Frequency-dependent solid-fluid decoupled viscoelastic fluid factor prestack seismic inversion method

Abstract

The application relates to the field of exploration geophysical seismic fluid identification, in particular to a frequency-variable solid-liquid decoupling viscoelastic fluid factor prestack seismic inversion method. The method comprises the following steps: step 1, carrying out equal-interval frequency division processing on seismic data; step 2, carrying out frequency division elastic impedance inversion by using the frequency division seismic data in step 1; step 3, frequency-variable solid-liquid decoupling fluid factor inversion equation construction; step 4, carrying out frequency-variable solid-liquid decoupling fluid factor inversion equation coefficient inversion for each prestack angle stack and sampling point; and step 5, frequency-variable solid-liquid decoupling fluid factor inversion. The method improves the fluid factor inversion precision on the basis of conventional solid-liquid decoupling fluid factor inversion by establishing a reference frequency and frequency division frequency calculation process.

Description

Technical Field

[0001] This invention relates to the field of seismic fluid identification in exploration geophysics, and in particular to a pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors. Background Technology

[0002] Seismic reservoir fluid prediction is a key issue in oil and gas exploration. Currently, based on the differences in angle-stacked and frequency-stacked seismic data, seismic inversion methods such as fluid factor, frequency-varying fluid factor, and solid-liquid decoupled fluid factor have been developed. Invention patent CN108572389B discloses a pre-stack seismic inversion method using a frequency-varying viscoelastic fluid factor. This method constructs pre-stack seismic inversion equations for the viscoelastic fluid factor and shear modulus, achieving direct inversion of the frequency-varying fluid factor. However, due to the solid-liquid coupling problem, the application of the Gassmann fluid factor to identify reservoir fluids is affected by porosity. In his paper "Prediction of Unconformity Traps Based on Pre-stack Seismic Inversion," Li Wei, based on porosimetry theory, utilizes theoretical and empirical rock physics models, fully considering the influence of rock modulus, pore fluid, and pore size on reservoir fluids, and taking into account the viscoelasticity of the subsurface medium. He constructs a frequency-dependent solid-liquid decoupled fluid factor, clearly defining effective frequency-varying fluid sensitive parameters that can sensitively reflect reservoir and pore fluid information. This lays a theoretical foundation for conducting research on frequency-varying solid-liquid decoupled fluid factor inversion based on seismic data (Li Wei. Prediction of Unconformity Traps Based on Pre-stack Seismic Inversion [D]. China University of Petroleum (East China)).

[0003] The aforementioned methods have achieved good application results in seismic reservoir fluid prediction, effectively predicting favorable reservoirs and oil and gas-bearing areas. However, they sometimes suffer from significant prediction errors. System analysis reveals that the key to fluid factor inversion methods based on seismic data frequency division processing lies in utilizing the differences in reflection characteristics of seismic data from different frequency bands to calculate fluid indicator factors. Therefore, the selection of seismic data frequency division parameters and reference frequencies is crucial to the effectiveness of the inversion results. Existing prediction methods typically select a uniform reference frequency across the entire work area, and the selection of frequency division parameters often relies on the researchers' experience, thus affecting the accuracy of fluid factor inversion. Summary of the Invention

[0004] The main objective of this invention is to provide a pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors. Based on conventional solid-liquid decoupled fluid factor inversion, a calculation process for reference frequency and sub-frequency is established, improving the accuracy of fluid factor inversion.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors, comprising the following steps:

[0007] Step 1. Perform equal-interval frequency division processing on the seismic data;

[0008] Step 2. Perform frequency-division elastic impedance inversion using the frequency-division seismic data from Step 1;

[0009] Step 3. Construction of the inversion equation for the frequency-varying solid-liquid decoupled fluid factor;

[0010] Inversion equations for frequency-varying solid-liquid decoupled viscoelastic fluid factors:

[0011]

[0012] Where θ1, θ2, ..., θ N This represents the stacking angle of N pre-stack gathers, where ω0 represents the reference frequency, and ω1, ω2, ..., ω... M EI(θ) represents the M frequency divisions used in seismic data inversion. n ,ω m ) to utilize θ n Pre-stack gathers of angle superposition, ω m The elastic impedance obtained by inverting frequency-division seismic data, where n = {1, 2, ..., N}, m = {1, 2, ..., M}, a(θ) n ,ω m )Δω m b(θ) n ,ω m )Δω m Here are the coefficients of the system of equations, Δω m =ω m -ω0, lnI Kf This represents the logarithmic form of the solid-liquid decoupled viscoelastic fluid factor to be inverted. Logarithmic form of the solid rigidity parameters to be inverted;

[0013] Step 4. Perform coefficient inversion of the frequency-varying solid-liquid decoupled fluid factor inversion equation for each pre-stack angle stacking and sampling point;

[0014] Step 5. Frequency-varying solid-liquid decoupled fluid factor inversion.

[0015] Furthermore, in step 1, according to the accuracy requirements of seismic inversion, the seismic data is divided into equal intervals within the seismic data frequency band.

[0016] Furthermore, the wavelet transform frequency division method is used to decompose the seismic record into a series of narrow-band profiles with centroid frequencies, thereby achieving the separation of seismic amplitude information in different frequency bands.

[0017] Furthermore, in step 2, frequency-varying elastic impedance inversion is performed on the seismic reflection records at each scale or frequency in step 1.

[0018] Furthermore, a sparse-constrained elastic impedance inversion strategy is adopted, taking into account that pre-stack seismic data contains richer amplitude and frequency information. Using the elastic impedance equation, an elastic impedance inversion objective function is established within the Bayesian inversion framework to achieve frequency-varying elastic impedance inversion estimation at different angles.

[0019] Furthermore, step 4, the inversion of the coefficients of the frequency-varying solid-liquid decoupled fluid factor inversion equation, specifically includes the following steps:

[0020] (1) For each pre-stack angle superposition and sampling point, select an appropriate reference frequency ω0 and a frequency division frequency ω. m ;

[0021] (2) Based on the selected combination of reference frequency and sub-frequency, select seismic sampling points with similar reference frequency and sub-frequency combination and the same gather stacking angle in the seismic traces near the well to construct the inversion formula of the coefficients of the frequency-varying solid-liquid decoupled fluid factor inversion equation:

[0022]

[0023] Among them, t1, t2…t NN This represents the different times of N sampling points; This represents the logarithmic form of the solid-liquid decoupled viscoelastic fluid factor calculated using well logging data. The logarithmic form of the solid rigidity parameter, EI(t1,θ), is calculated using well logging data. n ,ω m ) for the well-side seismic trace at time t1 using θ n Pre-stack gathers of angle superposition at ω m Elastic impedance obtained by inverting frequency-division seismic data;

[0024] (3) Calculate the current position reference frequency ω0 and the frequency division ω m The equation coefficients under the given conditions.

[0025] Furthermore, in step (1), a reference frequency ω is selected. m The method for dividing the frequency ω0 is as follows:

[0026] a. Perform time-frequency analysis on seismic data or spectral analysis at the current location, selecting the centroid frequency ω of the time-frequency or amplitude spectrum at the current location. z Select the option in step 1 that corresponds to ω z The closest frequency is the reference frequency ω0;

[0027] b. Perform polynomial fitting on the current location's time spectrum or amplitude frequency within the effective frequency band, with the fitting order between 2 and 6;

[0028] c. Differentiate the polynomial in step b, calculate the corresponding extreme frequency, and select the frequency in step 1 that is closest to the extreme frequency as the division frequency.

[0029] Furthermore, the method for selecting "seismic sampling points combining similar reference frequencies and sub-frequency ratios" in step (2) is as follows:

[0030] S1. Calculate the difference between the reference frequency of the sampling point and the other sampling points, and the difference between the frequency divisions;

[0031] S2. Sum the difference between the reference frequency and the divided frequency exponentially; the exponent value ranges from 1 to 5.

[0032] S3. Arrange the exponents calculated in step S2 in descending order, and determine the value with the smaller sum of exponents as "the seismic sampling point of the combination of similar reference frequency and sub-frequency".

[0033] Furthermore, in step 5, the coefficients a(θ) of the system of equations are... n ,ω m )Δω m b(θ) n ,ω m )Δω m Substitute the formula (1) in step 3 to deduce the solid-liquid decoupled viscoelastic fluid factor and solid rigidity parameter.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] This invention establishes a systematic calculation process for the key step of "selecting the reference frequency and the subdivision frequency" in the solid-liquid decoupled fluid factor inversion process, which significantly improves the inversion accuracy of fluid factors. Specifically, it has the following advantages:

[0036] (1) The present invention establishes a method for calculating “reference frequency and frequency division”, which has higher certainty and accuracy than conventional methods based on the experience of inversion technicians.

[0037] (2) This invention addresses the problem that conventional fluid factor inversion methods do not consider the differences in the location of different reservoirs and select the same reference frequency and sub-frequency for the entire work area. Based on the time-frequency characteristics of the current location, the reference frequency and sub-frequency are dynamically selected, making the fluid factor inversion results more targeted.

[0038] (3) The present invention calculates the reference frequency by centroid frequency, which can effectively improve the stability of the inversion results;

[0039] (4) This invention determines the position of the fastest spectral energy transformation as the frequency division frequency by performing frequency fitting calculation on the time spectrum or amplitude spectrum of the inversion position, and the fluid factor inversion results are more sensitive. Attached Figure Description

[0040] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0041] Figure 1 This is a flowchart of the pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors described in Embodiment 1 of the present invention;

[0042] Figure 2 This refers to the 15-degree superimposed seismic data in Embodiment 2 of the present invention;

[0043] Figure 3 This refers to the 25-degree superimposed seismic data in Embodiment 2 of the present invention;

[0044] Figure 4 This refers to the 37-degree superimposed seismic data in Embodiment 2 of the present invention;

[0045] Figure 5 This is a spectrum analysis of the well bypass channel in Embodiment 2 of the present invention;

[0046] Figure 6 This refers to the original seismic profile superimposed at 15 degrees in Embodiment 2 of the present invention;

[0047] Figure 7 This is the 15-degree superimposed 17Hz frequency division profile in Embodiment 2 of the present invention;

[0048] Figure 8 This is the 15-degree superimposed 29Hz frequency division profile in Embodiment 2 of the present invention;

[0049] Figure 9 This is the 15-degree superimposed 45Hz frequency division profile in Embodiment 2 of the present invention;

[0050] Figure 10 This is the inversion result of the original seismic elastic impedance superimposed at 15 degrees in Embodiment 2 of the present invention;

[0051] Figure 11 This is the result of the elastic impedance inversion with a 15-degree superposition and a 17Hz frequency division in Embodiment 2 of the present invention;

[0052] Figure 12 This is the result of the 15-degree superposition of 29Hz frequency-divided elastic impedance inversion in Embodiment 2 of the present invention;

[0053] Figure 13 This is the result of the 15-degree superposition of 45Hz frequency-divided elastic impedance inversion in Embodiment 2 of the present invention;

[0054] Figure 14 This is the inversion result of the frequency-varying solid-liquid decoupled viscoelastic fluid factor in the upper section of the Guochengbei 271 well in Embodiment 2 of the present invention;

[0055] Figure 15 The seismic frequency-dependent solid-liquid decoupled viscoelastic fluid factor results described in the literature were used in the pre-stack section of the upper section of the Guochengbei 248 well.

[0056] Figure 16 The seismic frequency-dependent solid-liquid decoupling viscoelastic fluid factor results of the upper section of the Guochengbei 248 well were obtained using the method described in Example 1. Detailed Implementation

[0057] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0058] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0059] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0060] Example 1

[0061] like Figure 1 As shown, the pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors includes the following steps:

[0062] Step 1. Perform equal-interval frequency division processing on the seismic data;

[0063] According to the accuracy requirements of seismic inversion, the seismic data is divided into equal intervals within the frequency band of the seismic data; the frequency interval is between 2-5Hz.

[0064] The wavelet transform frequency division method is used to decompose the seismic record into a series of narrow-band profiles with centroid frequencies, thereby achieving the separation of seismic amplitude information in different frequency bands.

[0065] Step 2. Perform frequency-division elastic impedance inversion using the frequency-division seismic data from Step 1;

[0066] For the seismic reflection records at each scale or frequency in step 1, frequency-varying elastic impedance inversion is performed. A sparse-constrained elastic impedance inversion strategy is adopted, considering that pre-stack seismic data contains richer amplitude and frequency information. Using the elastic impedance equation, an elastic impedance inversion objective function is established within the Bayesian inversion framework to achieve frequency-varying elastic impedance inversion estimation at different angles.

[0067] Step 3. Construction of the inversion equation for the frequency-varying solid-liquid decoupled fluid factor;

[0068] Inversion equations for frequency-varying solid-liquid decoupled viscoelastic fluid factors:

[0069]

[0070] Where θ1, θ2, ..., θ N This represents the stacking angle of N pre-stack gathers, where ω0 represents the reference frequency, and ω1, ω2, ..., ω... M EI(θ) represents the M frequency divisions used in seismic data inversion. n ,ω m ) to utilize θ n Pre-stack gathers of angle superposition, ω m The elastic impedance obtained by inverting frequency-division seismic data, where n = {1, 2, ..., N}, m = {1, 2, ..., M}, a(θ) n ,ω m )Δω m b(θ) n ,ω m )Δω m Here are the coefficients of the system of equations, Δω m =ω m -ω0, lnI Kf This represents the logarithmic form of the solid-liquid decoupled viscoelastic fluid factor to be inverted. Logarithmic form of the solid rigidity parameters to be inverted;

[0071] Step 4. Perform coefficient inversion of the frequency-varying solid-liquid decoupled fluid factor inversion equation for each pre-stack angle stacking and sampling point;

[0072] Specifically, the following steps are included:

[0073] (1) For each pre-stack angle superposition and sampling point, select an appropriate reference frequency ω0 and a frequency division frequency ω. m ;

[0074] Select reference frequency ω m The method for dividing the frequency ω0 is as follows:

[0075] a. Perform time-frequency analysis on seismic data or spectral analysis at the current location, selecting the centroid frequency ω of the time-frequency or amplitude spectrum at the current location. zSelect the option in step 1 that corresponds to ω z The closest frequency is the reference frequency ω0;

[0076] b. Perform polynomial fitting on the current location's time spectrum or amplitude frequency within the effective frequency band, with the fitting order between 2 and 6;

[0077] c. Differentiate the polynomial in step b, calculate the corresponding extreme frequency, and select the frequency in step 1 that is closest to the extreme frequency as the division frequency.

[0078] (2) Based on the selected combination of reference frequency and sub-frequency, select seismic sampling points with similar reference frequency and sub-frequency combination and the same gather stacking angle in the seismic traces near the well to construct the inversion formula of the coefficients of the frequency-varying solid-liquid decoupled fluid factor inversion equation:

[0079]

[0080] Among them, t1, t2…t NN This represents the different times of N sampling points; This represents the logarithmic form of the solid-liquid decoupled viscoelastic fluid factor calculated using well logging data. The logarithmic form of the solid rigidity parameter, EI(t1,θ), is calculated using well logging data. n ,ω m ) for the well-side seismic trace at time t1 using θ n Pre-stack gathers of angle superposition at ω m Elastic impedance obtained by inverting frequency-division seismic data;

[0081] The method for selecting seismic sampling points based on combinations of similar reference frequencies and frequency divisions is as follows:

[0082] S1. Calculate the difference between the reference frequency of the sampling point and the other sampling points, and the difference between the frequency divisions;

[0083] S2. Sum the difference between the reference frequency and the divided frequency exponentially; the exponent value ranges from 1 to 5.

[0084] S3. Arrange the exponents calculated in step S2 in descending order, and determine the value with the smaller sum of exponents as "the seismic sampling point of the combination of similar reference frequency and sub-frequency".

[0085] (3) Calculate the current position reference frequency ω0 and the frequency division ω m The equation coefficients under the given conditions.

[0086] Step 5. Frequency-varying solid-liquid decoupled fluid factor inversion.

[0087] The coefficients a(θ) of the system of equations n ,ω m)Δω m b(θ) n ,ω m )Δω m Substitute the formula (1) in step 3 to deduce the solid-liquid decoupled viscoelastic fluid factor and solid rigidity parameter.

[0088] Example 2

[0089] Taking the Guochengbei 271 well as an example, the pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors described in Example 1 is explained in detail:

[0090] First, select different angles to overlay seismic data, such as... Figures 2 to 4 As shown, these are superimposed seismic profiles at θ1 = 15 degrees, θ2 = 25 degrees, and θ3 = 37 degrees, respectively.

[0091] For pre-stack angle gathers at 15°, 25°, and 37°, frequency division processing was performed at 1Hz intervals, with a frequency division range of 1-80Hz. Figure 6 This is the original seismic data profile. Figures 7 to 9 The frequency division profiles of the 15-degree pre-stack gather at 20Hz, 35Hz and 45Hz are shown.

[0092] Taking the 15th channel as an example, the optimal selection of the reference frequency and the frequency division is carried out at the 1.25-second position of the target layer:

[0093] (1) For track 15, at the 1.25-second position, time-frequency analysis was performed at 15 degrees, 25 degrees, and 37 degrees respectively. The results are as follows. Figure 5 As shown, the following calculations are performed using a small-angle gather (15 degrees) as an example:

[0094] (2) Its centroid frequency is 28.6Hz, therefore its reference frequency is chosen to be 29Hz;

[0095] (3) Perform a fourth-order term fitting on the frequencies in step (1) (and the results are as follows) Figure 5 As shown), the extreme value after differentiation is 16.8Hz, therefore its reference frequency is 17Hz; calculate the elastic impedance of different frequency division profiles, where Figures 11 to 13 The elastic impedance profile is obtained by inverting the pre-stack gather at 17Hz, 29Hz, and 45Hz frequency division data.

[0096] Based on different elastic impedances, and according to the selected combination of reference frequency 29Hz and sub-frequency 17Hz, seismic sampling points with similar reference frequency and sub-frequency combinations and the same gather stacking angle are selected from the seismic traces near the well to construct the inversion formula for the coefficients of the frequency-varying solid-liquid decoupled fluid factor inversion equation:

[0097]

[0098] Among them, t1, t2…t NN This represents the different times of N sampling points; This represents the logarithmic form of the solid-liquid decoupled viscoelastic fluid factor calculated using well logging data. The logarithmic form of the solid rigidity parameter, EI(t1,θ), is calculated using well logging data. n ,ω m ) for the well-side seismic trace at time t1 using θ n Pre-stack gathers of angle superposition at ω m Elastic impedance obtained by inverting frequency-division seismic data.

[0099] The method for selecting seismic sampling points based on combinations of similar reference frequencies and frequency divisions is as follows:

[0100] S1. Calculate the difference between the reference frequency of the sampling point and the other sampling points, and the difference between the frequency divisions;

[0101] S2. Sum the difference between the reference frequency and the divided frequency exponentially; the exponent value ranges from 1 to 5.

[0102] S3. Arrange the exponents calculated in step S2 in descending order, and determine the seismic sampling points with smaller sums of exponents as the combination of similar reference frequency and sub-frequency.

[0103] By solving equation (2), we obtain [a(θ)] n ,ω m )Δω m b(θ n ,ω m )Δω m = [0.85 1.37], similarly, the reference frequency of the 25-degree pre-stack gather can be calculated as 31Hz, the frequency division as 18Hz, and the coefficients of the equation set as [0.65 1.2]; the reference frequency of the 37-degree pre-stack gather is 32Hz, the frequency division as 20Hz, and the coefficients of the equation set as [0.77 1.35];

[0104] Substitute the coefficients of the equations corresponding to 15 degrees, 25 degrees, and 37 degrees at 1.25 seconds into formula (1) to deduce the solid-liquid decoupling viscoelastic fluid factor and solid rigidity parameter of the 15th equation at the 1.25-second position;

[0105] Similarly, the solid-liquid decoupling viscoelastic fluid factor and solid rigidity parameters at other time points in this (track 15) can be calculated;

[0106] Further calculations were performed on the solid-liquid decoupling viscoelastic fluid factor and solid stiffness parameters of other channels, such as... Figure 14 As shown, the anomalous region of the frequency-varying solid-liquid decoupled viscoelastic fluid factor in well Guochengbei 271 is highly consistent with the comprehensive logging interpretation results.

[0107] The solid-liquid decoupled fluid factor was calculated using the method described in the literature (Li Wei. Prediction of Unconformity Trap Reservoirs Based on Pre-stack Seismic Inversion [D]. China University of Petroleum (East China)) based on the seismic profile of Well Chengbei 248, and the frequency-varying solid-liquid decoupled viscoelastic fluid factor inversion proposed in this invention (the method described in Example 1 of this invention) were used. The results are as follows: Figure 15 , Figure 16 As shown in the comparison of the inversion results, the fluid factor calculated by the method of the present invention has a higher resolution, the calculation results are more consistent with the well results, and the distinction between oil, gas and water is clearer.

[0108] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors, characterized in that, Includes the following steps: Step 1. Perform equal-interval frequency division processing on the seismic data; Step 2. Perform frequency-division elastic impedance inversion using the frequency-division seismic data from Step 1; Step 3. Construction of the inversion equation for the frequency-varying solid-liquid decoupled fluid factor; Inversion equations for frequency-varying solid-liquid decoupled viscoelastic fluid factors: in This represents the stacking angle of N pre-stack gathers. Indicates the reference frequency. This represents the M frequency divisions used in seismic data inversion. To utilize Pre-stack gathers of angle superposition The elastic impedance obtained by inverting frequency-division seismic data, where , , , The coefficients of the system of equations , This represents the logarithmic form of the solid-liquid decoupled viscoelastic fluid factor to be inverted. The rigidity parameters of the solid to be inverted in logarithmic form; Step 4. Perform coefficient inversion of the frequency-varying solid-liquid decoupled fluid factor inversion equation for each pre-stack angle stacking and sampling point; Step 5. Frequency-varying solid-liquid decoupling fluid factor inversion; In step 2, frequency-varying elastic impedance inversion is performed on the seismic reflection records at each scale or frequency in step 1. A sparse-constrained elastic impedance inversion strategy is adopted, taking into account that pre-stack seismic data contains richer amplitude and frequency information. Using the elastic impedance equation, an elastic impedance inversion objective function is established under the Bayesian inversion framework to achieve frequency-varying elastic impedance inversion estimation at different angles. Step 4 involves the inversion of coefficients in the frequency-varying solid-liquid decoupling fluid factor inversion equation, specifically including the following steps: (1) Select an appropriate reference frequency for each pre-stack angle superposition and sampling point. and frequency division ; (2) Based on the selected combination of reference frequency and sub-frequency, select seismic sampling points with similar reference frequency and sub-frequency combination and the same gather stacking angle in the seismic traces near the well to construct the inversion formula of the coefficients of the frequency-varying solid-liquid decoupled fluid factor inversion equation: Among them, t1, t2…t NN This represents the different times of N sampling points; This represents the logarithmic form of the solid-liquid decoupled viscoelastic fluid factor calculated using well logging data. The logarithmic form of the solid rigidity parameters was calculated using well logging data. For the well-side seismic tunnel Make use of every moment Pre-stack gathers of angle superposition Elastic impedance obtained by inverting frequency-division seismic data; (3) Calculate the reference frequency of the current position and frequency division Equation coefficients under the given conditions; Selecting the reference frequency in step (1) and frequency division The method is as follows: a. Perform time-frequency analysis on seismic data or spectral analysis at the current location, selecting the centroid frequency of the time-frequency or amplitude spectrum at the current location. Select the option in step 1 that matches The closest frequency is the reference frequency. ; b. Perform polynomial fitting on the current location's time spectrum or amplitude frequency within the effective frequency band, with the fitting order between 2 and 6; c. Differentiate the polynomial in step b, calculate the corresponding extreme frequency, and select the frequency in step 1 that is closest to the extreme frequency as the division frequency.

2. The pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors according to claim 1, characterized in that, In step 1, according to the accuracy requirements of seismic inversion, the seismic data is divided into equal intervals within the seismic data frequency band.

3. The pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors according to claim 2, characterized in that, The wavelet transform frequency division method is used to decompose the seismic record into a series of narrow-band profiles with centroid frequencies, thereby achieving the separation of seismic amplitude information in different frequency bands.

4. The pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors as described in claim 1, characterized in that, The method for selecting seismic sampling points for the combination of similar reference frequency and frequency division in step (2) is as follows: S1. Calculate the difference between the reference frequency of the sampling point and the other sampling points, and the difference between the frequency divisions; S2. Sum the difference between the reference frequency and the divided frequency exponentially; the exponent value ranges from 1 to 5. S3. Arrange the exponents calculated in step S2 in descending order, and determine the value with the smaller sum of exponents as "the seismic sampling point of the combination of similar reference frequency and sub-frequency".

5. The pre-stack seismic inversion method for frequency-varying solid-liquid decoupled viscoelastic fluid factors according to claim 1, characterized in that, In step 5, the coefficients of the system of equations are... , Substitute the formula (1) in step 3 to deduce the solid-liquid decoupled viscoelastic fluid factor and solid rigidity parameter.

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