Residual amplitude compensation method based on well control AVO characteristics

Abstract

The invention provides a residual amplitude compensation method based on well control AVO characteristics. The method comprises the following steps: S1, obtaining a pre-stack CRP gather of residual amplitude compensation; s2, calculating an amplitude attenuation curve of the pre-stack CRP gather; s3, obtaining an amplitude background trend in combination with a forward modeling analysis result of the logging rock physical model; s4, superposing the CRP gathers to obtain a seismic section, inputting acoustic logging and density data, making a well control synthetic record, and optimally matching the well control synthetic record with a well-side seismic trace; s5, calculating a well control model; and S6, calculating a compensation parameter to carry out residual amplitude compensation of the well control AVO characteristics. And in combination with the forward modeling analysis result of the logging rock physical model, the amplitude background trend is obtained through the forward modeling model to perform all-directional residual amplitude compensation, the compensated data amplitude background trend is consistent with the forward modeling model, and the reflection characteristics of fluid abnormality are highlighted.

Description

Technical Field

[0001] The present invention relates to the field of geophysical processing technology, and in particular to a residual amplitude compensation method based on well control AVO characteristics. Background Art

[0002] In order to eliminate the influence of wavefront diffusion and absorption factors during the propagation of seismic waves, as well as the amplitude energy changes caused by differences in surface conditions and excitation and reception factors, a combination of spherical diffusion compensation, surface consistency amplitude compensation, and residual amplitude compensation is used in the processing process to eliminate the influence of amplitude differences on data imaging, so that the changes in seismic wave amplitude can more realistically reflect the changes in underground lithology.

[0003] Spherical diffusion compensation is mainly used to compensate for the energy difference in the longitudinal direction caused by the spherical diffusion factor, so that it maintains an amplitude value related only to the reflection coefficient of the underground reflection interface. The spherical diffusion compensation technology is used to correct the attenuation of shallow, medium and deep amplitudes caused by wavefront (spherical) diffusion and earth absorption.

[0004] Due to the change of surface conditions, the energy between shots and channels changes. The purpose of surface consistency amplitude compensation is mainly to eliminate the change of seismic wave amplitude caused by the inconsistency of surface excitation and receiving conditions. The amplitude of common shot points, common detection points, and common offset gathers is compensated in a surface consistency manner to effectively eliminate the abnormal energy difference between each shot and channel, so that the amplitude is relatively balanced and fidelity is maintained. Its basic principle adopts the same mathematical model as surface consistency deconvolution, which is also to obtain each component by taking the logarithm of its frequency domain representation and then adding the constraint of surface consistency.

[0005] Basic idea: First, calculate the root mean square amplitude of each shot point, receiver point, offset distance and common center point, calculate the average amplitude of each, and then calculate the compensation required to reach the average amplitude energy. Repeat this process and iterate the calculation until the calculation accuracy reaches the required level. After surface consistency amplitude compensation, the influence of spatial changes in surface conditions and excitation and receiving conditions on the amplitude of seismic waves can be basically eliminated, so that the spatial changes in seismic wave amplitude can truly reflect the spatial changes in underground lithology. Through the application of surface consistency amplitude compensation, the energy differences between shots and channels are well compensated, making the energy tend to be consistent.

[0006] Usually, residual amplitude compensation is performed on the gathers based on spherical diffusion compensation and surface consistency amplitude compensation to further eliminate the impact of non-geological factors on the amplitude caused by irregular arrangement of shot points, receiver points, offset distances, etc. However, residual amplitude compensation based on AVO characteristics is not considered during compensation. The gathers after migration still have weak local amplitudes, which is not conducive to subsequent pre-stack AVO attribute extraction and inversion. Summary of the invention

[0007] In view of the above problems, the present invention is proposed to provide a residual amplitude compensation method based on well control AVO characteristics, which overcomes the above problems or at least partially solves the above problems.

[0008] According to one aspect of the present invention, a residual amplitude compensation method based on well control AVO characteristics is provided, the compensation method comprising:

[0009] Step S1: Obtain pre-stack CRP gathers for residual amplitude compensation;

[0010] Step S2: Calculate the amplitude attenuation curve of the pre-stack CRP gather;

[0011] Step S3: combining the forward analysis results of the logging rock physics model to obtain the amplitude background trend;

[0012] Step S4: stacking the CRP gathers to obtain a seismic profile, inputting the acoustic logging and density data, making a well control synthetic record, and optimally matching the well control synthetic record with the wellside seismic trace;

[0013] Step S5: Calculate the well control model;

[0014] Step S6: Calculate compensation parameters to perform residual amplitude compensation for the well control AVO feature.

[0015] Optionally, the step S1: obtaining pre-stack CRP gathers for residual amplitude compensation specifically includes:

[0016] Obtain pre-stack CRP gather data of common imaging points in the time domain or depth domain that require residual amplitude compensation.

[0017] Optionally, the step S2: calculating the pre-stack CRP gather amplitude attenuation curve specifically includes:

[0018] A(x,t) is the seismic data that changes with the offset x in the target time window of the CRP gather. With T as the time window length, the root mean square amplitude in the time window is Formula (1) shows:

[0019]

[0020] Optionally, the step S3: combining the forward analysis results of the well logging rock physics model to obtain the amplitude background trend specifically includes:

[0021] Combined with the forward analysis results of the logging rock physics model, the amplitude background trend is obtained through the forward model.

[0022] Optionally, the step S4: stacking CRP gathers to obtain a seismic profile, inputting acoustic logging and density data, making a well control synthetic record, and optimally matching the well control synthetic record with the wellside seismic trace specifically includes:

[0023] The CRP gathers are superimposed to obtain the seismic profile, and the acoustic logging and density data are input to produce the well control synthetic record. The wavelet extracted from the CRP gathers near the well is used for the wavelet. The well control synthetic record is matched with the seismic trace near the well, and the logging curve is stretched at the same time to achieve the best match between the well control synthetic record and the seismic trace near the well.

[0024] Optionally, the making of well control synthetic records specifically includes: making well control synthetic records using all well logging data in the same manner.

[0025] Optionally, after the step S5: calculating the well control model, the step further includes: tracking the marker layer on the seismic section, and extrapolating the acoustic logging and density logging data along the seismic layer to the entire three-dimensional CRP data volume.

[0026] Optionally, the step S5: calculating the well control model further comprises:

[0027] If dipole shear wave logging data are available, extrapolate along the seismic horizon in the same way;

[0028] If there is no shear wave logging data, the a priori formula is used to convert it according to the geophysical parameters.

[0029] Optionally, the step S6: calculating compensation parameters to perform residual amplitude compensation of well control AVO characteristics specifically includes:

[0030] In the 3D work area, the AVO synthetic record is calculated with a larger grid, and the root mean square amplitude y(x) of the synthetic record is calculated with the same time window according to formula (1). Assuming the compensation parameter is f(x), the root mean square amplitude of the CRP gather after compensation is formula (2):

[0031]

[0032] Optionally, the step S6: making the amplitude compensated CRP gather best fit the synthetic record, then

[0033] δ i =φ(x i )-y i (i=1,2,…,N) (3)

[0034] Where N is the total number of channels in the CRP gather, and i is the channel sequence number;

[0035] Then the least squares objective function is formula (4):

[0036]

[0037] If it is minimized, formula (4) becomes formula (5):

[0038]

[0039] Its matrix form is Ax=b, where

[0040]

[0041] but

[0042]

[0043] The canonical equation formula (8) is obtained:

[0044]

[0045] Then find a 0 、a 1 、a 2 ;

[0046] According to formula (2), the amplitude compensation of each CRP gather is obtained as formula (9):

[0047]

[0048] Optionally, in step S6, f(x) calculated on the grids greater than the grid threshold is linearly interpolated to the entire plane to achieve residual amplitude compensation based on the well control AVO feature of the three-dimensional CRP gather.

[0049] The present invention provides a residual amplitude compensation method based on well control AVO characteristics, the compensation method comprising: step S1: obtaining a pre-stack CRP gather for residual amplitude compensation; step S2: calculating the amplitude attenuation curve of the pre-stack CRP gather; step S3: combining the forward analysis results of the logging rock physics model to obtain the amplitude background trend; step S4: stacking the CRP gather to obtain a seismic profile, inputting the acoustic logging and density data, making a well control synthetic record, and optimally matching the well control synthetic record with the wellside seismic trace; step S5: calculating the well control model; step S6: calculating the compensation parameters to perform residual amplitude compensation for the well control AVO characteristics. Combined with the forward analysis results of the logging rock physics model, the amplitude background trend is obtained through the forward model to perform all-round residual amplitude compensation, the amplitude background trend of the compensated data is consistent with the forward model, highlighting the reflection characteristics of fluid anomalies, and facilitating the subsequent pre-stack AVO attribute extraction and inversion.

[0050] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0052] Figure 1 A flowchart of a residual amplitude compensation method based on well control AVO characteristics provided by an embodiment of the present invention;

[0053] Figure 2 There are pre-stack angle gathers with weak amplitude in the embodiment of the present invention;

[0054] Figure 3 This is the application effect of the pre-stack angle gather based on the well control AVO pre-stack residual amplitude compensation in the embodiment of the present invention;

[0055] Figure 4 This is the pre-stack angle gather for the well control forward modeling simulation in the embodiment of the present invention;

[0056] Figure 5 This is a pre-stack angle gather with weak amplitude at small angles in the embodiment of the present invention;

[0057] Figure 6 The figure shows the application effect of the pre-stack angle gather based on the well control AVO pre-stack residual amplitude compensation in the embodiment of the present invention. DETAILED DESCRIPTION

[0058] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0059] The terms "comprises" and "having" and any variations thereof in the description embodiments, claims and drawings of the present invention are intended to cover non-exclusive inclusions, for example, including a series of steps or units.

[0060] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0061] A residual amplitude compensation method based on well control AVO characteristics includes:

[0062] Step S1: Prestack CRP gathers that require residual amplitude compensation;

[0063] Step S2: Calculate the amplitude attenuation curve of the pre-stack CRP gather;

[0064] Step S3: combining the forward analysis results of the well logging rock physics model, and obtaining the amplitude background trend through the forward model;

[0065] Step S4: superimpose the CRP gathers to obtain a seismic profile, input the acoustic logging and density data, make a well control synthetic record, use the wavelet extracted from the CRP gathers near the well as the wavelet, match the synthetic record with the seismic trace near the well, and stretch the logging curve to make the synthetic record best match the seismic trace near the well;

[0066] Step S5: Calculate the well control model, track the marker layer on the seismic section, and extrapolate the acoustic logging and density logging data along the seismic layer to the entire three-dimensional CRP data volume;

[0067] Step S6: Calculate compensation parameters to perform residual amplitude compensation of the well control AVO feature, so as to achieve the purpose of compensating the residual amplitude with amplitude preservation.

[0068] In step S1, pre-stack CRP gather data of common imaging points in the time domain or depth domain that require residual amplitude compensation are input.

[0069] In step S2, the amplitude attenuation curve of the pre-stack CRP gather is calculated. Specifically, it includes:

[0070] A(x,t) is the seismic data that changes with the offset x in the target time window of the CRP gather. With T as the time window length, the root mean square amplitude in the time window is Formula (1) shows:

[0071]

[0072] In step S3, the amplitude background trend is obtained through the forward modeling model in combination with the forward analysis results of the well logging rock physics model.

[0073] In step S4, the CRP gathers are superimposed to obtain a seismic profile, and the acoustic logging and density data are input to produce a well control synthetic record. The wavelet extracted from the CRP gathers near the well is used to match the synthetic record with the seismic trace near the well. At the same time, the logging curve is stretched to ensure that the synthetic record is optimally matched with the seismic trace near the well.

[0074] In step S4, all logging data are used to generate well control synthetic records in the same manner.

[0075] In step S5, the well control model is calculated, the marker layer is tracked on the seismic section, and the acoustic logging and density logging data are extrapolated along the seismic layer to the entire three-dimensional CRP data volume.

[0076] In step S5, if there is dipole shear wave logging data, it is extrapolated along the seismic horizon in the same way. If there is no shear wave logging data, it can be converted from other geophysical parameters using a priori formulas.

[0077] In step S6, the compensation parameters are calculated to perform residual amplitude compensation of the well control AVO feature, so as to achieve the purpose of amplitude-preserving compensation of the residual amplitude. Specifically, it includes:

[0078] In the 3D work area, the AVO synthetic record is calculated with a larger grid, and the root mean square amplitude y(x) of the synthetic record is calculated with the same time window according to formula (1). Assuming the compensation parameter is f(x), the root mean square amplitude of the CRP gather after compensation is formula (2):

[0079]

[0080] In step S6, the amplitude compensated CRP gather is made to best fit the synthetic record.

[0081] δ i =φ(x i )-y i (i=1,2,…,N) (3)

[0082] Where N is the total number of CRP gathers, and i is the sequence number of the gather. The least squares objective function is formula (4):

[0083]

[0084] If it is minimized, formula (4) becomes formula (5):

[0085]

[0086] Its matrix form is Ax=b, where

[0087]

[0088] but

[0089]

[0090] The canonical equations formula (8) can be obtained:

[0091]

[0092] Then a0, a1, and a2 can be calculated. According to formula (2), the amplitude compensation of each CRP gather can be obtained as formula (9):

[0093]

[0094] In step S6, f(x) calculated on the larger grid is linearly interpolated to the entire plane, so that the residual amplitude compensation based on the well control AVO feature of the three-dimensional CRP gather can be realized.

[0095] like Figure 1 As shown in FIG. 1 , the residual amplitude compensation method based on the well control AVO characteristics includes:

[0096] Step S1: Prestack CRP gathers that require residual amplitude compensation;

[0097] Step S2: Calculate the amplitude attenuation curve of the pre-stack CRP gather;

[0098] Step S3: combining the forward analysis results of the well logging rock physics model, and obtaining the amplitude background trend through the forward model;

[0099] Step S4: superimpose the CRP gathers to obtain a seismic profile, input the acoustic logging and density data, make a well control synthetic record, use the wavelet extracted from the CRP gathers near the well as the wavelet, match the synthetic record with the seismic trace near the well, and stretch the logging curve to make the synthetic record best match the seismic trace near the well;

[0100] Step S5: Calculate the well control model, track the marker layer on the seismic section, and extrapolate the acoustic logging and density logging data along the seismic layer to the entire three-dimensional CRP data volume;

[0101] Step S6: Calculate compensation parameters to perform residual amplitude compensation of the well control AVO feature, so as to achieve the purpose of compensating the residual amplitude with amplitude preservation.

[0102] Specific embodiment 1: Figure 2 There are pre-stack angle gathers with weak amplitude; Figure 3 This is the application effect of the pre-stack angle gather based on the well control AVO pre-stack residual amplitude compensation of the present invention; Figure 4 It is the pre-stack angle gather of the well control forward modeling. Figure 3 It can be seen that the amplitude trend after pre-stack residual amplitude compensation based on well control AVO is consistent with the amplitude trend of forward simulation, achieving the application effect of pre-stack amplitude-preserving residual amplitude compensation.

[0103] Specific embodiment 2: Figure 5 It is a pre-stack angle gather with weak amplitude at small angles; Figure 6 This is the application effect of the pre-stack angle gather based on the well control AVO pre-stack residual amplitude compensation of the present invention. Figure 6It can be seen that after pre-stack residual amplitude compensation based on well-controlled AVO, the amplitude trends of small, medium and large angles are consistent, achieving the purpose of amplitude-preserving residual amplitude compensation, which is more conducive to subsequent pre-stack AVO attribute extraction and inversion.

[0104] Beneficial effects: The present invention obtains a more accurate true amplitude effective signal, ensuring that the relationship between the amplitude of pre-stack data and the shot offset is satisfied; the present invention combines the forward analysis results of the logging rock physics model, obtains the amplitude background trend through the forward model to perform all-round residual amplitude compensation, and the amplitude background trend of the compensated data is consistent with the forward model, highlighting the reflection characteristics of the fluid anomaly, which is beneficial to the subsequent pre-stack AVO attribute extraction and inversion.

[0105] The present invention provides a residual amplitude compensation method based on well control AVO characteristics, which obtains a more accurate true amplitude effective signal and ensures that the relationship between the amplitude of pre-stack data and the variation of the offset is satisfied.

[0106] The present invention combines the forward analysis results of the logging rock physics model and obtains the amplitude background trend through the forward model to perform all-round residual amplitude compensation. The amplitude background trend of the compensated data is consistent with the forward model, highlighting the reflection characteristics of the fluid anomaly, which is beneficial to the subsequent pre-stack AVO attribute extraction and inversion.

[0107] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A residual amplitude compensation method based on well control AVO characteristics, It is characterized in that The compensation method includes: Step S1: Obtain pre-stack CRP gathers for residual amplitude compensation; Step S2: Calculate the amplitude attenuation curve of the pre-stack CRP gather; Step S3: combining the forward analysis results of the logging rock physics model to obtain the amplitude background trend; Step S4: stacking the CRP gathers to obtain a seismic profile, inputting the acoustic logging and density data, making a well control synthetic record, and optimally matching the well control synthetic record with the wellside seismic trace; Step S5: Calculate the well control model; Step S6: Calculate compensation parameters to perform residual amplitude compensation for the well control AVO feature.

2. A residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that The step S1: obtaining pre-stack CRP gathers for residual amplitude compensation specifically comprises: Obtain pre-stack CRP gather data of common imaging points in the time domain or depth domain that require residual amplitude compensation.

3. A residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that The step S2: calculating the amplitude attenuation curve of the pre-stack CRP gather specifically includes: A(x,t) is the seismic data that changes with the offset x in the target time window of the CRP gather. With T as the time window length, the root mean square amplitude in the time window is Formula (1) shows:

4. A residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that The step S3: combining the forward analysis results of the well logging rock physics model to obtain the amplitude background trend specifically includes: Combined with the forward analysis results of the logging rock physics model, the amplitude background trend is obtained through the forward model.

5. A residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that The step S4: stacking the CRP gathers to obtain a seismic profile, inputting the acoustic logging and density data, making a well control synthetic record, and optimally matching the well control synthetic record with the wellside seismic trace specifically includes: The CRP gathers are superimposed to obtain the seismic profile, and the acoustic logging and density data are input to produce the well control synthetic record. The wavelet extracted from the CRP gathers near the well is used for the wavelet. The well control synthetic record is matched with the seismic trace near the well, and the logging curve is stretched at the same time to achieve the best match between the well control synthetic record and the seismic trace near the well.

6. A residual amplitude compensation method based on well control AVO characteristics according to claim 5, It is characterized in that The making of the well control synthetic record specifically includes: making the well control synthetic record by using all the well logging data in the same way.

7. A residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that The step S5: after calculating the well control model, further includes: tracking the marker layer on the seismic section, and extrapolating the acoustic logging and density logging data along the seismic layer to the entire three-dimensional CRP data volume.

8. The residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that The step S5: calculating the well control model further comprises: If dipole shear wave logging data are available, extrapolate along the seismic horizon in the same way; If there is no shear wave logging data, the a priori formula is used to convert it according to the geophysical parameters.

9. A residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that The step S6: calculating compensation parameters to perform residual amplitude compensation for the well control AVO feature specifically includes: In the 3D work area, the AVO synthetic record is calculated with a larger grid, and the root mean square amplitude y(x) of the synthetic record is calculated with the same time window according to formula (1). Assuming the compensation parameter is f(x), the root mean square amplitude of the CRP gather after compensation is formula (2):

10. A residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that Step S6: Make the amplitude compensated CRP gathers best fit the synthetic record, then d i =φ(x i )-y i (i=1,2,…,N) (3) Where N is the total number of channels in the CRP gather, and i is the channel sequence number; Then the least squares objective function is formula (4): If it is minimized, formula (4) becomes formula (5): Its matrix form is Ax=b, where but The canonical equation formula (8) is obtained: Then find a 0 、a 1 、a 2 ; According to formula (2), the amplitude compensation of each CRP gather is obtained as formula (9):

11. A residual amplitude compensation method based on well control AVO characteristics according to claim 1, It is characterized in that In step S6, the f(x) calculated on the grid greater than the grid threshold is linearly interpolated to the entire plane to achieve residual amplitude compensation based on the well control AVO feature of the three-dimensional CRP gather.

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