A seismic attenuation compensation method and device based on wave number domain spectral ratio method

Abstract

The embodiment of the specification discloses a seismic attenuation compensation method and equipment based on a wave number domain spectral ratio method. By obtaining baseline seismic data before CO2 injection and monitoring seismic data after CO2 injection; performing wave number domain transformation on the baseline seismic data and the monitoring seismic data to generate amplitude spectra of the baseline seismic data and the monitoring seismic data; calculating a logarithmic amplitude spectrum ratio of the baseline seismic data and the monitoring seismic data; performing linear fitting on the logarithmic amplitude spectrum ratio and a wave number k, and determining a slope of a fitting result as an equivalent attenuation slope S; and performing amplitude compensation and phase correction on the monitoring seismic data according to the equivalent attenuation slope, which is conducive to improving the identification capability of a CO2 injection area, a reservoir boundary and an abnormal change area, and provides a convenient and efficient data processing scheme for CO2 geological storage monitoring.

Description

Technical Field

[0001] This specification relates to the field of geophysical exploration technology, and in particular to a seismic attenuation compensation method and equipment based on the wavenumber domain spectral ratio method. Background Technology

[0002] Seismic waves are affected by inelastic absorption, scattering, and energy dissipation during propagation in the subsurface medium. This manifests as a decrease in amplitude, a reduction in dominant frequency, and phase distortion as the propagation distance increases. These attenuation effects are typically characterized by the quality factor Q.

[0003] In oil and gas exploration and CO2 geological storage monitoring, seismic attenuation characteristics are highly sensitive to changes in reservoir fluids, pore pressure, and the absorption properties of the medium. Particularly in time-lapse seismic monitoring before and after CO2 injection, the absorption characteristics of the injection zone and surrounding strata may change, leading to significant amplitude and phase differences in the monitored seismic data compared to the baseline data. If the actual formation changes caused by CO2 injection cannot be effectively distinguished from signal distortion caused by propagation attenuation, the accuracy of identifying the CO2 distribution range, reservoir boundaries, and injection anomaly zones will be affected.

[0004] Existing seismic attenuation compensation methods typically require the prior establishment of a relatively accurate Q-model, combined with migration imaging, inversion, or wave equation-based compensation methods to process seismic data. However, obtaining a Q-model often depends on well data constraints, empirical parameter selection, or complex inversion processes, resulting in problems such as high modeling difficulty, insufficient stability, and limited applicability. Furthermore, Q-model-based compensation methods are usually computationally intensive and prone to introducing numerical noise under conditions of low signal-to-noise ratio, multipath propagation, and complex geological conditions, making it difficult to meet the demands of large-scale CO2 geological storage time-lapse monitoring for rapid, stable, and efficient processing.

[0005] Therefore, there is an urgent need for a more convenient seismic attenuation compensation scheme that does not rely on a high-precision Q model. Summary of the Invention

[0006] This specification provides a seismic attenuation compensation method and device based on the wavenumber domain spectral ratio method to solve the following technical problem: achieving more convenient and efficient seismic attenuation compensation in the CO2 geological storage process without relying on a high-precision Q model.

[0007] To solve the above-mentioned technical problems, one or more embodiments of this specification are implemented as follows:

[0008] In a first aspect, embodiments of this specification provide a seismic attenuation compensation method based on the wavenumber domain spectral ratio method, applied to the CO2 geological storage process. The method includes: acquiring baseline seismic data before CO2 injection and monitoring seismic data after CO2 injection; performing wavenumber domain transformation on the baseline seismic data and the monitoring seismic data to generate amplitude spectra of the baseline seismic data and the monitoring seismic data; calculating the logarithmic amplitude spectral ratio of the baseline seismic data and the monitoring seismic data; performing linear fitting on the logarithmic amplitude spectral ratio and the wavenumber k, and determining the slope of the fitting result as the equivalent attenuation slope S; and performing amplitude compensation and phase correction on the monitoring seismic data according to the equivalent attenuation slope.

[0009] In a second aspect, one or more embodiments of this specification provide an electronic device, comprising:

[0010] At least one processor; and,

[0011] A memory communicatively connected to the at least one processor; wherein,

[0012] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method as described in the first aspect.

[0013] In a third aspect, embodiments of this specification provide a non-volatile computer storage medium storing computer-executable instructions, which, when read by a computer from the storage medium, cause one or more processors to execute the method described in the first aspect.

[0014] The above-described at least one technical solution adopted in one or more embodiments of this specification can achieve the following beneficial effects: By acquiring baseline seismic data before CO2 injection and monitoring seismic data after CO2 injection; performing wavenumber domain transformation on the baseline seismic data and the monitoring seismic data to generate amplitude spectra of the baseline seismic data and the monitoring seismic data; calculating the logarithmic amplitude spectrum ratio of the baseline seismic data and the monitoring seismic data; performing linear fitting on the logarithmic amplitude spectrum ratio and wavenumber k, and determining the slope of the fitting result as the equivalent attenuation slope S; and performing amplitude compensation and phase correction on the monitoring seismic data based on the equivalent attenuation slope. This reduces the dependence of traditional attenuation compensation methods on the accuracy of the Q model, reduces the uncertainty brought about by Q modeling or Q inversion, and can reflect changes in reservoir absorption characteristics, fluid saturation state, and seismic response characteristics after CO2 injection through the attenuation difference between baseline seismic data and monitoring seismic data. This is beneficial for improving the identification ability of CO2 injection areas, reservoir boundaries, and areas of abnormal changes, providing a convenient and efficient data processing scheme for CO2 geological storage monitoring. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic flowchart illustrating a seismic attenuation compensation method based on the wavenumber domain spectral ratio method provided in this specification.

[0017] Figure 2 This is a schematic diagram of the baseline seismic data profile before CO2 injection provided in the embodiments of this specification;

[0018] Figure 3 This is a schematic diagram of the monitoring seismic data profile after CO2 injection provided in the embodiments of this specification;

[0019] Figure 4 This is a schematic diagram of the CO2 distribution location and its attenuation influence area provided in the embodiments of this specification;

[0020] Figure 5 This is a comparative analysis chart of the single-channel amplitude of CO2 at a distance of 2000 m, provided in the embodiments of this specification.

[0021] Figure 6 This is a schematic diagram showing the comparison of single-channel amplitude spectra of baseline seismic data at a distance of 2000 m and monitored seismic data provided in the embodiments of this specification.

[0022] Figure 7 This description provides an example of an attenuation anomaly region distribution map calculated based on the wavenumber domain spectral ratio method.

[0023] Figure 8 This specification provides a schematic diagram showing the comparison of cross-sections before and after compensation for the monitored seismic data in the embodiments.

[0024] Figure 9 The embodiments provided in this specification show a schematic diagram illustrating the comparison results of single-channel amplitude of baseline seismic data, monitored seismic data, and compensated monitored seismic data at a distance of 2000 m.

[0025] Figure 10 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this specification. Detailed Implementation

[0026] This specification provides an embodiment of a seismic attenuation compensation method, device, and storage medium based on the wavenumber domain spectral ratio method.

[0027] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0028] like Figure 1 As shown, Figure 1 This is a flowchart illustrating a seismic attenuation compensation method based on the wavenumber domain spectral ratio method, provided as an embodiment of this specification.

[0029] Figure 1 The process may include the following steps:

[0030] S102: Acquire baseline seismic data before CO2 injection and monitoring seismic data after CO2 injection.

[0031] The scheme proposed in this application is mainly applied to the CO2 geological storage process. In this process, firstly, baseline seismic data before CO2 injection and monitoring seismic data after CO2 injection are acquired.

[0032] like Figure 2 As shown, Figure 2 This is a schematic diagram of the baseline seismic data profile before CO2 injection provided in the embodiments of this specification, where the horizontal axis represents distance, the vertical axis represents depth, and the grayscale amplitude represents the seismic amplitude response. This baseline seismic data is used as reference data for subsequent monitoring seismic data attenuation analysis, wavenumber domain amplitude spectrum ratio calculation, and compensation effect evaluation.

[0033] Figure 3 This is a schematic diagram of the monitoring seismic data profile after CO2 injection provided in the embodiments of this specification. The horizontal axis represents distance, the vertical axis represents depth, and the grayscale amplitude represents the seismic amplitude response. Compared with the baseline seismic data, the seismic wave amplitude in the area marked by the red circle is significantly weakened, indicating that an attenuation anomaly has occurred in this area due to the CO2 injection.

[0034] Figure 4This diagram illustrates the location of CO2 distribution and its attenuation effect area as provided in the embodiments of this specification. The diagram shows the location of CO2 distribution and its attenuation effect, with the white area representing the location of CO2. Because seismic waves experience energy absorption and phase delay after passing through the CO2 distribution area, the seismic response in both the CO2 distribution area and its propagation path below it may be affected by attenuation.

[0035] Furthermore, after obtaining baseline seismic data and monitored seismic data, necessary preprocessing can be performed on both sets of data. This preprocessing includes, but is not limited to, data format standardization, sampling interval matching, spatial location registration, amplitude normalization, noise suppression, and selection of the target analysis area. Through preprocessing, the baseline seismic data and monitored seismic data become comparable in spatial location, sampling method, and amplitude scale, thereby reducing the impact of non-attenuation factors on the subsequent spectral comparison analysis results.

[0036] S104, perform wavenumber domain transformation on the baseline seismic data and the monitored seismic data to generate the amplitude spectra of the baseline seismic data and the monitored seismic data.

[0037] Subsequently, wavenumber domain spectral analysis is performed on the target location or region. In this embodiment, a single-channel seismic record at a distance of 2000 m can be selected for analysis. Figure 5 As shown, Figure 5 This is a single-channel amplitude comparison analysis diagram of CO2 at a distance of 2000 m, provided in the embodiments of this specification. Specifically, it shows the comparison results of single-channel amplitude between baseline seismic data and monitored seismic data at this location. As can be seen from the diagram, the amplitude of the monitored seismic data decreases relative to the baseline seismic data within a certain depth range, indicating a significant attenuation characteristic in the seismic response after CO2 injection.

[0038] S106, Calculate the logarithmic amplitude spectrum ratio of the baseline seismic data and the monitored seismic data.

[0039] Furthermore, wavenumber domain transformation was performed on the selected baseline seismic data and monitoring seismic data to obtain the amplitude spectra of the baseline seismic data and the amplitude spectra of the monitoring seismic data, respectively. Figure 6 This is a schematic diagram showing the comparison results of the single-channel amplitude spectrum of baseline seismic data at a distance of 2000m and monitored seismic data provided in the embodiments of this specification.

[0040] A significant difference exists between the amplitude spectra of the baseline seismic data and the monitored seismic data, with the monitored seismic data exhibiting energy deficiency. This energy difference forms the basis for subsequent extraction of attenuation information using the wavenumber domain spectral ratio method. In the wavenumber domain, let the amplitude spectrum of the baseline seismic data be... The amplitude spectrum of the monitored earthquake data is , where k is the wave number. The logarithmic amplitude spectrum ratio between baseline seismic data and monitored seismic data can be expressed as:

[0041]

[0042] Where Δz is the seismic wave propagation distance, Q is the quality factor, and H(k) represents the combined influence of instrument response, spherical diffusion, and other non-attenuation factors.

[0043] S108, perform linear fitting on the logarithmic amplitude spectral ratio and wavenumber k, and determine the slope of the fitting result as the equivalent attenuation slope S.

[0044] By analyzing the logarithmic amplitude spectrum ratio The relationship between wave number k and wave number k allows us to extract the equivalent attenuation information of seismic waves during propagation. In practical calculations, A linear fit is performed with wavenumber k, and the slope of the fitting result can be used to characterize the difference in seismic wave attenuation caused by changes in formation absorption characteristics before and after CO2 injection. This equivalent attenuation slope (denoted as S) can then be used as the basis for amplitude compensation and phase correction to recover the energy loss and waveform distortion caused by CO2 injection and propagation attenuation in the monitored seismic data.

[0045] like Figure 7 As shown, Figure 7 This description is a distribution map of attenuation anomalies calculated based on the wavenumber domain spectral ratio method provided in the embodiment. The high attenuation areas identified are in good agreement with the influence range of CO2 injection, indicating that the method can effectively extract seismic wave attenuation information caused by CO2 injection.

[0046] S110, Amplitude compensation and phase correction are performed on the monitored seismic data according to the equivalent attenuation slope.

[0047] Obtaining the attenuation slope Then, this slope is used to perform amplitude compensation on the monitored seismic data. When seismic waves are affected by absorption and attenuation during propagation, their high wavenumber components and effective reflected energy are weakened. Therefore, in this embodiment, the wavenumber domain amplitude spectrum of the monitored data is inversely compensated based on the attenuation slope obtained by fitting. The compensated amplitude spectrum can be expressed as:

[0048]

[0049] in, The amplitude spectrum of the monitoring data after attenuation. The amplitude spectrum is the compensated value, k is the wavenumber, and S is the equivalent attenuation slope obtained by fitting the wavenumber domain spectrum ratio. Through this compensation, the high wavenumber components and effective reflection energy weakened by CO2 injection and propagation attenuation can be enhanced, thereby improving the resolution and reflection phase axis continuity of the monitored seismic data.

[0050] Meanwhile, seismic wave attenuation not only causes amplitude loss but also phase delay and waveform distortion. To mitigate this effect, this embodiment further utilizes an equivalent attenuation slope S to perform phase correction on the monitored seismic data. The phase correction amount can be expressed as:

[0051]

[0052] Where Δφ(k) is the phase delay caused by attenuation, and k0 is the reference wavenumber. During phase compensation, the phase of the monitoring data is reverse-corrected based on this phase delay, thereby reducing the phase distortion caused by absorption attenuation and making the compensated monitoring data closer to the true formation response in terms of amplitude and phase characteristics.

[0053] After amplitude compensation and phase correction are completed, the compensated wavenumber domain data is inversely transformed to obtain the compensated monitoring seismic data.

[0054] By acquiring baseline seismic data before CO2 injection and monitoring seismic data after CO2 injection; performing wavenumber domain transformation on the baseline and monitoring seismic data to generate amplitude spectra; calculating the logarithmic amplitude spectrum ratio of the baseline and monitoring seismic data; linearly fitting the logarithmic amplitude spectrum ratio and wavenumber k, and determining the slope of the fitting result as the equivalent attenuation slope S; and performing amplitude compensation and phase correction on the monitoring seismic data based on the equivalent attenuation slope, this approach reduces the dependence of traditional attenuation compensation methods on the accuracy of the Q-model, reduces the uncertainty caused by Q-modeling or Q-inversion, and can reflect changes in reservoir absorption characteristics, fluid saturation state, and seismic response characteristics after CO2 injection through the attenuation difference between baseline and monitoring seismic data. This is beneficial for improving the identification ability of CO2 injection areas, reservoir boundaries, and areas of abnormal changes, providing a convenient and efficient data processing scheme for CO2 geological storage monitoring.

[0055] like Figure 8 As shown, Figure 8The embodiments in this specification provide a comparison of the seismic profiles before and after compensation. The left figure shows the seismic data before compensation, and the right figure shows the seismic data after amplitude compensation and phase correction. As can be seen from the figures, the reflection phase axis and amplitude characteristics weakened by attenuation in the seismic data are restored to a certain extent after compensation, indicating that the method of the present invention can improve the seismic wave attenuation effect caused by CO2 injection.

[0056] Figure 9 The embodiments provided in this specification show the comparison results of single-channel amplitudes of baseline seismic data, monitored seismic data, and compensated monitored seismic data at a distance of 2000 m. As can be seen from the figure, the amplitude characteristics of the compensated monitored data are closer to the baseline data than the uncompensated monitored data, indicating that the method of the present invention can effectively recover the attenuated seismic response at a single-channel scale.

[0057] In summary, this embodiment extracts the equivalent attenuation slope by analyzing the wavenumber domain amplitude-spectrum ratio between baseline seismic data and monitored seismic data, and uses this attenuation slope to achieve amplitude compensation and phase correction of the monitored data. This method eliminates the need for explicit construction of a high-precision Q-model, directly extracts attenuation difference information from time-lapsed seismic data, and compensates for the seismic wave attenuation effect caused by CO2 injection. It is suitable for attenuation anomaly identification, reservoir change analysis, and compensation imaging processing in time-lapsed seismic monitoring of CO2 geological storage.

[0058] In the second aspect, such as Figure 10 As shown, Figure 10 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this specification. The device includes:

[0059] At least one processor; and,

[0060] A memory communicatively connected to the at least one processor; wherein,

[0061] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method as described in the first aspect.

[0062] In a third aspect, based on the same idea, embodiments of this specification also provide a non-volatile computer storage medium corresponding to the above method, storing computer-executable instructions, which, when read by a computer from the storage medium, cause one or more processors to execute the method described in the first aspect.

[0063] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the embodiments of apparatus, devices, and non-volatile computer storage media are basically similar to the method embodiments, so the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0064] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0065] The above description is merely one or more embodiments of this specification and is not intended to limit this specification. Various modifications and variations can be made to the one or more embodiments of this specification by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of one or more embodiments of this specification should be included within the scope of the claims of this specification.

Claims

1. A seismic attenuation compensation method based on wavenumber domain spectral ratio, applied to CO2 geological storage processes, the method comprising: Acquire baseline seismic data before CO2 injection and monitoring seismic data after CO2 injection; Wavenumber domain transformation is performed on the baseline seismic data and the monitored seismic data to generate the amplitude spectra of the baseline seismic data and the monitored seismic data; Calculate the logarithmic amplitude spectrum ratio of the baseline seismic data and the monitored seismic data; Linear fitting is performed on the logarithmic amplitude spectral ratio and wavenumber k, and the slope of the fitting result is determined as the equivalent attenuation slope S; Amplitude compensation and phase correction are performed on the monitored seismic data based on the equivalent attenuation slope.

2. The method as described in claim 1, wherein, Calculating the logarithmic amplitude spectrum ratio of the baseline seismic data and the monitored seismic data includes: The logarithmic amplitude spectral ratio is calculated as follows: , Among them, the amplitude spectrum of the baseline seismic data is The amplitude spectrum of the monitored earthquake data is Δz is the seismic wave propagation distance, Q is the quality factor, and H(k) represents the combined influence of other non-attenuation factors.

3. The method as described in claim 1, wherein, Amplitude compensation is performed on the monitored seismic data based on the equivalent attenuation slope, including: The amplitude compensation of the monitored seismic data is performed according to the equivalent attenuation slope as follows: in, The amplitude spectrum of the monitored seismic data after attenuation. This is the compensated amplitude spectrum.

4. The method of claim 1, wherein, Phase correction is performed on the monitored seismic data based on the equivalent attenuation slope, including: The phase correction of the monitored seismic data is performed based on the equivalent attenuation slope as follows: Where Δφ(k) is the phase delay caused by attenuation, and k0 is the reference wavenumber.

5. The method of claim 1, wherein, Before performing wavenumber domain transformation on the baseline seismic data and the monitored seismic data in the selected target area, the method further includes: The baseline seismic data and the monitored seismic data are preprocessed, including: data format unification, sampling interval matching, spatial location registration, amplitude normalization, noise suppression, or selection of target analysis area.

6. An electronic device, comprising: At least one processor; as well as, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, such that the at least one processor can perform the method as described in any one of claims 1 to 5.

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