narrow band range near the main frequency is w0-Δw to w0+Δw, where w0 represents the main frequency of the first arrival wave data at this layer, and Δw is greater than 0.

[0105] The main frequency amplitude value corresponding to each acquisition depth is subjected to curve fitting according to the acquisition depth to obtain a fitting amplitude curve.

[0106] Preferably, when the amplitude curve fitting module performs the amplitude curve fitting process, the main frequency amplitude values corresponding to each acquisition depth are curve-fitted in a logarithmic coordinate system according to the acquisition depth.

[0107] Preferably, the value range of Δw is 2 to 5.

[0108] Preferably, when the first arrival wave extraction module extracts the first arrival wave data from the VSP well data, the first arrival wave amplitude picking and excision are performed according to the first preset rule, and the first preset rule is specifically as follows:

[0109] After picking up the first arrival wave peak amplitude time t from the VSP well data, move upward according to the peak amplitude time t, and the moving time point is the second positive and negative change time point t1;

[0110] Move downward according to the peak amplitude time t, and the moving time point is the first or second positive and negative change time point t2;

[0111] Set the transition zone according to the time point t1 and the time point t2, and the transition zone interval is expressed as taper;

[0112] Set the amplitude of the first arrival wave within t < t1 - taper and t > t2 + taper to 0, keep the amplitude of the first arrival wave within t1 < t < t2 unchanged, multiply the amplitude of the first arrival wave within t1 - taper < t < t1 by the coefficient k1, and multiply the amplitude of the first arrival wave within t2 < t < t2 + taper by the coefficient k^2, where k1 = (t - t1 + taper) / taper; k2 = (t2 - t + taper) / taper.

[0113] On the other hand, the present invention also provides a device, which specifically includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the above computer program, the formation quality factor extraction method mentioned in the above embodiments can be realized.

[0114] On the other hand, the present invention also provides a machine-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the formation quality factor extraction method mentioned in the above embodiments can be realized.

[0115] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting formation quality factors, characterized in that: include: Extract the first arrival wave data from the VSP well data, and perform velocity stratification on the first arrival wave data. After velocity stratification, the interval velocity and depth interval of each layer are obtained. For each layer, the amplitude curve fitting process is performed to obtain the fitting amplitude curve corresponding to each layer; The starting depth amplitude value and the ending depth amplitude value of the first arrival wave of the layer are determined by using the fitting amplitude curve corresponding to the layer, and the attenuation factor corresponding to the layer is calculated according to the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer and the layer velocity; The formation quality factor of the layer is calculated according to the attenuation factor corresponding to the layer and the main frequency information of the layer.

2. The formation quality factor extraction method according to claim 1, characterized in that: The amplitude curve fitting process is specifically as follows: The first-arrival wave data received at the layer is transformed in time-frequency mode to obtain the amplitude value of each acquisition depth in the first-arrival wave data. The amplitude value of the first-arrival wave data in the main frequency single frequency or the narrow band near the main frequency in the frequency domain is curve fitted according to the acquisition depth to obtain the fitting amplitude curve corresponding to the layer.

3. The formation quality factor extraction method according to claim 1, characterized in that: When the attenuation factor corresponding to the layer is obtained according to the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer and the layer velocity, the following formula is used for calculation: Among them, α represents the attenuation factor, V represents the layer velocity, Indicates the end depth amplitude value, represents the starting depth amplitude value, and ΔX represents the depth interval of the layer.

4. The method for extracting formation quality factor according to claim 1, characterized in that: When calculating the formation quality factor of the layer according to the attenuation factor corresponding to the layer and the main frequency information of the layer, the following formula is used for calculation: Among them, Q represents the formation quality factor, α represents the attenuation factor, and W represents the main frequency of the layer.

5. The formation quality factor extraction method according to claim 2, characterized in that: The first arrival wave data received at the layer is subjected to time-frequency transformation to obtain the amplitude value of each acquisition depth in the first arrival wave data, and the amplitude value of the first arrival wave data in the main frequency single frequency or the narrow band range near the main frequency in the frequency domain is subjected to curve fitting according to the acquisition depth to obtain the fitting amplitude curve corresponding to the layer, which is specifically: Select the first arrival wave data received at this layer; Performing Fourier transformation on the first arrival wave data received at the layer obtains the frequency domain expression of the first arrival wave data at each acquisition depth in the layer; For each acquisition depth, the amplitude value of the main frequency single frequency of the first arrival wave data in the frequency domain, or the average value of each amplitude value in a narrow band range near the main frequency, is determined according to the frequency domain expression, and the amplitude value of the main frequency single frequency or the average value is determined as the main frequency amplitude value corresponding to the acquisition depth, and the narrow band range near the main frequency is w0-Δw~w0+Δw, w0 represents the main frequency of the first arrival wave data of the layer, and Δw is greater than 0; The main frequency amplitude value corresponding to each acquisition depth is subjected to curve fitting according to the acquisition depth to obtain a fitting amplitude curve.

6. The method for extracting formation quality factor according to claim 5, characterized in that: The main frequency amplitude value corresponding to each acquisition depth is subjected to curve fitting in a logarithmic coordinate system according to the acquisition depth.

7. The method for extracting formation quality factor according to claim 5, characterized in that: The value range of Δw is 2-5.

8. The method for extracting formation quality factor according to claim 1, characterized in that: When extracting the first arrival wave data from the VSP well data, the first arrival wave amplitude is picked up and removed according to the first preset rule, and the first preset rule is specifically: After picking up the first arrival wave peak amplitude time t from the VSP well data, according to the peak amplitude time t Move upward, the moving time point is the second positive or negative change time point t1; Move downward according to the peak amplitude time t, and the moving time point is the time point t2 of the first or second positive or negative change; A transition zone is set according to time point t1 and time point t2, and the interval of the transition zone is represented as taper; Set the amplitudes of the first-arrival waves within t < t1 - taper and t > t2 + taper to 0, keep the amplitudes of the first-arrival waves within t1 < t < t2 unchanged, multiply the amplitudes of the first-arrival waves within t1 - taper < t < t1 by the coefficient k1, and multiply the amplitudes of the first-arrival waves within t2 < t < t2 + taper by the coefficient k2; where k1 = (t - t1 + taper) / taper; k2 = (t2 - t + taper) / taper.

9. A formation quality factor extraction device, characterized in that: Including: A first-arrival wave extraction module for extracting first-arrival wave data from VSP well data; A velocity layering module for performing velocity layering on the first-arrival wave data extracted from VSP well data, and obtaining the layer velocity and depth interval of each layer after velocity layering; An amplitude curve fitting module for performing an amplitude curve fitting process for each layer to obtain a fitting amplitude curve corresponding to each layer; An attenuation factor calculation module for determining the starting depth amplitude value and the ending depth amplitude value of the first-arrival wave of the layer using the fitting amplitude curve corresponding to the layer, and obtaining the attenuation factor corresponding to the layer according to the starting depth amplitude value, the ending depth amplitude value, the depth interval and the layer velocity of the layer; A formation quality factor calculation module for calculating the formation quality factor of the layer according to the attenuation factor corresponding to the layer and the main frequency information of the layer.

10. The formation quality factor extraction device according to claim 9, characterized in that: The amplitude curve fitting process is specifically as follows: Perform time-frequency transformation on the first-arrival wave data received at the layer to obtain the amplitude values of each acquisition depth in the first-arrival wave data, and perform curve fitting on the amplitude values of the main frequency single frequency or the narrow band range near the main frequency in the frequency domain of the first-arrival wave data according to the acquisition depth to obtain the fitting amplitude curve corresponding to the layer.

11. The formation quality factor extraction device according to claim 9, characterized in that: The attenuation factor calculation module calculates the attenuation factor corresponding to the layer according to the starting depth amplitude value, the ending depth amplitude value, the depth interval of the layer and the layer velocity by using the following formula: Among them, α represents the attenuation factor, V represents the layer velocity, Indicates the end depth amplitude value, represents the starting depth amplitude value, and ΔX represents the depth interval of the layer.

12. The formation quality factor extraction device according to claim 9, characterized in that: The formation quality factor calculation module calculates the formation quality factor of the layer according to the attenuation factor corresponding to the layer and the main frequency information of the layer, and uses the following formula for calculation: where Q represents the formation quality factor, α represents the attenuation factor, and W represents the main frequency of the layer.

13. The formation quality factor extraction device according to claim 10, characterized in that: When the amplitude curve fitting module performs the amplitude curve fitting process, perform time-frequency transformation on the first-arrival wave data received at the layer to obtain the amplitude values of each acquisition depth in the first-arrival wave data, and perform curve fitting on the amplitude values of the main frequency single frequency or the narrow band range near the main frequency in the frequency domain of the first-arrival wave data according to the acquisition depth to obtain the fitting amplitude curve corresponding to the layer. The specific process is as follows: Select the first-arrival wave data received at the layer; Perform Fourier transform on the first-arrival wave data received at the layer to obtain the frequency domain expression of the first-arrival wave data at each acquisition depth within the layer; For each acquisition depth, determine the amplitude value of the main frequency single frequency in the frequency domain of the first-arrival wave data or the mean value of each amplitude value within the narrow band range near the main frequency according to the frequency domain expression, and determine the amplitude value of the main frequency or the mean value as the main frequency amplitude value corresponding to the acquisition depth. The narrow band range near the main frequency is w0 - Δw ~ w0 + Δw, w0 represents the main frequency of the first-arrival wave data of the layer, and Δw > 0; Perform curve fitting on the main frequency amplitude values corresponding to each acquisition depth according to the acquisition depth to obtain the fitting amplitude curve.

14. The formation quality factor extraction device according to claim 13, characterized in that: When the amplitude curve fitting module executes the amplitude curve fitting process, the main frequency amplitude values corresponding to each acquisition depth are curve-fitted in a logarithmic coordinate system according to the acquisition depth.

15. The formation quality factor extraction device according to claim 13, characterized in that: The value range of the Δw is 2 to 5.

16. The formation quality factor extraction device according to claim 9, characterized in that: When the first arrival wave extraction module extracts the first arrival wave data from the VSP well data, the first arrival wave amplitude picking and excision are performed according to the first preset rule, and the first preset rule is specifically: After the first arrival wave peak amplitude time t is picked up from the VSP well data, move upward according to the peak amplitude time t, and the moving time point is the second positive and negative change time point t1; Move downward according to the peak amplitude time t, and the moving time point is the first or second positive and negative change time point t2; Set a transition zone according to the time point t1 and the time point t2, and the transition zone interval is expressed as taper; Set the amplitude of the first arrival wave within t < t1 - taper and t > t2 + taper to 0, keep the amplitude of the first arrival wave within t1 < t < t2 unchanged, multiply the amplitude of the first arrival wave within t1 - taper < t < t1 by the coefficient k1, and multiply the amplitude of the first arrival wave within t2 < t < t2 + taper by the coefficient k2; Among them, k1 = (t - t1 + taper) / taper; k2 = (t2 - t + taper) / taper.

17. A device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, it implements the formation quality factor extraction method described in any one of claims 1 to 8.

18. A machine-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the formation quality factor extraction method described in any one of claims 1 to 8.

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