Seismic data driven non-reservoir seismic strong reflection interference suppression method

Abstract

The invention provides a seismic data driven non-reservoir seismic strong reflection interference suppression method. According to the method, a reflection coefficient accurate calculation method of reweighted L1 norm constraint inversion is adopted, time-frequency domain high-precision instantaneous amplitude energy is combined, a strong reflection event in seismic data is accurately identified and positioned, and a self-adaptive suppression factor is designed, so that accurate and controllable suppression of non-reservoir seismic strong reflection interference in a target area is realized, and the method is suitable for large-scale popularization and application. And meanwhile, effective amplitude and phase information of the seismic weak reflection signal is reserved. According to the method, the fidelity, the resolution and the calculation efficiency are remarkably improved, and a universal and efficient technical solution is provided for reservoir recognition and fine evaluation of deep and complex structure regions under the influence of seismic strong reflection shielding.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of energy and resource seismic exploration, and particularly relates to the field of shale oil and gas, conventional oil and gas, geothermal resource, coal and coalbed methane exploration and development, and is a data processing method for removing non-reservoir seismic strong reflection interference from seismic exploration data, thereby highlighting the seismic reflection signals of favorable reservoirs such as oil and gas, geothermal, coalbed and coalbed methane, improving the quality of data, and providing high-quality data support for more reliable exploration and efficient development of these energy and resources. BACKGROUND

[0002] In the field of shale oil and gas, conventional oil and gas, geothermal resource, coal and coalbed methane reservoir exploration and development, when the seismic reflection energy of other strata (non-reservoir) adjacent to these reservoirs is relatively stronger, it seriously interferes with and adversely affects the extraction of information of these reservoirs from seismic data and the depiction of spatial distribution of the reservoirs. Suppression of non-reservoir seismic strong reflection is a crucial and challenging task. Such strata often have the characteristics of high speed and high density, and form strong impedance interfaces with the surrounding rocks above and below. When seismic waves propagate to such stratum interfaces, they often exhibit strong energy seismic reflection characteristics, showing continuous and energy-protruding seismic strong reflection events on seismic profiles. In addition, such strata may form a seismic shield layer, which significantly weakens the seismic reflection energy of the lower part, and is not conducive to the extraction and prediction of effective seismic information of the lower part of the reservoir, and the reservoir information is blurred or even disappears. Therefore, effective suppression or stripping of non-reservoir seismic strong reflection events helps to accurately identify and depict the structural configuration, lithological changes and key information such as hydrocarbons of potential favorable reservoirs.

[0003] Current seismic strong reflection suppression techniques can compensate for the seismic reflection energy of weak reflection layers to some extent, but cannot fundamentally separate the seismic strong reflection signals of non-reservoirs. The core problems are: (1) It is difficult to accurately quantify the energy level and spatial distribution of non-reservoir seismic strong reflection, and conventional energy balancing methods are prone to cause "over-suppression" damage or "under-suppression" residual shielding information; (2) The traditional sparse pulse inversion method is limited by the quality of seismic data and computational efficiency, and the sparsity of L1 norm constraint is insufficient, making it difficult to stably and high-resolutionly invert reliable seismic reflection coefficient sequences in a high-noise background, so as to provide a reliable physical model basis for accurately stripping non-reservoir seismic strong reflection. The above problems lead to the fact that the existing technology often cannot effectively balance the fidelity, resolution and computational efficiency in practical application, which restricts the accurate identification and evaluation of reservoirs. SUMMARY

[0004] The application provides a seismic data driven non-reservoir seismic strong reflection interference suppression method.

[0005] The method comprises the following main steps:

[0006] (1) inputting actual seismic data S and seismic wavelet W of a work area;

[0007] (2) constructing an x as a reweighted L1 norm constraint inversion objective function:

[0008] ;

[0009] wherein, λ is a regularization factor, is a Frobenius norm, is an L1 norm, and Q is a reweighted matrix:

[0010] ,

[0011] wherein, r is a seismic reflection coefficient, is a damping factor;

[0012] (3) calculating the reweighted L1 norm constraint inversion objective function according to the following formula:

[0013] ,

[0014] wherein, is a fast iterative soft threshold function;

[0015] (4) calculating the seismic reflection coefficient r according to the following formula:

[0016] ;

[0017] (5) calculating high-precision instantaneous amplitude energy E of the seismic data S, and the formula is as follows:

[0018] ,

[0019] wherein,

[0020] ,

[0021] In the formula, * represents convolution operation, t is time, ω is angular frequency, A is an instantaneous spectral envelope of the seismic data S, and L is a time-frequency basis function envelope constructed according to a signal local structure of the seismic data S;

[0022] (6) According to the value range distribution of the non-reservoir near seismic reflection coefficient of the actual work area, the seismic reflection coefficient threshold a is determined, the seismic reflection coefficient is divided into the linear combination of the seismic strong reflection coefficient r b ,the seismic weak reflection coefficient r a , and is expressed as follows:

[0023] ;

[0024] (7) According to the value range distribution of the high-precision instantaneous amplitude energy E and the seismic strong reflection coefficient r b , the non-reservoir instantaneous amplitude threshold p is determined, and the non-reservoir seismic strong reflection suppression factor is calculated according to the following formula:

[0025] ,

[0026] Wherein, q is an adaptive seismic amplitude suppression proportion factor;

[0027] (8) The seismic reflection coefficient after suppressing the non-reservoir seismic strong reflection is calculated , and the formula is as follows:

[0028] ;

[0029] (9) The seismic data after suppressing the non-reservoir seismic strong reflection is calculated by using the following formula: :

[0030] . BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings are used to provide further understanding of the embodiments of the present application, and constitute a part of the specification, and are used to explain the embodiments of the present application together with the following specific embodiments, but do not constitute a limitation to the embodiments of the present application. In the drawings:

[0032] Figure 1 is a flowchart of a data-driven non-reservoir seismic strong reflection interference suppression method of the embodiments of the present application.

[0033] Figure 2 is a time domain seismic wavelet used in the embodiments of the present application, the time length is 0.2 seconds, and the time sampling rate is 2 milliseconds.

[0034] Figure 3 is a time domain P-wave impedance model used in the embodiments of the present application, the black dotted line in the figure indicates the position of the non-reservoir seismic strong reflection top and bottom interface, wherein the dark red color scale shows the impedance value of the non-reservoir seismic strong reflection area, up to 9km / s×g / cm 3 .

[0035] Figure 4 is the time domain seismic record synthesized by the embodiment of the present application, and there are 500 data in total, and the time sampling rate is 2 ms. The top and bottom interface positions of the non-reservoir seismic strong reflection are marked in the figure. The reflection phase axis of "black-red-black" is formed at the top interface position, and the reflection phase axis of "red-black-red" is formed at the bottom interface position, and the amplitude values thereof are significantly stronger than those at other positions.

[0036] Figure 5 is the reconstructed seismic record after the non-reservoir seismic strong reflection suppression performed by the embodiment of the present application, and there are 500 data in total, and the time sampling rate is 2 ms. The top and bottom interface positions after the suppression are marked by a black dashed line in the figure.

[0037] Figure 6 is the residual between the theoretical seismic record and the reconstructed seismic record of the embodiment of the present application, and the top and bottom interface positions of the non-reservoir seismic strong reflection suppression area are marked in the figure. DETAILED DESCRIPTION

[0038] The present application will be further described below in combination with the drawings, but the protection scope of the present application is not limited to the following description. As shown in the figure, a data-driven non-reservoir seismic strong reflection interference suppression method comprises the following steps: Figures 1 to 6

[0039] (1) input the post-stack seismic data as shown in the figure Figure 4 and the seismic wavelet as shown in the figure Figure 2 ;

[0040] (2) construct the x as a reweighted L1 norm constraint inversion objective function:

[0041] ;

[0042] wherein λ is a regularization factor, is the Frobenius norm, is the L1 norm, and Q is a reweighting matrix:

[0043] ,

[0044] wherein r is a seismic reflection coefficient, is a damping factor;

[0045] (3) calculate the reweighted L1 norm constraint inversion objective function according to the following formula:

[0046] ,

[0047] wherein is a fast iterative soft threshold function; ​​​

[0048] (4) Calculate the seismic reflection coefficient r according to the following formula:

[0049] ;

[0050] (5) Set a suitable window function , and calculate the high-precision instantaneous amplitude energy E of the seismic data S according to the following formula:

[0051] ,

[0052] wherein,

[0053] ,

[0054] In the above formula, * represents convolution operation, t is time, ω is angular frequency, A is the instantaneous spectral envelope of the seismic data S, and L is the time-frequency basis function envelope constructed according to the signal local structure of the seismic data S;

[0055] (6) According to the value range distribution of the seismic reflection coefficient near the non-reservoir of the actual work area, determine the seismic reflection coefficient threshold a, and divide the seismic reflection coefficient into the linear combination of the seismic strong reflection coefficient r b and the seismic weak reflection coefficient r a , which is expressed as follows:

[0056] ;

[0057] (7) According to the value range distribution of the high-precision instantaneous amplitude energy E and the seismic strong reflection coefficient r b , determine the non-reservoir instantaneous amplitude threshold p=7500, and calculate the non-reservoir seismic strong reflection suppression factor according to the following formula:

[0058] ,

[0059] wherein q=4 is an adaptive seismic amplitude suppression proportion factor;

[0060] (8) Calculate the seismic reflection coefficient after suppressing the non-reservoir seismic strong reflection , according to the following formula:

[0061] ;

[0062] (9) Calculate the seismic data after suppressing the non-reservoir seismic strong reflection as shown in the following formula: Figure 5 :

[0063] .

[0064] Figure 5 ​​The seismic record obtained after the non-reservoir seismic strong reflection interference is suppressed by the embodiment of the present application. It can be clearly observed from the figure that the seismic record after the suppression processing has significantly eliminated the non-reservoir seismic strong reflection interference. Figure 6 The residual between the theoretical seismic record and the reconstructed seismic record of the embodiment of the present application indicates that the method of the present application accurately preserves the phase information of the original weak amplitude signal to the greatest extent, only removes the energy of the non-reservoir seismic strong reflection interference area, and at the same time maintains the relative energy relationship. This fully shows that the method adopted by the present application can not only effectively suppress the energy of the non-reservoir seismic strong reflection interference area, but also does not cause damage to the information integrity and accuracy of other areas.

[0065] The method of the present application has the following advantages: (1) The method of the present application is based on data driving, accurately identifies the non-reservoir strong reflection interference area through time-frequency domain instantaneous amplitude energy analysis, avoids the problems of "over-suppression" or "under-suppression" of the traditional method, and at the same time, maximally protects the integrity of the effective reservoir seismic weak signal; (2) The method of the present application enhances the adaptability of the method in the application of actual complex geological seismic conditions, and also improves the robustness of the method.

[0066] The above embodiments are only used to illustrate the present application, wherein each implementation step of the method and the like can be changed, and any equivalent transformation and improvement on the basis of the technical scheme of the present application should not be excluded from the protection scope of the present application.

Claims

1. A seismic data driven non-reservoir seismic strong reflection interference suppression method, comprising the following main steps: (1) inputting seismic data S and seismic wavelet W of an actual work area; (2) constructing an x as a reweighted L1 norm constraint inversion objective function: ； wherein λ is a regularization factor, is the Frobenius norm, is the L1 norm, Q is a reweighting matrix: ， where r is the seismic reflection coefficient, is a damping factor; (3) calculating the reweighted L1 norm constraint inversion objective function according to the following formula: ， wherein is the fast iterative soft thresholding function; (4) calculating seismic reflection coefficient r according to the following formula: ； (5) calculating high-precision instantaneous amplitude energy E of seismic data S, and the formula is as follows: ， Wherein, ， In the above formula, * represents convolution operation, t is time, ω is angular frequency, A is the instantaneous spectral envelope of seismic data S, and L is a time-frequency basis function envelope constructed according to the signal local structure of seismic data S; (6) According to the value range distribution of the seismic reflection coefficient near the actual work area, the seismic reflection coefficient threshold a is determined, and the seismic reflection coefficient is divided into the linear combination of the seismic strong reflection coefficient r b , the seismic weak reflection coefficient r a , and is expressed as follows: ； (7) According to the value range distribution of high-precision instantaneous amplitude energy E and the strong reflection coefficient r of the earthquake b , the non-reservoir instantaneous amplitude threshold p is determined, and the non-reservoir seismic strong reflection suppression factor is calculated according to the following formula : ， Wherein, q is an adaptive seismic amplitude suppression proportional factor; (8) Calculate the seismic reflection coefficients after suppressing the strong reflections of non-reservoirs The formula is as follows: ； (9) The seismic data after suppressing the strong reflection of the non-reservoir is calculated by using the following formula : 。

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